1st Gen RX7 rear lower links

[joeracerx95]

I'm almost complete on the changes to my ITA Rx7 except for the rear lower links. Currently I still have the stock parts.

In theory they look like they would be very simple to make; steel tubing of the correct size and length, one left and one right rod end on each end. Install and adjust.

But theory and practice aren't always the same thing. What tubing will I need and where am I likely to find it? Can I use the stock parts and just cut off the ends?

Rod ends should be a straightforward purchase from Pegasus or Summit. I assume I'm going to need the "good" ones to tolerate the loads. I.E. expensive.

Any other tips? Or better yet, anybody got some for sale, cheap?

-chuck-

[ddewhurst]

Chuck, save yourself some time & money. Go to your local oval track parts house to get your R & L hand rod ends & to get your threaded lengths of tubing. There are both alum & steel lengths of threaded tubing complete in one inch incerements. :D

That's where I got my same stuff your looking for. ;)

[joeracerx95]

Thanks David. Through the magic of Google I think I'm on the right track. Once I stumbled across the correct term for this, "Radius Rod", I found several sources.

Next question, steel or aluminum? It would be nice to go lightweight with aluminum, but is it strong enough? One of these links failing by having the rod end pull out would be pretty ugly. Anyone using aluminum?

-chuck-

[lateapex911]

Huh???????????/

Is any of what you guys are talking about legal?????

My opinion is that you may replace the bushing material in the existing suspension location device (the lower rod) but you may not throw it away and fabricate one of carbon or aluminum or change the length or shape or anything...

what the heck am I missing!?

[joeracerx95]

Perhaps I'm misinterpreting the GCR. I know that this is common practice in ITA on the West coast.

Doesn't this cover what we're discussing?

"Any anti-roll bar(s), traction bar(s), panhard rod or watts linkage may be added or substituted, provided its/their installation serves no other purpose. The mounts for these devices may be welded or bolted to the structure of the vehicle. No suspension control mount or component shall be located in the trunk or driver/passenger compartment unless installed by the manufacturer as original equipment. Traction bars used to control axle rotation shall be one piece solid bar or tube. Heim rod ends may be fitted."

[dickita15]

Jake, don't you know anything, those links are traction bars. :D

[lateapex911]

Uh, OK.

But, if the lower axle locating links were removed from the car, would the car suffer more from wheel hop (because of the lack of traction bars) or from complete undrivablity (because they hold the axle in place)??

I would be interested to see how the appeals court would rule on this, as the defense is that these are pure traction control devices and not suspension locating devices.

[joeracerx95]

I'm new to this class so I'm not trying to cause trouble, I just thought this was an accepted change on these cars.

Jake, I don't think the answer is black and white. The upper arms also hold the axle in place. Either the upper or lower bars missing would result in uncontrolled axle rotation, something a traction bar prevents. You need both the upper and lower arms to control axle rotation, doesn't that make them both traction bars?

But like a leaf spring which serves two functions, these rods also serve two functions. Fore-aft control as well as rotation. Without this interpretation, third link components that "replace" the upper links would be illegal, wouldn't they? Aren't a bunch of people running the G-Force and ISC third links in ITA?

-chuck-

[joeracerx95]

"Perhaps I'm misinterpreting the GCR. I know that this is common practice in ITA on the West coast."

BTW, when I said this I meant that replacing the lower arms was a common practice out here, not misinterpreting the GCR. :D

Wait a minute, now that I think about it...... :unsure:

-chuck-

[lateapex911]

I hear you Chuck, and it's an area that is rather debatable. The tri link adds a part, and the upper links remain in place. Now, effectively, their role is diminished, by the soft bushings.

Another method of solving the issue (Poor axle geometry when the car is lowered) would be to use offset bushings in the upper and lower links, but I assume when Susko (G Force) did the math, he decided he could get better latitude by using the "Add a traction bar" option in the rule book.

I know it's a fine line, but I fall on the side of the issue that thinks that the links are clearly suspension location devices, and that considering them traction control devices only (the rulebook doesn't list the allownace for traction control devices/suspension locating devices) is pushing things more than I'd feel comfortable with. I love a good rule loophole as much as anybody, (I've disovered and closed a few actually), but I've decided to stay out of the gray on this one. But others, as you've mentioned, have other opinions, and thats fine.

[ddewhurst]

Chuck, IMHJ you are reading the rule correctly. I had some, people looked at them & walked away after asking a question or two.

This has been discussed a couple times on this site & those that say it's gray or illegal usually walk away from the discussion without using common sense :o as to why the "upper link" is a traction bar & the "lower link" is not a traction bar. Some within this thread admit that the "lower link" is a traction bar yet they say it's a gray area. The friken rule don't say traction bar/Banjo location link, the rule says traction bar.............

The word "added" works for G-Force & the word "substituted" works for DD-Force.

Someone PLEASE explain why the "lower link" is not a traction bar.

