Diff pinion preload

[Huicho417]

I am replacing the pinion bearings in my 8 3/4” diff. The sheet I got from dr diff that notes the preload specs is different from the service manual. The service manual is more but I don’t have it with me now to list the actual numbers. Should I go with the dr diff specs or stay true to the service manual? Thanks

 

[bm02tj]

How far apart give us the numbers

 

[493 Mike]

I am replacing the pinion bearings in my 8 3/4” diff. The sheet I got from dr diff that notes the preload specs is different from the service manual. The service manual is more but I don’t have it with me now to list the actual numbers. Should I go with the dr diff specs or stay true to the service manual? Thanks

Chrysler did design and manufacture the 8 3/4 for over 20 years.
Mike

 

[Nate S]

I wouldn’t mess with the Chrysler loads. Bearings haven’t changed. Everyone else will use the Chrysler loads. What would you gain by changing? Curious what the figures are for comparison. Designed a huge number of opposed tapered roller bearing joints before, wondering if one set matches the current standards.

 

[dvw]

15-25 in/lb will work for just about anything.
Doug

 

[Cliff Ramsdell]

Mopar called out 0-15” lb for used bearings on almost everything.

741 and 742 new bearings were 20-30 new and the 489 was 20-35 new.

Biggest difference was the nut torque with either shim style or crush sleeve.

The Dr Diff sheet attached.

Cliff Ramsdell

 

[Nate S]

Thank Cliff!

So they basically tightened up the range. No harm there but I wouldn’t exactly start sweating bullets if I was out of the Dr Diff range but still in the Chrysler range.

 

[Cliff Ramsdell]

@Nate S , your doing bearings only, correct? Just the pinion bearings or are you doing the carrier bearings also since you need to pull the carrier out.

Which center section, 741, 742, 489? Same gears, just new bearings?

Get some info and let’s help you out.

Cliff Ramsdell

 

[Nate S]

I’m not the OP. Sounds like he’s doing pinion bearings only though.

 

[Huicho417]

Thanks everyone I am doing the pinion and carrier bearings as well. It’s a 741 case with the the original 2.94 gears that came with the car. I torqued the nut to 240 foot pounds and ended up with 25 inches of preload. This was about after redoing it 4 times with different shims since I only had about 12 inches of preload at the beginning. My task tomorrow is to set the backlash and check the wear pattern.