Camber adjustment 300zx

[Tristan Smith]

ok, so there is no camber adjustment possible on the 90-96 z32 300zx. It's all factory set, much like McPhearson Strut is. Like a strut, as the car is lowered the camber increases. So like a strut equiped suspension, can I ask for a rule allowance to substitute the upper control arm with an adjustable one? It's only function would be camber. It doesn't/can't change any any other setting. Camber plates on strut cars perform the same function. In fact you can also change caster with camber plates but not with what I would be requesting.

this is stock:

.http://www.twinturbo.net/nissan/300zx/tech/aarms/a-arms002.jpg



adjustable :


http://www.uniqueautosports.com/pricelists/General/300ZX%20parts/widebodyzedctrlarms-s.jpg (http://www.uniqueautosports.com/pricelists/General/300ZX%20parts/widebodyzedctrlarms.jpg)


or this:


4.http://www.twinturbo.net/nissan/300zx/tech/aarms/a-arms004.jpg


If not, why the allowance for strut cars and not something that performs a similar function for a slightly different suspension set up?


What do the Honda guys do with their double a-arm, or cars with a similar set up as above? Thanks.

[lateapex911]

They use, I bet, eccentric bushings.

[Tristan Smith]

yes, that's what I figured. Looks like I may have to create some. It is odd that the allowance is made for one type of suspension but not for others. Having had strut cars, I have never really thought about it till now. It seems a bit unfair that one type of suspension is allowed to put in an after market piece while other types are not. Especially if they perform no other function.

[dickita15]

There is an allowance for an aftermarket part to fix it, as Jake said eccentric bushings.

[Ron Earp]

yes, that's what I figured. Looks like I may have to create some. It is odd that the allowance is made for one type of suspension but not for others. Having had strut cars, I have never really thought about it till now. It seems a bit unfair that one type of suspension is allowed to put in an after market piece while other types are not. Especially if they perform no other function.

I'm with you on this one.

That "ITR" 300zx that Jeff got has some aftermarket contraption to adjust camber. It is not legal for sure but it won't be raced in that configuration here in the SE.

With my ill-fated Jensen we never get around to solving the problem with bushings. So, since I just wanted to get the car on track and see if it had potential I slotted the ball mount mount holes so I could pull the top of the upright in. Illegal, yes, but at that time I did not have the money or skills to figure out how to do it correctly with bushings. Fortunately it never raced so no animals or children were harmed in the making of the Jensen.

[JeffYoung]

The Jensen nearlly killed you. It stole my sanity. It took your money. I said plenty of harm done.

Tristan, I remember when I was looking around on the Millen and other webpages, I think the answer to the camber "problem" was eccentric bushings and they were available. The aftermarket upper arms with camber adjustment are, unfortunately, both easy to use and illegal.

[Ron Earp]

The Jensen nearlly killed you. It stole my sanity. It took your money. I said plenty of harm done.


But no animals or children were harmed.

Eccentric bushings are certainly the ticket but it is a bit of an anomaly in the rules set that you are forced to use that rather inelegant solution while other designs enjoy proper changes for the sole effect of allowing camber improvements.

Ron

[JeffYoung]

Tristan, I found it. PDM has the camber adjusters. The bad news is only 1 degree up front, 1.5 in the rear.

Here's the link. Scroll down.

http://www.pdm-racing.com/products/suspension.html

[Greg Amy]

Eccentric bushings are certainly the ticket but it is a bit of an anomaly in the rules set that you are forced to use that rather inelegant solution while other designs enjoy proper changes for the sole effect of allowing camber improvements.
I want all you multi-link haterz to note (that hurt to write) that the all-conquering Honda double a-arm adjusts camber by...aftermarket eccentric bushings...that's right: it's not adjustable from the factory, unless you install eccentrics in the "bushings".

:shrug:

But, in reviewin' the GCR deh-fun-ishin of "strut", one has to wonder: does the upper attachment of the 300ZX possibly "not move", thus truly being classified as a "strut" and all that that implies? Or it is really a "long tall knuckle assembly" that's nothing more a non-adjustable multi-link (like the Honduh) and Tristan's just not happy about that? Just askin'...

I'll shuddup now.

[JeffYoung]

I looked long and hard at my 300zx. It's a bit "different" than most double wishbones I've seen because the top is just an arm, not really a wishbone, and the spring/shock are not "inside it" as on most Honda (and Jensen, good lord) suspensions I've seen.

But I still don't think the upper arm is a "strut" and I think we (Tristan and I, whenever I get around to building this thing) are stuck with using bushings for camber.

How much front and rear camber can a Honda/Acura usually get with eccentric bushings?

[Greg Amy]

How much front and rear camber can a Honda/Acura usually get with eccentric bushings?
Not much: degree, degree-and-a-half? But they get good negative camber as you drop 'em, so that's "enough".

Read the GCR def on "struts". You'll find one of two things: A, the 300ZX ain't much different in practice (vis-a-vis geometry) than what Honda offers, or two, they're struts and you can "have at 'em"...the downfall on true "struts" ain't camber curves, it's roll centers...the former can be fixed, the latter is built in... - GA

[JeffYoung]

Really? I've talked to a lot of folks about fixing bumpsteer legally and haven't come up with anything (my car and Ron's are Macpherson struts up front).

But I may be completely wrong, truly just asking.


the downfall on true "struts" ain't camber curves, it's roll centers...the former can be fixed, the latter is built in... - GA

[Greg Amy]

Really? I've talked to a lot of folks about fixing bumpsteer legally and haven't come up with anything (my car and Ron's are Macpherson struts up front).
Bump steer is totally different from roll centers is totally different from camber curves...

[JeffYoung]

Understood, well some of it. Roll center I know. Bump steer I thought was the change in camber, or camber curve, as the suspension travelled up and down?

[Greg Amy]

Bump steer I thought was the change in camber, or camber curve, as the suspension travelled up and down?
No, but it's related.

Roll center (I know you know, just clarifying): that's the geometrical (some say theoretical) point in space about which the car rotates. This is based on the suspension geometrical design, angles and positions of arms, struts, ball joints, etc. To change roll centers you need to change suspension geometry (e.g., move arm pickup points). Most "normal" people know this as "look at the angle of the arms and make sure they're not pointing up". As a general rule, strut cars have s****y roll centers.

