Spring rate on posi clutch preload pack in 1965 differential

[Joseph E.]

Can any of the members tell me what the stock spring rate in the clutch preload pack is for a 1965 Corvette differential? The springs that I've removed are colored dark green. I've seen 200, 400 and 800 lb springs for this application. The ones that I took out are relatively easy to compress and I've got a new pack with 400lb springs in it that are much stiffer and more difficult to compress. I was going to install the heavier springs but don't want to have an issue with the rear not differentiating around corners due to the extra spring rate. I've got the 400 lb springs in a 1968 prostreet Camaro with a narrowed rear that I own and that car has no issues with cornering and the differential operating correctly. Would the rear function the same in the Corvette with the 400 lb. rate springs? Thank you for any responses received.

Joe

[Gary R.]

Re: Spring rate on posi clutch preload pack in 1965 differential

With the exception of 1 or 2 later 70's vette posi's that I found blue springs in, all were green and rated at 400 lbs. I even called Eaton to see if they used the blue and they possibly could be 200's but maybe swapped out in an effort to eliminate chatter.

With that said I never use the springs or plates building a Eaton posi. I use only solid steel clutches as well, stay away from the fiber or slotted steels.

The heavier the force the more likely they will chatter but the spider lash setup has to be correct. I also use 2 bottles of GM additive now.