Technical Tips > Post 84

Lowering my C4

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Thunder Kiss:
You'll find the rear will be dead easy, here is a (poorly focused) photo highlighting the bolt.
Looks like I need new spring cushions;mmm

corman:
OK, thats great Thunder Kiss . I'm grateful, when the bits arrive I'll get them in, hopefully before I come down in December.

77CVT:
For the rear, support the rear on jackstands.  Then jack up the spring making sure you use a c clamp (on the inner side) to stop the jack from moving and sending you to hospital.  Use a thin block of wood to stop the clamp from marking the spring.

Jack each side one at a time.  When the spring bolt becomes loose (spray som WD40 on the threads) undo the nut and remove the bolt taking note of where each spring pad was.

Put in the new bolt and spring pads, tighten up the nut and gently lower the spring.  When both sides are done you can remove the jackstands.  You can tighten/adjust with full pressure on the nut.  Hint:  It will be easier to do the nut up a fair way and loosen it to the height you want with the spring fully down.

The lower the nut on the bolt the lower the car.  To raise it tighten the nut up.

For the front - follow the Haynes manual to undo the lower control arms etc.  There are rubber/aluminium strips on top of the spring in the centre.  Replace these with the lowering wedges.  (Good luck with the ball joints!!!!)

Note: If you want to remove the spring, if you have a stock spring (non Z51) you will need to jack the car up at least 50-60cm !!!!

Remember - spray everything with WD40 or the like, make sure the beer is already cold and ensure little kiddies are out of earshot.  Have fun!

Vette Obsessed:
Good post 77CVT


--- Quote ---Originally posted by 77CVT

For the front - follow the Haynes manual to undo the lower control arms etc.  There are rubber/aluminium strips on top of the spring in the centre.  Replace these with the lowering wedges.  (Good luck with the ball joints!!!!)


--- End quote ---


Great step by step procedure there 77CVT, here is my two cents in addition to what you posted for the front:

Some cars may have more than one aluminium shim - remove them all and then you have to remove/cut off the rubber cushion that is bonded to either side of the top section of the spring.  Be forewarned that cutting the rubber bushing off the top of the spring is the most tedious part of the job - I hated doing it (be careful not to gouge the fibreglass spring or remove a finger while doing it).  If you measure the height of the rubber ontop of the spring (the bit you cut off) + the shim(s) above it combined, subtract the height of the replacement plastic shim to determine how much to trim the top edges of your spring retainer down.  You may want to keep the aluminium shims from atop the spring for use under the spring retainer* if you run out of thread on the retainer bolts (you probably will).

I measured the height at the chassis on each corner of my car before lowering (so as to keep track of changes and maintain the factory "rake" from front to rear.  Lowering just the rear may cause issues at high speed (more air under the front).  I can't verify this firsthand but don't want to find out either...

*If your car is a pre-87 car you may need to buy the updated aluminium spring retainers for the front spring (which you will have to trim down after lowering the car).  If you don't trim them your spring won't be securely mounted.

corman:
Thanks guys I grateful for your input. I not sure that lowering is worth the trouble yet, and I can see your point Vette Obsessed with just lowering the arse. I was a bit concerned with tyre clearance also on the back, I might wait and see the other Vettes in the club to find out how mine compares in height.

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