OK, so I dug out the manual to do some homework here.... (I haven't put the C4 on the lift yet to look at the car - Greg's project is immobile at the moment) ;) so go easy on me, :blueangel: I'm just getting a 3D visual in my head from drawings. I haven't logged much C4 under car time at all yet. :lol:

How do you guys unload the ends of the rear spring? I know on the C3 I was able to use a 2x4 just the right length and jack it up. But that was with the car on stands low to the ground. The guys at Tony's corvette had a really long pry bar they used and leveraged against the camber rod. Is it possible to do that with the C4? If not, how do you unload the spring when it's in the air on a lift? I'm presuming the energy in that fiberglass spring is similar to the C3 spring (which is substantial!)

Also, I've seen mention in other threads of delaminating springs and it being caused by some overly aggresive cleaners or something. Would simple green be OK to use on the spring? What kinds of cleaners damage the composite material? :eek:

In my other thread someone posted a tip to mark the spring bolt setting to get the ride height set back correctly afterwards. What's a good way to do this on a dirty bolt? :cuss Just count the number of turns of the bolt or ???

Thanks, ~Juliet

 

I replaced my rear spring this year because of delamination. I used a spring from VBP. The job is pretty easy on the rear spring. Here's how to do it:

1. Jack up the rear of the car, remove the rear wheels.
2. Take a floor jack, and with a wooden or rubber block in the jack cradle, position it under the outboard side of the spring. Jack it up against the surface of the spring until you see it take the tension off the spring bolt. When the tension is off the bolt, remove the nut and then lower the floor jack (gently) until the spring is free.
3. Repeat this process for the other side.
4. Remove the bolts which bolt the center of the spring to the rear differential case.
5. Slide the spring laterally out via one of the rear wheel wells. This requires a bit of gymnastics, but it will slide out.
6. Basically reverse this process to install your new spring.
7. I strongly urge you to replace the old outboard bolts, and the bushing as well.

Hope this helps. If you have any other questions that I can help out with let me know.

 

Thanks Tom, That's pretty much the same way I removed the rear spring on my C3. Is there a way to use a lever and remove the spring tension with the car up higher in the air? ~Juliet

 

GM has a special tool that clamps to the spring and simply pushes both ends up.

the other option would be a transmission jack.

 

I just had another idea...

you have a lift, right?

ok... get a nice solid 4x4 from the local lumber yard. take said 4x4 and prop it under the car, then SLOWLY lower the car onto the 4x4. That should take enough off the spring...

repeat for other side. :D

 

On my '95 the bolts have a cotter pin hole in them. When the nut is positioned on the bolt such that the cotter pin slides through the bolt and fits in the slots on the nut then it is at stock setting. This is if you're referring to the 8" ride height bolts. I'm still learning in this area, as recent post about my rear suspension is evidence of :hat

 

Jack the spring to take the tension off, it's that easy.

Vic

 

I have removed the spring bolts several times and my method is to get the car on stands, take my floor jack and place the lip of the jack pad just under the outer end of the spring, there is a steel reinforcement there and jack the weight off enough to remove the bolt, then let it down. I have had absolutely not problems with this method. The OEM rear spring doesn't have quite as much arch unloaded as the front one does. That's my story and I'm stickin' to it...

 

Thanks for the input everyone. One more question nobody has addressed yet, so if someone has any info please post it. :)

 

I am not convinced that cleaners are attacking the resins in the spring. I guess it is possible... but the amount would have to be killer.

and yes, simple green is safe on just about any surface. I have even used it to clean stubborn stains off of paint.

 

I use a floor jack with a piece of wood on it after the car in on jack stands. Since you are on a lift, then you could just use the 4x4 as mentioned earlier and lower the car onto it. Do each side one at a time and no problems. Springs aren't that sensitive to chemicals. The things are surrounded by petroleum products all the time. I mean what's harsher then gas, tranny fluid, motor oil, diff lube, antifreeze, axle grease and whatnot. The rear may delaminate because of impact with road debris, improper maintenance, excess heat, hard driving abuse (envision dukes of hazzard jumps), and an exwife with a hacksaw fetish.


[Modified by Goody, 8:10 AM 12/2/2002]

 

Thanks. :)

:lol: :jester Gawd, I hope not! :rolleyes:

 

Man, if its an air/hydraulic lift like I have worked around, i wouldn't dare try this method. There is really no direct control over the height of the car. You let some air out of the lift, and then a few seconds later, the car settles to its new height. Your guess is as good as mine about where that will be. You might knock the car right off the lift if you propped something under it and tried to bleed air from the lift.

Just thought I would put out the warning in case someone tried it before thinking it through.

-Ken

 

:nono:
I would have to agree that trying to lower the car from a lift to decompress the spring sounds unsafe. I would not ever try such a thing. Either do it with the car on jackstands using a floor jack, buy the spring compression tool from GM, or pay a dealer to replace the spring. For pete's sake don't try to drop a car on a lift precisely enough to compress the spring. That's an accident waiting to happen.

 

Hmm, Okay I guess I will forego my recommendation on the lift/spring Wyle E. Coyote trick....do it on the floor with a regular jack. If something fails, it shouldn't be as traumatic.

 

for some reason, I don't think its an air lift, but an electric one...

I agree - an air lift that would get tacky. no real control... but on an electric one? I think it would work ok. we are only talking a couple of inches to compress the spring.

Also, the tranny jack sounds like the best solution... just spin that ole handle and watch it compress the spring.

 

Thanks for all the inputs. I'll admit I wasn't going to try the lower the lift onto a 4x4 thing. ;) THe lift operation is not that smooth and controllable and I'm not going to be under the lift without the locks engaged and the car locked in position. I can just get the spring unsprung with the car near the ground using the regular floor jack and then raise up the car to take care of the rest of the work. Or else put a long 4x4 on the floor jack and use the floor jack (which is easy to inch up slowly & controlably) to get the tension off the spring. Greg takes the old Dana rear to the shipping terminal tomorrow, so he'll be able to get his 65 moved over so I can get the 87 on the lift and get started on it this week. :yesnod: Thanks for the input & suggestions. :) ~Juliet

 

I'm not sure I agree with this part. I've done this job (too) many times myself to replace a sereis of defective differentails and I'm a little confused about sliding the spring out. I have always removed the rear exhaust y-pipe and mufflers before doing anything else in order to get to the four bolts holding the spring on. Are you saying that the spring can be taken out with the exhaust in place?

My other two cents of advice is to be very careful when tightening down the aluminum spring retention brackets. If they are in any type of bind, they will break. Trust me, I know. Also, you should check to see that the spring is level by measuring from some point on the frame above to the end of the spring on both sides before putting the long bolt back in and preloading it at the knuckle. I was able to correct a leaning condition by removing one of the thin shims from the high side.

 

Thanks for asking that Vetracer. I haven't a clue, but hopefully others will chime in here with their experiences. :yesnod:

On the subject of removing the rear spring... I was hoping to just take the tension off the ends, and physically leave it connected to the diff & the diff in place. Do I really need to fully remove the spring to get at the U-joints and half-shafts? :confused:

 

If it is the half shafts that you want out, then you shouldn't HAVE to take the spring off, but it would sure make things easier, especially since you WILL have to take the bolts out connecting the spring to the knuckle. you would also be well served to remove your camber rods and toe link assembly, as you wil need to be able to move the knuckle outwards far enough to get the half shafts out. I think it is better to just remove the three 15mm bolts holding the toe rods to the back if the carrier to get the movement you need than it is to remove the toe rod ends from the knuckle. It will also help to have another person help you pull the wheel/knuckle assembly outward while you pull the half shaft out.