Question: Poly vs. rubber bushings

[Flowjoe]

Going to do the strut rods and control arms on the '82. Opinions on using polyurethane or rubber bushings? In the 1st and 2nd gen world the opinion, by and large, is to use rubber these days...poly has a lot of detractors. In reading in various spots and looking at vendors products it seems polyurethane is very much in use on C3's. Is there a consensus here?

 

[Hib Halverson]

Polyurethane is an acceptable choices for front control arm bushings but used the graphite impregnated "poly" because urethane bushings tend to squeak when they get cold and graphite impregnated poly has the least chance of squeaking.

Don't use polyurethane in the rear strut rods. The rods must twist as they move up and down. Urethane resists that necessary twisting and, thus, restricts or even binds the suspension near the end of its travel making the car seem "twitchy" or unpredictable if you drive it hard. For strut rods use OE-type rubber, or if you can stand the harshness, use spherical bearings.

 

[Flowjoe]

Polyurethane is an acceptable choices for front control arm bushings but used the graphite impregnated "poly" because urethane bushings tend to squeak when they get cold and graphite impregnated poly has the least chance of squeaking.

Don't use polyurethane in the rear strut rods. The rods must twist as they move up and down. Urethane resists that necessary twisting and, thus, restricts or even binds the suspension near the end of its travel making the car seem "twitchy" or unpredictable if you drive it hard. For strut rods use OE-type rubber, or if you can stand the harshness, use spherical bearings.

Given that logic (which I am not questioning) it is stunning the number of manufacturers that supply "upgraded" adjustable strut rods with poly bushings.

Like you I too am in Southern California so cold is not an issue. I have installed poly-graphite bushings in a number of 1st gen Camaros with only positive results (none of the oft referenced binding in squeaking) and no harsh ride.

When we bought the '82 the upper control arms had been done already using rubber. Is it advisable to mix and match rubber and poly between upper and lower control arms? I'd hate to throw out perfectly good bushings.

 

[Vettehead Mikey]

I wouldn't mix and match. The more I learn about suspension dynamics and the inherent design features of a captured rubber bushing vs. a sliding poly bushing, the more I dislike poly.

There's also some vendors who are finding that poly doesn't really last any longer than rubber.

 

[Flowjoe]

I wouldn't mix and match. The more I learn about suspension dynamics and the inherent design features of a captured rubber bushing vs. a sliding poly bushing, the more I dislike poly.

There's also some vendors who are finding that poly doesn't really last any longer than rubber.

Essentially, that echoes the current line of thinking in Camaro world.

Looks like I am best off to just go rubber here (need it for strut rods and need to match the uppers).

I have heard that some of the current crop of rubber bushings do not meet the quality of OE (for longevity and durability), same root cause as many current products apparently - poor, overseas production. Recommendations on brand/source for rubber bushings?

 

[HammerDown]

I replaced my rear strut bushings with 'black poly' and...so far, no complaints.
Reason...the OEM rubber bushings were quite thick however, every replacement rubber bushing had an inner and outer metal sleeve > this made the actual rubber part of the bushing very thin and in 'my' opinion a poor replacement for the original 'thick' rubber strut bushings.

 

[Flowjoe]

I replaced my rear strut bushings with 'black poly' and...so far, no complaints.
Reason...the OEM rubber bushings were quite thick however, every replacement rubber bushing had an inner and outer metal sleeve > this made the actual rubber part of the bushing very thin and in 'my' opinion a poor replacement for the original 'thick' rubber strut bushings.

That is an interesting analysis of the new rubber bushings. It would be interesting to see how much, if any, difference there is.

 

[kpic]

A. avoid offshore.

That being said the durometer (elasticity/compressibility etc.) of rubber and poly are quite different. As a material, rubber is susceptible to UV, chemicals (oil. gas, road salt, antifreeze and other solvents) and it even decays from water. All of that causes rubber to lose the properties it had when new. No one can change that, whereas polyurethane is not affected and its properties last.

Over the years, folks correctly decided that polyurethane's problems were noise, hardness, and vibration which was true once. Depending on the material composition some of today's polyurethane bushings are excellent and some are off shore junk.

 

[Vettehead Mikey]

That being said the durometer (elasticity/compressibility etc.) of rubber and poly are quite different.

This is true and one of the reasons that rubber is the better choice for strut rod ends, followed by a heim joint. Poly is a distant third and a downgrade in my mind.

 

[kpic]

This is true and one of the reasons that rubber is the better choice for strut rod ends, followed by a heim joint. Poly is a distant third and a downgrade in my mind.

Depending on the durometer, it could be even worse than a downgrade. If the durometer is the same; then it has material properties advantages over rubber. If one keeps the rubber up and replaces it when it's life is over; then all things are equal.
Unless I have a specific reason (known failure, wanna go faster etc.) to do so; I'm prone to stay with the OEM.


You might enjoy this: Polyurethane Suspension Parts | Hemmings Motor News

"Additionally, Daystar has developed several polymer formulations that allow them to match a specific application to the proper material durometer rating.With several manufacturers offering replacement polyurethane bushings, it is recommended that you do some research before attempting to swap your conventional rubber suspension parts for longer lasting, firmer polyurethane bushings. Each manufacturer will have durometer ratings for their products available through their technical service department, which will give you an idea how their bushings will improve your suspension system."

Sometimes I don't want firmer because I like the way my car rides and keeping the fillings in my teeth.

(Not to hyjack the thread but I bought the Corvette Black Book; very informative-thanks. I also picked up Mueller's Complete book of Corvette)