REAR Wheel Bearings and
Idler Arm/Swing Arm/Tension Lever Bearing Replacement FAQ
compiled, written & edited by Kristian #562
 updates edited 14/3/03 & 23/05/03 by PDuffy#1210
 Many Thanks to Richard #424 for some of the detailed Photos.
Many Thanks to Haakon #626 for the detailed Bearing Information
 Please read the Disclaimer before attempting any work in this FAQ.

See the new Shocks Maintenance FAQ section on suspension linkage for idler arm / suspension linkage related maintenance.

From a Boxer Site: Wheel Bearings are probably the most neglected part of any motorcycle, and on the older, twin-shock Boxers the near-side bearing in the rear wheel can totally fail with little warning. Its seal becomes worn by exposure to grit, allowing road grit and water to contaminate the grease. The off-side bearing is well protected within the hub, and like the front wheel bearings, gives little trouble. Always remove the inner races of your bearings every year or so, washing out all the old grease, and re-packing before replacement with new seals. If you ride throughout the winter, re-grease the near-side rear bearing in Autumn and Spring. Remember - new seals are cheaper than bearings! The front wheel bearings of the later Monolever Boxers and K-Series models give little trouble, even after extreme use.

Rear Wheel Bearing Replacement
by Kristian #562
15/10/01

While I was waiting for the parts for my Water Pump, I think I turned into a Bearing and Seal fiend. I think replacing Seals & Bearings is almost more satisfying than a new pipe and slippers, sorry I mean pipe and jets, which is why I'm writing a few things up here. A blowtorch/propane torch is very much the answer for bearings. And a Refrigerator. Replacing the Wheel Bearings really makes me feel good about my bike, especially those crunchy Russian (Yep, Stamped made in Russia) Rear wheel bearings.

General:

Flash's abridged version of this FAQ.


Heat up the HUB with a propane torch until it is hot enough to make spit sizzle. Take a big screwdriver and knock the spacer between the bearings sideways slightly. This will push the bearing out slightly AND it will allow the spacer to be pushed further aside. Then you can hit the inner race of the bearing with the screwdriver. Use a BIG hammer. Have the new bearings COLD and ready to install. You want to knock out what is there and then drop the new ones in while the hub is hot. Do NOT hit the new bearings on their inner races or shields, ONLY the outer races.

 

Part Numbers:

Tools:

Terminology:

When referring to two similar items:

"Outside" means closest to the Outside of the Bike.

"Inside" means closest to the Bike Centreline.

Method:
Rear Wheel Bearings:

Classic Sprocket Carrier:

Replacing the Seal and Bearing in the Sprocket Carrier is easy and I'd recommend it first if you're not experienced in bearing replacement, because it's easy and satisfying. Instant Gratification, or almost.

Removal:

  1. After Removing the Rear Wheel, take off the Sprocket Carrier (Parts #2-#8, it just pulls out from the rest of the wheel), to expose a series of black wedges (Part #8), called the "Cush Drive". You can just  peel out these wedges to save them getting fried if you apply heat.
  2. Remove the flanged "Outside Spacer", Part #3 from the Sprocket Carrier. Mine just fell out, but Mark #403 and James #523 note that this Spacer CAN take a bit of levering out with a screwdriver as it is wedged in the Bearing, or you can use a puller to remove it. Don't lose the spacer. Perhaps put it in the Freezer, so it is easier to re-insert it.
  3. Lever out the Seal (Part #4) with a screwdriver (I'm Assuming you will replace it, so you don't need to worry about damaging it). Use a Blunt Screwdriver (not a Sharp one you will damage the Metal Surface the Seal Mates with).
  4. There is an INTERNAL Circlip (Part #5) under that seal. Remove.
  5. Now heat the HUB around the seal. The old bearing will scorch a bit and a bit of grease might even come out. Use a hot blue flame, not a yellow one, and get used to getting your direction right for the other bearings later. Try not to heat the bearing itself. You might scorch some dust and a bit of paint in the hub too if it's already started peeling like mine had (BEFORE the Blowtorch). Actually amazed how resilient the paint was on the stuff that hadn't already peeled though).
  6. Place the Sprocket Carrier (which is fairly robust, if it was more delicate like e.g. the clutch carrier, I'd advise placing it on a piece of wood), on something solid, with a hole in it which should be bigger than the one the bearing fits in. There is ANOTHER flanged spacer (Part #7) between the bearing and the INSIDE edge of the Sprocket Carrier, which you will have to hammer against to get the bearing out. The bearing will come out the sprocket (Circlip) side of the Sprocket Carrier. Using a Socket the same dia. as the Inside Spacer (Part #7), place the Socket against the Spacer and give the Socket a good couple of smacks from the BACK (i.e. the Inside) of the sprocket carrier using a hammer, but try not to hammer the spacer directly with the hammer, as you may damage or knurl the edges of the Inside Spacer. Wear thick leather or Cotton Gloves a the metal is HOT and stays that way a LONG time.

