Differential Pinion Seal

[bpossel]

I am planning on replacing my driveshaft this weekend, and while doing this job also plan on replacing the rear differential (pinion) seal.

I have read that you have to be careful in re-tightening the nut for the pinion seal and that you can "index" before removing the nut.

 :oops: I assume this means to simply mark the location of the nut before removing, then re-tighten to the same spot as the mark, or "index".   :?: Is this correct?

 :?: Also, is it recommended to use a bit of Permatex on the new seal ?  If yes, which Permatex?

Any other suggestions on this job?

I will take some pics for the group and post over Christmas.

  Thank you!
Bob


bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

[jeffc280sl]

Hi Bob,

Have a look at Job 35-8. There is a crush sleeve on the pinion shaft.  The nut provides for compression of the sleeve and tension on the pinion/ring gear meshing.  Your going to need a slotted nut socket wrench, a 200 ft/lb and an in/lb torque wrench.  The slotted wrench socket can be "home made" but it needs to fit snuggly in the nut in order to set the initial loading on the pinion shaft. Do not over torque this nut!  After setting the initial load you take a measurement with the inch/pound torque wrench to see if you are in spec. Then in very small, 1/8th of a turn increments, tighten the slotted nut and remeasure.  Continue this process until you reach the in/lb torque setting required.  Read the manual and then let me know if you have any questions.

Jeff C.
1970 280SL 4-speed

[Vince Canepa]

The problem with following the book in this case is that you can over crush the sleeve.  The book assumes you are starting from new with a new sleeve.  In this case, it is best to mark the nut relative to the pinion shaft, and install the nut to the marks.  It won't take anywhere the full torque spec to get there.  Most of the spec torque goes into crushing the sleeve.  This "index mark" procedure can be used on any diff with a crush sleeve.  Many Fords use a crush sleeve.

Ideally, you should recheck the torque required to turn the axle afterwards and then adjust the nut as necessary.  However, most of the dealer techs never did this final step.

Vince Canepa
1967 250SL
113.043-10-001543
568H Signal Red
116 Caviar MB-Tex

[jeffc280sl]

Vince,

Good advice.  I must say the pinion shaft nuts that I removed from two 3.27 W108 axles were not on very tight at all.

Jeff C.
1970 280SL 4-speed

[bpossel]

Hi Jeff, Vince,

Thanks!  Great advice!  It all makes sense and cant wait to get the driveshaft and pinion seal replaced...

Now I am wondering if I should also tackle the carrier rubber mount (round tube mount)?  Purchased it earlier this year and didnt have the guts to do it.  

Any suggestions on this one?

Thanks again!
Bob

bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

[jeffc280sl]

Bob,

Just a thought and someone else may have more information.  To replace the pinion seal you need to disconnect the drive shaft and move it out of the way in order to get at the nut. If the drive shaft will not move out of the way enough maybe you can remove the carrier nut and lower the axle just enough to remove the flange and pinion nut without doing anything else to the drive shaft. This may be an option if you can't get enopugh clearance for the pinion nut.  

On its own the carrier plate is not a big job.  I recommend putting your hydraulic jack in a location under the diff where you can lower and raise the axle in a straight line.  If you don't do this the carrier arm may get a bit out of alignment with the bracket when you lift the axle back up into place.

Jeff C.
1970 280SL 4-speed

[Vince Canepa]

The hanger mount can be done at this time.  I not sure I understand what Jeff is saying, but to get the hanger mount out you need to drive the pivot pin back to the point where the front is just flush with the eye on the right axle half.  The pivot pin has to pass through the steel sleeves for the bronze bearings in the eyes.  It will end up sticking out the rear of the eyes about 6" or so.  Of course, you need to support the center of the axle because it will no longer be supported from the top.  I have never done it this way, but Arthur Dalton, who used to frequent this board has done it.

Vince Canepa
1967 250SL
113.043-10-001543
568H Signal Red
116 Caviar MB-Tex

[jeffc280sl]

I was thinking of the bushing/plate in the trunk which holds the axle.  Now that I read more closely I guess Bob wants to replace the rubber rings on the carrier bolt.

