Lowering C2/C3 Corvette

Before

After

 

Front of my '68 sat higher then I liked and I wanted it lower. I took a few photos while lowering but as always not enough. But first due to danger of compressed springs and personal injury please read below


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These tips should work on C2 & C3 but you should be the judge of that.

There are lots of options and opinions on "how much" - "how to" - "suppliers" but this is just what I did for the results I was expecting. My '68 is just a Friday night cruiser and not track/race car so I didn't need the latest wiz-bang setup just replace springs, shocks and bolts. On my '65 I used a different approach which you can view here ===>> '65 Suspension

Vette is a 1968 (Serial # 76) Small Block 4 speed with Power Steering & Brakes and pretty much stock (iron head, intake and exhaust). This is important as to the amount of weight (load) the springs will be carrying. A Big Block with iron heads and A/C will have much greater load vs. a Small Block with aluminum heads and intake and will come into play when cutting coils.

I opted for a low load rated spring (Moog 5758) Spring Rate (Lbs/in) is #474 which you can find almost anywhere for about $50. Common ratings are #460 & #550. I also needed new shocks and went with KYB Gas-Adjust front & rear. Never used these before but had good luck with KYB GR2's on my '65. Also got 8" rear spring bolts (rubber bushings) for rear end. Didn't really to need to lower rear but definitely needed new bushings.

I also replaced brake pads, old rotting brake hoses and painted calipers while I was this for in but did not include in below steps.


Steps I used for front:
  1. Park car on level surface
  2. Leave in gear and set parking brake
  3. Measure all 4 corners ride height for reference
  4. Jack up / secure on jack stands ** high enough ** for control arm to swing down for spring removal
  5. Remove wheel.
  6. Remove shock.
  7. Disconnect stabilizer bar.
  8. Remove brake caliper from mount and secure out of way ** Be careful with brake hose **
  9. Place floor hydraulic jack under lower control arm and lift up until the spring starts to compress.
  10. Loosen upper ball joint nut several turns and lower jack away from the control arm. ** Do Not Remove Nut at this Point **
  11. Start hammering on the steering knuckle and let it pop upper ball joint loose from coil spring pressure.
  12. Place hydraulic jack back under control arm and jack up compressing spring.
  13. Put a chain through the spring at this point. ** MUST DO THIS STEP **
  14. Remove nut from upper ball joint.
  15. Lower jack slowly and lower control arm will fall way and coil spring pressure will be released.
  16. Remove chain ** If 100% sure pressure is released from spring **
  17. Pull spring out from assembly.
  18. ** Leave lower ball joint fully installed to steering knuckle.**

At this point you can replace with new spring or cut coils. Then reverse above steps.


Click on images for larger view

Note rear ride height Note front ride height New Parts Jack up & secure
Ready to start Chain installed Old vs. New Old vs. New

At this point I had replaced with new springs & shocks and remove from jack stands. Went for a 4-5 mile ride on bumpy streets/roads to make sure Vette settle and there wasn't any problems which there wasn't. Parked back on level ground and re-measured all 4 corners. ** Absolutely "NO CHANGE" in ride height ** So I start back at step 1 and pulled springs (1 at a time) and cut 1 coil off and reinstalled. This is where the various vehicle weight will make a difference, cutting 1 coil on mine resulted in 2" lowering, on yours it could be more or less. I'll leave that GUESS up to you. Had it not been enough I would have had to remove and cut more from coil spring. But results was what I was looking for.


As for as cutting I used a die grinder with premium cut off wheel. Other have accomplish with hack saw but the consensus is NO TORCH CUTTING.

 

Steps I used for rear:
  1. Park car on level surface ** I moved from outside into garage for rears **
  2. Jack up / secure on jack stands
  3. Remove wheel.
  4. Remove shock.
  5. Install new shock.
  6. C-Clamp block of wood to spring ** MUST DO THIS STEP **
  7. Jack up spring just enough to relieve pressure off of bolt/nut.
  8. Remove bolt/bushings
  9. Install new bolt/bushings
  10. Let jack down slowly

At this point you can raise/lower car by adjusting nut on bolt.

 

Jack up & secure Old vs. New Take pressure off of spring
New 8" Bolt Installed Before  After

Ride height

    Original 

New

RF    27 5/8 

25 5/8

LF   27 5/8  25 1/2
RR   27 3/8  27
LR 27 1/8   26 7/8

Will check and adjust at a later date & 50+ miles then have alignment done.

Initial opinion is that ride is smoother (shocks) and seem to handle better. Has a overall better feel.

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2009 GB Janssen