    Or put an old BOLT through the back (inside) of the Carrier and hit the head of the bolt. ONLY use a bolt for removal of the bearing.! The Bolt should have a Shaft the size of the AXLE and a Head smaller than the hole the inside spacer sits in.

Replacement:

  1. Find a socket JUST slightly smaller than the OUTER RACE of the Bearing.
  2. Now heat the Sprocket Carrier Hub AGAIN, until it's nice and HOT and get your little helper to bring your ICE-COLD bearing, Just the one that goes in the Sprocket carrier. They can bring an ICE-COLD Beer after you get it in.
  3. Drop in your inside Spacer First (If you FORGET this you will need to take the bearing out again.!
  4. Take off the heat, place the Sprocket carrier on a Piece of Wood, Drop the new bearing into position, MAKE SURE it's about level, then place your correct sized socket/pipe drift over the outer race and give it a couple of whacks until you hear a ringing sound of it coming up against the bottom flange. Do NOT hammer against the INNER RACE.!

    Mark #403 noted    : "The sprocket carrier bearing was the hardest to install because I didn't have anything to drive it in. That would be a huge socket. So, I ground down the outside of the old bearing by holding it in the centre with gloves on and touching the outside ring to a grinder. As the grinder did it's thing, it also turned the outside of the bearing keeping the whole thing perfectly round. I used this modified old bearing and a 30mm socket on top of that to drive in the new bearing. worked OK." If it goes in skew, straighten it up ASAP, BUT DO NOT REAPPLY the heat or You will invariably ruin the Grease in the Bearing and the rubber cover if it has one.
  5. Whack Harder when it looks like it's going in straight and is 2/3rds in as it is less likely to Skew at this stage. ALLOW to cool do NOT place under water to cool. Do NOT put in the Rubber Seal until the Sprocket carrier is cool.
  6. When Cool, Replace the Circlip (Snap Ring), then before insertion, thoroughly pack the inside of the seal with grease and with a piece of wood flat over the top of the seal, tap it into place. MOST of my seals I pushed in by hand and finished off with straight edge piece of timber. They are that easy.
  7. Place the Outside Spacer in the Bearing, through the outer seal and tap it gently into place.Sometimes this needs a little encouragement to get it back in. If you have to hit it with a hammer to get it in please ensure that you put something behind the bearing so that you are not transferring the force across the ball race and possibly damaging it. A spark plug socket may be long enough to serve this 'anvil' type task.

That's it for the Classic Sprocket Carrier.

The GS Sprocket Carrier is a little different.
Here is a Better Picture. GS Sprocket Carrier.

As you can see it has TWO Bearings, either side of a Circlip, and the Spacing Washer is now BETWEEN the Bearings. This presents a problem in removal, because you can't just remove the Circlip and Whack out the Bearing and unlike the Classic, the Bearings come out the INSIDE of the Sprocket Carrier, not the Outside.

