1st Gen RX7 rear lower links

[tom_sprecher]

I wish there wer some pictures of this discussin for those of us that can'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...............

Roland YES..............

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

Gerg ???.....................come on Greg, it's decision time.

Jeff Yes.................

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


joeracerx95 YES.......

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

Tom YES...................

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'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't) nothing to do with the rules during a protest.

Tom, thanks for the loading the picture. I don't know how to load pictures.

Guys, I'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.

[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'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'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 . There is no special name for a P, it'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. Agree from day one. 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't dazzel em with your brilliance baffel em with your alpha. 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.

[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.

Sorry david , was overly sensitive the other day.

[dickita15]

I&#39;ll answer yes but with a comment. They do multi functions and are NOT considered a roll bar.
[/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 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. And I have read the thousand words already. Probably twice. Maybe three times.

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. ()

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

[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