"Camber curve" is a vernacular term that refers to the change in static (relative) camber as the suspension is moved through its travel. To change camber curve you have to move the pickup points around. As a general rule, strut cars have s****y camber curves.

Bump Steer refers to the change in steering angle/toe as the suspension moves through its travel. This is usually caused by the tie rods moving past parallel as the car "bumps" (the suspension moves up); as bump increases the effective tie rod length (the horizontal part of the tie rod's "vector") gets shorter and changes toe (either out or in, depending on whether it's a rear-steer or front-steer car). To change bump steer you have to remount the tie rod attach points or move the rack. As a general rule, strut cars...well, you get the idea.

Of these, only camber curve can be reasonably affected within the IT rules. Ain't sayin' it can be "resolved", but you can give up some of the camber curve in exchange for less static camber, and vice versa, to a certain degree. But, most won't, because the dynamic camber (which can also be affected by caster) is about the only thing strut cars have going for them.

[Tristan Smith]

I want all you multi-link haterz to note (that hurt to write) that the all-conquering Honda double a-arm adjusts camber by...aftermarket eccentric bushings...that's right: it's not adjustable from the factory, unless you install eccentrics in the "bushings".

:shrug:

But, in reviewin' the GCR deh-fun-ishin of "strut", one has to wonder: does the upper attachment of the 300ZX possibly "not move", thus truly being classified as a "strut" and all that that implies? Or it is really a "long tall knuckle assembly" that's nothing more a non-adjustable multi-link (like the Honduh) and Tristan's just not happy about that? Just askin'...

I'll shuddup now.

Oh I think it is the latter. That's part of my problem. I just find it odd that struts have a easy means to adjust camber, where as an easy solution isn't available for a lot of other types of set ups.

[Greg Amy]

I just find it odd that struts have a easy means to adjust camber, where as an easy solution isn't available for a lot of other types of set ups.
'Cause they NEED it.

For the street, most multi-link cars, assuming no chassis tweaks, rarely need adjust ability on the street; it's truly set 'em and forget. On the other hand, simple ride height adjustments (spring sag, worn spring rubbers, etc) make a "big" difference in camber on struts.

Conversely, for the track, multi-link suspensions rarely need camber adjustability because their camber curves are usually designed such that camber adequately "works" through its range of motion. On the other hand, you roll into a corner on a Mac strut car and the camber quickly goes positive...

I don't know your 300ZX suspension; I'm trying to infer from the top photo what it's doing. But if that lateral upper link is there on top of the knuckle then you'd LIKE to think that Nissan put some thought into suspension geometry rather than just to packaging (as they did with the NX struts; hell those aren't even factory-adjustable for camber...) We like to think that any and all multi-link suspensions are good things, but we have to go with what thoughts the manufacturer puts in there...unfortunately, poorly-designed multi-links have to get tossed into the "warts and such, choose wisely" category...

:shrug:

[Andy Bettencourt]

Tristan, I found it. PDM has the camber adjusters. The bad news is only 1 degree up front, 1.5 in the rear.

Here's the link. Scroll down.

http://www.pdm-racing.com/products/suspension.html

But when you add the -1 degree to what you have gained by lowering the car, I bet you will be in the ballpark of what you need.

I have to use EB's in my Miata to get what I need for camber as well.

[Tristan Smith]

Tristan, I found it. PDM has the camber adjusters. The bad news is only 1 degree up front, 1.5 in the rear.

Here's the link. Scroll down.

http://www.pdm-racing.com/products/suspension.html

That may work except that it doesn't look to be adjustable. I have a sneaky feeling I will be making my on versions of those, but adjustable.

[Tristan Smith]

unfortunately, poorly-designed multi-links have to get tossed into the "warts and such, choose wisely" category...

:shrug:


I get cha! Just like front wheel drive! Wink Wink :) Sorry just had to say that (but in good humor).

[DavidM]

I've seen a camber curve somewhere of the Z32 and it was decent. I have the adjustable upper links on my TT as well as rear upper adjustable links. Nice and easy swap out and camber adjustment is easy, though not as easy as camber plates for a strut car. Eccentric bushings sound like a pain, but it is what it is.

David

[esuvee]

They use, I bet, eccentric bushings.

I believe some a-arm cars may have hit a very large speed bump on the way to the track as well. Pretty known quantity in SS and I'm guessing it migrated to IT.

Alex

[Tristan Smith]

I believe some a-arm cars may have hit a very large speed bump on the way to the track as well. Pretty known quantity in SS and I'm guessing it migrated to IT.

Alex


what????!!! somebody is "bending the rules" a little? I am shocked and dismayed. :eek:

[JeffYoung]

I wish someone would have accident with my car and bend the axle tubes up a bit. Just a bit.

[TomL]

Greg Amy -

I'm confused. Why do you say you can fix camber curves but not roll centers? On strut cars, the RC is determined by the angle of the strut and the inclination of the lower control arm. You can't do much with the former, but the lower control arm inclination CAN be changed through the use of the so-called "turn-in spacers". As you note, you can't change the inner pickup point, but since you can modify the strut with the spacers, you can accomplish the same thing at the other end of the control arm, i.e., changing the lower control arm angle and thus the RC location.

To me, the camber change curve with struts has always been the bigger problem, as in, having to run 5 degrees static camber.

[Greg Amy]

Tom, care to expand on these ""turn-in spacers"? If you're referring to spacers between the ball joints and the strut, or between the steering arm and the strut, and you're not actually modifying the strut itself, then these are not legal in Improved Touring.

For example, on my NX2000 the strut bolted to a cast knuckle (this design is typical for FWD Volkswagens as well). The ball joints and the tie rod end bolted to the knuckles. None of this geometry between the ball joints and/or the tie roads and the knuckle could be corrected legally within the IT ruleset. If you're implying spaces in these cases are legal, then you're mistaken. I sincerely hope you are not currently doing this in IT with the misunderstanding it's legal.