  1. After Removing the Rear Wheel, take off the Sprocket Carrier (Parts #2-#8, it just pulls out from the rest of the wheel), to expose a series of 3 pairs of black wedges (Part #23), called the "Cush Drive". You can just pull out these wedges to save them getting fried if you apply heat.
  2. Remove the "Outside Spacer", Part #3 from the Sprocket Carrier. It fits over the Shaft of the INSIDE SPACER, Part # 8 and the Unnumbered bit to the left of it. Don't lose the spacer.
  3. Lever out the Seal (Part #4) with a screwdriver (I'm Assuming you will replace it, so you don't need to worry about damaging it). Use a Blunt Screwdriver (not a Sharp one you will damage the Metal Surface the Seal Mates with).
  4. Remove the "Inside Spacer", Part # 8 and the Unnumbered bit to the left of it, by tapping gently with a Rubber Hammer or a against a bit of Hard wood. Tap against it from the from the outside of the Sprocket Carrier and pull it through from the Inside. Don't lose the spacer.
  5. Now, placing the Sprocket Carrier inside Face Down, observed there is a Washer between the Bearings (Part #7), which you have to lever across a little way with a blunt drift or Screwdriver, to expose the lip of the Inner Race of the INNER Bearing. The Inner Bearing MUST BE REMOVED FIRST and unlike the classic it comes out the INSIDE. (There is no other way). Just push against the washer with a screwdriver. Don't hammer it if it jammed between the Bearings, you'll ruin it, unless of course you bought a Spare. In extreme cases, if it will just not budge, Heat the Sprocket Carrier around the INSIDE Bearing and use a Slide Hammer (Get someone to hold the SC Down) to try and dislodge the Inner bearing just enough to free the washer. Or after heating try gently whacking against the outer bearing to see if you can slightly separate the two.
  6. Once you have established you can move the washer across OK, find a good drift which you know will fit against the lip of the exposed inner race of the Inner Bearing.
  7. Now heat the INSIDE of the HUB around the INNER BEARING. The old bearings may scorch a bit and a bit of grease might even come out. Use a hot blue flame, not a yellow one, and get used to getting your direction right for the other bearings later. Try not to heat the bearing itself. You might scorch some dust and a bit of paint in the hub too if it's already started peeling like mine had (BEFORE the Blowtorch). Actually amazed how resilient the paint was on the stuff that hadn't already peeled though). Use Leather Gloves to Handle.!
  8. Now, place the Sprocket Carrier INSIDE BEARING DOWN. I'd advise placing it on a piece of wood), on something solid, with a hole in it which should be bigger than the one the bearing fits in. Using the Drift from the OUTSIDE of the S.C. with the Drift against the Bearing Lip, give the INSIDE Bearing a good couple of smacks. DO NOT hammer against the OUTSIDE BEARING as you may damage the Circlip or Circlip Slot. Wear thick leather or Cotton Gloves a the metal is HOT and stays that way a LONG time.
  9. Once the inner bearing is out, an INTERNAL Circlip (Part #6) will be exposed. Remove. The OUTSIDE BEARING will be exposed.
  10. If you were quick to remove the Inside Bearing and Circlip, you will not need to reapply heat. Otherwise, reapply Heat to the S.C. again, concentrating around the Outside Bearing. Again place the S.C. INSIDE BEARING DOWN.
  11. Using a hammer and a socket the Dia. of the INNER RACE hammer the Outside Bearing Out in the Same Direction the Inside Bearing Came out. i.e. Toward the inside of the S.C., FROM the Outside of the S.C.

Replacement:

  1. Find a socket JUST slightly smaller than the OUTER RACE of the Bearing.
  2. Now heat the Sprocket Carrier Hub AGAIN, until it's nice and HOT and get your little helper to bring your First ICE-COLD .... Bearing, one of the two that go in the Sprocket carrier. They can bring an ICE-COLD Beer after you get the job done.
  3. Take off the heat, place the Sprocket Carrier on a Piece of Wood Outside Face Down, Drop the new bearing into position, MAKE SURE it's about level, then place your correct sized socket/pipe (or whatever fits the Bearing Outer Race AND down the Hole), over the Bearing Outer Rim and give it a couple of whacks until you hear a ringing sound of it coming up against the bottom flange. If it goes in skew, straighten it up ASAP or remove it and try again BUT DO NOT REAPPLY the heat or You will invariably ruin the Grease in the Bearing and the rubber cover if it has one.
  4. Do NOT hammer against the INNER RACE.!
  5. Whack Harder when it looks like it's going in straight and is 2/3rds in as it is less likely to Skew at this stage. ALLOW to cool do NOT place under water to cool. That's ONE BEARING.
  6. Replace the Circlip (Snap Ring) and place the Spacer Washer in position inside the Circlip. DO NOT FORGET THESE TWO ITEMS.! Refer the GS Sprocket Carrier FAQ.
  7. Repeat a-e for the second (INNER) Bearing except don't hammer the inner bearing Hard up against the Washer. Just Snug, so the washer can JUST move between the Bearings, is OK.
  8. Do NOT put in the Rubber Seal until the Sprocket carrier is cool. Thoroughly pack the inside of the Seal with grease and with a piece of wood flat over the top of the seal, tap it into place. MOST of my seals I pushed in by hand and finished off with straight edge piece of timber. They are that easy.
  9. Place the Inside Spacer through the Bearings from the inside of the S.C.
  10. THEN, put the outside spacer over the top of the shaft of the Inside Spacer. Ensure the Outside face of the Outer Spacer goes snugly through the outer seal.

