greyghost79

I purchased a composite rear spring for my '79 vette a while back. when I installed it I discovered that the composite spring was not as wide as the factory steel spring I removed. This causes issues when trying to torque down the mounting plate. It bends and wants to curve around the spring. I believe I've read about others having this problem. Is there a spacer that can be used to take up the extra space, or some other option. Thx.

kanvasman

From what I understand there are 2 different widths for these springs. The change is in 1978 I believe. ( I willvknow for sure when the one I ordered gets here in a a few weeks). Most of the vendors show 2 different set ups but short of getting a new diff cover ( where the spring sits) I am not sure of what can be done. Haven't done much work on one yet, but will be in a short time. Good luck.

cagotzmann

You need something like this.
https://corvetteparts.com/c3/item/sp...-1-2-1978-1979

This is one I found with a quick google search. I would see if any of the sponsors here also have something similar. I still have problems with the plate bending if your not careful. I would torque in gradual steps. I started @ 15, 20,25,30,35.

greyghost79

ok, thx.

Ghunt

Send it back and get the right size. 68 to78 is 2 1/4", 78 to 82 is 2 1/2" wide,
I just changed mine, steel 9 leaf, 2 1/4" 1968 and no bending of the plate with
70ft lbs tork. I had to get longer grade 8 bolts because the after market spring is thicker.

cagotzmann

Proper torque specs for 79 is 33 ft lbs no need to go crazy on this.

Also 78-79 had 2 spring width's. 78-79 7 leaf (gymkhana) is 2 1/4" 78-79 9 leaf is 2 1/2". The diff cover is sized based on the factory spring installed. All the after market mono leaf springs usually are 2 1/4".
I believe 80-82 already changed to a mono spring design which is different than the 78-79 years.

There would be no value in sending it back since there is no 2 1/2 width mono springs for the 79 corvette. You have 3 options. Add the spacers, replace the diff cover to the correct width, install the original steel spring (9 leaf) @ 2 1/2" width.

Ghunt

My 68 steel spring according to the aim tork is 70ft lb. The bolts for the 68 are 9/16 diameter

cagotzmann

Thats a big difference from my 1979 GM Service Manual. I didn't think there would be that much of a difference. My VB&P install guide for the mono spring was listed @ 35-45 ft lbs. The GM Service manual for the steel spring only 33 ft lbs. ?

Ghunt

I think they reduced the bolt diameter from 9/16 to 7/16.

jb78L-82

I really would not be too worried about the bolt torque on the bolts. I put in my mono spring in 1986 and just tightened the bolts by hand like most fasteners on the C3 until reasonable tight-been perfect for 28 years….So far on the C3 the only areas where I use a torque wrench religiously are cylinder head bolts since the tension has to be correct and lug nuts for the wheels. Same on my other cars with the exception of wheel nuts for FWD cars for the front wheel bearing hub--too tight and the hub will fail prematurely….sometimes I think that folks get a little crazy about this stuff especially on C3 where a torque wrench probably was NEVER used to fix parts after it left the factory...

greyghost79

so nobody makes a 2 1/2 inch mono spring ???

Super6

Have you contacted the company that originally supplied the spring? Maybe they won't take it back if a long time has gone by, but they ought to be able to help you do the best thing now with the situation you have.

greyghost79

Yup, they gave me the same answer CAGOTZMANN did... best solution is to get a new differential cover with the 2 1/4" slot for the spring.... or can try to "rig" spacers..... however they did say that it should be ok the way it is.... the spring can't really go anywhere as long as the support bracket is attached... apparently the 78 and 79 corvettes went rogue on rear spring.... 9 leaf springs were 2 1/2 " in those years....... which apparently is an "off" size....

thegazman

GM made a set of spacers to compensate for the 1/4 inch difference in spring width on the 78-79. Corvette Central has them for $12.50 a set, part number 583179. A new heavy duty differential cover will cost you $159.95. The choice is yours.

cagotzmann

That is the direction I went (spacers) in 1982 when I changed from a 9 leaf to 7 leaf steel, and then I used the same spacers for the mono spring (VB&P) I installed 3 years ago.

Super6

You need to do something, I had the same problem years ago and the spring cracked. The spacers seem like the obvious choice.

greyghost79

I guess I'll try the spacers first. Thx for the info on where to get them