On the other hand, the ITB Audi Coupe has an all-in-one strut/knuckle assembly, where the strut and the knuckle assembly are one. In that case, since struts are free, you have a s**tload of latitude on how the toe rods and ball joints attach to the assembly (and it's a suh-weet setup, too).

Little more detail, please. Specific examples would be useful.

GA

On edit: I found the following after "googling" the term; scroll down for "turn in spacers":

http://www.gforceengineering.net/products.htm

Not being familiar with the Mazda RX-7 design, I cannot say whether this is legal as they claim. However, if the steering arm and/or ball joints do not attach directly to the strut - as is the case in most FWD McPherson strut applications - then these parts are decisively not "IT-legal". Jake? - GA

[TomL]

Greg -

You are correct. The term turn-in spacer seems to have originated with 1st Gen RX7s. For those not familiar, it's a spacer between the stock strut and the steering knuckle on the many cars that are built with the strut bolted to a separate steering knuckle. (I have an RX7 and a Nissan 200SX that are). I think is has been discussed here in the (long distant) past, but I thought most everyone agreed it's IT-legal, as long as you weld it to the stock strut, i.e., it's a "substitute strut" at that point. For your NX or VW, you are probably correct about roll canters. Sorry I forgot that there are other designs, particularly on FWDs. But for cars like the RX7 that come with struts and separate steering knuckles, would you agree that roll centers can be corrected?

[JeffYoung]

As I understand it -- and my understanding may be wrong -- these bolt to the bottom of the strut and fit between the strut and the lower a-arm. They are essentially a "bolted on" extension of the strut itself, and that is the argument for their legality.

Check this link for some pictures of an RX7 front suspension:

http://www.google.com/imgres?imgurl=http://www.jickedoutbastards.automotiveexpression.com/suspension/fstartingpoint.jpg&imgrefurl=http://www.jickedoutbastards.automotiveexpression.com/suspension.html&h=480&w=720&sz=48&tbnid=2X_desS6ES7QkM::&tbnh=93&tbnw=140&prev=/images%3Fq%3Drx7%2Bfront%2Bsuspension%2Bpicture&hl=en&usg=__ti4XmoDJrOrd-V7XEVV7fpWFXmM=&sa=X&oi=image_result&resnum=2&ct=image&cd=1


Tom, care to expand on these ""turn-in spacers"? If you're referring to spacers between the ball joints and the strut, or between the steering arm and the strut, and you're not actually modifying the strut itself, then these are not legal in Improved Touring.

For example, on my NX2000 the strut bolted to a cast knuckle (this design is typical for FWD Volkswagens as well). The ball joints and the tie rod end bolted to the knuckles. None of this geometry between the ball joints and/or the tie roads and the knuckle could be corrected legally within the IT ruleset. If you're implying spaces in these cases are legal, then you're mistaken. I sincerely hope you are not currently doing this in IT with the misunderstanding it's legal.

On the other hand, the ITB Audi Coupe has an all-in-one strut/knuckle assembly, where the strut and the knuckle assembly are one. In that case, since struts are free, you have a s**tload of latitude on how the toe rods and ball joints attach to the assembly (and it's a suh-weet setup, too).

Little more detail, please. Specific examples would be useful.

GA

On edit: I found the following after "googling" the term; scroll down for "turn in spacers":

http://www.gforceengineering.net/products.htm

Not being familiar with the Mazda RX-7 design, I cannot say whether this is legal as they claim. However, if the steering arm and/or ball joints do not attach directly to the strut - as is the case in most FWD McPherson strut applications - then these parts are decisively not "IT-legal". Jake? - GA

[lateapex911]

Ahhh, Greg, who was it that said "It's a whole new world out there""??

Part of the strut.

[Greg Amy]

Got it. In that case, I'd agree that it's legal.

You have to understand that especially in the case of FWD it's very, very, very unusual to have struts like that. Most manufacturers, to improve production and decrease costs, will have separate strut and knuckle assemblies and the ball joints and and tie rods attach to the knuckles. The primary reason for this is that FWD knuckles also have to not only accommodate the strut, ball, joint, and tie rod attachments, but the drixe axle pass-through and wheel bearings assembly. Thus, it's much more cost-effective to build a separate casting (and it makes replacement struts very easy and cheap). In fact, with the noted exception of the Audi, I can't right off the top of my head think of another FWD car that does what's illustrated above...

Further note that if the tie rod and ball joint attach to the knuckle, changing the location of its attachment to the strut has zero effect on the suspension geometry; moving the strut up and down relative to the knuckle only affects the location of the piston rod and the position of its stroke within the bore. So, no geometry advantage.

I'd be all over redesigned front struts on the RX-7...and I even might go so far as to suggest it not get the strut subtractor... - GA

[TomL]

Greg -

It isn't bolted to the strut, it's welded. As Jake said, it's now "part of the strut", thus a making the new assembly a legal "substitute strut". The pictures you showed don't include the spacers, but if they did they would be attached to the bottom of the strut tube.

But back to the original question, I can see how on your design why you couldn't change roll centers. But another question is, how do you change the camber curves (significantly)?

[Greg Amy]

...how do you change the camber curves (significantly)?
By moving the top of strut strut around. Farther out = less camber gain, farther in = more camber gain. Keep in mind that camber change is not solely a function of the arm angle, but more that of the angle of the strut. Then you correct the static camber by adjusting the hub-to-strut angle.

Taken to an extreme, you can even design a strut that causes POSITIVE camber as the wheel moves up in bump... - GA

[JeffYoung]

You lost me on that last part. How do you do that on an IT car? You machine the spindle?


By moving the top of strut strut around. Farther out = less camber gain, farther in = more camber gain. Then you correct the static camber by adjusting the hub-to-strut angle. - GA

[Greg Amy]

You lost me on that last part. How do you do that on an IT car? You machine the spindle?
Keep in mind, Jeff, that most strut cars do not have integral hubs and struts, the above is unusual...so that bolting interface between the knuckle and strut is completely free. - GA

On edit: Here's a pic of a typical FWD strut:

http://www.kakashiracing.com/images/DCP_0968.JPG

[JeffYoung]

My experience is admittedly limited with strut cars -- basically the Z and mine.

