Little Mouse or datindsas are pretty much on the same page as am I. TA's, in particular, inherently move in more than one plane by the nature of the C2/C3 rear suspension's design. Poly rather than [relatively] compliant rubber or sphericals (Johnny Joints work well) will introduce torques into the TA's and their mounting points, and when poly is so loaded the likelihood of increased binding stiction presents (which you won't necessarily hear). Such stiction in bushings or bearings is NOT your friend, as it is best to leave the amount, frequency and rate of unsprung suspension component movements to springs, shocks and bars. Fundamentals there; not opinion.

Haven't seen cracked/crumbled poly TA or camber strut bushings first hand (never used them myself), but have heard of them from others including CF'ers, DC'ers and VM'ers. Poly has its place, and I use it, but prefer heim's and sphericals for 3D applications.

 

Rubber trailing arm bushings generally last a lot of yrs they at least work right for the non serious person.

I probably upset some people telling them poly in the trailing arm is a bad plan just tried to explain it in the simplest of terms why it is a bad plan using the front control arms there one way motion as an example where ploy can work, it should be obvious to them why its not the plan for the trailing arm unless I did a poor job of trying to explain it.

 

If your poly t/a bushing have to be set up using thin washers to get a desired air gap that is to be checked by a feeler gauge, then you have the aftermarket bushings. And they can be staked by you, at home using the supplied bolt and conical nut to stake the inner sleeve. Thses bushings will be wider, and depending on the amount of shims you have on either side of your factory bushing MAY effect the setting of the toe. Like I wrote before, I have been burnt by this style of bushing before and would hate to read that it got you also. I asm hoping that it won't.

As for the lubricant that I use for the poly bushings, I buy the tubs of lube from Energy Suspensions. It is super sticky and glings to no end and is repellant to water and WILL NOT SQUEAK when used. I have way to many carsvout on the road and NONE of them squeak.

"DUB"

 

Little Mouse and Skunk;
Thanks for the explaination. Now I get to take out my trailing arms and replace the poly busings with rubber. Not so thankful about that. You guys are animals (couldn't help it)

 

TheSkunkWorks, littlemouse and datindsas,

I TOTALLY understand what has been written eventhough some of it I already knew and was the benefit for others on the forum.

But....knowing the fundamentals in suspension geometry and having documented proof WHY a component design is BAD is another.

Guys I AM on your side here, But I need proof instead of well thought out written text of WHY poly should not be used. Especially the amount of deflection that actually occurs under cornering / body roll has yet to be defined. And if this deflection is actually being hindered by the use of poly versus rubber and transmitting this energy to suspension components and fasteners that could cause for failure in the future.

For the life of me I can get it into my head that many of the companies that manufacture these products, that have them put into magazines, have acticles written about them, and so many cars on the road with them are dangering the lives of the drivers and others IF they are BAD. Like I mentioned before. IF you have PROOF of documented failure or tests perfromed that show that they are "not the way to go" I am ALL EYES AND EARS.

Best to all,
"DUB"

 

You're very welcome. I just love coming up with "little" projects for others, such as TA work.

Curious; can you use Johnny's? ...might be worth considering during the next off-season.

Anyway, I'm glad to hear adding some compliance back to the front anti-roll bar helped that corner entry issue. Everything else seem to be in good order now?


Charlie

 

DUB, at the risk of stating the obvious and not completely answering your query (but perhaps for the benefit of other viewers), the inherent amount of deflection at the TA mount (C2/C3 generations only) is equal in degrees to that of rear toe-steer during rear suspension travel from bump to droop, plus/minus however much pre-load there is in the static rear toe alignment setting. I haven't gone to the trouble to document the additional loads poly vs. rubber vs. sphericals would actually introduce, but I sincerely believe you can trust that they are there.

That said, (and please don't take this as my being argumentative) my view on this wasn't developed from only my own suppositions, but has been influenced by a number of engineers with whom I've worked track-side, over the phone and by those whom I have read while racking up ~100 road races (yes, I've won a few), and from tinkering with and/or consulting for a good number of sharks over the years, not to mention being open to listening to a lot of very sharp owners on these forums. Not saying you're experiences or any skepticisms you hold aren't valid, or that you have sufficient cause to appreciate my background in this sort of thing; just from my perspective I nave no reason not to stick with what I think I've learned whether I can prove it to anyone else just now or no. Hope we're good.




FWIW, if/when I can ever get properly funded to follow thru with prototyping any of the several serious new components which have long been gathering dust on my drawing board, collecting such info as this and much else is on my ever growing list of things to do, as I don't intend to produce or go to market without being able to accurately explain and backup benefits and claims.

 

As to being able to prove that poly is not as good as other materials for the TA's, I am currently running poly TA bushings and can say without a doubt that they are binding when I am on the track. Someday, I will change them out for something else, probably Johnny Joints.

Here's what I experience. On the street, there is no noticable effect using the poly TA bushings. However, when taking turns hard (greater than 0.9 g's) I hear a definitely and LOUD popping sound coming out of the TA front bushing area. There is definitely stick/slip action going on in the suspension. It's so loud I'm suprised that none of my instructors have said anything, because you can clearly hear it even with a helmet on.

When ever I get the time & money and my other projects finished, I will be going back into the TA bushings. Until then, I will live with it probably for another couple of years.

 

I also have poly in my rear struts. I'm using the Vette brake threaded units and have been having problems with the nuts coming loose. Now I know why. The poly bushings aren't compliant in 3D and causing the nuts to come loose. NOT GOOD and a safety issue. I'll be replacing them soon with rubber.

Charlie, changing from poly to rubber really helped the sway bar issue. Now when I run a course that is highly transitional I tighten the bar till the bushing bulge then loosen for a course that has a lot of sweepers and on asphalt. Pretty high tech, but it works.

SCCA won't allow a change to Johnny joints, and stay in the same class.
I need to either sell my car or move to Street Mod which will cost serious money, engine, wheels/tires, flairs, and associated suspension joint stuff.

 

TheSkunkWorks<
YES we are good now. Eventhough documented proof has not been provided, your knowledge in this area while performing extreme driving situations has made you conclude that the poly is not the BETTER choice. I can CLEARLY understand your views in this area. I have concluded that the issue with the poly bushings in the trailing arms / strut rods pertains to the amount of "flex" that the rubber provides versus the poly...under hard driving conditions....like mentioned by Jason Staley. When the suspension is taken to the extremes, I totally agree with the issue. With you being a racer, (congrats on your wins) you mind set is for total performance and safety. AS it should be. And I know it is hard for you to think another way due to having raced cars and taken them to the max of their ability. Your brain gets trained to make sure EVERYTHING is the best possible or catastrophic results can occur. I am that way also in certain areas of my profession. I will not budge, even if I can't prove itscientifically, 'cause I KNOW what I KNOW, and what I know is RIGHT( in those areas). Experience has proven it to me. IN this issue, I KNOW that YOU KNOW WHAT IS BETTER. And if is only a design of bushing that is the hold-up, what is the big deal. It truely isn't a big deal for a street car...but if the car is driven with alot of "spirit", then it can, or will be an issue like stated by Jason Staley.

Thank you for your reply.
"DUB"

 

Thanks for explaining the problems with poly bushings. I've had them since 2001 and never had a problem but my 185 HP Vette is only street driven and not raced, so it seems that I can leave well enough alone. PG.

 

If I had to do it all over again Id leave the polygraphite in the rear and put stock rubber up front save for sway bar bushings.