Differential Pinion Seal

[230slhouston]

I am in the process of replacing my pinion seal. Removed the yolk today, is the crush sleeve nylon? If it is mine is in two peices, is this normal?

Does anyone have a picture of what the crush sleeve looks like? Where can I buy one from if I need too?

Thanks
Maistran.

[jeffc280sl]

The crush sleeve is cylindrical and is located between two bearings which support the pinion shaft gear.  The attached diagram may help.

[230slhouston]

Jeff,
Thanks for the reply. I marked up the drawing you sent me as item 1 and 2 with a comment. My questions are:

1. When I removed my yolk, a nylon type of spacer/sleeve broken in three pieces and fell out from between the seal and yolk. I am now assuming this may be the raised lip on the seal that sheared off and is hard and brittle from age.

2. I removed the flange to work easier on the seal, do I just tap the seal out of the flange, is the OD of the seal bored all the way through the flange?

The seal is hard and brittle, I am wondering if this is an indication of the state of all the other seals in the car. After all it is a barn find that was mothballled for 20 years.

Thanks for all the help.

Maistran

[jeffc280sl]

The seal is composed of a metal band and a nylon type material.  The metal band is sometimes coated in the same material is held in place by friction.  The nylon inner ring material fits snuggly against the inner pinion shaft to seal the area and keep diff fluid from leaking out the seal.  Your seal appears to be bad with the inner nylon part broken into pieces.  At this point there is no reason the keep the outer metal band in place.  See if you can drive something sharp on the lip of the band and crush it inward.  Once the tension is released the outside metal band part of the seal can be removed and a new seal pressed in place.  If you have trouble visualizing the seal buy a new one so that you can see what your dealing with.

There are other seals to be concerned with that may also need replacement.  Rear wheel seals being one.

[waqas]

Jeff,
I have a follow-up question: can the crush sleeve be replaced from the drive pinion seal access area? (removing the flange cover, etc, but without dismantling the entire differential). I assume the front tapered roller bearing will need to be removed first. Does this bearing need to be pressed off the pinion?

Thanks in advance!

[Naj ✝︎]

Waqas,

Question about your question:
Why would you want to change the crush sleeve?

naj

[waqas]

Waqas,
Question about your question:
Why would you want to change the crush sleeve?

Naj,
That's a very good question about my question.

When I changed out the pinion seal (an early job I performed on the car soon after I bought it some years ago), I fear I may have over-torqued it (hence over-crushing the crush sleeve).

I've since educated myself a bit more about getting the correct crush torque setting (thanks to the people contributing here), and I'm still in that data-gathering mode regarding if and when I want to tackle this.

[mbzse]

.../...When I changed out the pinion seal (an early job I performed on the car soon after I bought it some years ago), I fear I may have over-torqued it (hence over-crushing the crush sleeve).../...

Pinion pre-load is lost gradually over the life of the differential as the bearings and or race wears with use. This can cause the pinion to move axially, and be the source for howling noise etc.
Pinion pre-load is the force (pressure) between the pinion conical roller bearings and the pinion bearing's race. As the pinion nut is tightened it tightens the crush sleeve, designed to "control" collapse under force. The pre-tension needs to be present during all the different operating temperatures of the diff.

Too much pinion pre-load (when tightening the nut) can cause the roller bearings to overheat, causing severe degradation of the bearing. This too high pinion pre-load cannot be undone. The crush sleeve, once compressed, stays compressed. Backing off the pinion nut once the sleeve has been compressed does not result in less pinion pre-load, it results in no pinion pre-load.
The conical rollers can then begin to stand still and slide against the race, instead of rolling – this is no sort of good...
/Hans in Sweden

[jeffc280sl]

Wagas,

I don't know the answer to your question for sure.  If the crush sleeve has failed I imagine it would be deformed and stuck onto the pinion gear shaft.  Good chance you would have to remove the outer tappered bearing, inner bearing and pinion gear/shaft to repair. 

[waqas]

If the crush sleeve has failed I imagine it would be deformed and stuck onto the pinion gear shaft.  Good chance you would have to remove the outer tappered bearing, inner bearing and pinion gear/shaft to repair. 