The hub on my car slides on the spindle and his held there by the spindle nut -- same as a Z. I could see maching or planing an angle into the "contact patch" between the hub and strut, but that's all that comes to mind.

So on your car (the NX) how did you correct it?


Keep in mind, Jeff, that most strut cars do not have integral hubs and struts, the above is unusual...so that bolting interface between the knuckle and strut is completely free. - GA

[Greg Amy]

So on your car (the NX) how did you correct it?
Check the link in the above post - that's the stock one, modified - and the link below - which is the struts we fabricated for the 8611 inserts. I can't seem to find a photo of the knuckle - if I find one I'll post it - but the knuckle assembly bolts onto those tabs with the two bolts holes. you can see that those tabs are fully legal to modify in any way you wish.

http://www.kakashiracing.com/temp/DSCN4201.JPG

[JeffYoung]

Ok, I see now. Your knuckle/spindle that the hub mounts to (or is the hub, is that more accurate?) is bolted to those tabs, which I agree you can move around?

I guess the analog on my car is I could fab up an entire strut (like you guys did) and change the angle and location of the spindle.

Very nice work. Very nice.

[TomL]

Okay, I guess we have the legality issue settled, and that it may not apply to FWDs. And I understand how you change your camber curve. My first thought was "that can't be much of a change", but when I calculated it out, I see that it is significant.

But I still don't understand why, for my car at least, you don't think that the spacers would change the roll center. I agree it doesn't change the relationship of the ball joint and tie-rods to the knuckle. But what it does do is it changes the relationship of the knuckle, ball joint, etc. to the ground (i.e., hub height is fixed and the ball joint is now spaced down relative to the hub), thus changing the lower arm angle (and roll center).

And even in the case of your car (or any strut car), I'm fairly sure there is some interrelation between roll center and camber change, so almost any change of one would affect the other at least a little.

As far as getting rid of the strut subtractor, I seriously hope you are joking.

[lateapex911]

I'd be all over redesigned front struts on the RX-7...and I even might go so far as to suggest it not get the strut subtractor... - GA

HAr har har..

Want to trade that for 50 for the boat anchor of a live axle with all that weight banging around and no alignment possibilities?
;)

Oh, it's hard for the ITAC to know which struts can, and which can not be utilized in this fashion, so it's all for one and one for all! Pick your warts carefully, ;)

[Greg Amy]

...(or is the hub, is that more accurate?) is bolted to those tabs, which I agree you can move around?
Well to be technically accurate, the strut bolts to the knuckle, which encompasses the bearing/axle assembly that retains the hub.

....why, for my car at least, you don't think that the spacers would change the roll center.
I don't recall saying that; if I did I was mistaken. However, changing the spacing of the center of the wheel at the end of that lever arm is not going to have a significant affect on the roll center.

As far as getting rid of the strut subtractor, I seriously hope you are joking.
HAr har har..
Not joking, but not a serious suggestion. Having a front suspension such as that virtually negates all the geometry problems of a strut design. When I saw the front end of Tim's (nee, Alan's) Audi coupe I was suitably impressed. If I ever decided to take a shot at ITB it would absolutely be in an Audi coupe (5-cyl torque *and* a good front suspension). In fact, I wish I had the coin to buy Tim's, or at least talk him into a partnership... - GA

[Z3_GoCar]

Got it. In that case, I'd agree that it's legal.

You have to understand that especially in the case of FWD it's very, very, very unusual to have struts like that. Most manufacturers, to improve production and decrease costs, will have separate strut and knuckle assemblies and the ball joints and and tie rods attach to the knuckles. The primary reason for this is that FWD knuckles also have to not only accommodate the strut, ball, joint, and tie rod attachments, but the drixe axle pass-through and wheel bearings assembly. Thus, it's much more cost-effective to build a separate casting (and it makes replacement struts very easy and cheap). In fact, with the noted exception of the Audi, I can't right off the top of my head think of another FWD car that does what's illustrated above...

Further note that if the tie rod and ball joint attach to the knuckle, changing the location of its attachment to the strut has zero effect on the suspension geometry; moving the strut up and down relative to the knuckle only affects the location of the piston rod and the position of its stroke within the bore. So, no geometry advantage.

I'd be all over redesigned front struts on the RX-7...and I even might go so far as to suggest it not get the strut subtractor... - GA

BMW's also use a forged knuckle, which bolts to the strut and a ball joint pressed in the control arm. The solution from James Clay is to replace the ball joint with a spherical bushing (sound familiar) and put spacers between the knuckle and the control arm to regain the correct angle. This neccetates a kit to correct for bump steer. I'd argue that it's perfetly legal under free bushing material.

As for Tristian, you can slot the holes in the rear, but not the front. That should get you a little more that ecentric bushings would.

[jimmyc]

So the way im reading the rules... for a typeical DWB

Bushing material, including that used to mount a suspension
subframe to the chassis, is unrestricted. This includes
the use of spherical bearings, so long as no suspension
component is modified to facilitate their installation. Retention
of spherical bearings by use of tack welds is allowed,
as long as the welds serve no other purpose.

Roll center adjusters are legal. And you might be able to make a case for bump steer adjustment being legal.

Ball joint = Suspension bushing

[JeffYoung]

A ball joint is a bushing?????

[TomL]

Okay, I guess we're mostly in agreement now.

Your original statement was.... "the downfall of true "struts" ain't camber curves, it's roll centers... the former you can fix, the latter is built in" (sorry I haven't figured out how to do the "quote" function) That's why I started this whole discussion in the first place.

And I still disagree about how much you can change roll centers. In a lowered RX7, the spacers mean the difference between having a roll center 2-3 inches underground versus something reasonable. And the spacers also mean the difference between having essentially zero camber gain and at least a little. So now I only have to run 5 degrees of static to make it work. :( If that qualifies as "virtually negat[ing] all geometry problems of the strut design", can we expect the GT1 guys to convert to struts in the near future?

Cheers

[jimmyc]

A ball joint is a bushing?????

what the heck else would it be? It allows controlled movement in the suspension. Kinda of a weirdly designed Spherical bearing.