IMHJ there is more within this rule that could be implemented very successfully. One may do about anything with the traction bars & their mounting as long as one has two or more bars. But that's for another arguement. Oh, I ment to say rule disagreement. ;)

Chuck, I'll pay the protest fee & whatever when someone has the sack to protest your car. :023:

***I've disovered and closed a few actually***

Threats Jake, when you going to CHANGE this rule. :dead_horse:

[Greg Amy]

...those that say it&#39;s gray or illegal usually walk away from the discussion without using <strike>common</strike> Dewhurst sense...[/b]
Sorry, couldn&#39;t resist... ;)



Someone PLEASE explain why the "lower link" is not a traction bar.[/b]
Just as an apple is a fruit, but a fruit is not an apple.

That lower link performs all the actions of a traction bar, but a traction bar does not perform all the actions of that lower link. To justify the modification you are picking a single function of that link and giving it the specific definition you choose to ("cherry-picking") which is the essence of the "prohibited function" clause of the IT rules...

[lateapex911]

Threats Jake, when you going to CHANGE this rule. :dead_horse: [/b]

I&#39;m not going to sponsor any rewrite, David, because as has been explained here, by both Greg and I, the component is not just a traction bar. The rule is fine as written.

Don&#39;t assume those who have looked at your car, have decided that your interpretation is the fianl word, by their "walking away". For example, would I protest you on the items ? No, not worth the effort, honestly. But that shouldn&#39;t be taken as me judging them legal, because IMHJ, they are not.

[ddewhurst]

***The word "added" works for G-Force & the word "substituted" works for DD-Force.***

***without using common Dewhurst sense...***

I like that ^ Greg, it&#39;s kind of like using a "substituted" lower link by DD-Force. :happy204: :023:

Now on to the fruit of the subject.

***That lower link performs all the actions of a traction bar, but a traction bar does not perform all the actions of that lower link. To justify the modification you are picking a single function of that link and giving it the specific definition you choose to ("cherry-picking") which is the essence of the "prohibited function" clause of the IT rules...***

Greg, it would be my humble judgement that the "upper link" & the "lower link" do the exact same function. (Other than that the uppper links shape & mounting points screw up the rear 4 link geomerty.) If one disconnects either pair of links both traction & location will be eliminated from the OEM function. :o

Greg, when you explain what is different between the lower link & the upper link & their capability that each functions as a traction bar & that each functions as a location link I&#39;ll buy your thoughts. IMHJ both fruit do the same functions. If you don&#39;t buy these thoughts ^ how about YOU talk to Jake G. about taking either pair of links off his 1st gen RX-7 & we&#39;ll see the results in a hurry. Also disconnect the Tri-link when the upper links are disconnected. NO location/NO traction & a bunch of busted parts.

If G-Force may say that the "upper link" is a traction bar, DD-Force says that the "lower" link is a traction bar.

***because as has been explained here, by both Greg and I,***

Jake, I almost forgot about you ^. You could have said by all of us, Greg, Jim & I. When one looks at the information by Jim, he calls the upper & lower links trailing arms. Well my friend, the rule says NOTHING about addition or subistution of trailing arms. Oh, I forgot the master of G-Force can call stuff anything he pleases. He also told me that I had the ONE 1st gen in the entire world that had the odd ball strut mounting holes different than every other 1st gen with respect to his G-Force strut spacers fitting. BS............ Hey, I don&#39;t dislike Jim, I don&#39;t like people who pass gas.

All said with a :D

[Greg Amy]

To be honest here, David, I am not intimately familiar with the design of the rear suspension on the RX-7. However, inferring from what is being written in this topic, the link(s) in question performs a function other than that of a true traction bar. If that is correct - that link(s) you&#39;re talking about have a function of *anything* other than what a pure traction bar does - then its replacement is performing a prohibited function, and is expressly prohibited by the rules. - GA

[Joe-Racer]

The rules aside, I&#39;m not sure why you&#39;d want solid lower links WHEN a 3 link is used. The upper link is bushingless (sp) and must remain per the rules. Yes, it rattles like crazy - but its a soothing rattle :023:

I just wonder if the combination of a tri and sold lower would bind in compression and induce snap oversteer. Just speculating so let the flames begin :P

[dickita15]

Okay really I am not being a jerk here or at least not trying to be one. I understand the argument that the lower links can be swapped out, but if that is the case why do you have to retain the upper links. Can’t you remove them by the same argument.

[Joe-Racer]

No the links must remain in place. The ends can be hollowed out, but anyone in IT7 will get protested if they arent running them.

The tri-link is open b/c its considered a sway. At least thats my interpretation. :blink:

[dickita15]

Actually I think they are calling it a traction bar rather than a sway bar.

I guess I am not sure why if the lower meets the definition why the restraint on the upper link.

In the SE IT7 is the lower link replacement accepted practice? Just curious. I can see some advantage is squaring the rear end placement in the car, are there any other advantage available with adjustment of the length.

