Anyone know the stock spring rates for third gen z28?

 

Stock, NEW, anywhere from around low 400s to about 700 front; and around 125-140 in the rear.

They could be ALOT ALOT less than that, if you checked old used ones now.

 

How exactly does that work sweetheart?

Heres a link to all(?) of the springs used in third gen applications. Obviously the heavier duty springs were used in the heavier/performance applications. As to exactly what springs were used what years with which options I didn't note that during my research.

https://www.thirdgen.org/forums/susp...ring-info.html

 

Iunno... by putting weight on them maybe?

Those are the Moog replacement springs, not the stock ones. They're generally stiffer than the ones that GM used in any given application, although not always. Also note, that's EVERY spring Moog supplies that has the right type of ends to fit these cars; not just the ones that are spec'ed for F-bodies, and not just the ones for Z28s.

Great list though.

 

wow i used the site and looked up my application 87 formula 350

front springs from moog are 748lbs spring rate!! i got the sportlines that are only 700lb spring rate and that was a huge improvment over stock!! wat if i were to cut these to sportlines height... i wonder how stiff the spring would get...? hmm.

i dont understand how the sportline/prokit are performance spring kits when the spring rates are lower than moogs.

 

Sorry but that isnt the whole truth. Springs dont lose rate over time, unless they are physically damaged (rust). They do lose height over time which when couple with certain stock rates can cuz travel (bumpstop) issues.

And yes that is is compiled over only springs that were speced as replacements for certain third gen cars. I'm in the process of redoing the data and saving which cars with which options got which springs. Once again I assure you that there are more Federal Mogul springs with the correct ends than what are on that list.

The site is kind of flakey. It doesn't list data for certain models/combinations ( 87 5.7 iroc being just one. and the fact that they have the iron duke listed as an option for longer than it was in production in our cars).

I just actually finished the camaro list, but have yet to start on the pontiacs. This is quite time consuming, tedious and repetitive.

knowledge is power. here, i'll try to attach the word file.

 

If you notice my chart from the other thread I question that spring specifically. In the search they spec 748lb/in., but the part numbers and spring rates both increase systematically together with all the other springs. I think that maybe at somepoint there was a typo in the data and the rate should be actually 648lb/in.

This is purely speculation and common logic. Here is just one data point that makes me think the previous statement is true.

In 1989 5.7 Irocs excluding convertibles speced the 5662 spring (748), while the 1989 5.7 Iroc convertibles called for the 5664 springs (707). Now seeing as how its commonly accepted that verts are heavier than coupes, why would they spec the lighter spring in that application? Wouldn't it make more sense if the actual rate for the 5662's was 648 lb/in

In most (all?) other applications, that ive noticed, where the vert and the coupe called for different springs, the vert always got the stiffer springs.