Lyndwood

well I decided to swap out my rear leaf springs with another set to see if it helps my high rear end problem. going back to last year I discussed on here how my 74 sits awe-full high in the *** end like 3" to high over stock even with new 8" lowering bolts. after driving it around a bit (not much-no tags) and letting it sit it dropped about 1". I suspected that the rear spring was changed because i found some evidence of body work and the passenger side trailing arm/rotor/caliper had been replaced at one time, maybe a rear wheel impact or curb impact? so over the summer I was able to pick up a 7 leaf set up and figured I'd try it, maybe one of the last 3 owners replaced the original 9 leaf with an aftermarket 9 leaf and it was sprung too much? I went to drop the spring and after removing tension and the end bolts found one of the 4 spring bolts to be not very tight and the other 3 I had to break torque. after removing the bolts & spring I found the sides of 3 of the bolts threads were smashed flat and basically only 3-4 threads were engaged into the rear housing. I decided to replace the bolts with new ones and found that the 9 leafs should have 3.5" bolts and a 7 leaf should use 3.25" bolts, the bolts I took out are 3.125"! I am replacing the bolts with 3.250" and the 7 leaf but it makes me wonder if the 74 had a 7 leaf and an owner put in a 9 leaf and reused the shorter 7 leaf bolts?

'75

9 leaf was standard and the 7 leaf was optional.

Lyndwood

new up date:

Got my new 3.25" 9/16-12 bolts and installed the 7 leaf with no problems went in smoothly! went and looked at the 9 leaf I took out and found it was a 2.5" wide leaf and probably the reason the bolt threads were worn flat from rubbing against the sides of the leafs? If I am correct from my research the '74 came with a 2.25" 9 leaf rear spring and and option of a 7 leaf. If correct I believe one of the past owners had some sort of accident (hence the replacement parts in the rear area + the body work) and replaced the damaged original spring that may have been a 7 leaf due to the stock bolt length being re-used 3.25" x 9/16-12 and not the correct 3.50" x 9/16-12 bolts for a later year 9 leaf? Also this may explain why my car sat so high as the wider 9 leaf rear (late '78 & up) was a higher rate spring for a heavier car? correct me if I am wrong please.
even the 8" lowering bolts I previously put on look to long now bolted to the 7 leaf vs how they looked bolted to the 9 leaf I took out?

SwampeastMike

I believe you are correct about the spring width difference as the '78 gained about 200# over the '74.

Do you have the rear stabilizer bar running between the rear wheels at their rear. Do you also have the really beefy (1 1/8" diameter I believe) front stabilizer bar. If so yours very likely came with the Gymkhana suspension and the 7-leaf spring. If not it almost certainly came with the 9 leaf.

Lyndwood

no rear sway bar and a 13/16" or 7/8" front standard sway bar. I think your right it was originally a 2.25" 9 leaf its just the bolt length that is throwing me off and making me conclude it may have been a 7 leaf (as the 3.25" bolts are perfect with the 7 leaf I put in and barely bite 2-3 threads with the removed 9 leaf?
I found an read a few posts about what a vette should have suspension wise when its equipped with a 7 leaf set up, I'm not going to do any of that stuff at the moment. I'm just trying to get my *** end down to where is should be with out removing leafs from a 9 leaf for now, I will deal with the handling later ( I have put new koni's on the back and will be putting new koni's on the front but not changing anything else for now.

another prospect I am considering is that someone put an aftermarket 2.5" 9 leaf in as a replacement and it was arched to high???

RU7376vettes

78 and 79 had 2.5" wide springs all others are 2.25". A long time ago if the rear spring perch/rear cover cracked, the go to was to replace it with the 78-78 because it was stronger. My 73 had this done to it before I got it. I went through the same height issue you are fighting and ended up sending my 9 leaf spring to Eaton Detroit and they re-arched my spring to get the right height I wanted. I measured it before and told them where I wanted the car and they fixed it! My spring was in good condition, they can make you a spring to get where you want to be. I tried the TRW composite and it was higher than my 9 leaf!! I wrote all this up in an earlier post. The front has Global West A Arms with Viking Coil-overs.