[kbailey]

Okay- here is my $.02. What I was told by several people as I was building my car is also what makes sense to me:

The upper and lower links are locating arms, not traction bars.

The popular setup I have seen is:
Add a tri-link to the top of the axle. This is an added traction bar, there is no question it is legal.
Replace the bushings on the stock upper locating arms with soft foam. This effectively renders them non-functional, and it is clearly legal.
Replace the bushings in the lower arms with spherical bearings. I personally think the interpretation of the old GCR wording "any bushing material" meaning spherical bearings was legal was crap. Now the wording has been changed in the GCR and it is officially legal now without argument. The Mazdamotorsports part listing for the bearings is below.

Nowhere do I see allowances to replace ther locating arms or the ends. Just my opinion.......but it seems to be the common interpretation of the folks I race with.

0000-04-7422 C BRG KIT,LOW TRAIL. ARM 1 ALL RX-7 1979-85 $263.40

Kit includes four (4) spherical bearings to replace stock rubber bushings in lower trailing links. Requires pressing rubber bushings out of stock links. Uses stock bolts. Legal for SCCA &#39;IT&#39; classes. Recommended to use with old, soft, upper bushings to prevent binding. Kit also available via special order that includes modified lower trailing links, fitted with sperical bearings (0000-04-7423).

[JeffYoung]

I think Kevin nailed it. My car has similar links, and they are more than just traction bars. They are essentially suspension mounting points as the locate the axle, the spring and the shocks.

Dick, to answer your question, a fair number of cars in the SE Div run foam bushings on the top links, sphericals on the bottom and a tri-link. Others just run a panhard in addition to the stock four links.

I&#39;m not aware of anyone replacing links entirely with homebrewed stuff, but I don&#39;t look under EVERY RX7 in the SEDiv. Just the ones that beat me......lol....seriously, it may be done, but this is the first I&#39;ve heard of it and I&#39;ve talked to a lot of folks here in the SEDiv with 1st Gen RX7s because your rear axle setup is nearly identical to mine.

[JoshS]

Does anyone have any good diagrams or photos of what a stock RX-7 rear suspension looks like?

[JeffYoung]

Hmm..Josh, think of your rear suspension with the lower trailing arms. Then picture a solid rear axle with two additional links running from the body tub, essentially behind each seat, to the top of the pumpkin.

[lateapex911]

Jeffs description was for the TR8. I&#39;ll dig around and see if I can find a pic.

RX-7:
Live axle.
Lower links run parallel with centerline of car, (or darn close) are about 18" long, attach to the chassis just inboard of the wheelhousing, and attach to the axle on a bracket on the bottom.

Upper links are essentially the same, BUT. (I think) the are angled inward on the axle a couple degrees, and are shorter, about 12" or so. They mount on the outer ends of the axle as well.

Stock, the car uses a watts link, which has rubber bushings at it&#39;s ends.

When you lower the car to race height, the arcs described by the two links are in conflict, and the watts link gets all twisted. It&#39;s out of it&#39;s designed range of motion.

The solution is to remove the Watts link (or replace the bushings with high misalignment spericals) and change the lengths of the links. But, it&#39;s more effective and easier to Keep the lower links stock length, and add a traction bar on the top of the pumpkin, attaching to the chassis in the driveshaft tunnel, and effectively "decommissioning" the upper links by removing the bushings and replacing them with very soft foam bushings.

This allows the axle to remain at an appropriate angle for driveshaft longevity, and the range of motion is restored.

(It&#39;s actually quite similar to those old Formula cars where the links could be seen on the outside of the car, usually all chromy, but of course, they had independent hubs)

[ddewhurst]

The "upper & lower links", OEM name are both very similar other than length. A length of tubing with a short cross tube at at each end with molded rubber inside (bushing) with a second steel tube inside the rubber that the mounting bolt goes through. For this discussion please forget the fact that the upper links on the front end mount inward with respect to the mount location of the rear end. That&#39;s (binding) part of the reason the Tri-Link was implemented.

The Banjo is positioned in longitude with four links. Two upper links & two lower links. They mount to the Banjo approx 6 inches above & Banjo center line & approx 6 inches below the Banjo centerline.

IMHU of the rule we need to read the words written in the written rule that "ANY traction bar may be ADDED or SUBSTITUTED". The G-Force Tri-Link is ADDED & the DD-Force lower links are SUBSTITUTED. ;)

Now if it&#39;s an accecpted practice to foam bush the upper links (accecpted as traction bars) & ADD a new TRACTION BAR which happens to be called a Tri-Link please explain why the OEM lower links do not do the same functions as the OEM upper links.

That ^ is question number one. It needs an answer to coutinue this communication IMHJ.

My answer to this question has all ready been posted in another post. I would like to have others explain their thoughts as to why the upper links are traction bars & why some think that the lower links are not traction bars. Not what Bo Bo thinks. Dam, just wait & see there will be a Bo Bo lurking. :D

[lateapex911]

David, I know we will agree to disagree on this, but to my eye, the upper AND the power are BOTH suspension members, and ONE of their numerous functions is to resist torque effects.

