rick1500

Do you guys recommend getting a poly body mount kit (for a '73+) instead of the standard aluminum kind for my '70?

I know that the poly kit will need to be ground down slightly so the body sits at the right height, and it looks more expensive. But, I've heard that the poly washers reduce harsh vibrations in the body which lead to cracks, etc.

Is it worth the extra $ and effort to get a poly body mount kit and modify it for my '70? If so, does anyone have any directions on just how to modify the washers, or do I just grind them down to match the thickness of my old aluminum ones?

dboncio99

Poly bushings are indeed a harsher ride and will cause stress cracks overtime. They also have a tendancy to skeak! I would stick with rubber - they're good for 20 years!

rponfick

I agree, stay with rubber. You will not notice the ride height difference. Put them on my '69 convert. and love them.

Ralph

rick1500

The body mount cushions for 1970 were aluminum...do you guys mean stick with the original aluminum kit? I'm talking about body mount kits, not suspension bushings, just in case I wasn't clear. Here are some pics:

'68-'72 original aluminum:
http://www.zip-products.com/Zip/prod...EDE3EEC01FB052

'73+ poly:
http://www.zip-products.com/Zip/prod...EDE3EEC01FB052

'73+ rubber:
http://www.zip-products.com/Zip/prod...EDE3EEC01FB052

I guess I may have 3 choices though: original aluminum, rubber, or poly. I believe that the rubber/poly are used on '73+ and will need to be modified for use on my '70. Can anyone a.) tell me if it's a good idea to switch to rubber/poly, b.) tell me how to modify the rubber/poly kit, if at all, and c.) if rubber is a better choice than poly (sounds like it might be, but I noticed rubber is the most expensive of the 3). Thanks!

jimmygmartin

I don't know about ZIP, but VBP assured me that there Poly body bushings were the same as stock. I would not use rubber as they raise ride height and allow for more body flex. I have solid bushings on my vert, my buddy has rubber on his vert. He has cowl shake, mine does not. He is switching from rubber to poly. Alot of what is refered to as stress cracks in the body is really the result of none gel-coated fiberglass body parts.

rponfick

I was recommending the rubber mounts used on '73 up. There are no modifications necessary. Poly is so hard you may as well stay with aluminum, and therefore I see no advantage to the poly. GM switched for some reason and I figure they had done more engineering than me.

Ralph.

I'm Batman

Energy Suspension makes poly body bushings in the same thickness as the C2/early C3 aluminum inserts. They'll be less harsh than aluminum, and if you grease them properly they won't squeak. Don't listen to the haters.

flynhi

I've had rubber mounts on my 71 for 10+ years. No problems and much smoothr ride.

Jclgodale3

Poly's here

Cory1970

doing mine at the end of the summer... interested in more opinions

Razorhorn

Zwede has done rubber mounts on his big block 71. He's got a web site detailing it. I'll ping him and see if I can get him to come out of his cave...

zwede

I'd recommend the rubber mounts. They are a much better engineered product than the poly. If you compare them side by side you'll see what I mean.

The body height will go up about 3/8". Not enough to be visible and the steering column has enough adjustment to line up.

Here's the article I wrote about the install. Unfortunately the forum messed up the formatting.

https://www.corvetteforum.com/techti...=210&TopicID=3

Jason Staley

Poly will be better than the aluminum, but the rubber is even nicer. I have had poly mounts in my 76 for over 5 years and they were a bit harsh and resulted in alot of rattles inside the interior. I just switch back to rubber mounts tonight and took it out for a test run. Wow, I forgot how smooth the rubber mounts make these old vettes.

I'm Batman

Rubber decays and crumbles. Poly should just about last forever.