I'm trying to find which Moog springs to run on my 88 GTA - I have returned it to stock and am wanting a stock-ish height.
I've tried:
Moog 5662 (706lbs) - These sat just a bit too high for my liking, cutting them made the ride too harsh.
Moog 5658 (579lbs) - sat just barely too low, putting weight on fender would compress to bumpstops. Rode nice/bouncy.

Does anyone have input on 5660s (639lbs) or 5608s (420lbs taller load/free height)?

Moog's website recommends 5662 w/16" wheels & 5608 w/15" wheels so I'm curious if anyone has any input on that too?

 

Wish i could remember what i came up with when i reseached that some years back.

 

Call Sam Strano.
stranoparts.com

 

Moog springs are designed to have 11 inch compressed height under the weight listed on their website. Those weights are sprung weight on springs, not the weight on tires. You'll end up sitting too tall if you use the scale weight of the vehicle.

 

I've always felt Moog springs sit the car way too high for the model they list for your car's options (A/C, etc). It's kind of a crap-shoot finding ones that you like the ride height and feel of.

 

Back in 2020 I crawled the Moog website for every spring tied to any 82-92 Firebird and found 13 part numbers for front, 2 part numbers for rear. I just crawled their website again today and I'm shocked how many of those part numbers have been eliminated.

 

Based on Moog's published spring specs from their website, https://www.moog-suspension-parts.co...il_springs.asp

Static height with Moog-5660 will be right in the middle between Moog-5662 (taller) and Moog-5658 (lower).
Out of curiosity, how did you find that Moog-5660 part number?

Moog-5608 will sit taller than all those unless the car is on the very heavy side. Even then it will never sit as low as Moog-5660.

 

Hey OP check out my older thread - 'Spring rates for Moog 5660......'

 

You have the factory 350 in this car, correct? I am spring shopping for my iron block LS swapped Firebird and I am thinking the 5658 might be what I need since the LS is lighter than the Gen II small block.

 

I'd try asking Sam Strano, at stranoparts.com.
He's primarily a 4th Gen guy, but I'll bet he can help and he won't steer you wrong...

 

Thanks, I will check in with him when I get a chance.

 

Generally, new springs will sit WWWWWWAAAAAAAAAAAYYYYYYY too high at first, butt will settle in over time. The Moog springs behave much like the OE ones did, only, they don't sag so much as the years go by.

Might want to check out this thread and see what these cars looked like when they were built.

https://www.thirdgen.org/forums/hist...od-1986-a.html

 

Sorry for not updating, I installed 5660 springs with KYB AGX adjustable struts.
I found the ride is not as harsh and sits at a good spot, about 27.5" on the fronts.
(Rear is Moog CC635 with 4th gen isolators).

The fronts are a little bouncy at times, trying to find the best setting for the AGX's.

 

Thanks for the update. I think I may try the 5658 springs on the front since the LS is a little lighter than the small block. Are the 4th gen rear isolators thicker than the 3rd gen?

 

Yeah 5658 will probably work well for you with the LS.
Yes I believe they are an inch or so taller, the rear of my car sits at 28.5" roughly.

 

I know the current trend is to lower these cars to the ground, but I think yours looks fine. Thanks again!

 

Thank you! I love the original ride height of these cars.
Good luck with your install!