The bushing change in the uppers is allowed under the free bushing rule for suspensions as is the lower change. The added member is allowed under the rule that allows the addition of a traction bar.

Note that, when the tri link fails, the suspension will still function...not ideally, but it will function.

[joeracerx95]

Hmmmm, trying to decide if I&#39;m sorry I brought this up. :(

Any way, here&#39;s what I&#39;m wondering about.

We all seem to agree that the upper and lower links perform three functions:
1) Fore-aft location of the axle
2) Control of axle rotation
3) Completely screwing up the handling of the rear of the car

We&#39;ll ignore #3 for now. :P

So the question is, if a component has multiple functions how does SCCA Tech handle this? For example, if you run a car that has leaf springs in the rear, they are the springs but they also locate the axle fore-aft. (In fact, leaf springs are WHY traction bars exist!) Does that mean I&#39;m not allowed to alter the springs in my Pinto, which the rules allow, just because it could affect their other function? (BTW, if you aren&#39;t a SCCA tech official, your opinion doesn&#39;t count)

And I&#39;ll also observe from a "spirit of the rules" perspective that the end result of using a radius rod and two heim joints will be EXACTLY the same as buying the bearing kit from Mazda and installing them in the stock links. Except that it&#39;ll cost about $300 to do it with the Mazda parts vs. $100 with radius rods and heim joints. Would anyone like to contribute to the, "Keep Chuck 100% Legal In Everyone&#39;s Opinion" fund? :lol:

-chuck-

[Hahn63]

Chuck, follow the set-up on post #20 and you&#39;ll have a great handeling race car and you&#39;ll be legal for sure. No need to jump through all the hoops and reinvent the wheel, this set-up is fast as anything else, honest! :023:


Roland

[ddewhurst]

***Now if it&#39;s an accecpted practice to foam bush the upper links (accecpted as traction bars) & ADD a new TRACTION BAR which happens to be called a Tri-Link please explain why the OEM lower links do not do the same functions as the OEM upper links.

That ^ is question number one. It needs an answer to coutinue this communication IMHJ.***

Have you doubters answered the above ^ question? DO THE LOWER LINKS RESIST TORQUE?????? Lets use the KISS principle. THE ANSWER IS YES or NO.

David YES......... :D

Roland

Jake

Gerg

Jeff

Josh

joeracerx95

Kevin NO (The upper and lower links are locating arms, not traction bars.) To which I say then get rid of one pair of your locating arms & attach the remaining pair of locating arms to the vertical centerline of the Banjo & let&#39;s see how well the suspension functions. It only takes one pair of location arms to locate the Banjo. :o

Guys, this is not brain surgey. If one of the functions of the OEM named "upper link" is being a traction bar (we agree, YES), then why is it so hard for some of you to admit that one of the functions of the OEM named "lower link" is also a traction bar.

Once you admitt that the lower link is also a traction bar the remainder is simple.

Some of you guys buy into ADDING the third upper link but you just will not open your minds that what I have done for less than $100.00 is SUBSTITUTION of the lower links just as the rule allows. Why don&#39;t some of you understand the rule, ANY TRACTION BAR MAY BE ADDED OR SUBSTITUTED.

If some of you don&#39;t understand that one of the functions of both the upper & lower links is to resist traction then you need to get to reading in a simple suspension explanation book. I am not attempting to be sarcastic, just trying to be everyday realistic. Come on 1st gen RX-7 owners that are lurking take part in the FUN. :cavallo:

Roland, post # 20 is no different than what I have used for lower links except that I spent less than $100.00 to get the job done based on the written rule.............................. ;)

[joeracerx95]

I think we all agree that the lower links are used to limit axle rotation. The disagreement is that you can&#39;t substitute them because they also act as a control arm. A traction rod CAN be substituted, a control arm CAN&#39;T. I think we can agreed to that also. Like they do in court, show me a precedent where something similar was argued and decided by SCCA and we&#39;ll have an answer. Everything else is just opinion.

Suggesting that this is an prohibited function is not correct. Prohibited function means making a part do something it isn&#39;t supposed to do. E.G. True story. A SM guy installed a plate in the right rear of his car to mount one of the bars of his cage to. The problem was, the "plate" was a forty pound block of steel. He was protested and SCCA ruled that the plate was performing an prohibited function; acting as ballast in an area of the car where it isn&#39;t legal to mount ballast. He had to remove it. What this driver was trying to do is what the GCR refers to as "strained or tortured interpretation." (GCR 1.2.4) "It&#39;s just a mounting plate!" A very tortured interpretation of the word "plate" to justify its use. However, no one is suggesting that the links under discussion do anything they aren&#39;t designed and meant to do by Mazda, so there is no "prohibited function" taking place.

