Steering Head Bearing Replacement FAQ
compiled & edited by Kristian #562
updates edited by PDuffy#1244 & Kristian #562
Please read the Disclaimer before attempting any work in this FAQ.

Steering Head Bearing Replacement
by Kristian #562



As often reported on the Message Board, the F sometimes came with a less-than-desirable amount of Grease from the Factory, resulting in "Notchy" bearings after about 20-25K Miles, but sometimes earlier.

Check FIRST however that your tires aren't just worn.

Typical Q. "My recently acquired '97 feels as though it is falling into turns, especially left handers. I did note the front Trail Wing is showing cupping and edge wear, but is that the cause or the result? I can't see anything else visually that would cause this effect."


What’s a C-Spanner ?



Some HIGH Temperature Bearing Grease. 

You MUST also get the Lower "Rubber Washer" with the Metal Backing Plate that sits underneath the bottom Bearing.

The rubber boot/cover on top is part # 31 42 2 345 290. (Again many thanks to Mark #403 for supplying parts details). However the old one can be reused!


Tightening Torques:

Note: Spakur's 1995 F Manual says 32Nm on the 2# Allen Bolts Front Brake Calliper to Fork Leg so Check the year of your Bike.!


Feeling Whether it’s really needed:


You will need to remove in order, The Tank, The Front Wheel & Attached Brake Line & Odometer Cable, the Handlebar (Unless you have the BMW tool), the Triple Tree Fork Clamp Bolts, the 30mm Triple Tree Nut, The Triple Tree, The Upper Bearing Slotted Nut (Using C-Spanner), the Front Forks and FINALLY the Steering Head Bearings (Outer Races (2# in Frame), Inner Race, 1 # on Shaft.  Sounds a lot but it goes fine if you work your way slowly through it.!

Tank: Removal

This will allow MUCH better access to the steering head.  To do this you should first turn OFF the GAS petcock.  Also remove the SEAT.  Preferably done with an almost empty Gas Tank. 

See the Gas Tank Removal-Replacement FAQ for photos and detailed procedure for the Gas Tank Removal


Front Wheel (& Attached Cables & Lines) Removal:

You need to do this because otherwise you can’t get the forks LOW enough to get the Steering Head Shaft out of the Frame.  You could conceivably drop it into a pit, but front wheel removal is so quick and you really don’t want to be putting bearings onto a shaft that has a wheel at the bottom.

  1. Place the Bike on the Centrestand & Prop the Bike Under the Engine.  You might like to remove the Plastic.!  “Bash Plate” to do this.  Prop it with something stable, i.e.  build up a Pile of Bricks.  Alternatively you CAN Tie Down the rear of the bike to a couple of tie down points, because after you get the front wheel & Fork off, the weight distribution is over the back wheel anyway. 
  2. Remove the Plastic Cover to the Front Brake (Small Allen key Bolts) and LOOSEN but do not remove the large Allen Bolts that Hold the front Brake onto the Lower Fork Leg.
  3. Undo the connection of the Brake Line and the Odometer Cable from the Semi-Circular Splash Plate (8mm Bolts) under the front fairing.  All the Parts attached the Forks should now be free of the forks.  Unclip the (Electrical) Horn Spade Connector.  You also need to get that Circular Black Splash Plate off too.
  4. Remove the front wheel.  You do not need to completely remove the four SMALL 10mm nuts, Front Axle Clamp Nuts just loosen them sufficiently to get the Front Wheel Bolt (8mm Allen) Undone and pulled out.  That way you won’t lose the little suckers.  Ease the front wheel off, taking care the disc gets past the Brake.  Careful that you do NOT Squeeze the FRONT Brake at any time during this repair as the Brake Piston will Pop out when the disc is free.  You can Push it back in by hand but not too far.
  5. Now remove the (8mm Allen) Bolts holding the front brake on. You might like to tie up the calliper a bit so it doesn't hang down and kink the brake line somewhere.
  6. Protect all the wiring/cables/plastic with heavy aluminum foil (heat protection) before heating the steering head area

Removing the Handlebars:

  1. Prise off the plastic Handlebar Mount covers and Mark the Position of the handlebars with respect to the Mounts with a Pen.  Use an Allen Key to remove the Allen Key Bolts holding the handlebar on.  Remember that the arrows, when putting it back, should be in the driving direction, meaning straight ahead.
  2. You do not need to remove all the cable & Lines to the Handlebars, simply Tie the whole lot back to your Windscreen or Dash, but put a Cloth over them first.  Take CARE you do not bend any of the lines or cables, i.e. use as large a radius as possible.  Don’t Grab the Brake Lever.!  To do this feed each line that is both attached to the Handlebars AND enclosed inside the two black holding bars beside the Ignition key, OUT of this holding area.  They will be much longer and freer to work with.

If you have the BMW 30mm Tool, I guess you can skip this as the Triple Tree Fork Bridge will come off with the Handlebar Mounts & Handlebars attached, but frankly taking off the Handlebars is not a Large Problem.

Removing the Forks:

  1. Undo the 6mm Allen Key Bolts CLAMPING the Triple Tree to the Forks i.e. Clamp nuts, marked yellow. (Do NOT remove the Large Aluminium Caps off the Forks). Marty #436 provided this annotated Photo of the Triple Clamp Top and Sides. You do not need to undo the LOWER Triple clamp bolts only the upper ones.
  2. Undo the 30mm Nut between the Handlebar Mounts. Fork Bridge Clamp Nut. (Do not worry the Forks won’t drop out until the Slotted Nut that you undo with the C-Spanner is undone).
  3. Ease off the Triple Tree. If it doesn't come off
  4. Undo the Slotted Nut with the C-Spanner and get someone to HOLD the forks up until you’re done then get them to gently ease the Forks Downwards until the Fork Shaft is clear of the Frame.  If after you’ve undone the Slotted Nut the Forks Don’t drop out, use a rubber hammer to Tap the Top of the Shaft.  Normally I would recommend putting the nut back on the shaft and driving that but the thread is SO FINE and the NUT so thin I do NOT recommend it.
  5. Now you should have set of forks with a bearing (Inner Race Only) on the lower part of the shaft.  The inner race of the Upper Bearing should just be sitting in the Outer race of the Upper Bearing.  You can take this out by hand.
  6. Make sure you take a note of where your cables and lines are routed, you will need to put them all back later and the correct routing is important.!

