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C5 Suspension Spring Swap

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Tools Needed:

- 21mm wrench
- 10mm socket
- 13mm socket
- 15mm socket
- 18mm socket
- 19mm deep socket or lug nut wrench for wheel removal
- 2 Jackstands
- Floor jack
- Car Ramps
- Torque wrench

Things you will need:

- Front and/or Rear spring to install
- Tube of medium strength loctite

Torque specs used in this document:

- Spring bracket bolts 46 lb/ft
- Upper A-Arm bolts 48 lb/ft
- Brake Caliper Bolts 23 lb/ft
- Swaybar endlink nuts 53 lb/ft
- Shock Absorber lower bolts 21 lb/ft


One of the great things about the C5 Corvette is that it achieves great handling while still offering a luxury like ride. For a majority of people, this base (FE1) suspension is perfect. For some of us, we want just a *little* more than the next guy. GM realized this and offered the "Z51" (FE3) option package which, among other things, increased the spring rate on the suspension. For those that needed even something more than that, the Z06 (FE4) package came along in 2001 and it offered a stiffer rear spring over the Z51 package.

What this all means is that we now have some OEM choices to pick from for upgraded springs. There are also some aftermarket choices out there if that is more what you are interested in. For me, OEM was the way to go.

The GM part numbers for the different suspension springs are:
- Z06 Front spring: 22178729
- Z06 Rear spring: 22188038
- Z51 Front spring: 22178729 (note: same as Z06)
- Z51 Rear spring: 22179020
- Base Front Spring: 22178728
- Base Rear Spring: 22179019

All GM springs come with the bushings pre-installed. The front springs will come with the adjusters, while the rear spring will not (you can reuse your stock ones).

One last thing before we get started.....I'd like to thank 97C5Envy for some tips on this upgrade. He told me it was easy, and sure enough, it was!

Lets begin:

Rear spring swap:

First we need to get the rear of the car in the air. Chock off the front wheels and jack up the rear of the car by jacking up the rear crossmember (the big aluminum support under the differential), and then place 2 jack stands under the cross member and lower the car onto it.
Now, look under the car and see how the spring is setup. It's a big black bar of fiberglass that runs from one side of the car to the other. At the ends of the spring, a big long bolt goes through the spring and attaches to the lower A-arm. This is what controls the rear of the car's ride height. More towards the middle of the spring, there are 2 brackets that mount the spring to the cross member. It's a pretty simple layout.

What I do next is optional, however it really helped me to get the car sitting at an even height after the spring swap. I took some tape (in my case, yellow tape) and wrapped it around the bolt so that the top of the tape was even with the metal of the lower A-arm. It's just a visual way to see how far in the bolts should be so we can at least get it close when we re-assemble things later.
We need to relieve all the tension on the springs next. Place a 21 mm wrench on the top nut on one of the spring adjuster bolts, and then use an 18mm socketwrench on the head of the bolt to loosen it. Your tape marking should be moving downwards as you loosen. Do this for the other side as well.

NOTE: When you remove the bolt, keep the bushings in order and remember how they bolt on.
The spring is now under no tension at all. Using a 13mm socket wrench, unbolt both brackets that hold the spring up so the brackets are loose, but leave the bolts all threaded in at least a few threads. Once all 4 are loose, remove one side's bolts totally, then do the other and the spring will be totally lose. Remove it from the car and set it aside.
Now you have no spring! This is what the underneath of your car looks like with no spring mounted. Hopefully yours is a little cleaner than mine was.
Now that we've got the spring off lets see how it compares to the new spring we're putting it in. The Z06 spring is stiffer, so obviously to have the car retain a somewhat similar ride height the spring will need to have less arch in it.

When we set the springs side by side, you can see the difference between the stock (FE1) and Z06 (FE4) springs. The FE4 spring is pictured in front of the FE1 spring.
Let's get back to reassembly.

Lift the new spring up in place (the spring should be symmetrical, but if in doubt, on a stock car the casting number goes towards the passenger side, facing down, so just put your spring back like that.

