Body Mounts...Rubber or Poly?

[Blown353]

The poly mounts I used on my car were extremely high durometer... it barely took any rotation of the bolt after contact with the body to achieve spec torque on the body bolts (35 ft/lbs.) With a very objective (cough, cough) educated fingernail hardness test they were almost as stout as Delrin.



So yes, run either poly, plastic (delrin, etc), or solid of some kind. Going from fairly fresh rubber body bushings to poly bushings on my car made a very noticeable improvement in the "solidity" of the car. A bit of increased NVH but the stiffening of the overall frame/body combo was worth it.

One thing about the poly mounts though is they don't include the metal sleeves & washers, you have to reuse the old steel bits from the factory rubber mounts. If they're in bad shape then you'll have to find/make/buy new hardware.

[83hurstguy]

83hurstguy - there must be something semi-universal about "10% effects and smaller being negligible for first cut analysis". That's about what I've settled on, just playing around with structural analysis in general. To go much stiffer probably puts you into the realm of diminishing returns, stiffness vs added weight anyway.


Norm

It has to do with a "springs in series" equation from what little I remember (where the overall rate is summed by 1/kt = 1/k1 + 1/k2, etc...) All our chassis judges seemed satsified with that number, and we never had a problem with the car being unresponsive to bar changes. I'm not sure if Smith mentioned it in one of his books or not. Definitely one of those "semi-universal" things though...

[slimneverdies]

So 79 g-body!! What did you decide to go with poly or rubber? Im at the same point in my build.

[jackfrost]

So 79 g-body!! What did you decide to go with poly or rubber? Im at the same point in my build.

i didn't think there was still a question.

go poly.

[GBodyGMachine]

Poly

[Peti Boi]

go with SOLID!!!!!

[slimneverdies]

The poly is actually cheaper. I was still asking cause on another site a few guys with el camino's went with some poly and some solid. I have this car completely apart and dont want to take it apart again because of binding issues or some annoying sqeaking noises. Im spending alot of money on this car and would hate to have road noise because of bushings.

[Peti Boi]

mine doesn't squeak and the body feels real stable

[79_GBody]

So 79 g-body!! What did you decide to go with poly or rubber? Im at the same point in my build.

Yeah I ended up going with the poly...I haven't driven the car yet, but the body is back down on the frame. Now here comes the fun part of running the new brake and fuel line that ran on the inside of the rail. Thinking about just taking it somewhere and having it done.