Hello. I have a few questions about the standard 10 leaf spring for a `75. The TIM&JG gives part # 356825 for `75 and # 370388 for `76-`77. The AIM gives part # 346906 for `75. Which part # would be correct and what would be the difference between these springs? Is there another year the same as the `75? One last question, is the part # located anywhere on the spring assembly? Thanks for any help.
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75 vs. 76/77 rear spring differences; not much
Brian,
The production part number for the 1975 standard 10-leaf spring is 346906. The production part number for the 1976 and 1977 standard 10-leaf spring is 362153. These springs are virtually identical; 10-leaves, 9 liners, 0.194" leaf thickness for all leaves; 2.390" assembled thickness; stiffness of 196 lb/in @ design load of 1420 lbs. The only difference between them is the camber or arch at the design load. The 1975 spring has a -0.10" camber at a design load; the 76/77 spring has a +0.21" camber at the same design load. This indicates that the arch of the two springs when unloaded is ever so slightly different.
I can only guess that the part numbers listed in the TIM&JG are for spring assemblies that might include attaching hardware. Joe Lucia might be able to give you confirmation of this.
In any case, all GM leaf springs for C3 cars have been discontinued and I doubt you will be able to find an NOS example on e-bay or anywhere else. I've been looking for a GM NOS standard 9-leaf spring for 64-74 and I have never seen one for sale on e-bay in more than 4 years of looking.
If you know for certain that your spring needs to be replaced, I suggest you contact Mike Eaton at Eaton Detroit Spring. His contact info can be found by a google search.
Gary Beaupre -
Re: 75 vs. 76/77 rear spring differences; not much
Thanks for the detailed answer Gary. The original spring on our car was changed a few years ago when we had a new differential cover installed. The back squatted quite a bit and the shop owner told us the spring was " shot ". I had no idea at the time that a spring could be rebuilt or even rearched so I didn`t keep it. What I would like to do is find a good spring to rebuild that would fit a `75. Thanks again for the answer. BrianComment
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Re: `75 C3 Rear Spring
Brian,
I may have a spring that might fit your requirements. I bought it off of e-bay, but it is not correct for my 69. It is a 10 leaf spring that was from a 1976. The spring appears to be in good original condition. If you're in interested in purchasing it I can take some pictures and e-mail them to you.
Regards,
GeorgeComment
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Re: `75 C3 Rear Spring
George, I`m going to look at a couple of springs locally but I would like to see the spring you have and what you want for it. Thanks, BrianComment
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