What to do, what to do. To save the $200 difference in cost between home grown and a Mazda part I&#39;ll take my chances with a protest. Or maybe I&#39;ll just leave that part stock. Or not. :lol:

-chuck-

[ddewhurst]

***The disagreement is that you can&#39;t substitute them because they also act as a control arm. ***

Ahh, this is where some people are NOT understanding (or don&#39;t want to admit to being on the wrong side of the fence for Oh so long) the function of the upper links. They serve the EXACT same OEM functions (suspension link/location link/traction bar) as the lower arms. Therefore one may per the rule SUBSTITUTE the lower links.

If I didn&#39;t want the Tri-link I could using the rules SUBSTITUTE all four links with home brewed links....... The word ANY traction bar & SUBSTITUTE free things up in a hurry. ( a couple of long standing nerd card holders may need their cards revoked :unsure: )But first we need to understand the functions up this suspension & the four links.

Anyone try removing removing the lower set of links to see how the car functions. Trust me it would function just like this odd ball :026: , it wouldn&#39;t be capable of walking.

If I thought I needed to do a streach to make this SUBSTITUTE of the lower links legal I would say something about the Purpose of the class which has a statement of "to compete in low cost cars". ;) ;) Hey, the DD-Force parts are less than $100.00 & the mazdamotorsports parts are approx $300.00. :D

Darn, I almost forgot. Did you folks answer the question below woth a YES or NO?

Have you doubters answered the above ^ question? DO THE LOWER LINKS RESIST TORQUE?????? Lets use the KISS principle. THE ANSWER IS YES or NO.

David YES......... :D

Roland

Jake

Gerg

Jeff

Josh

joeracerx95 YES........ :D

Kevin NO......... :( (The upper and lower links are locating arms, not traction bars.) To which I say then get rid of one pair of your locating arms & attach the remaining pair of locating arms to the vertical centerline of the Banjo & let&#39;s see how well the suspension functions. It only takes one pair of location arms to locate the Banjo. :o

joeracerx95, the question response trend is positive therefore do the cost effective parts. :023:

[Hahn63]

How do I get sucked into these things! :024: :D

Ok, here is what I truly believe.

The stock suspension is a 4 link with a watts. The car can be driven with out the watts (been there done that).

The car can not be driven with the lower links gone. (Watts removed) So it has to be stock.

The car can not be driven with the upper links gone. (Watts removed) So it has to be stock.

So both of those need to be in place for the car to move and thus it is its suspension type, a 4 link.

The tri-link is basically turning the car into a different suspension type (a 3 link with a pan hard bar) with the air upper bushings installed. I do not believe this was the intent of the rule but others (of greater power than me) think that it is, so it is legal.

Roland

[tom_sprecher]

Under the subtopic of Suspension Control from the 2007 GCR pg. 300,

"Traction bars used to control axle rotation shall be one piece solid bar or tube. Heim rod ends may be fitted."

The Mazda rear suspension using a 3-link and panhard setup could run effectively w/o the upper links OR the lower links if the 3rd link is properly attached to the top OR bottom of the pumpkin. In either case whichever links you decided to keep must have proper bearings as well, albeit plain or spherical, but not foam. Of course actual removal of any link is prohibited and was suggested only to prove a point.

With this in mind what is the function of any of the links at this point? In the case of the RX-7 are they really all just one in the same? One thing for certain is they all are used to control axle rotation. The only element that truely locates the rear axle and does not control axle rotation is the panhard or watts.

The GCR does not differentiate a traction bar from a location link so why are we trying? The GCR does provide a definition of a trailing arm but it is only referenced in the Formula Section. Are we making up rules based on what each of us feels is right or wrong?

RTFGCR!

On edit: One thing&#39;s for sure, when my no longer available, $200 a pair, ISC lower links crap out I&#39;m replacing them with $100 worth of Heims and steel tube available at any of the thousands of circle track speed shops nation wide. I run IT7 in the SEDiv where as gentlemen we tend to look past the BS rules. ;)

[joeracerx95]

"Are we making up rules based on what each of us feels is right or wrong?"

Uhhhh, yeah. And your point was? :P

-chuck-

[dickita15]

You know I am starting to see David’s point. GCR 9.1.3.D.5.c.2
On those cars where an anti-roll bar also acts as a suspension locating device, the diameter of the bar may be changed. Barr attachment and pivot points on the chassis and control arms shall remain as stock, except as provided for in these Rules, Section D.5.d.1., and 3.
Those two sections deal with camber adjustment.

That does kind of describe a Rx7 control arm.

[ddewhurst]

***"Are we making up rules based on what each of us feels is right or wrong?"***

Chuck, absolutly not, I always go by the words of the written rules. :023: If I were to go with rules that feel right my 1st gen RX-7 would be winning ITA races. :P

Ya see how those that think they understand the rules are lurking at present. :unsure:

[Hahn63]

You all can do what you want; I&#39;ll stick with the stock bars as they work well for me. I find it very interesting how you can call all four bars traction bars but if you want to call them that then "go for it", doesn&#39;t bother me in the least. However, keep in mind someone will eventually call you on the carpet for it and you may not get the answer you have hoped for. If I wanted to do something like that I would first call Jeremy in Topeka and get his take on it. This is a very similar conversation to one we had a couple years ago at the Run-offs about E prod RX7&#39;s and the answer is more along the lines of what I said earlier.

