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:

.



adjustable :

or this:

4.

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".



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".



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...

[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...

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