engine and drivetrain Short Neck Differential Bearing Install

[Resto02]

I've replaced the front and rear pinion bearings and the side carrier bearings. Has anyone tried to assemble the differential with out a new crush sleeve? I was thinking (there I go again) that as long as I have the same amount of drag on the pinion when measured with a in-lb torque wrench, I should have just about the same amount of preload needed for pinion to ring mating and clearance. If anyone has any experience on this, I would appreciate your insight. Thanks a bunch, --- Mike B

[Emyers]

Mike,

  Yes, I have and no, you can not get the correct amount of preload without replacing the crush sleeve.

Earl

74 02Lux

02 M Roadster

72 Volvo 1800ES

[jimk]

People try to do things without the knowledge or skill that a skilled person at a shop would do and want an education on a chat  board.  This situation requires study and experience.  This is also why buying one of these old cars is a pig in a poke because of a mutitude of home fixes in areas too sensitive for home work.  Asking this question shows the task at hand is way beyond the knowledge level of the doer.  Have at and and have fun.  If the dif howels or burns out the pinion bearing down the road, call the shop next time.

[Preyupy]

I have never tried to "reuse" a crush sleeve when installing new bearings.  They are cheap, why not get a new one?  Get a copy of the repair manual and just follow the instructions, it is not a tough job if you are not changing the pinion and having to set the depth and back lash. 

[DaHose]

Ok. so the hostile answer from Jim does have truth in it.  You really should study up before tackling assemblies like differentials, gearboxes and engines.  There is a lot going on and being unaware of the complexities can have catastrophic results.

 

As a rule, anything that crushes down to its final fit should ALWAYS be replaced when refurbishing a component.  Yes that goes for oil pan drain washers.  I know we all reuse them, but technically they should be replaced each time.

 

With a differential, there is one instance I can think of where you could reuse the crush sleeve.  IF you are only replacing a leaking input flange seal, you can mark the position of the nut holding the input flange to the pinion and then remove the nut.  You should take a picture of it too as a double check measure.  When you remove the nut, carefully count the revolutions, remove the flange, replace the seal and reinstall everything.  When you tighten the nut back on, you turn the specified number of rotations and line up your mark EXACTLY and you will be good to go.

 

Otherwise, I completely agree with Preyupy.  Read a good manual, understand the process, get a new crush sleeve and follow instructions.  Just be sure you have all the right tools and for God's sake get a good torque wrench if you are doing any kind of engine or complex assembly work.  Most clicker torque wrenches are off by 10% or more.  My digital Gearwrench is accurate within 0.2% in the heart of its range.  You should get something like mine, or a "break beam" torque wrench.

 

Jose

[TobyB]

Yes, you can reuse the pinion crush sleeve.

 

No, the pinion bearings will not survive that.  It kills them.  Seen that.  Several times.

 

You COULD make a fixed- length sleeve to replace it.  It's more commonly done in Land Cruisers and other heavy

equipment where the crush sleeve can get whacked and come loose.

It very seldom does that in a 2002- it's very robust. 

You need to be able to machine to about .0005" to really get the sleeves to work.

 

The sleeves cost $5 and were still in the aftermarket chain last I looked- cheaper than the pinion seal, almost.

 

You don't really need a torque wrench to do the pinion crush sleeve-

and the one you should use, if you do,  is typically found in pedalbike shops.

 

t

[Resto02]

Many thanks to all that responded. One additional question concerning the differential rebuild, The factory manual indicates the drag on the pinion with one haft shaft flange installed should be 14.46 ft-lbs! is this correct? I've assembled several chevy and ford diff's and there initial drag is 25 to 45 in-lbs depending on the manufacturer. If anyone could verify this I would appreciate it.

[Tommy]

I had same question couple of months ago. It's not correct and then I got several different values from different sources.

Ended up doing it by finger touch.

 

  Tommy

[TobyB]

Yeah, it's inch- lbs, that's a misprint.

 

When you're doing it, you'll find that once you start crushing the sleeve, you're pulling REALLY hard to crush it.

 

So you'll cautiously creep up on it- tighten a little, wiggle, tighten, wiggle--- when it gets to the point where you

can ALMOST not wiggle, you have to go very slowly- one tighten, all of a sudden, the wiggle's gone, but it turns very easily.

THEN you need to turn about 3 degrees more to where you can feel 'some' bearing drag.  If you've set up tapered roller

bearings before, you'll know it- it'll go 'firm' but not crunchy.  If you go 2 degrees too far, it'll get 'stiff' or 'crunchy'- and you

get to do it again, with a new sleeve and probably seal.

The first sleeve is easy to kill- after that, it's pretty easy to do a good job.

 

The only one I ever got wrong, I left it too loose- and it vibrated like hell.  Made a quick mess of the bearings, too.

 

t

[Resto02]

Thanks for the clarification on the drag setting,  and I do appreciate the feedback.

[M3M3M3]

did you read andrew's article on diff rebuilts in the articles section??

http://www.bmw2002faq.com/_/technical-articles/engine-and-drivetrain/strongest-2002-limited-slip-differential-build-r74