[Z3_GoCar]

A ball joint is a bushing?????

Sure, BMW's use lots of ball joints for bushings. The inner pivot on the control arm is a ball joint, even the sway bar is connected in the stock form with mini ball joints.

http://www.realoem.com/bmw/diagrams/y/f/147.png

[JeffYoung]

Tough one for me to swallow guys. GCR specifically defines ball joint and bushing separately:

Ball Joint - A bearing coupling, generally in suspension or steering systems, consisting of two (2) mating surfaces, one (1) convex and one (1) concave, which permits a range of angular displacements of the two (2) attached shafts over a prescribed range.

Bushing/Bush - A sleeve or tubular insert, whose purpose is to reduce the dimension(s) of an existing hole. A protective liner that cushions noise, friction, or movement such as a rod end or spherical bearing.

[Greg Amy]

I'd argue that it's perfetly legal under free bushing material.
No way, dude. Not even a gray area.

[jimmyc]

Tough one for me to swallow guys. GCR specifically defines ball joint and bushing separately:

Ball Joint - A bearing coupling, generally in suspension or steering systems, consisting of two (2) mating surfaces, one (1) convex and one (1) concave, which permits a range of angular displacements of the two (2) attached shafts over a prescribed range.

Bushing/Bush - A sleeve or tubular insert, whose purpose is to reduce the dimension(s) of an existing hole. A protective liner that cushions noise, friction, or movement such as a rod end or spherical bearing.


Sure it does because it is a specific kind of bushing. Just like a spherical bearing is a specific kind of bushing.

Just because they are defined differently does not mean that they aren't both suspension bushings.

[jimmyc]

No way, dude. Not even a gray area.


I disagree, this is perfectly legal.

Reasonable minds differ. But hey whats new, people have differing opinions on many things....

Just like i think that taking a non sun roofed chassis turning it into a model that was ONLY available with a sunroof and NOT adding the extra bracing that the sunroof equipped model has, is not legal. Not even close to being a gray area.

[Ron Earp]

I, and most of the people I race with, are WAY too conservative and concerned about being legal. Man these discussions are eye openers.

[Greg Amy]

And I still disagree about how much you can change roll centers. In a lowered RX7, the spacers mean the difference between having a roll center 2-3 inches underground versus something reasonable...
Dude, you're losing me here with confusing terms and mixing around all your cars and suspension designs. Some clarifications:

- First, the whole original point of this topic was about a 300ZX. You came into this discussion with an RX-7 as your base premise. Ergo, your initial posts became immediately confusing.

- B, in the last couple of posts, when you said "spacers" I thought you meant wheel spacers. That's what my last response to you, wher eI said spacers would have insignificant effect on roll centers, was in reference to.

- Trois, yes I agree your "turn in spacers" or "correctors" or whatever as used on the front suspension of the Mazda RX-7 will significantly correct roll centers. That's why I made all those posts about how much I liked that and the Audi's front suspension.

- Quattro: BUT, since MOST CARS cannot use those ball joint/tie rod spacers legally (please read ALL my posts above) then the fact remains that the VAST MAJORITY OF CARS CANNOT correct roll centers. This is what my original premise of the lack of roll center correctability was based on.

Capiche?

GA

[Greg Amy]

I disagree, this is perfectly legal.

Reasonable minds differ. But hey whats new, people have differing opinions on many things...
Excellent. Let me know when we'll be at the track together and for $25 I can get the stewards' reasonable opinions.

:shrug:

GA

(P.S., No personal offense intended. But, you're wrong. And I have a very low tolerance for rules intorturation and/or outright cheating.)

[jimmyc]

Excellent. Let me know when we'll be at the track together and for $25 I can get the stewards' reasonable opinions.

:shrug:

GA

(P.S., No personal offense intended. But, you're wrong. And I have a very low tolerance for rules intorturation and/or outright cheating.)

But you are doing it with the non sunroof car, and turning it into a sunroof car without adding in he extra bracing. (out right cheating)

No personal offense taken.

PS i don't currently race IT.

[Z3_GoCar]

No way, dude. Not even a gray area.

So because mini ball joints are used on the sway bar, we can't change to spherical bearings for the sway bar link?:shrug: If suspension bushings are allowed to be swaped out with sperical bearings, all of them, then why not any ball joint like bushings? IISYCTYBWC Doesn't the 240sx use ball joints to locate the rear? I seem to remember it had a roll steer system built in. It's not like I purchased this kit, but I thought given the spherical bearing debate it was legal.

[Greg Amy]

But you are doing it with the non sunroof car, and turning it into a sunroof car. (out right cheating)
Not that it's relevant, but "even if" I were cheating, that doesn't make "your" cheating legal or acceptable, nor does it make my premise that you're cheating incorrect or out of line.

And, you too have the ability - nay, the responsibility - to protest me if you truly believe the above (assuming you were racing in IT, and since you're not I hardly understand why you're stepping into this discussion other than just to argue...though you're certainly entitled to your misguided opinion.)

And finally, despite its irrelevance, you have zero clue about what I'm actually doing.

GA

[Greg Amy]

So because mini ball joints are used on the sway bar, we can't change to spherical bearings for the sway bar link?
Swaybars are free. Ball joints are not.

...then why not any ball joint like bushings?Because ball joints are not suspension bushings.

Doesn't the 240sx use ball joints to locate the rear?Yes, sphericals are used in place of suspension bushings, explicitly allowed as per ITCS.

Sorry, man...

GA

[Z3_GoCar]

Swaybars are free. Ball joints are not.

Because ball joints are not suspension bushings.

Yes, sphericals are used in place of suspension bushings, explicitly allowed as per ITCS.

Sorry, man...

GA
Sorry, maybe I'm confused... first you say ball joints are not suspension bushings, then you say they are??:shrug:

[Greg Amy]

Sorry, maybe I'm confused... first you say ball joints are not suspension bushings, then you say they are??:shrug:
Where did I say that ball joints are suspension bushings?

On edit:
James, just to make sure we're not cross-posting on terminology, look at your graphic above. #6 is not a ball joint, as you stated; it's a suspension bushing which may, depending on its design, incorporate a bearing. It is legal to replace #6 with a spherical bearing.

