'65 rear spring cushion replacement

[Blake W.]

I've read here that rear spring cushions should be replaced more frequently than most are. Mine look like the've been on a long time. My question is regarding the overall increase in ride height (if any) when changed. I measured thickness of the existing cushions @ approx 1/2". The New cushions are 1" thick. I realize some compression of the new rubber will occur when installed but I'd like to know what others have experienced when they made this change. I have a very nice ride height front to back now and would hate to have the back end "standing up". If this matters it is an F40 suspension. thanks Blake

[Gary B.]

Re: '65 rear spring cushion replacement

Blake,

I know it doesn't answer your question, but if your F40 spring is a GM original, then I don't see how installing new cushions can do anything except make the rear ride height closer to the original GM spec. If your rear spring is a repro, then that's another story.

Gary

[Blake W.]

Re: '65 rear spring cushion replacement

Thanks, It's an original spring.

[Russ S.]

Re: '65 rear spring cushion replacement

changing out an old cushion makes very little if any difference in ride height. I know theatrically it should and if your old one is really bad so that it is a lot thinner than a new one then it could make a little difference. I doubt if even then you would notice the difference without measuring.

[Blake W.]

Re: '65 rear spring cushion replacement

Thanks Russ, Guess I'll change them and see what happens. I was under the impression that the rear body height would be taller. I'm hoping it will help the ride too.

[Gary B.]

Re: '65 rear spring cushion replacement

Thanks Russ, Guess I'll change them and see what happens. I was under the impression that the rear body height would be taller. I'm hoping it will help the ride too.

Blake,

If the cushions on the car now are very old and very squashed, then I guarantee that you will see at least some increase in height after new cushions are installed, but again it should get things back into spec if you're using correct GM parts.

Gary

[Blake W.]

Re: '65 rear spring cushion replacement

Yep, Bushings are old and cracked. New ones I got are GM parts. Lastly, do I need to replace the long bolt and retaining nut? they look to be in good condition; no rust.

[Duke W.]

Re: '65 rear spring cushion replacement

There will be a slight increase in rear ride height. I bet if you measure the D dimension it's low.

You should also notice a dramatic decrease in rear ride harshness.

It never hurts to replace 48 year old rubber parts!

Duke

[Gary B.]

Re: '65 rear spring cushion replacement

... Lastly, do I need to replace the long bolt and retaining nut? they look to be in good condition; no rust.

Blake,

I know that some people will advise you to replace the bolts. But if having the original bolt headmark is important to you, and if they are in as good shape as you describe, then I wouldn't necessarily replace them. In terms of safety, it depends on how you drive the car. If you're auto-crossing the car, then definitely replace them. But if the car only goes out for a leisurely trip to be judged or to a show & shine, then I wouldn't bother replacing them.

Gary

[Blake W.]

Re: '65 rear spring cushion replacement

Good to know Gary. I do drive the car but my drives don't include redline pulls anymore. Can't afford to lose an original motor. thanks for all the advice. Blake