Rear Wheel Play

[roger albert]

I'm probably not explaining it well. Play in the rear pivot would not cause relative motion between the wheel/disc and the rear-drive. I'm looking at the disc's light/shadow cast on the rear drive housing. Clearer? I'm not saying I don't have play at the pivot too, I'm just saying I definitely see relative motion between the wheel/disc and the rear housing. The pivot doesn't lie between, and thus is factored out of the equation.

Clear as mud?

Roger

[DavidSoine]

Now that I have the rear drive in-hand I see what Dr. Curve meant by needing a precise drift - only a tiny surface on the outer race is exposed.

Anyone have any more tips on extracting these bearings from the housing? What specific tools did you use, or did you make your own?

BTW - Do the new bearings come with grease in them? They don't just fall apart like other bearings I'm used to working with...

best,

Dave

[BeemerErik]

David, I am in the process of finishing up this job right now. I heated up the area around the bearing with a MAPP torch until it was spit hot (this can cause the powder coating to discolor a bit). I then took a flat punch and angled it in behind the bearing and caught the edge of the lip and gave it a whack. The bearing came right out. The new bearings I got from BMW have grease on them already. I froze the new bearings, heated up the housing and tapped in the new bearings.

QUESTION for anyone who has done this. Do you apply locktite to the outer fixed pin? I have read threads that stated BMW said not to put locktite on the inner floating pin. The torque value for the outer pin is pretty small so I was wondering if locktite is necessary.

[DavidSoine]

Torque on the fixed bolt is 160 Nm! I'd say loctite is in order on that side.

The debate is whether to use loctite on the floating stud...since its use will affect the "feel" required for preloading the bearing.

-ds

[Dale Flowers]

For what it’s worth I think the loctite was specified originally as an insurance/liability consideration more than a functional requirement. While the torque for the pin controlling bearing pre-load is relatively low, the jam nut is spec’d. at a much higher value. The jam nut is the critical component in keeping the pin adjustment from changing.
With the need for re-adjustment of this bearing pre-load on a regular basis, the dried Loctite becomes a hindrance and should therefore be eliminated IMHO. I suspect BMW came to this conclusion when it became apparent that this needed to be added to the scheduled service list of tasks.

Tip: Be sure to drive the new bearings in all the way to the shoulder and check for play in the assembly on a regular basis, especially just after this procedure, to insure they haven’t moved to the shoulder and therefore become sloppy.

Observations: I have a feeling the stud torque setting is a bit on the low side and that a bearing in this application pre-loaded to the heavy side is better than too low.
Part of the root cause of bearing pre-mature failure could be contributed to flexing of the drive shaft housing causing changes in the bearing pre-load when under extreme loads. Increasing preload may help this to some degree.

[BeemerErik]

Sorry guys, when I said the fixed pin torque is on the low side I was thinking it was around 9nm. I have the shop manual at home and must have looked at the wrong line. I have reassembled the rear drive to the bike but have not torqued anything yet as I have to get a torque wrench that can go to 160nm

[roger albert]

I'd echo everything Dale just wrote. Perfectly explained and stated.
Especially about rechecking down the road a ways. Bearings have a way of not being seated 100% until they see some use. Of course, this is much more common with vertically loaded bearings like conventional steering ones, but still bears/warrants a recheck.

So, some of you are further into this procedure than me (I'm probably a week away from starting) Any reason a blind bearing (expanding collet type) with a slide hammer wouldn't do the trick (as opposed to drifting)

I have a big assortment of transfer punches that will normally allow me have the right diam to drift if there is any lip at all exposed, but still prefer a blind-puller and slidehammer whenever possible.

later
roger

[Dave Hopkins]

Erik
The 9nm is for the pin, 12mm allan head piece. The 9nm is just enough to overcome the thread friction and close the play in the bearing if the threads are plugged up with old dry loctite it will take a little more but the idea on adjusting a tapered roler is to just very slightly add friction to the bearing. The 160nm is for the jamb nut which secures all the parts in place! And as stated above loctite should not be needed, probubly made some lawyer happy.

[DavidSoine]

One reason to use loctite - the pins can back out! This happened to me on my old K11LT. So I'd say loctite the right, no loctite on the left side - and be sure to check it occasionally. Of course, after this thread and with our collective experience, we will all be checking the play down there now more often.

best,

Dave

[BeemerErik]

Alright, just so I am straight. Both the inner and outer pins are torqued ~9nm. The only thing that is torqued to 160nm is the locknut (jam nut) on the inner pin?