Your #3 is interesting, in that it is a suspension attach point that incorporates a ball joint, but it's not a suspension bushing. This one is open to reasonable interpretation, and could possibly be a gray area in regards to ITCS allowance. But, by the same token, since it's not a suspension bushing, one can also argue it is not eligible for "alternate material" consideration.

Your #s 16 and 17 are swaybar end links, which use a type of ball joint, but are not considered THE ball joint. And, under the ITCS allowances for swaybars, are free in design.

Your #4 is "the suspension ball joint", which is not a suspension bushing, and thus not legal to replace with alternate material under the suspension bushings ITCS allowance.

This #4 part is the one in question when we're talking about "the suspension ball joint". If you're trying to say someone is claiming that your #4 is considered a suspension bushing, and thus can be replaced with a spherical bushing/bearing and spaced out to correct roll center, they are incorrect. That part must remain equivalent to stock.

This is not to be confused with Tom's discussion above in regards to the Mazda RX-7 design. In that case, since the strut incorporates all the attach points for the tie rods and ball joints, then those attach points can be moved around to correct geometry under the "open strut" rule; however, the stock-equivalent ball joint must still be used. - GA

[jimmyc]

Not that it's relevant, but "even if" I were cheating, that doesn't make "your" cheating legal or acceptable, nor does it make my premise that you're cheating incorrect or out of line.

And, you too have the ability - nay, the responsibility - to protest me if you truly believe the above (assuming you were racing in IT, and since you're not I hardly understand why you're stepping into this discussion other than just to argue...though you're certainly entitled to your misguided opinion.)

And finally, despite its irrelevance, you have zero clue about what I'm actually doing.

GA

No but it does make you seem a bit hypocritical. Here you are calling me out for for something that i see as perfectly legal, and you spent i don't know how many pages arguing that you didn't need to have a structural part of the car on the car.

No i don't have any clue about what you are actually doing, but, again, you spent many of post in that thread saying how it was legal, and so on and so on.

You see my opinion as misguided and i see your as the same.

It is the internet, people have different opinions and life goes on.

[Z3_GoCar]

Doesn't the 240sx use ball joints to locate the rear?


Yes, sphericals are used in place of suspension bushings, explicitly allowed as per ITCS.

Sorry, man...

GA


Where did I say that ball joints are suspension bushings?

Right there:shrug:

[Greg Amy]

Right there
I do not know what the rear suspension design is on a 240SX. But, if they use the same design as your #3, then my same position applies (read my edit in the above post).

But that still doesn't allow #4 to be replaced with anything but a stock-equivalent ball joint. - GA

[Andy Bettencourt]

Struts aren't a subtractor.

[Z3_GoCar]

I do not know what the rear suspension design is on a 240SX. But, if they use the same design as your #3, then my same position applies (read my edit in the above post).

But that still doesn't allow #4 to be replaced with anything but a stock-equivalent ball joint. - GA

Here's one upside down:
http://gallery.voodoo-people.com/albums/album499/02_G.jpg

Notice the ball joint on the lower a-arm, that's what binds when the 240sx gets lowered, that's why they need spherical bearings. Since this ball joint can be swaped out for a spherical bearing, why not the front one?

[Andy Bettencourt]

100% with Greg here guys. Suspension bushings are suspension bushings. Ball joints are ball joints. Ball joints may 'act like a bushing', but they are not 'suspension bushings'. There is no provision in the ITCS to modify or upgrade the ball joints.

[JoshS]

Notice the ball joint on the lower a-arm, that's what binds when the 240sx gets lowered, that's why they need spherical bearings. Since this ball joint can be swaped out for a spherical bearing, why not the front one?
I can't make out the specifics from the photo, but assuming that it's similar to a standard front suspension ball joint, then what gives you the idea that it can be swapped out for a spherical bearing?

[Andy Bettencourt]

then what gives you the idea that it can be swapped out for a spherical bearing?

The answer will be: because all the 240SX guys do it.

The REAL answer: because nobody ever protested it and got a ruling from HQ.

[lateapex911]

The answer will be: because all the 240SX guys do it.

The REAL answer: because nobody ever protested it and got a ruling from HQ.

Ding ding ding!!

And now, for the $64,000 question...

"But everyone's doing it, and it's been this way for years...it should be legal!"

And slipparooni, down the slope we go.

[Z3_GoCar]

Bite me, Knestis. Or we could sit around and and debate rules that have already been clarified by national...........endlessly. It is not a case of just believeing. It is a case that has already been discussed and clarified. I know you guys love to discuss philosphically the nature of the rules, but some time it feels like "navel contemplation"................endlessly. Granted, I don't have to read it.

Also, the meaning of life is open to interpertation. Like some of our rules.

The sky is blue, because someone protested it, and SCCA National upheld the ruling that indeed it was!

Any other questions. I have answers for them all, and it won't take 12 pages.



The answer will be: because all the 240SX guys do it.

The REAL answer: because nobody ever protested it and got a ruling from HQ.

:shrug: Sounds like it was upheld. So if it's legal on the back why not the front?

[lateapex911]

:shrug: Sounds like it was upheld. So if it's legal on the back why not the front?

HuH???

Fist, where does that first quote from Tristan come from?? Not this thread that I can find. And Kirk (Knestis) the fellow referenced in the quote in the "Bite me" section.. (?!?!?!?!?) hasn't even posted on this thread.

So, I fail to see how this particular item has been protested and or upheld. Can we see proof?

[Z3_GoCar]

HuH???

Fist, where does that first quote from Tristan come from?? Not this thread that I can find. And Kirk (Knestis) the fellow referenced in the quote in the "Bite me" section.. (?!?!?!?!?) hasn't even posted on this thread.

So, I fail to see how this particular item has been protested and or upheld. Can we see proof?

Jake,

I'm from Missouri, so I understand your need for proof. But, really you should remember it's from Greg's spherical "bushings" thread top of page 14.

http://www.improvedtouring.com/forums/showthread.php?t=18347&highlight=240SX+rear+suspension&page=14

Again, if it's legal on the rear why not the front? Back to the definition the first two words are, "A Bearing" seems to me that we're just swapping one "Bearing" for another.

ps. I was going to take the reference to Kirk out, but then it didn't make sense. So I appologise for draging that part back up after it's been water under the bridge for years.

