FD wheel bearings???

[Funride]

I have been trying to learn exactly what keeps the rear wheel on my 09 RT from twisting right to left (90 degrees from forward rotation) due to the bike weight as I travel down the road at high speed and hit bumps.

 

From what I can tell, all there is in the FD is a single ball bearing set only about a half inch wide. I am guessing the balls are only about a 1/4 inch in diameter. I understand it would be able to handle any forward rotating loads of the bike.

 

But what about the side to side??

 

When I grab the rear tire at 12 and 6 o'clock and try and rotate it 90 degrees from normal rotation (pushing with one hand while pulling with the other) what keeps it from moving back and forth??

 

Please tell me it is more than that little groved ball bearing race??

 

Don't scare me.........

 

[BMWED]

Yes there is, a tapered roller bearing.

 

Ed

[Selden]

See if you can find the September 2008 issue of Motorcycle Consumer News. There is an article by Bill Shaw, starting on page 32, that goes fairly extensively into the engineering of the 1st and 2nd generation Paralever designs, including cross-section drawings of the bearings.

[smiller]

 

There is no tapered roller bearing. Here is a description of operation (scroll down to the bottom of the page.) The good news is that since there is no tapered bearing to preload there isn't any critical shimming required (as in the case of the oilhead design where the ring gear assembly must be preloaded enough to satisfy the tapered roller bearing without overloading the crown bearing, an issue that caused more than a few failures due to improper setting.) The bad news is that yes, the crown bearing appears to be responsible for handling the axial loads in the new (actually not-so-new) design. I'm not sure if this has yet been responsible for any actual problems or not.

 

[Ken H.]

Yes there is, a tapered roller bearing.

 

Ed

Not on the R1200xx series.

[BMWED]

Hmmm, so what is actually failing in these units? Can preventative maintenance be done, ie: repacing bearings, whatever every X number of miles or so?

[Highway41]

My personal experience was a failed seal at 61K miles which was caught before I lost all the lube and FD. The seal was the one connecting to the driveshaft so the lube was going into the driveshaft housing and hence no oil on the rim/tire. The FD lube has been changed every 12K miles.

Bill

[smiller]

Hmmm, so what is actually failing in these units?

That is sure something I'd like to know but I don't think there's much specific information out there yet, i.e. is there a common failure mode or they disparate problems? It seems that since this final drive design is still on relatively new bikes most of the problems have been dealt with under warranty, and as usual BMW isn't talking...

[marcopolo]

I'm the furthest thing from a mechanic, but I did have my FD fail on a long road trip. The symptom was excessive play in the rear wheel, i.e., it moved noticeably when I pushed and pulled simultaneously at 3 o'clock and 9 o'clock, and residue on the wheel somewhat like brake dust (but it was not brake dust). The wheel bolts to the wheel flange (star-shaped thing in parts diagram above). The flange in turn mates to the axle tube; it's a compression fit. There are matching splines on both the flange and the axle tube. There is also a snap ring that's your last line of defence. When I discovered my problem in Lander, Wyoming, there was no friction whatsoever remaining in the friction fit. Once we removed the snap ring, the flange came right off the axle tube with ease. The only thing holding the wheel on was that snap ring. Yikes! In essence, the splines on the flange and axle tube were wearing away and where they mated became very loose. The entire FD assembly, along with the rear rotor and all lug bolts were replaced under warranty (in Salt lake City). My '06 RT had about 38,000 kms on it at the time. That's about 23,000 miles. There was a service bulletin on the GS's issued in early 2005 describing this exact failure.

[Funride]

Smiller and others:

 

Great information and thanks. It looks like with my newer R1200RT I do NOT have the issue of pre-loading the bearings to keep them working properly. I guess the "crowned bearing" basically ride in a track which gives some ability to handle 90 degree offset rotation force.

 

The only purpose of the shims is for the ring and pinion alignment/spacing.

 

Oh, from what I can tell the rear wheel would never actually come out from the spline if the c-ring snapped. The brake rotor and brake caliper would prevent this. (you may wear a brake pad, but you would not crash and burn).

 

This gives me a much better undersatanding of just what I am checking for when I feel for loose play sideways and at a 90 degree roataion from forward travel.

 

I am an Electrical Engineer not Mechanical. (I slept thru the rotational forces and Newton Force lectures).

 

Some day I will have to stop by my BMW Dealer and see if the guys in the service shop have an FD assembly apart to check it out.

 

Great web site, keep up the great info......

[Paul Mihalka]

Very interesting subject for me. My problem is that with the mileage I put on the bike there is always a chance that mine fails before there is general knowledge of problem areas and possible fixes. My clutch spline problem was one of those things. They don't fail on hexheads...Yeah, sure...