Hold the spring up with one hand and with your other hand start the mounting bracket bolts until all four are started. Apply some red loctite to the showing threads of all 4 bolts.

Now, tighten up the spring mounting bracket bolts a little at a time on each side and make sure spring is centered. The bushings will not be exactly dead center on in each spring mounting bracket, but you still need to ensure that the spring itself is centered on the car. Keep tightening these bolts until the bracket is totally bolted up, and then torque the bolts to 46 lb/ft.
Now, reinsert your stock adjusting bolts on each end of the spring, making sure to keep the bushings how they were oriented before the install. Tighten the bolts back up so the marking is about in the same location as it was before (using the tape as reference), then tighten 2-3 turns more on each bolt to compensate for arch change between springs if you went from FE1 to FE4 springs. You may find you need to do a couple more turns later once the car settles, but for now this should be somewhat close.

That is it for the rear springs. Jack up the car, remove the stands, and lower it. When you first lower it the car will look MUCH higher than before, but after a test drive or two it'll settle back down to where it'll stay. If the height is too high or too low, you can easily get back in there and add or subtract a few turns on the bolts.

Front spring swap:

First, we need to get the front of the car up in the air. The method I use is to drive the car up on rhino ramps first, and then break the lugnuts free on both of the front wheels using a 19mm deep socket on a breaker bar (a tire iron will work just as well). Then I use a jack to jack up the front crossmember and then place 2 jack stands to support the crossmember. This is shown in the picture to the left.

Once the car is up, you can then finish unscrewing the lug nuts and remove both front wheels.
Next we're going to work on the drivers side of the car for a while. Some things we're ONLY going to do on the drivers side, other's we'll end up doing on the other side of the car as well. You can do everything to both sides if you want, but not doing it will save you time.

On the drivers side ONLY, we need to unbolt the two caliper bolts that hold the caliper onto the caliper frame. Using either a 16mm open ended wrench or a adjustable crescent wrench, hold the metal sleeve that the caliper bolt goes through and use a 15mm socket wrench to loosen the 2 caliper bolts. The picture on the right shows one of the 2 bolts being removed.

While we're at it over here, also unplug the ABS wheel sensor that's going to the drivers side spindle. It's the only wiring connector going over there so it'll be easy to find and should just easily unclip.
Next we need to unbolt the drivers side swaybar endlink.

On 2002 cars, or cars with the new aluminum style endlinks, you'll need an 18mm open ended wrench and an 18mm socket wrench to remove it. They remove similar to the way the brake caliper bolts were, you use the open wrench to keep the shaft from spinning and the socket wrench to loosen the nut.

If you have the old style plastic endlinks, you'll need an 18mm wrench to turn the nut and a T-45 torx bit to keep the threads from spinning.
Now we're going to start unbolting some of the suspension on the drivers side. To make sure we're safe, we need to place a floor jack under the ball on the lower A-arm and jack up the A-arm just about 1/8" (just enough to provide just a slight bit of tension). Once we unbolt suspension parts, we'll slowly lower the jack and that will relieve tension our spring is under.
So, lets get started unbolting stuff. The upper A-arm is the first thing we need to unbolt. It mounts to the frame using 4 13mm bolts as shown in the picture. Under each bolt there may or may not be some shims. If there is a shim (looks like a washer), make SURE you keep the shim on the proper bolt and keep the bolts in order. This is essential to keeping your alignment setup properly.

Once all 4 bolts are removed, the A-arm will be free and the rotor/spindle will be pretty floppy. This is good.
Next, at the bottom of the shock absorber, there are 2 13mm bolts with 2 13mm nuts on the bottom ends of them. Unbolt both of these and remove the bolts. Your lower A-arm is now totally free to hang down, so lets let it do that. SLOWLY lower the jack and the a-arm will drop down somewhat until all spring pressure is relieved. We're done on the drivers side!

