I'm confused about measuring and setting the 12-point nut on the diff's driveshaft pinion/flange.

Since my mechanic failed to measure/count the threads on how far-down the original 12-point nut was down, how do I determine how far to screw down the 12-point nut?

The W124 CD-ROM and paper manual is very vague here.

The MB manual states a range of 50-100 N-centimeters on old bearings, 100-150 N-cm on NEW bearings. Both readings are taken with the diff dry/empty of oil and NO spider-assembly.

1) What should the range be with the spider-assembly in?

2) Do I attach the appropriate range torque wrench to a 12-point socket and slowly tighten the 12-point nut until it reads the torque-range (TBD)?

OR

3) Do I attach a rotating/spinning torque meter to a 12-point socket, and spin the pinion by rotating the output flanges in unison at 60 RPM?

Something else?

Thanks in advance,

:-) neil

When I was at Mercedes All the Techs used the Dreaded Impact to r/r the nut when seal repacement was done..Only IF bearings or other Diff work was done did we get into Backlash checking
Never saw a car come back for any problems......
Here is the MB site it will have step by step instructions w/specs
http://www.startekinfo.com/StarTek/

ke6dcj,
We are putting the cart before the horse on this problem.

The number one reason for diff replacement is a botched pinion seal replacement according to the warranty department at M-B.

The start up and rotating torque should have been measured before removing the nut, we use a 1/4 dial torque wrench and record the readings.

However the "normal" reading are in the 3 newton meter startup and 2 newton meter rotate. We slowly tighten the nut using the dreaded impact and check the torque many many times. I wish you good luck and remember tighten in small increments.

__________________
Paul

Thanks Paul. I'll have to make a counter-hold to get the nut to the 180Nm torque spec and NOT crush the pinion seal/cone.

BTW: how do you take your readings? The diff in question is already OUT of the car and dry (no oil).

:-) neil

Call Joe at E-Autoparts in Jacksonville, FL.
Tell him Neil with the Mercedes sent you.

$75+ shipping.

BTW: aren't most a 3.46 diff? Make sure you tell them you want a 3.06 diff for a W123!

1983 Carrier
Mercedes 300 D CD/TD AT,2WD 8H05 $75

1980 Carrier
Mercedes 300 D CD/TD AT 8B46 $75
1978 Carrier
Mercedes 300 D CD/TD 123 95384 $75

E Auto Parts Inc USA-FL(Jacksonville)
1-800-366-9815