78 Rear Spring Cushion replacement

[David W.]

I need to replace the 4 rubber cushions ( no poly) on the outside ends of my stock rear spring. I have not done this before and am looking for a few tips before I proceed. All hardware is in good shape so it would only be the cushions i am replacing. I assume lifting the rear end is the first step. Will I need to use my floor jack to hold the spring in place etc.................I will be doing one side at a time if that makes sense. Thanks for the advice in advance.

[Tom R.]

Re: 78 Rear Spring Cushion replacement

I believe the shop manual may describe how to do this but my recollections are as follows:

Rear of vehicle up, support frame on both sides on jack stands, tires off. Its easy with the spare tub off but when I did it, it was to replace differential gasket. You may be able to do it with tub in place. At this point your spring should be replaced.

I used a piece of two x four on the spring and then place the floor jack inboard of the cushion a few inches so you can work (avoid metal on metal and scratches). You are now putting tension back on the spring to reduce tension on the link and its cushions. Unbolt, replace cushions and do the other side. Make a mental note which way the cotter pin faces on the castle nut and return it in the same position, assuming this is its first removal.

If I have missed something, I am sure others will jump in.

[Duke W.]

Re: 78 Rear Spring Cushion replacement

I've always done the job with the car on the ground. As long as the nuts aren't rusted onto the link bolts, it's an easy job.

...car should be on a level surface, parking brake on tight, in gear or Park, double chock at least one front wheel.

Place a wood block on the jack puck like a short piece of 2 x 4 and place the puck as far outboard on the spring as possible while still allowing you to access the nut and remove the link once the nut is off. Placing the jack axis at an angle to vehicle centerline up to about 45 degrees should give adequate work clearance.

Jack the spring up about and inch because the new cushions will take up more vertical space than the old compressed cushions. Prior removing the cotter pin wiggle/bump the jack around a little to make sure it's stable, and if so it should be safe to continue. Work space is a little tight, but you should be able to do the job without removing the wheel.

Depending on what else you decide to do in terms of cleaning or whatever, the job shouldn't take more than about an hour to do both sides.

Us new cotter pins once the nut is installed.

New spring link cushions should restore ride height and yield a dramatic reduction in rear ride harshness. There are a lot of Corvettes out there that need this simple maintenance task, but it is commonly overlooked and owners and mechanics think the car needs a new spring to restore ride height.

Duke

[Michael W.]

Re: 78 Rear Spring Cushion replacement

Support the rear of the vehicle on jack stands just high enough for the rear tires to be clear of the ground.

Wrap the outer section of the spring with rags to prevent scratches. Clamp a block of wood to the spring to prevent the anvil of the floor jack from skidding along the spring surface.

Apply enough pressure to the spring end with the floor jack to relieve tension on the spring bolt.

Remove the cotter pin and castellated nut.

Remove the spring bolt.

Replace the cushions.

Reassemble.

[Duke W.]

Re: 78 Rear Spring Cushion replacement

Support the rear of the vehicle on jack stands just high enough for the rear tires to be clear of the ground.

That means the spring will have a lot of arc and I worry about the jack slipping out as you raise the spring, which is why I prefer to do the job with the car on the ground, which means the spring is basically flat and the load will be purely vertical which minimizes the chance that the jack can slide out, even though work space is tight with the tire installed.

Duke

[David W.]

Re: 78 Rear Spring Cushion replacement

Thanks for your time everyone. Seems easy enough. Confirms my approach options.

[Michael W.]

Re: 78 Rear Spring Cushion replacement

That means the spring will have a lot of arc and I worry about the jack slipping out as you raise the spring, which is why I prefer to do the job with the car on the ground, which means the spring is basically flat and the load will be purely vertical which minimizes the chance that the jack can slide out, even though work space is tight with the tire installed.

Duke

Good point.

[David W.]

Re: 78 Rear Spring Cushion replacement

Duke;
Looking at doing this while on the ground how is the bolt removed to replace the top cushion. It appears to be boxed in? Looks like the sway bar is attached to the top. The bottom cushion is easy. What am i missing here? Thanks

[Leif A.]

Re: 78 Rear Spring Cushion replacement

Duke;
Looking at doing this while on the ground how is the bolt removed to replace the top cushion. It appears to be boxed in? Looks like the sway bar is attached to the top. The bottom cushion is easy. What am i missing here? Thanks

There is an access hole in the top of the "box" for the bolt to slide out and thru.

[David W.]

Re: 78 Rear Spring Cushion replacement

Yep I do see that but with my FE7 suspension looks like the sway bar needs to be removed and plate that covers hole. Right?

[Duke W.]

Re: 78 Rear Spring Cushion replacement

Duke;
Looking at doing this while on the ground how is the bolt removed to replace the top cushion. It appears to be boxed in? Looks like the sway bar is attached to the top. The bottom cushion is easy. What am i missing here? Thanks

The few I've done or helped out with didn't have rear anti-roll bars, so the bolt and upper hardware could be easily extracted through the trailing arm top access hole as previously stated. If the bar hardware is in the way, you'll have to do more disassembly. Hopefully you can just remove the bar from the bracket and the bracket from the trailing arm, and to do that it would be best to jack up the rear and remove the tire to do the job from the wheelwell, then lower it back down, replace the cushions and jack it back up again to install the bracket.

Obviously this complicates the job, but you should find the results rewarding.

BTW as an experiment you should do a test drive without the rear bar attached. You should notice heavy understeer compared to having the rear bar attached. It may not be noticeable in normal around town driving, but it you push it to eight tenths or more around some corners it should be noticeable.

Duke

[David W.]

Re: 78 Rear Spring Cushion replacement

Thanks for the reply Duke...........yeah your procedure outlined above is what i plan to do. Quite a bit of up and down but really no choice. I just hope the bar will go back together ok and tension won't be a problem. I will probably soak the hardware and de-rust everything even though they look pretty good so it will be a 2 day deal. I would like to see how the rear sway bar affects performance too but unfortunately I have a couple feet of snow on the ground. Minnesota this time of year is not kind to vettes.