Also for a note. In removing the jam nut, and both pins I did not use heat. I went to Home Depot and bought a 3` length of iron pipe to slip over the handle of my ratchet. I was able to remove everything easily

[roger albert]

Yes, with enough force, you can get by without heat. I use old forktubes for that pretty often. I cases where loctite is used, there's really not much downside. In cases of dry threads, you are more prone to gallling. Usually not a problem, but worth keeping in mind. Once the threads have galled even a bit, you'll never have an accurate torque reading again. Just a small caveat I thought I'd mention.

later
roger

[RBMann]

BeemerErik, my CD repair manual states 160 Nm. for the fixed stud(outside right side of bike), floating stud(inside/left) set to 7Nm. then tighten lock nut to 160 Nm. while making sure the floating stud does not turn.

My mechanic added that he tightens the floating stud once, loosens it up then tightening it a second time before setting the lock nut.

RB

[DavidSoine]

FWIW bearing extraction was easy. I heated the housing with our new heat gun, and tapped out the bearing using a socket. (20mm craftsman 12pt (half inch) was just right). My wife called me in before I could attempt drifting in the new bearings. They now sit on the bottom shelf in my freezer, awaiting my return to the job...

Dave

[BeemerErik]

David,

I noticed in the shop manual that you could press out the driveshaft spline and universal assy out of the rear drive with a screwdriver. Did you do this? Is this how you were able to get a socket in to drive out the old bearings? If so, does it come out easily and look like reassy will be a snap?

I finished the install last night, torqued everything up and the play is now gone out of my rear wheel. Ready for a test ride soon.

[DavidSoine]

That is exactly what I did - lever out the U-joint. It came out with a minimum of effort. That made it real easy to drive out the bearing from the other side.

Installation "should" be a snap.

[roger albert]

Hi David,

Did you ever finish that job? How did it go?

roger

[Joe]

I've read this thread a couple times and every time I read it I'm more confused.

I had the shock out and checked play on every axis and had play at the wheel only about 1/8 " at outer edge 3/9 O'Clock or 6/12 (feels like a loose wheel bearing) Since I have an extended warranty the local dealer will do the job but he thinks it's the big housing bearing. Looks like a big job needs to remove swing-arm and use special BMW tools set up gears ect.

Have you guys replaced this bearing?

[roger albert]

Hi Joe,

I haven't yet, but mine looks to be the main bearing too. I think it's confusing because of the initial debates and responses, plus that two different bearing plays are discussed.

I compared mine to over a dozen other oilheads last week at the dealer and my place, all with higher or much much higher mileage. Only two were similar or worse than mine. One was a police RT, the other a GS that has been absolutley thrashed down in Mexico for many of it's >70,000 miles.

The dealer agreed mine was loose and needed shimming, though there was disagreement in the service department about how bad it was. They're never the less scheduled to look at it next week officially (as opposed to the parking lot quick look-see/wiggle. I'll try and remember to post back what is found. If I forget, feel free to ping me any time.

Yeah, special tools are needed, as well as a selection of $3 and $10 shims.

roger

[DavidSoine]

Roger,

The bike is back together. Drifting in the bearings went OK - I used an appropriate sized socket. Rear drive installation was not difficult - tho I'd like to do it another 10 times or so to get a better feel for the bearing preload. As it stands I will check it often once I get it back on the road. Right now there is no play whatsoever.

FWIW another set of hands makes the rear drive installation _much_ easier - tho I could have done it alone.

I am a bit concerned about indexing the u-joints, tho, since I paid no attention to that when putting it back together.

best,

Dave

[roger albert]

Yeah, I'm a might concerned about that too, though I'm not convinced it matters. Definitely not for Ujoints in good condition (w/o play) I'm not even sure about those with play. Not only does BMW not offer guidance, car driveshafts I've dealt with (just watched, never rebuilt one myself) have the ends pressed on, which can affect Ujoint position. I've never seen that taken into account either. I'm pretty sure that if it matters, it's symptomatic of another issue. Wish I could say for sure. I'm not 100% positive on this one.

???

roger