Leaf spring oddity

[Tom L.]

last year at Carlisle I purchased a "new to me" spring for my '72. The gentleman that sold it to me said it came out of a '69 and that he took it out himself. Brought it home and put it on a shelf.

fast forward to a few weeks ago. When I looked at it more closely I noticed that it had 10 leafs, an extra small flat one on top. After disassembly I observed that the liners were in their correct order, they has typical wear marks on the ends there the spring above it moved, the leafs had the typical greyish finish around the bolt hole and that the bolt seemed original. The bolt had head markings that indicated that it was a grade 8 bolt and had the head marking ABN. Nothing about the spring indicates that its not an original piece. Any ideas on the extra???

[Russ S.]

Re: Leaf spring oddity

With the top leaves straight instead of curved, I believe I am correct in saying that this spring is out of a mid year.

[Edward J.]

Re: Leaf spring oddity

Tom, I believe what you have I a later GM service replacement spring. I have seen this before. rear springs came in the 7 or 9 leaf from the factory.

[Tom L.]

Re: Leaf spring oddity

Thanks Ed, from your comments you're suggesting that the additional to leaf might be typical for a replacement spring? I've never read anything about a 10 leaf, two stage spring for these cars.

Reaching back to Russ's comment, I'm almost positive that all standard rear springsup to '72 were two stage, 9 leaf srings. The exception was the F-41, 7 leaf spring.

[Joe L.]

Re: Leaf spring oddity

With the top leaves straight instead of curved, I believe I am correct in saying that this spring is out of a mid year.

Russ------

The same rear spring used for standard suspension 1964-67 Corvettes was also used for standard suspension 1968-69 Corvettes.

[Joe L.]

Re: Leaf spring oddity

Thanks Ed, from your comments you're suggesting that the additional to leaf might be typical for a replacement spring? I've never read anything about a 10 leaf, two stage spring for these cars.

Reaching back to Russ's comment, I'm almost positive that all standard rear springsup to '72 were two stage, 9 leaf srings. The exception was the F-41, 7 leaf spring.

Tom------


The GM replacement spring for standard suspension 1963-72 Corvettes was, for many years, a 10 leaf spring.

[Tom L.]

Re: Leaf spring oddity

Joe, was the replacement GM spring a single or two stage spring?

Not saying I won't use it but just want to be sure that the extra leaf on top is not a ride height issue.

[Patrick B.]

Re: Leaf spring oddity

I think the standard 70 to at least 72 spring is the same 9 leaf spring as earlier Corvettes. My 70 certainly has a 9 leaf spring that appears identical to the spring in my 67. I have seen the extra plate tenth leaf before and also associated it with later GM replacement springs. If the spring thickness of your new spring minus the extra plate is the same as your old spring the rest of it is probably a good replacement for the 70 spring.

[Joe L.]

Re: Leaf spring oddity

Joe, was the replacement GM spring a single or two stage spring?

Not saying I won't use it but just want to be sure that the extra leaf on top is not a ride height issue.

Tom-----

The 10 leaf replacement springs was a two stage spring.

However, much later it was eventually replaced for SERVICE by the 7 leaf spring also used for HD suspension applications.

[Joe L.]

Re: Leaf spring oddity

I think the standard 70 to at least 72 spring is the same 9 leaf spring as earlier Corvettes. My 70 certainly has a 9 leaf spring that appears identical to the spring in my 67. I have seen the extra plate tenth leaf before and also associated it with later GM replacement springs. If the spring thickness of your new spring minus the extra plate is the same as your old spring the rest of it is probably a good replacement for the 70 spring.

Patrick-----


Yes, the 9 leaf spring was used for standard suspension 1964-1974 Corvettes. The AIM's do indicate that the same part number, GM #3850839, was used for all of these years. However, I believe that the part number actually changed to GM #3977579 beginning with the 1970 model year. The 3977579 appears identical to the 3850839 but there must be some difference, albeit not readily discernible, between the 2 part numbers.