The GS/Dakar Sprocket Carrier bearing is 6204-2RS1/ C3. The "/C3" designation is rather important as the bearing is a "shrink" fit in the carrier. The C3 tell us the bearing has a bigger internal bearing clearance than normal. That is used so that when the carrier cools down it clamps onto the bearing a bit and thus eliminates any "looseness". If you fit a standard clearance bearing in the carrier it will be a bit "tight" internally. from Haakon #626.

That's it for the GS Sprocket Carrier.

Rear Wheel Bearings: Wheel

The problem with both of the Wheel Bearings is that there is a Long Tubular Spacer between the bearings. Because this spacer is the same internal diameter as the bearing the teeth of a conventional slide hammer cannot get any purchase on the underside of the bearing. I didn't have any other tools and the thought about using the Hilti-Bolt hadn't yet occurred to me (See the Clutch Cover Removal FAQ for details - useful for BLIND Bearings, where there is not a through-hole.). So this is what I did:

Removal:

  1. Now the sprocket carrier Side Wheel bearing has NO Seals and NO Circlips, So you don't have to worry about taking them out. However the brake rotor side has a Seal and a Circlip. Gently Lever out the seal with a Blunt Screwdriver (not a Sharp one you will Damage the Metal Surface the Seal Mates with) and remove the Circlip.
  2. On ONE END of the spacer (discussed above) there is a (centralizing) washer, which stops the spacer dropping into the hub. Of course you could go and buy BMW Special Tool "XYZ" but it's expensive and I need both my arms and legs. So you need to find the end of the spacer that moves across MOST (beneath the Bearing) and heat the Hub Casing around the Bearing on THIS side for removal. (Do not heat it yet). It is not shown in the manual. One of the wheel bearings will be easier to gain purchase on than the other, due to the centre spacer between them having a locating washer pressed onto its outer surface (between outside of spacer and inside of wheel hub, but closer to one end than the other).  What you need to do is to determine WHICH end of the Spacer moves across the most and remove this Bearing first.

    Mark #403 notes    : "When pushing the spacers (both front and rear hubs) to the side, if the spacer doesn't seem to move much, turn the wheel over and try the other side. The centering washer is of course at     one end of the spacer, except you don't know which end. Once I found the end that would move, it was very easy to get purchase on the bearing with a long drift. Two good whacks and the bearing was out."

      
     
  3. Some people have a devil of a time getting the spacer moved over enough to get a drift to catch on the old bearing. Of course the end WITH the Washer on it will not move across. Also, if the Bearings are hard up against the Spacer, (which when you put them back they should NOT be), even the free end of the Spacer is hard to move across enough to get any purchase on the Bearing with a Drift, because both ends are trapped by the Bearing Races. (Not sure if BMW installs the spacers all facing the same direction).

    My trick, because you're going to Trash the old Bearing anyway, is to either:

    (a) - After an initial heating, (or you CAN do it cold) hammer the Centre (one or Two Whacks on a Correctly Sized Socket) of one Bearing (on any side) to move the opposite end bearing away from the Spacer just enough to free the Spacer just enough to slide across i.e. it LOOSENS the Spacer between the bearings just enough so you can move it across (and you can only move it across at the end without the washer around it.!).

    or:

    (b) - After an initial heating (or you CAN TRY to do it cold) try and use a Puller to get some purchase on one of the bearings, to move it out just far enough to get the Spacer loose as (a) above.

