Quote:
Originally Posted by HWYSTR455
I think the real moral to the story is that you need a spring that is basically in the center of the travel range of the suspension at ride height. Doing that would allow use of a 'standard' travel-length shock.
I still say if you use crappy suppliers with poor tolerances you will never get an expected result. And I personally have had issues with Eaton, CCS, and a number of other places that tout 'factory correct spec springs'.
Also, many just lump together applications so they can limit the production runs for savings.
Although a Bonnie is longer than a Cat, they are still both B-bodies, like the GP for those 2 years. You should be able to get a spring that works, guessing it would be the rate what matters. 122lbs seems pretty light to me, but not sure what the goal is for the car.
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Yes, the claim of "factory specs" is BS. Clearly I mismatched the shock/spring combo on my car thinking they'd work and paid dearly for it. Never worked as it should. They make the one HD spring that will work on all P8 cars, yet fail to inform the buyer that the short wheel base cars will set at least an inch higher in the rear due to the lower downward forces on the spring, so put the long 24" Monroes in to cover the extension.
At ride ht, the shock ratio of extension to compression should be about 40/60, but 50/50 is OK too.
When those cars were new, they sat on the low side. Note the tire and wheel coverage on the rear wheel. I've compared a lot of the 65-6 car stances in profile photos and you can tell which cars still have stock rate springs and which have HD. If you see some tire above the top of rim, it's likely an HD spring. Given that Monroes are a popular shock for these cars, it's good odds that was used with the HD spring. I prefer that it set higher than stock, they look kind of dumpy when they're that low with 14" wheels.
Factory spring rate specs of 122 and 140 were sourced from the AMA specs for the '65 Pontiac that they provided in the PHS packet. The parts catalog lists several more rear springs, but that's another story.