[Andy Bettencourt]

Who said it's legal in the rear? Again, just because people are doing it, doesn't make it legal.

[Andy Bettencourt]

Just got off the phone with the local guys who run 240SX's. They do not know anyone who has replaced the rear ball joints with anything aftermarket. In fact, he went on to say that with all the 'real' rubber suspension bushings replaced, there is no bind AT ALL with that ball joint. He ran the suspension through way more than its normal range (with no shock) and proved that to himself.

We also pointed out that the original supplier of the 'kit' for SB's, Westek (sp?), did NOT provide anything aftermarket for the rear ball joints.

[lateapex911]

Jake,

I'm from Missouri, so I understand your need for proof. But, really you should remember it's from Greg's spherical "bushings" thread top of page 14.

http://www.improvedtouring.com/forums/showthread.php?t=18347&highlight=240SX+rear+suspension&page=14

Again, if it's legal on the rear why not the front? Back to the definition the first two words are, "A Bearing" seems to me that we're just swapping one "Bearing" for another.

ps. I was going to take the reference to Kirk out, but then it didn't make sense. So I appologise for draging that part back up after it's been water under the bridge for years.

yea, like i remember individual posts in a 14 page thread, LOL. Thanks for the vote of confidence, but I'm a theory guy, i suck at specific item memory.

And who says it's legal!!?!? Lets see the protest result.

[Knestis]

LOL - I'm glad the forum has the "view post" feature in quotes, 'cuz I had no luck searching on the string "bite me." :)

I'm late to this party (who knew it would get interesting?) but golly, please do let it be true. Please, please, please.

I'd personally front development and the first production run of CMS "super proven-legal spherical lower strut bushing kits" for the full range of Golves. And if you order two sets (should have spares, you know), we'll throw in a pair of CMS "super proven-legal tie rod end bushing replacement kits," featuring Steer-O-Matic(r) correction.

K

EDIT - I'm positively giddy here! Imagine Pablo being able to drive around a corner at Mid-Ohio. Whew. I'm going go sit down for a minute.

[Z3_GoCar]

Just got off the phone with the local guys who run 240SX's. They do not know anyone who has replaced the rear ball joints with anything aftermarket. In fact, he went on to say that with all the 'real' rubber suspension bushings replaced, there is no bind AT ALL with that ball joint. He ran the suspension through way more than its normal range (with no shock) and proved that to himself.

We also pointed out that the original supplier of the 'kit' for SB's, Westek (sp?), did NOT provide anything aftermarket for the rear ball joints.

I'll admit I'm not an expert on anything Nissan, I just remembered that TurboICE posted a picture of the rear suspension, and remembering how it worked, I looked for his post.

That being said, the reason for alternate bushing material is what? To remove rubber elements anywhere In the suspension, right? So what about rubber isolation in the balljoint?

[lateapex911]

Wow, I just went back and read the last couple pages of that thread...

(low whistle)

man, those were good times huh!? ;)

Place seems quieter now that DD is SM-ing.

I'll say this, my NEXT car looks like it's gonna have some trick chit under the fenders.

[Greg Amy]

...but golly, please do let it be true. Please, please, please.
+819trillion. Thought that NX was hot shit before? Hoh-lee kee-rap: imagine that engine and it handles...oh, Timmy...? Looking for some easy "partnership investment" to get that car back online...? I only want to use it, oh, one event a year...

Keep me posted on this "ball joints is bushings" stuff, please?

GA, watching intently...

[ekim952522000]

So what about the RSX it's stock shocks look like this with a built in steering arm.

http://www.k-series.com/media/albums/album82/aal.jpg

Now Ignoring the remote resevoir would it be legal to replace the RSX strut with one shown like below with a adjustable height steering arm?

[Andy Bettencourt]

I enjoy Greg and Jake's "please let ME do this" posts, but I can guarantee you guys RIGHT NOW that nobody on the ITAC or the CRB thinks this is even CLOSE.

[Tristan Smith]

Ding ding ding!!

And now, for the $64,000 question...

"But everyone's doing it, and it's been this way for years...it should be legal!"

And slipparooni, down the slope we go.

Wow you guys don't know what the hell you are talking about. First off, as a former 240sx racer, I replaced all the rubber suspension bushings with spherical bushings (bearings). There is still a ball joint on the lower control arm that is stock. Completely in compliance with the rules. And all of the 240 guys I know did the same thing.
The reason spherical bearings are used is because as the suspension moves through it's arc, the bushings twist in two planes. Usually this is accomplished with the rubber compressing or flexing. Now if you were to replace these bushings with say solid material, like delrin, then the suspension would bind.
As far as I know there is no issues with the ball joints binding. And if there was, more than likely you have lowered the car so much that your roll center is 6 inches underground anyway.

Trust me, if there was an easier, cheaper way to fix that issue, I would be all over it.

[Tristan Smith]

HuH???

Fist, where does that first quote from Tristan come from?? Not this thread that I can find. And Kirk (Knestis) the fellow referenced in the quote in the "Bite me" section.. (?!?!?!?!?) hasn't even posted on this thread.

So, I fail to see how this particular item has been protested and or upheld. Can we see proof?


Wow that is digging up the past. And Jake you are right, it has nothing to do with this conversation. This was taken from the debate many years ago about whether spherical bearings could be used as a "bushing material" substitute.

And it's moot these days. As long as it is used in the proper rule set, spherical bearings have been approved by the rules. You can even tack weld them in.

There is no doubt that there are a lot of really smart people on this website. I always learn something in these debates. Sometimes it's only that logical, smart, well versed people come to completely different conclusions. But thats why we have the ability to protest folks.

Now lets not dig up anymore old threads. ha

[Greg Amy]

So what about the RSX...would it be legal to replace the RSX strut with one ... with a adjustable height steering arm?
Absolutely, just as you can in the RX-7: struts are free. In that case the bump steer can easily be corrected, but roll center cannot (except by spherical/eccentric at the inboard control arm, assuming bushings are there, and it isn't going to be a whole lot of correction.)