    (You will have to do a secondary heating to actually remove the bearings after this.).

  4. Once you have determined the end of the Spacer that WILL move across, the Bearing closest to this end of the Spacer is the one you should remove FIRST. Call it Bearing 1. Inserting a drift (about 8" long) through the Hub, from the OPPOSITE side to Bearing 1, push sideways on the drift, trying to push the spacer off-centre enough for the drift to be able to whack on the inner race of what is now the far bearing (Bearing 1).  (Do NOT use a sharp screwdriver to push the spacer across or you will score the inside of the spacer).
  5. When you have determined you can push the Spacer across with the Drift in a couple of different directions, heat the Hub around Bearing 1. Be VERY careful NOT to heat the spokes. They are very thin and will glow red in a short time. Perhaps a short section of steel pipe placed over the hub is a good idea to protect the spokes.
  6. Place the Wheel over a Piece of timber with a Hole in it. (Place the wheel bearing you want to knock out, down). Now with the Drift pushing the spacer across and the Tip of the Drift on the inside Race of the Bearing (Bearing 1) hammer the end of the drift. Note that considerably less than half of the Bearing Race will be exposed and it is tricky to hit. Two or three Good Solid Whacks will do it. If it is difficult, try pushing the Spacer across in another spot and hit the race of the Bearing again, say across a Diameter.
  7. With this bearing out, remove the spacer, heat the Other Bearing, Bearing 2  (make sure the Circlips are OUT) and drive out with a drift through the Hub.Pat #1210 notes: I couldn't get this spacer out in the manner mentioned here (ie BEFORE bearing No. 2 is removed) so I placed a suitably sized socket on the bearing 1 side of the spacer and a couple of hits had the bearing out.
  8. Note also that driving sealed bearings (in or out) with the drift on or near the inner race, when the bearing SEAT is on the outer race, will stuff the bearing. So always tap in the NEW wheel bearing on the Outer Race. Knocking Bearings OUT on the inner race is not so important as you're not going to use those bearings again anyway, right.!. Same goes for hitting the outer race when the inner race goes onto a shaft, like the Steering Head bearings. OK, that's the removal.

Replacement:

  1. Putting them back is easier, BUT be careful, the HUB is narrower in the middle than the outsides and the washer around the spacer won't fit past it. So (a) Do not forget the spacer and (b) put the spacer in the right way around, i.e. The End WITHOUT the Washer to the First bearing installed.
  2. Having frozen your bearings in the freezer, Heat the Hub again, good and hot, (Spit Sizzles aka Flash) and have the bearings close at hand in ice water or in a Freezer in your Garage. They warm very quickly.
  3. Installation is the SAME as for the Sprocket carrier above BUT two things to watch out for. The first is the Bearing with the Circlip must be driven as far as you can see the Circlip slot exposed. The second is Do NOT Drive the second bearing in too far that it JAMS the spacer hard up against the first (installed) bearing. It must be just a little slack. So it makes sense to put in the bearing WITH the Circlip FIRST.
  4. The 30mm socket used on the countershaft nut is absolutely perfect for driving in the four wheel bearings, but not the sprocket carrier bearing. Thanks to Mark #403.
  5. ALLOW to cool, Install the Circlip, Pack the seals with grease, press them in by hand and straighten with a FLAT piece of Timber. Remount your wheel, et Voila.

Grease your Axle: If the bearings fail and the Axle doesn’t have enough grease, the wheel bearing inner race(s) can weld themselves to the axle. This is an expensive example of why it is a good idea to grease the axle with a good wheel bearing grease before re-installing it (delays the "welding" process of Axle to Bearings if your wheel bearings fail !).

 

For Reinstalling the Wheel refer the Rear Wheel Removal FAQ.

 

Experiences:

by Marty #436
Here are some Photos of completely wrecked Bearings i.e.. No Balls, just BALL DUST. Thanks to Marty #436.
Photos courtesy of Greg Olsen of Alaska who graciously came to my aid in the repair adventure.
 

