Adjustable rear suspension arms

D

DragonRacing17

New member
Is it legal for me to instal an adjustable panhard rod and adjustable traction rods to bring the rear end back into alignment? Lowering the car pushes the rear end toward the driver side slightly causing alignment problems. IPD sells adjustable bars that fit the stock mounting points.

The ITCS says "Any anti-roll bar(s), traction bar(s), panhard rod, or watts linkage may be added or substituted, provided its/their instalation serves no other purpose."

I would like to hear whatever opinions you have.
 
Your homework has already been done by the first-generation RX7 guys: Go see what they do.

You can't replace the stock control arms but you CAN add bars to "control rear end motion" and replace the stock bushings with REALLY soft material. Some have suggested "air," in fact.

K
 
I don't want to start a huge discussion, but I'm interpreting the ITCS to mean that I can remove the stock bars.

"Any anti-roll bar(s), traction bar(s), panhard rod, or watts linkage may be added or SUBSTITUTED, provided its/their instalation serves no other purpose."

Doesn't substituted mean that you can remove the stock bars and replace them with different ones?

Substituted - "One that takes the place of another" (http://dictionary.reference.com/search?q=substituted)

Please tell me where my argument went wrong.
 
You can lose the watts linkage and install an adjustable panhard rod that you can use to center your axle housing. You cannot substitute your trailing arms unless you can convince the tech gods that they are actually traction bars. Uhhh! Are we talking about a 1g RX-7 here?
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Ray
 
This is a 1983 Volvo 242. What are you refering to as the trailing arm? Are you talking about the bar that the shock and spring bolt to or the bar that attaches to the top of the axle and extends forward to the frame? The one I wanted to replace was the second one I described.
 
***You cannot substitute your trailing arms unless you can convince the tech gods that they are actually traction bars.***

Ray, not trying to be disrespectful but I have had the same question as DragonRacing17 with the word "substituted". If we look up the word traction bar in the GCR glossary & if we disconnected the upper OR lower rear links of a 1st gen RX-7 I think the tech gods would agree the links are traction bars. Lets also disconnect the stabilizer bar. & when the third link breaks we'll wish we had a fail safe link/traction bar.

Have Fun
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David

[This message has been edited by ddewhurst (edited November 25, 2004).]
 
Originally posted by DragonRacing17:
... The one I wanted to replace was the second one I described.
Click to expand...

It actually does sound like you are talking about a "traction bar."

Traction Bar - A link to an axle housing or hub carrier which resists torque reaction from the wheel by acting in compression or tension. (GCR definition)

I think that can be "substituted."

K
 
Originally posted by ddewhurst:
Ray, not trying to be disrespectful but I have had the same question as DragonRacing17 with the word "substituted".
Click to expand...

Believe me David. I've asked this question a bazillion times and got a different answer every time referring to the lower trailing arms. We all know what substitute means but it's the part being substituted that could cause some issue.

Originally posted by ddewhurst:
If we look up the word traction bar in the GCR glossary......
Click to expand...

Hold it right there before we start the "if's". The next word in the GCR glossary is "trailing arm" and the definition.:-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 to the wheel carrier at the rear of the arm-: If it walks like a duck....
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The following is an ad listing from Mazda Motorsports.

0000-04-7423 C TRAILING ARM KIT, LOWER 1 RX-7 ALL 1979-85 $377.85 Notes: Includes two (2) new modified lower trailing links. Rubber bushings are replaced with spherical bearings. helping to eliminate 'binding' problem in rear end. Available by special order only. Spherical bearing also available separately (0000-04-7422).
Italics mine.
Now, will someone please convince me that lower trailing arms are indeed traction bars. This way I can go to the local roundy round shop and buy an alum rod fitted with rod ends for a fraction of the cost of the MazComp legally done ones and do some substituting.
smile.gif

Ray
 
The answer you should get, Ray is embedded in the fact that you are asking questions about "lower trailing arms" - your term - hoping to take advantage of an allowance written for "traction bars."

Mazda calls them "trailing arms," you call them "trailing arms," and the ITCS makes no mention of subsituting them. I'm not saying that it makes sense, only that it's how the rules are written.

We get in these binds when we pick and choose from among the diagnostic characteristics of a car part and try to make the case that an X is actually a Y.

K

EDIT - but you CAN add a pair of traction bars, optimized for rear end control, and essentially take the existing arms out of the action with smooshy bushings. That's the point of this thread, right?

[This message has been edited by Knestis (edited November 26, 2004).]
 
Hope all had a friendly turkey day.
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Nuff said about eating.
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Lets have some more FUN with with the extensions attached to the rearend banjo of a 1st gen RX-7.
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Disconect the shocks & disconnect the stabilizer bar. At this time we have the car weight being supported by the rear springs & the banjo located fore/aft by four (4) links. Two (2) upper links & two (2) lower links. Upper & lower links is the Factory Workshop Manual name for the links. The Watts linkage is providing lateral location of the car body to the Banjo. The Banjo could very nicely be located fore/aft by two (2) links attached at the center line of the Banjo. The car manufactures don't duplicate the Banjo location links for no good reason. Disconnect one set of these links & the Banjo will "rotate" binding the Watts linkage to non operable. Therefore IMHJ because we know two (2) links will hold the Banjo fore/aft the function of the other two links is to eliminate Banjo rotation therefore they are "traction bars" for our technical description with the tech people. During this technical discussion lets define the lower links as the Trailing arms & the upper links as the Traction arms/bars.

Continue the Fun
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David
 
Thank you David for that entertaining bit of explanaton. It all makes sense now.
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Originally posted by ddewhurst:
During this technical discussion lets define the lower links as the Trailing arms & the upper links as the Traction arms/bars.
Click to expand...
That is usually what it boils down to so we'll leave it at that.
DragonRacing17- If your Volvo rear end setup is similar to the RX-7, then I hope all this made sense to you. Kirk actually answered your question a long time ago(his 2nd post) but this wouldn't be fun if we didn't stir the pot a bit.
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Ray
 
Speaking of stirring the pot....

Some guys with RX-7s convert to the tri link set up, and in so doing, eliminate the upper trailing arm and watts link effectiveness. Some remove them totally, some don't.

So, that begs the question, reading the rules, what is the legality of not running with the parts?

Specifically, these items are of interest:
1- upper links...in or out? air or foam bushings?
2- if you go to a panhard rod, what about the same question applied to the watts link??



------------------
Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]
 
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