David, some of us do understand the rules and intent. I like playing with the grey area&#39;s as others do but some of them are best left alone cause they are like playing with fire...you will get burnt. :D :birra:

Roland

[JoshS]

***The disagreement is that you can&#39;t substitute them because they also act as a control arm. ***

Ahh, this is where some people are NOT understanding (or don&#39;t want to admit to being on the wrong side of the fence for Oh so long) the function of the upper links. They serve the EXACT same OEM functions (suspension link/location link/traction bar) as the lower arms. Therefore one may per the rule SUBSTITUTE the lower links.
[/b]

Here&#39;s my take.

In my mind, it&#39;s not important whether or not the upper and lower links are the same. One needs to look at any individual part on its own merit, define it, and then decide whether or not the rules allow it to be changed in any way.

Now, keep in mind ... I&#39;ve never really looked at one of these suspensions, and no one has provided me photos. So the following opinion is based only on the descriptions in this thread. Also understand that I tend to be conservative when it comes to rules interpretation.

Given all of that, in my opinion, I&#39;d probably come to the same conclusion on all four of these links: they are dual-purpose devices. They *are* traction bars, all four of them. But they are also trailing arms, all four of them. The rules say that traction bars may be substituted, but has no allowance for trailing arms. If you replace one of these arms, then it is a defensible position that you have substituted a control arm. If I were hearing the protest, I believe I would find that a driver that had substituted one of these links to be in violation of the rules.

BTW, the function of the arms once you make modifications (such as adding a tri-link on the top that basically replaces the control arm function of some of the bars) is, to me, irrelevant. The definition of a part is based on its function when 100% stock.

[nswanberg]

I wish there wer some pictures of this discussin for those of us that can&#39;t read or write. :(

[JeffYoung]

It is a traction bar and a control arm. The rules say you can replace a traction bar. For me, that ends it. Rules says you can.

Isn&#39;t this the same analysis as the front strut tube rule? The front strut tube can be replaced or modified per the express words of the GCR. But, it is also a suspension locating device. The fact that it is doesn&#39;t change the fact that most beleve you can replace or modify it (so long as the stock attachment points stay the same).

Interesting discussion. If you had asked me before reading this thread, I would have said no way.

[tom_sprecher]

I wish there wer some pictures of this discussin for those of us that can&#39;t read or write. :(
[/b]

See attached.

[ddewhurst]

DO THE LOWER LINKS RESIST TORQUE?????? Lets use the KISS principle. THE ANSWER IS YES or NO.
(Just about any chassis book will tell everyone that the longitudinal links of a 4 bar car locate the rear axle fore & aft & they control the axle torque loads of accelaration & braking.)

David YES............... :D

Roland YES.............. :D

Jake YES.................. :D (Not fair to change one of your previous posts.)

Gerg ???.....................come on Greg, it&#39;s decision time.

Jeff Yes................. :D

Josh YES..................You get a smile except the board will not allow any more emoticons within this message.


joeracerx95 YES....... :D

Dick YES.................... You get a smile except the board will not allow any more emoticons within this message.

Tom YES................... :D

Kevin NO................. :( (The upper and lower links are locating arms, not traction bars.) To which I say then get rid of one pair of your locating arms & attach the remaining pair of locating arms to the vertical centerline of the Banjo & let&#39;s see how well the suspension functions. It only takes one pair of location arms to locate the Banjo.

Roland, the previous inference was not aimed at you. & I always attempt to use the written rules because INTENT has (shouldn&#39;t) nothing to do with the rules during a protest. ;)

Tom, thanks for the loading the picture. :023: I don&#39;t know how to load pictures.

Guys, I&#39;m not picking on anyone. But we are finally opening up this discussion much more that we ever have in the past. & the name of the discussion IMHJ is use the written rule words & glossary description/functions of parts to come to conclusion. :birra:

[JoshS]

It is a traction bar and a control arm. The rules say you can replace a traction bar. For me, that ends it. Rules says you can.

Isn&#39;t this the same analysis as the front strut tube rule? The front strut tube can be replaced or modified per the express words of the GCR. But, it is also a suspension locating device.[/b]

The difference is that *all* struts are suspension locating devices. But only some traction bars are also control arms. Not the same thing.

[lateapex911]

Just a side note. The upper and lower links act in concert in the original design, and change the toe of the rear axle as the car rolls. Their job is multi function. (And yes, David, I agree that ONE of their jobs is to react to engine and brake originated torque)

[JoshS]

The question is simple here. The answer isn&#39;t.

