Why isn't Polyurethane a good bushing material?

[V6Bob]

And, in case anybody thinks rod ends are the answer because they're used on race cars:

First, they are very harsh, transmitting roughness, noise, and vibration.

More importantly, they're not designed for street car use in any way. They work well on a race car where they are carefully examined and cleaned every outing. On a street car they can fail catastrophically over time. Rubber usually lets you know by getting sloppy over time.

Finally, no one here would pay for actual race car/aircraft rod ends. I see guys talking all the time about "good rod ends". In the words of Crocodile Dundee, those aren't good rod ends. These are good rod ends:

http://www.bakerprecision.com/nhbb1.htm

Stainless steel, teflon lined, with the proper and different stainless alloy used for each of the three pieces. Some rod ends sold are two piece, which is way inferior.

A set of lcas with these babies would run something over $400. And they'd still be a maintenance/safety issue. But they're what the pro racers use.

[T-Punk]

rod ends are not worth it to me over poly and poly last longer than even hard rubber so i will stick with the tried and true poly bushings ;)

[Jerriko]

Are you listening to yourselves? Rubber as its applications as does poly. Why are you guys treating this as poly is good for EVERYTHING or nothing. I used poly because I dragrace, not roadrace. Yes, poly is noisy! But that's not why I use it. And no, a lot of people I know use poly over rod-ends. Why, I have no idea. I don't care. So for all of you people who just like a good ride, stop with the poly hate and enjoy your 'jello'.

[The Crow]

I did a total overhaul of my stock suspension and have Poly bushings in my LCAs, Panhard, Front and Rear Sway bars and I am real happy with them. Yeah they will squeak every now and them but, I'm willing to put up with that for the performance.

[oil pan 4]

mmmm... jello
I don't like rubber bushing in the frount control arms any more because me and the guys at work killed one in one of our work trucks. It's not our fault if they have enough torque to lift there frount end off the ground.
My polaris ATV back home has poly bushings stock form the factory. It rides great and it's all off road.
I might keep rubber in the rear LCA's for the v6.
Rubber motor mounts all the way for the V6.

[FirebirdGT]

Originally posted by Jerriko:
Are you listening to yourselves? Rubber as its applications as does poly. Why are you guys treating this as poly is good for EVERYTHING or nothing. I used poly because I dragrace, not roadrace. Yes, poly is noisy! But that's not why I use it. And no, a lot of people I know use poly over rod-ends. Why, I have no idea. I don't care. So for all of you people who just like a good ride, stop with the poly hate and enjoy your 'jello'.

Agreed, you need to determine your use before deciding.

Refer to this link, which is in the Tech Database suspension section along with other links to additional information.

http://www.globalwest.net/camaro93.htm

[zlexiss]

Just a caution to those using poly bushings in the front LCA's, especially Energy Suspension ones..

Link: They don't seem to last too long!

Quote from thread: "...heres what you get after a few track days and ZERO street miles..."



[ February 03, 2005, 06:16 PM: Message edited by: zlexiss ]

[y87inside]

So to recap all this info.... You want to use bushings with little or no deflection(poly) on suspension componets that are intended not to require near as much movement correct? Example: sway bar bushings & endlinks. But, you want to keep a bushing(rubber) that does deflect some for ride quality and saftey purposes in susp. components such as tranny mounts, panhard bars, lca's etc. Are these correct assumptions?

Brandon

[zlexiss]

y87: Yes, I agree with your recap, and that's how my car is set up for autocrossing, road racing, and street driving use.

[oil pan 4]

The only time I have seen poly do that is in a wreck.

[njspder]

this thread has gotten completely off base.
here are the facts of teh metter. an ideal handl;ing and safe vehicle is one that has reduced deflection in the suspension.
poly covers both of these points nicely in a street car. it will not deflect as much as rubber which allows the control arms guide the movement of teh suspension instead of leaving it up to whichever way a piece of rubber feels like bending. ride "quality" being subjective i will leave that up to you. it will return a smoother range of motion, and a much firmer feel over bumps.
rod ends are teh ultimate no deflection. a common misconception is that they are only for racing, in fact they are fantastic on teh street. being metal they have 0 deflection and a perfect range of motion. since it is not a soft material it does not bind at all through the range of motion, therefore leading to a longer range of motion. since the range of motion is true it leads to the best and purist handling charactoristics that you cna ever hope for.
factory rubber is junk. the simple truth is that your suspenssion was designed to move in a specific range of motion. the weak quality and deflection of the factory rubber bushings allows the suspension to get outside the lines that your stock suspension was intended to swing through.
to improve handling, safety, and durability od your suspension go with a firmer and lower deflection material. if you like replacing parts and having less than predictable handling keep rubber bushings and hope for the best.

later
tim

[V6Bob]

Rod ends are not great for the street. Yeah, theoretically they move in all the right ways. But, in practice, they're simply not designed to put up with the water, dirt, etc. in long term street use. And the ones sold on cheap aftermarket gear are often junk, often just two piece carbon steel. Rod ends can fail suddenly, and a rod end failure can cause really bad things. The SCCA will not let you use rod ends, even on a pure race car, unless you design the attachment points to contain the part in case of sudden rod end failure.

Lcas do not move simply up and down. They must twist slightly when the car rolls, poly won't do that, and the suspension binds. It's not huge, but an fbody simply will not handle best with poly lcas. Far from allowing the part to move outside the desirable range, rubber allows it to do so. It's poly that causes problems here, by _not_ allowing the twist.

Ferraris and Porsches use rubber bushings. Would they do that if rubber automatically meant decreased handling?

[njspder]

i had rod ends on my last camaro fro 4 years, it was my daily driver teh whole time. never a hint of any problem or potential failure in over 50k miles. i don't know where you got that "sudden failure" thing, but it is a log.
as for poly not allowing twist type deflection, then i supposed you are opposed to boxed control arms that prevent the same twisting motion as well. the amount of diagnal deflection in an f-body suspension is minimal. the deflection that exists in that vain is also less than desireable. it prevents teh proper arc of the panhard and will cause inconsistant handling at the limit.
the scca rules regarding most suspension components are very very old. if you are a member i am betting you know as many oputdated rules and interpretations as i do.
look at the world of endurance racing. i am in daytona at the rolex 24 weekend and i can tell you after 2 days of walking around tthe paddock that the classes that allow rod ends all run them. stock stuff is still regulated to lame *** rubber bushings, but every porsche, bmw, and corevette i see in the gt classes has many rod ends.
ferrari's ahs rubber on old cars, the new cars actaully use compact high durometer bushings. same with porsche. these are a much tougher rubber than the crap that gm supplied all of us with. especially when you take a look at 4th gen rear control arm bushings that aren't even complete.
the replacement of the stock soft rubber with even a better rubber would be beneficial, a tougher material like poly even better. the complete elimination of deflection and full range of motion from rod ends wins outright.

[V6Bob]

"as for poly not allowing twist type deflection, then i supposed you are opposed to boxed control arms that prevent the same twisting motion as well."

Not at all. There's a big difference between proper motion at suspension pivot points (good) and flexibility in suspension arms (bad). In fact, if you use poly in lcas the arms are _forced _ to twist when the car rolls (bad).

"the amount of diagnal deflection in an f-body suspension is minimal. the deflection that exists in that vain is also less than desireable. it prevents teh proper arc of the panhard and will cause inconsistant handling at the limit."

It's not negligible at all in the lcas when the car rolls. It's one degree twist for every degree roll. The resulting bind from poly lcas at suspension pivots is what will cause inconsistent handling.

[PewterBird]

Im glad I started this thread. There is a ton of good info in here.