When I'm back from Torrey in a month my bike will have 90K miles. If there was a part in the rear drive known to wear out, I would replace it. I already think of regular clutch spline check/lube servicing. These things are very expensive, but less than being stranded in Middle of Nowhere.

By the way, any suggestions of what to overhaul at high mileage would be very gratefully received.

 

[smiller]

By the way, any suggestions of what to overhaul at high mileage would be very gratefully received.

Unfortunately that's kind of hard to say for the exact reason you noted, not all that many cumulative miles on a relatively new design. In terms of the final drive I suppose you could replace the crown bearing (even though there's no real indication of a weakness in that area thus far AFAIK) only because it's a fairly highly stressed bearing with 100k miles on it. And on the oilheads there's definitely some things I'd be concerned with in the transmission at 100k+ miles, but I'm not aware of any such weaknesses showing up in the hexheads (yet.) You may have to be satisfied with being a test pilot and knowing that your experiences will benefit others...

[Funride]

Paul,

 

I agree.

 

I would be interested in knowing if you have any issues with the FD bearings. You have a heck of a lot more miles than a "fair weather Sunday Rider" like me has.

 

So far my FD bearings feel fine but my bike still has the "new leather smell", I mean new tupperware smell.......

 

[RichardSpag]

After my FD bearings went I had a new drive installed - but managed to hold on to the old unit (which is currently a door stop in my office - since I reckon it can just about cope with the appied loads!). I will dismantle it in the next couple of weeks and post some pictures if the board would be intersted?

 

Cheers

 

Richard

[Funride]

Richard,

 

Yes I would be interested in what you find out about it.

 

I used to travel to Histon on business, just north of Cambridge. Also flew into Bristol on the coast.

 

From CambridgeI used to take several trips into London on the train to check out the Pubs. I finally learned what that number ment that was posted after the different beers........

[T__]

Tom, I wouldn’t count of the rear brake holding the rear wheel on.. Remember the rear caliper is a single piston caliper so the entire caliper floats latterly on sliding pins.. Obviously it doesn’t have enough movement to follow the wheel all the way off but it would allow a fair amount of wheel lateral movement (sliding off the spline).. If it would allow enough movement then the wheel drive flange could maybe slide over far enough to allow it to tip enough then spread the rear brake pads & come out..

 

You would think the rear tire would hit the muffler pipe first or the rider would feel the rear wheel displacement but you just never know how heads up some people ride..

 

Twisty

 

[marcopolo]

Tom, I wouldn’t count of the rear brake holding the rear wheel on.. Remember the rear caliper is a single piston caliper so the entire caliper floats latterly on sliding pins.. Obviously it doesn’t have enough movement to follow the wheel all the way off but it would allow a fair amount of wheel lateral movement (sliding off the spline).. If it would allow enough movement then the wheel drive flange could maybe slide over far enough to allow it to tip enough then spread the rear brake pads & come out..

 

You would think the rear tire would hit the muffler pipe first or the rider would feel the rear wheel displacement but you just never know how heads up some people ride..

 

Twisty

 

I sure as hell would not trust my safety to the rear brake. In my personal case, when this happened, I had just ridden two-up/loaded through many miles of construction -- the kind where the road is mainly a pile of baseball-sized rocks.

[smiller]

After my FD bearings went I had a new drive installed - but managed to hold on to the old unit (which is currently a door stop in my office - since I reckon it can just about cope with the appied loads!). I will dismantle it in the next couple of weeks and post some pictures if the board would be intersted?

Hi Richard,

 

I think we'd all be most interested in whatever you can determine, i.e. was the cause due to a crown bearing failure or something else? Please let us know what you find!

[BanjoBoy]

I have been trying to learn exactly what keeps the rear wheel on my 09 RT from twisting right to left (90 degrees from forward rotation) due to the bike weight as I travel down the road at high speed and hit bumps.

 

From what I can tell, all there is in the FD is a single ball bearing set only about a half inch wide. I am guessing the balls are only about a 1/4 inch in diameter. I understand it would be able to handle any forward rotating loads of the bike.

 

But what about the side to side??

 

When I grab the rear tire at 12 and 6 o'clock and try and rotate it 90 degrees from normal rotation (pushing with one hand while pulling with the other) what keeps it from moving back and forth??

Not much!

 

Please tell me it is more than that little groved ball bearing race??

 

Don't scare me.........Be afraid, be very afraid!

[Selden]

By the way, any suggestions of what to overhaul at high mileage would be very gratefully received.

You are asking us for advice?