This one gets filed under the "warts and all, pick your car carefully" category.


On edit: I wanted to clarify this position above; I got a PM pointing out some confusion..

On the first-gen RX-7, the ball joint attaches directly to the strut, but the steering arm is on the knuckle/hub assembly. So, on the RX-7, roll centers can be adjusted, either via spacers and/or a strut with a custom-located ball joint attachment (using the stock ball joint only). But, bump steer cannot be adjusted.

On the RSX illustrated above, the tie rod end attaches to the strut, but the ball joint attaches to the knuckle. So, on the RSX, bump steer can be adjusted via spacers and/or a strut with a custom-located steering arm (using a stock tie rod end!). Bump, roll centers cannot be adjusted (except via eccentrics used in place of suspension bushings.)

On the Audi Coupe both the ball joints and the steering arm are part of the strut, thus both bump steer and roll centers can be adjusted (using stock ball joints and tie rod ends!)

Sorry for the confusion. - GA

[lateapex911]

Wow you guys don't know what the hell you are talking about. First off, as a former 240sx racer, I replaced all the rubber suspension bushings with spherical bushings (bearings). There is still a ball joint on the lower control arm that is stock. Completely in compliance with the rules. And all of the 240 guys I know did the same thing.


Read back carefully Tristan. We made those statements in reaction to the claim that the lower ball joint WAS replaced, therefor the "Ball joint is a bushing" rule was 'sound', and that "If you can do it in the back you can do it in the front" logic was getting trotted out.

Our comments were, IF that's actually what is going on under those cars, then, the next argument would be: "But it's been done this way for years..." bla bla bla.

Our point was ...tough sh!t.

[JeffYoung]

Jake, I'm pretty sure Tristan was referring to the guy who said "All 240sx guys are doing this" when (and he should know) Tristan makes it clear they are not.

It still boggles my mind that anyone would consider a ball joint a "bushing" that is free, and really disappointing that this seems to be an accepted "fix" on those 325s that were already kicking my ass a few years back.

[Andy Bettencourt]

Here's one upside down:
http://gallery.voodoo-people.com/albums/album499/02_G.jpg

Notice the ball joint on the lower a-arm, that's what binds when the 240sx gets lowered, that's why they need spherical bearings. Since this ball joint can be swaped out for a spherical bearing, why not the front one?

Tristan,

Here is the quote to suport Jake's post. It was posted as fact that this is what was needed for the 240SX to be effective and what guys are doing. I did some research and pointed out that the replacement of the ball joint was NOT part of the typical spherical replacement job.

We all know 'sphericals as bushings' are now legal per the ITCS but the assertion that ball joints are suspension bushings is just not so.

[lateapex911]

Who's the guy half cropped in the picture? he looks pissed!

"They won't let me replace these ball joints with titanium sphericals!?!?! Bastards!"

And further, whats the black cylinder in the center, with the shiny silver label and the two "steering links" projecting out? is that some sort of rear steer thing?

[Tristan Smith]

Sorry guys if I was unclear. I was responding to the implication, like Jeff stated, that somehow it was "only legal cause everybody was doing" statement. So never mind....since you all know what I meant...I think.

[Tristan Smith]

Who's the guy half cropped in the picture? he looks pissed!

"They won't let me replace these ball joints with titanium sphericals!?!?! Bastards!"

And further, whats the black cylinder in the center, with the shiny silver label and the two "steering links" projecting out? is that some sort of rear steer thing?


Probably the HICAS system. Yes, essentially rear steering. Factory option on Nissans in the 90's. Don't think they use the system nowadays.

[TomL]

Greg -

At the risk of me possibly misunderstanding what you said in describing RX7 struts -

The ball joint on the 1st gen RX7 is bolted to the steering arm, not the strut directly. The steering arm is then bolted to the strut, which includes the stub axle and attached hub, strut tube, etc. This arrangement is used on (I think) all RWD Nissan/Datsuns until the 240SX (510s, Zs and ZXs thru '89, 200SX for sure). Plus 1st Gen RX7s and I'm sure several others.

Unlike a strut which bolts directly to the ball joint, adjusting the roll center on the RX7 through adding a spacer at the bottom of the standard strut is very simple. The one piece strut I have (on a 1974 Capri) is a much trickier thing to modify, because the ball joint hole is part of the stub axle forging. I've never been brave enough to try welding an extension to that part and, fortunately, it isn't much needed on the Capri.

[Greg Amy]

The ball joint on the 1st gen RX7 is bolted to the steering arm, not the strut directly....
Ugh.

OK, Tom, then let's go at this generically. Struts are free. As such, anything that is part of the strut - not bolted to it, but physically welded to the strut, such as a steering arm or a ball joint mounting location - is also free. If the steering arm is part of the strut, it can be relocated (and, thus, bump steer can be adjusted). If the ball joint mounting location is part of the strit, it can be relocated (and, thus, roll center can be adjusted).

If, however, The steering arm and/or the ball joint mounting location is NOT part of the strut, then you CANNOT relocate their position, neither via modifications or via spacers.

Said really generically: struts are free. Have at it.

How's that?

GA, done (I hope)....

[TomL]

All I said was that, on the RX7, the ball joint doesn't attach to the strut as you stated earlier. See Jeff Young's attachment in #28 for a picture. Now I'm not sure if you think I can legally use the spacers for roll center correction or not. :shrug: (BTW, I can.) But you're right -it's pointless to continue this conversation. I'm out, too.

[DavidM]

Probably the HICAS system. Yes, essentially rear steering. Factory option on Nissans in the 90's. Don't think they use the system nowadays.
HICAS was on the twin-turbos. I don't think it was even an option on the NAs. I don't think anybody who tracks the car leaves it operational. They might have used a version of it on the Skylines as well.

David

[JeffYoung]

You could get it on the 240sx as well, I am pretty sure.

[Andy Bettencourt]

Yes you could. I think it was even standard on the top of the line model 240SX.

The 240SX and 300ZX rear suspension is the exact same and a bolt for bolt swap from what I have learned. I think the comment was about the picture and the picture was of a 240?