What are the most common spring rates for front and rear coilover setups? not an auto cross car but just a nice street ride. 69 cutlass, no air cond, does have power steering, 350 motor. Looking at CPP products.

 

What were the factory W-31/FE-2 specs?

 

I have searched for that with no luck. I see a number of spring rates out there but not a clear rare for the W31. My gut would say in the 450 range for the front? maybe 180 to 200 for the rear?

 

I have no idea, but those seem a little extreme for factory. What are you looking for?

 

What I have found you may be right. But going with a 400 to 450 rate in the front would be a little firmer then stock, and maybe 150 in the rear. I want to be able to set my own ride height without guessing on springs. But I did look hard for the stock spring rates for the car but turned up zero. I think it feels a little on the soft side and some of that is the 20 year old stock shocks that were used for the resto. Will be using the Viking double adjustable on the new setup.

 

I have the following info I gleaned from an online Moog database:
Front:
Moog 5390 350 w/o AC 336 lbs/in
Moog 5382 350 w/AC, 455 w/o AC 358 lbs/in
Moog 5536 442/HD, 350 w/AC, 455 w/o AC 488 lbs/in

Rear:
Moog 6321 Coupe 119 lbs/in
Moog 5385 HvyDuty 168 lbs/in
Moog 5379 Convertible 122 lbs/in

I don't have too much confidence in the application notes but it's a respectable starting point. It seems the performance oriented, stock height replacement springs are 450-550 lbs/in (front) and around 130 lbs/in (rear).

Rodney

 

Thank you for the info, the numbers seem to be all over the place. As for a W31 I could not find anything, maybe the same as the 442? but at this point I know the rates I will go with.

 

It's all very subjective. I had IROC (Moog 5662s, 640 lb/in) in the front of my 4dr, V6 G body, and still thought they were soft.
I think a coilover minimum would be 450, and still very soft.

 

Agreed. I've had 500+ lb/in springs up front on mine for 20 years now (two different manufacturers and ride heights), small block first, big block later, and its about right for a cruiser. It is VERY soft for carving corners. Most of the mild coilover setups I see are in the 550 lb/in range (front). The aggressive ones are in the 800+ lb/in range (front).