Now, go to the passenger side and place the jack under that side and raise it up 1/8" like you did the other side. On the passengers side, unbolt the 4 upper a-arm bolts (REMEMBER, keep the shims in order!) and 2 bottom shock bolts. Now lower the jack. NOTE: You should be able to leave the caliper mounted and the swaybar attached on the passengers side. Once the jack is lowered, make sure the brake line going to the caliper isn't getting stretched too much. As long as your wheels were pointed straight ahead you should be fine.

The spring should now be relieved of tension. If there is still tension, it's probably because your spring height adjusters are adjusted out some. If this is the case, mark where the threads on the adjusting bolts are with tape and turn the adjusters with a 10mm wrench on the top of the bolt so the threads are sticking up as much as possible (thus relieving tension).
Now that the spring is totally relieved of pressure, we can unbolt the 2 metal spring mounting brackets that hold the spring to the crossmember. Using a 13mm wrench, unbolt the 4 bolts (2 on each mounting bracket).
Now the spring is loose, we need to lower the drivers a-arm as much as possible, and slide the spring out about 6" to 12" over towards the drivers side. Remember when we removed the caliper and swaybar endlink on this side? That is so we can push this a-arm down as far as possible so we can slide the spring over. The diagram on the left shows what I'm talking about.
Once the spring is slid over enough, we can then LOWER the passenger side of the spring out of the opening in the passenger side A-ARM, and then pull the whole spring out. In effect, we're moving the whole spring towards the drivers side so we can lower the passengers side down. Once the passengers side of the spring is down, you can just pull the whole spring out from underneath the car. That's it!
So, grab your new spring and lay it down next to your old one. In this picture, my old spring is on the right. As you can see, I had my height adjuster cut down so my car could ride much lower. If you want to make your car ride much lower, now is a good time to cut your spring adjuster with a hack saw. You'll want to cut about 85% of the whole rubber bushing off.

Anyway, if you aren't planning on lowering the car, then just make sure you dial your new springs adjusters to the approximate same height that your old springs adjusters were. This isn't too big of a deal since the car's height can always be changed later. Just get it as close as possible for now.
Now, all that's left is to reverse the procedure above. The spring is symmetrical so it really shouldn't matter which way the spring goes in, but if in doubt it seems GM always puts the stamped casting number/part # sticker towards the passenger side (facing down). Now, slide in the drivers side of the spring up into the drivers side A-arm and slide it over until you can get the passengers side of the spring back up into place.

Center the spring as best as possible and start reinstalling the spring mounting brackets. You need to make sure you apply some loctite to the threads of the spring mounting bracket bolts before you reinstall them. Also, be sure to slowly tighten each side a little bit at a time so you can make sure the spring is indeed centered on the car as best as possible.

Now that the spring is mounted back up to the crossmember, we can reassemble the passengers side. Use the jack to jack up the A-arm again and reinstall the bottom two shock mounting bolts. Torque these to 21 lb/ft. Reinstall the 4 upper A-arm bolts (use loctite!) with proper shims in proper order, and torque them to 48 lb/ft. Lower the jack, and move over to the drivers side.

On the drivers side, we'll do it just like the passengers side. Jack it up, reinstall the shock bolts and reinstall the 4 a-arm bolts/shims. Now, re-mount the caliper onto the caliper frame and using the crescent wrench to hold the sleeve, torque these bolts (use loctite!) to 23 lb/ft. Re-attach the ABS wire sensor plug.

Finally, reattach the swaybar endlink and torque the swaybar endlink nut to 53 lb/ft

Lower the car back down and that's it! You're all done!

When you first lower the car you'll notice that it's sitting really high up. Go take it out on a test drive and let the suspension settle first. If it's still too high, or too low, you can then re-adjust the bolts.

After swapping to Z06 springs, the difference was definitly noticable. It felt like steering response was increased a fair amount and ride quality didn't really seem to suffer at all. Since I found the springs used off a wrecked car this modification was well worth the money.
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