Jeff C.
1970 280SL 4-speed

[bpossel]

Thanks Guys!  Jeff, the lower carrier mount that I am referring to is a metal tube surrounded by rubber, then encased in another metal tube.  See attached pic from SLS, item #151.

I purchased this part a while back and after reading some posts and other info, decided not to take a chance and screw up the rear end by replacing this part.  The rubber that is exposed is deteriorated.  Joe A. mentioned that it may be possible that the inner rubber, the area not visible, still may be intact.  So left this project go.

Based on this discussion so far, looks like I may pass on this one again?  Just focus on the new drive shaft and new pinion seal…  Still thinking on this…

Thanks again!
Bob


Download Attachment: rear.jpg
75.48 KB

bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

[hands_aus]

quote:Originally posted by bpossel

Thanks Guys!  Jeff, the lower carrier mount that I am referring to is a metal tube surrounded by rubber, then encased in another metal tube.  See attached pic from SLS, item #151.

I purchased this part a while back and after reading some posts and other info, decided not to take a chance and screw up the rear end by replacing this part.  The rubber that is exposed is deteriorated.  Joe A. mentioned that it may be possible that the inner rubber, the area not visible, still may be intact.  So left this project go.

Based on this discussion so far, looks like I may pass on this one again?  Just focus on the new drive shaft and new pinion seal…  Still thinking on this…

Thanks again!
Bob


Download Attachment: rear.jpg
75.48 KB

bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

Hey Bob,
If you are in a position to replace that lower mounting bush then you should do so.

The one on my car was soft and spongy and this allowed the axle to move. This happened while accelerating or slowing down.

If there is a clunk type noise or a movement feel then this could be the cause.

I can't offer any advice on how to do it because I had it replaced 2 years ago while having the rear axle rebuilt including new rubbers and wheel bearings ect.

Recently I had the front sub frame mounts replaced and new shock absorbers fitted and the front brakes rebuilt.

The car handles great, and so it should.


Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[bpossel]

I will have access to a lift this weekend, one that you drive on and is open in the center for working on the car.  So all 4 wheels will be positioned as if it was sitting on the ground.

If I support the differential and slide the piviot pin out of the rear ~6 inches, then it sounds like I should be able to replace the rubber mount (bushing)?

 :?: Question, it seems to me that my only risk is that the pivot pin not reamin in the horizontal position.  If the pin moves slightly up or down, then driving the pin back into the new rubber sleeve would be more difficult.

Any comments on this?

Thanks,
Bob

bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

[jeffc280sl]

Bob,

I think it is important to relieve tension on the pivot pin and stabilize all the components to minimize shifting.  I'm not sure having weight on the axles provides sufficient flexibility for relieving this tension.  With the rear of the car suspended on jack stands under the side rails spring tension is reduced.  A jack under the center diff and one properly placed under each axle tube would seem to provide the adjustability you may need to minimize tension on the pivot pin. I'll defer to others that have done this job with the axle on the car.  I've done it with the axle off.  Be carefull when forcing the pin to the rear not to push the chrome plated bushing # 161 out of the brass eyelet in the right axle tube.  If you do re-alignment will be more difficult. My experience with this bushing indicates that it is going to want to stay with the pivot pin versus the axle tube eyelet. Remember to remove the nut and punch out the locking bolt #162 or the shaft will be locked in place.  When returning the pivot pin make sure the pin as not rotated because the locking bolt has to mesh with a flat spot on the pivot pin.

Jeff C.
1970 280SL 4-speed

[Vince Canepa]

I think a search for hanger mount, pinion seal and Arthur Dalton may find some info on the procedure.  Jeff is correct that the aft steel sleeve (for the aft eye) will want to drift out with the pin.  I'm not sure that would be a huge problem.  An option is to drive the pin back a bit, drive the sleeve forward and so on until the pin is free.  You might need some help to back up the forward end of the pin when driving the sleeve forward.

Vince Canepa
1967 250SL
113.043-10-001543
568H Signal Red
116 Caviar MB-Tex