The question:
Due to some clever engineering, a single part P on car C serves 2 functions, normally served by 2 different parts (A and B). There is no special name for a P, it&#39;s just a part that serves two functions. The rules allow for As to be replaced with alternate parts, but make no mention of Bs. The implication of this lack of mention of Bs is that Bs CANNOT be replaced. Given all of that ... can P be replaced?

The conservative rules-readers among us say "no", and the liberal rules-readers say "hell, yes!" So this sort of thing is the very definition of "gray."

David, I hear you saying very loudly that your part P is an A, and an A can be replaced, so P can be replaced. What do you say about the fact that P is also a B, and Bs cannot be replaced? You just continue to ignore that little tidbit of information. Do you deny that your arms are not only torque arms, but are also trailing arms?

[dickita15]

The Bar in question resists torque and also acts as a suspension location device. The following section seems to apply.

GCR 9.1.3.D.5.c.2
On those cars where an anti-roll bar also acts as a suspension locating device, the diameter of the bar may be changed. Barr attachment and pivot points on the chassis and control arms shall remain as stock, except as provided for in these Rules, Section D.5.d.1., and 3.
Those two sections deal with camber adjustment.

It seem to me that if the people who wrote this section did not want a control arm such at the Rx7’s to be replaceable the above paragraph would not exist.

[ddewhurst]

***Just a side note. The upper and lower links act in concert in the original design, and change the toe of the rear axle as the car rolls. Their job is multi function.***

Jake, no question the upper & lower links are multi functional. :D Agree from day one. :D BUT, with your above comment, after the Tri-link is installed what happens to the OEM toe generated by the 4 OEM links. ;)

Josh, IMHJ your talking out in space somewhere with your Alpha. If ya can&#39;t dazzel em with your brilliance baffel em with your alpha. :D From day one I agree that the links are multi functional. Both sets of OEM links are locators & both sets of OEM links resist torque.

When I ADD the Tri-link to function in harmony with the upper links <_< & SUBSTITUTE the lower links (per the rule) which are a functional traction bar to ANY traction bar (per the rule) of which my traction bar happens to be a real cost effective traction bar why do you say this is not legal. With the SUBSTITUTED lower links/traction bars the exact same function is being executed.

You agree the lower links are trailing arms/traction bars. Then within the rules which say ANY traction bar may be SUBSTITUTED what am I not reading within the written rules that that you are reading within the written rules. Ya, we all know that the upper & lower links do more than resist traction. :D

[Hahn63]

DO THE LOWER LINKS RESIST TORQUE?????? Lets use the KISS principle. THE ANSWER IS YES or NO.

Roland, the previous inference was not aimed at you. [/b]


I&#39;ll answer yes but with a comment. They do multi functions and are NOT considered a roll bar. :dead_horse:

Sorry david , was overly sensitive the other day. :wacko:

[dickita15]

I&#39;ll answer yes but with a comment. They do multi functions and are NOT considered a roll bar. :dead_horse:
[/b]

I agree they are not anti-roll bars but I think they may be traction bars that also locate the rear end

[mustanghammer]

The Bar in question resists torque and also acts as a suspension location device. The following section seems to apply.

GCR 9.1.3.D.5.c.2
On those cars where an anti-roll bar also acts as a suspension locating device, the diameter of the bar may be changed. Barr attachment and pivot points on the chassis and control arms shall remain as stock, except as provided for in these Rules, Section D.5.d.1., and 3.
Those two sections deal with camber adjustment.

It seem to me that if the people who wrote this section did not want a control arm such at the Rx7’s to be replaceable the above paragraph would not exist.
[/b]

I believe this applies to cars like the original Ford Capri which had a front anti-roll bar that is also one of locating points for the front suspension. Think of an RX7 with the anti-roll bar and the strut rod as one in the same and you have a Capri front end.

[roadracer]

Quoted from post number 20 in this thread:


09-12-2007, 08:03 PM
kbailey (http://www.improvedtouring.com/forums/member.php?u=10317) Offline
Join Date: Nov 2005
Posts: 25



Okay- here is my $.02. What I was told by several people as I was building my car is also what makes sense to me:

The upper and lower links are locating arms, not traction bars.

The popular setup I have seen is:
Add a tri-link to the top of the axle. This is an added traction bar, there is no question it is legal.
Replace the bushings on the stock upper locating arms with soft foam. This effectively renders them non-functional, and it is clearly legal.
Replace the bushings in the lower arms with spherical bearings. I personally think the interpretation of the old GCR wording "any bushing material" meaning spherical bearings was legal was crap. Now the wording has been changed in the GCR and it is officially legal now without argument. The Mazdamotorsports part listing for the bearings is below.

Nowhere do I see allowances to replace ther locating arms or the ends. Just my opinion.......but it seems to be the common interpretation of the folks I race with.

