8-3/4 clutch type Dana power lock

[john-9]

picked up a Brand New after market 8-3/4 clutch type power lock unit at a swap meet.did a rotating torque check and found about 90 ft/lbs rotating .
i am familiar with stock Chrysler 8-3/4 power locks and with new Mopar clutch kit installed the rotating torque is always around 190 - 200 ft/lbs.
i took the unit apart and found out that the clutch pack was assembled with only one tabbed Bellville spring (curved plate ) and stacked the same as a Dana 60 powerlock - curved plate against the inside of the case half.
stock Mopar clutch kits have one tabbed Bellville spring and a curved splined plate that stack together which would increase the preload.

what i want to know is will this unit work OK as is with 90 ft/lbs preload or what should the minimum rotating torque be for proper function .

i know Cass reworks his after market units with shims -- maybe he can chime in as to what he sets his units preload at -- if its not a trade secret, lol.
thanks in advance

 

[john-9]

am i the only one that checks the preload of limited slip differential carriers after a rebuild or when bought new to make sure they operate properly. some one on here must have some info.

guess i'll have to give Cass (Dr. Diff ) a call and pick his brain.

 

[mderoy340]

am i the only one that checks the preload of limited slip differential carriers after a rebuild or when bought new to make sure they operate properly. some one on here must have some info.

guess i'll have to give Cass (Dr. Diff ) a call and pick his brain.

I've rebuilt several OEM units using the kit Cass sells and never had a problem. The aftermarket unit may not be the same disk count. Cass has always been helpful when I ask questions.

 

[crackedback]

There is one curved plate in the powerlocks.

The arrangement of the disc is different in each carrier. Service manual has proper order in the rear axle section.

Here's what I have saved.

 

[john-9]

yes ,, the above pic shows the correct stack for the factory stock clutch pack disc's showing 2 dished plates --giving an average preload of 200 ft/lbs in a stock factory power lock.---- replacement clutch pack Mopar Performance P4529484 has the identical number and shaped disc's giving an average 200 ft/lbs rotating torque in a stock factory power lock.

the new aftermarket powerlock unit i purchased-- --has the same number of plates and discs but replaces the second from right dished disc with a another flat disc and a thicker tabbed end plate giving an average of 90 ft/lbs rotating torque.---- the case halves are also machined an average of .020 - .030 deeper than the factory cases.

this is probably why DR Diff shims his units to bring up the rotating torque so the unit operates correctly -- but what is the number he strives for., so i guess a phone call is next.
( i know the built in ramps contribute to the loading of the side gears as well.)

just like to know what the minimum rotating torque should be for proper operation of the aftermarket power lock units being sold

 

[oldkimmer]

The 1957 to 1964 units had all flat plates/ discs. 0 preload. They work perfectly fine. And if u spin 1 tire forewards the other rotates backwards giving u the impression it’s an open diff or a ruined 1. Kim