97F650 Classic - rear wheel bearing failed catastrophically at 13,000 miles just north of Anchorage, on the way back from a trip to the Arctic Circle. I was refused warranty work by Anchorage BMW dealer, as bearings are a "normal wear item". I've been told that the "service interval" (i.e. remove & replace) is 25,000 miles. Local dealer and BMWNA gave me the royal run around, never resolved (ask me if I'll bother to buy a BMW new enough to have a warranty again). Have had the bike since 7200 miles, my mileage had been (at that point) approximately 15% graded gravel road, the rest pavement (almost all street now). Based on the condition of the bike, I suspect that the previous owner's miles were mostly pavement as well. Pictures of:

 Failed F650 Bearing. The metal outer part is all that remains of the seal; the outer spacer (3 o'clock position) is grooved at seal area. The inner race (5 o'clock) is missing the balls and cage (silver dust inside wheel hub). Outer race is still in the wheel, and notice that the inner spacer end is chewed up a bit.
 

 

 


 Bearing Dust. This is the material that poured out of the wheel when we dumped it out. Note the lack of indication of any lubricant. When the inner spacer was pulled out, some egg shaped balls fell out as well. Both bearings and the seal were replaced (other parts were not available). I will be redoing the whole job complete with new parts when I remove that wheel for a new tire/chain/sprocket (soon). Will use standard industrial/automotive bearings (# is in FAQ) and seal, ask for the "top of the line" bearing (forget the name), it's like US$2.00 more/bearing (price was less than $20/bearing, if I remember correctly).

 

Munched Rear Wheel Spacer

 

Back to bearings. Replaced the chain carrier bearing at 21k as it was "crunchy". Possibly related to stresses from the wheel bearing failure? Again, I replaced the bearing and seal with "top of the line" industrial/automotive bearings.

Replaced the front wheel bearings at 21K. Preventative maintenance, still seemed OK. Top line industrial/automotive bearings and seal.

Replaced the steering head bearings at 21K. Seriously notched, especially noticeable at highway speed behind semis. Replaced with the hi-performance ones listed in the FAQ (from local bearing house). Top and bottom seals had to be ordered from BMW. Used extremely high temperature waterproof grease, we'll see how long it lasts (stuff they use on steel mill/paper mill conveyors). This is definitely NOT advised as a project for a beginner to start with.

My observations are that these F650 bearings can be expected to wear much quicker. After all, they all lack serious environmental protection...the wheel hubs and sprocket carrier only have seals on one side, and the seals on the steering head are not that great, either. With more water and dust ingress comes more wear.

My plans are to carry a spare set of bearings and seals for the wheels and carrier. The work can be done in LOTS of places, IF you have the parts (otherwise, a day or more wait?). Steering head bearings tend to go slowly and is a much bigger job, so no point in carrying them (except round the world trips?).

Finally, while the rear wheel/chain/sprocket, etc were apart, thought it was a good time to replace the damaged parts I had to re-use when the rear wheel bearing turned to "dust" (you really liked those pics) in Alaska. I also took a picture of the "used" center spacer vs. the new one. Worked out OK because the ends were still square and the length correct. The walls are a little thin in places, though. Best I can figure is that the bearing cage failed, and the balls escaped to the inside (between spacer and hub) and never "escaped", just spun around inside, getting egg shaped, and grinding away the outer part of the spacer and the inner part of the wheel hub (fortunately, inboard of the bearing race seat and circlip groove). Couldn't take a decent picture of the inside of the hub, but looks like there is still plenty of meat there, although the inside surface resembles the used spacer. Guess that additional "support" on the inside of the wheel hub is why I didn't notice a SERIOUS problem with it (and the molybdenum disulfide grease on the axle didn't hurt, either).

 

FEELING WHEEL BEARINGS
by Flash #412
Additional comments by Kristian#562
October '01

Bearing Failure Feedback

Refer also Survey Section for early feedback

Miscellaneous Items & Q's

Rear Wheel Spacer:

Just rebuilt my 1994 model, and have just found out I am short of a rear wheel spacer ( Disc Side) anybody out there give me the dimensions so I can get one made up?

Bearing Grease:

What should I use?