0000-04-7422 C BRG KIT,LOW TRAIL. ARM 1 ALL RX-7 1979-85 $263.40

Kit includes four (4) spherical bearings to replace stock rubber bushings in lower trailing links. Requires pressing rubber bushings out of stock links. Uses stock bolts. Legal for SCCA 'IT' classes. Recommended to use with old, soft, upper bushings to prevent binding. Kit also available via special order that includes modified lower trailing links, fitted with sperical bearings (0000-04-7423).
__________________
Kevin Bailey
ITA/IT7 WDCR



Bringing a thread up from the dead here. I do so with trepidation. However, this thread has no photos and I am seeking a picture showing an example of the suspension described above. Does anyone have one?

Please. Please. I am asking a question here that is specific. For a picture. Not a thousand words.

The topics discussed here in this thread appear like they could be batted back-and-forth and debated forever. :014: And I have read the thousand words already.:024: Probably twice. Maybe three times. :blink:

The only reason I didn't post a NEW topic or thread asking my question is so that you would know what thread and topic I referenced in my quote above.

Sorry to sound rude guys, but specific questions on forums most often get watered down and lost among the debates. The thing I'm asking for is a picture. Not an opinion and interpretation. (:dead_horse:)

Thanks in advance if you can help!

Don

[dickita15]

Ok, i will give it a shot. hard to get a good picture, hope this helps.

[Tak]

Good conversation, and an example of what is wrong with the SCCA rules process. The conservative interpretation of the GCR tells us that it is legal to take a lower trailing arm/traction bar from a junk yard, remove a rubber bushing, and replace it with some precision machined sleeves and spherical bearings. But it is not legal to buy a readily available piece (circle track radius rod), that does exactly the same funtion as the heavily modified piece, costs less, and is easier to implement.
Doesn't this sound like the ECU rule? Or the Coil over rule?
Instead of focusing on liberal vs conservative interpretation, shouldn't we focus on updating a 30+ year old rule?

Let's go back to the intent of the IT rules. What was the intent of the original traction bar rule? I believe it was to enable solid axle cars to be lowered safely to the limits of the rules (and by safe I mean both reliability and functionally--a car that spits out drive shaft U-joints is not safe; neither is a car that has snap oversteer because of a bind or bottoming issue). Consider the rules allowance for cars of the time with semi-trailing arms (BMW 2002 and Datsun 510)--they are allowed to slot the trailing arm mounting points to correct camber and toe when the car is lowered. This is consistent with safely lowering the car per the definition above. Similarly, most of the solid axle cars of the day had axles located by leaf springs only. A means of lateral location was necessary for functional safety (predictable handling)--hence the panhard rule.

We would serve ourselves much better to develop basic intent of what the rules should be, rather than bickering about the rear suspension links of a now out dated and uncompetitive IT car. The ITAC took the first steps when they rewrote the overall class intent statement a few years ago. We need to help them help us by developing consensus on a reasonable list of high level intent. What is the intent of suspension modifications? What is the intent of chassis stripping? What is the intent of engine modifications? Stuff for a new thread...

Tak
#29 ITA (an Rx-7)
SFR, SCCA
And yes, my car has 5 traction bars locating the rear axle.

[ddewhurst]

***And yes, my car has 5 traction bars locating the rear axle.***

Mine did also. Two traction bars with foam bushings & three traction bars with adjustable rod ends. :) No one wrote paper, they looked, they smiled & they walked away thinking:shrug:

[lateapex911]

Currently Tak, the rules allow you to take your stock arms and tack weld in spherical bearings, you don't have to machine cassettes or sleeves. In this circumstance, you do need some high clearance spacers, as i think you know.

Now, it is not legal to just add rod ends to the existing links after lopping off the ends.

[Jim Susko]

As a former member of the Solo Events Board, which is responsible for writing and interpreting the rules for Solo II, I have some insight into how these rules are written and interpreted.
The GCR defines a traction bar as “A link to an axle housing or hub carrier which resists torque reaction from the wheel by acting in compression or tension.”
It defines a trailing arm as “A wheel control linkage locating the wheel in the fore/aft direction, which is attached to the car structure at the forward end of the arm, and the wheel carrier at the rear of the arm.”
It defines a suspension control arm as “A beam or frame intended to limit the normal motion of the affected suspension part to predetermined paths.
Why are there three definitions which overlap in many ways? Because the rules makers want to show that these links are different. When we use these generally accepted terms, we all know what they mean.
When faced with a convoluted reinterpretation of a rule which uses generally accepted terms, rules makers tend to go with the simpler, more straightforward interpretations, based on the intent of the rule. If you take the logic presented by some on this forum, one would wonder why the Comp Board didn’t write the rule to say, “any suspension control arm, trailing arm and traction bar may be added or substituted.” But they didn’t. That’s a big clue.
Why take a chance on a stretched interpretation of the rules which doesn’t make the car go any faster than a more conservative interpretation? As a competitor I would be suspect of any car which had a substituted trailing arm which is adjustable in length. One would wonder how many other illegal parts there were on the car. If the car finished ahead of mine in an important race I would protest the car on principle alone.
Anything can be argued, and this is just my personal opinion.
Jim Susko