Thanks all, for the detailed information.

Does anyone know if there's a way to test for excessive crushing on the sleeve? 

From Hans' description (and an old Arthur Dalton post), once the correct pre-load torque is exceeded, the crush sleeve is deformed. This means that the pre-load torque will either be excessive, or none at all. Would this be a valid test?

At any point (either at the non-pre-loaded or [incorrectly] pre-loaded setting of the grooved nut), will there be noticeable end-play on the pinion shaft? How much end-play is excessive?

Sorry for hijacking the thread-- I can start a new thread if there are objections to this digression.

[mbzse]

Thanks all, for the detailed information. Does anyone know if there's a way to test for excessive crushing on the sleeve? 

yes, you measure the rolling torque...  There are special tools for this. But you can make a tool yourself with a "drum" on the diff flange, a string and a fisherman's scale
type device, and some calculation...  Next you may ask "what should the rolling torque be..." Well it's all in the workshop manual or the book of tables,
which I would suggest you aquire since there are loads of other torques and measurements you need to adhere to as well, to do this job right...
Torque for pinion alone, a bare diff,
 is given as 16-18cmkp, well oiled new bearings. For the complete rear axle with brake calipers removed it is given as 26-30cmkp
See also this thread: http://www.sl113.org/forums/index.php?topic=7254.0

/Hans in Sweden

[Naj ✝︎]

Does anyone have a picture of what the crush sleeve looks like? Where can I buy one from if I need too?

Thanks
Maistran.

Back to original question.

Picture of crush sleeve and pinion seal.
Note: These are for a 108 'big pumpkin' axle. Parts for a normal 113 axle may be different.


naj

[George Des]

The crush sleeve on the 113 rear ends is much longer. Having just done this job, I can't see how the sleeve can be easily removed w/o disassembling the whole pumpkin. The sleeve is directly behind the front pinion bearing and unless you can remove that front bearing w/o pushing the pinion back through the housing you really can't get at it. I suppose there may be some way you can do it, perhaps you can drill through the outter portion of the roller bearing and pulll it off with some bolts, but I couldn't figure it out and I was doing a complete rebuild, so the removal process was pretty straight-forward for me.

George Des

[Naj ✝︎]

The crush sleeve on the 113 rear ends is much longer.
George Des

George,

Is yours a 230 SL?

Seems the 230s have a different crush sleeve.

250/280s use the same one as pictures above (below?)

naj

[waqas]

Naj, I believe you are correct. The SLS catalog shows the 230SL sleeve (item #21 in the figure below) as a long cylindrical object. There is a separate "Abstandbüchse" for the 250/280SL shown as item #22. Does this make sense?

[230slhouston]

Everyone,
Thank you for your comments, this forum provides invaluable help.

I ordered the seal from the local dealership ($26), it is the same part number as provided in Naj's picture. This helped in placing my order.

In a nutshell, I indexed the nut before removing it. I have an idea the number of turns to put it back. Not to get too technical, if I hold the yolk and torque the nut, what should the maximum torque be? I do not want to over torque (ft lb or NM). I have seen some really technical discussion on this.

Thanks,
Maistran

[George Des]

Naj,

Yes. The rear I rebuilt was off a 230SL. Identified by the drum brakes and the right axle shaft w/o the circlip setup we often hear mentioned. The sleeve is definitely longer and more cylindrical than the one pictured on the SLS diagram. The 230SL sleeve is the one w/ 2 dimples on the side. I found the best way to do the torque is with a beam scale torque wrench designed fopr torquing bicycle spokes since it is calibrated in in-lbs. The string scale technique I've seen mentioned to me is just too complicated and fraught with potential errors. Maistran, I'd be less concerned with the torque on the nut istself since you indexed it. What you need to be mindful at this point though is what I like to call the "running torque". This is the torque required to turn the whole setup once the nut is tightened into place and w/o the drag of the disks or shoes on the brakes. You'll see it described in almost all these discussions

Geoirg Des