Bearing Removal:

Bearing Removal is in two Parts: Outer Races (2#) and Inner Race 1# on the Shaft.  The Outer Races are like Steel Rings and are in the Frame at the Top & Bottom the of Headstock.

Outer Race Removal:

  1. To remove the outer races grab your torch and Heat the FRAME around the Race (not the race itself).  Take care to NOT burn or scorch the Cables/Brake Lines etc.  i.e.  put some layers of Aluminium Foil Around them or sheet of Aluminium.  You CAN drive the Upper race COLD if you have a BFH (BIG HAMMER) and a LONG Drift, but it’s like pulling teeth.  You need the Drift in any case.  Wear GLOVES, thick cotton Garden gloves or Leather ones.
  2. After applying the heat (Get them good and hot), Grab you LONG Drift and drive the Top Inner Race out from the Bottom, i.e.  stick the Long Drift in from underneath, through the bottom of the Steering Headstock and drive the Upper race out of the Top of the Frame.  Work your way around the circumference of the race until it pops out. Jean #636 notes: "The drift punch. I really fought hard dislodging the old outer races before using a Drift Punch with a 3/16" point. The one I used was made by DASCO Pro reference number 603-0. I am sure there are other tools you can use but this one made the job really easy. (for the Lower Bearing) the drift has to be at least 8-1/2" inches in length to go all the way through the frame tube."
  3. Removal of the Lower outer Race is the same as for the Upper, just heat the Lower Frame AROUND the Race and drive it out using a drift placed in from the top, so that you drive the race out the BOTTOM of the (Frame) Headstock.
  4. A good alternative, for those of you with access to a Welder, is to place a bead of weld around the RIM or the INSIDE of the OLD bearing race. When it cools, the bead of weld will try to contract and cause the Bearing to also contract, allowing it to be easily removed from the Headstock. 

Inner Race Removal:

The Upper inner race should already be out by now, so this is only relevant to the lower one, which is a tight fit on the shaft.

  1. This one’s a bit more tricky.  If you bought a new Gasket Ring (the one under the Bearing) you can both heat and whack that and not worry.  Apply heat to the bearing, but clean all the GREASE off it first so it doesn’t smoke you to death and do it in a WELL VENTILATED AREA.  Heat it good and hot.
  2. Lie the Steering Head Shaft and forks down on a Bench or on the floor, with the threaded end of the shaft hard up against a Solid Piece of Timber.  The threads are very fine so don’t drive against anything metal or concrete.  You will damage the threads.  Using a drift (or slide hammer if you can get the jaws on) drive the back of the bearing toward the threaded end of the shaft.  It’s hard to do without damaging that washer and the Bearing Race MUST Be HOT.  Wear Gloves.!
  3. Alternatively, cut a piece of thick foil to shield the lower grease shield. Then place a length of thick walled tubing over the stem and run a weld with a mig welder around the tube/bearing. Then used a hammer and chisel on the weld to force it off.
  4. Don't forget to take off the Rubber Gasket Ring if you damaged it.

Bearing Replacement:

Inner Race Replacement:

The Upper Inner Race Just Fits over the shaft without any hammering, so this is confined to the Lower Inner Race Only.

  1. Put the Lower one on First. Don’t forget the Rubber Gasket Ring with the Steel backing goes on FIRST, Before the Bearing.  The Rubber side faces the bearing (i.e. up).  If you damaged it and are 1 Million miles from a new one, use some Silicone to seal the tear.  If you can, use Lots of Ice in a water bucket and place the Steering Shaft (With forks etc attached) in the Bucket to cool the Shaft of the Forks as much as possible before replacing the bearing.  Alternatively if you have access to some Liquid Nitrogen, spray some of that on...  :-).  JOKE, but if you do use it, careful it’ll take all the skin off your hand.
  2. Place the Bearing Inner Race (It has the Rollers on it) over the shaft with the Rollers facing UP i.e.  Tapered so wide end is closest the Bottom of the forks) and let is slide down toward the Rubber Gasket Ring.  It will get stuck about an Inch or so above the Gasket Ring because the shaft is slightly bigger at that point.  Heat the Bearing with your Torch, Good and Hot JUST the Bearing.  Alternatively you can heat the Bearing First and WEARING your gloves, place it over the Cold Shaft and Drive it Straight away.  This way keeps the Shaft Cooler longer but you MUST be careful of the VERY HOT Bearing.  The best way to drive it is to use a piece of thick walled Pipe JUST larger than the shaft and drive that down onto the bearing.  A piece long enough to drive from the top above the threads is most ideal.  You don't HAVE to heat it, but it can make the job easier. Don’t Drive the needles or needle cage, drive the solid metal next to the shaft.  If you drive the needles or needle cage you will RUIN the bearing.  Don’t drive using a screwdriver.  Don’t use the OLD bearing it will get STUCK on the shaft.  Perhaps you can file out or sand out the old bearing so it is big enough to drive the old one without getting stuck, but test it FIRST.! Jean #686 notes: "Putting back the new lower bearing inner race I fought and swore long and hard again before getting a 1"x18" galvanized steel pipe with a rubber thingy on both ends at the local hardware store. It's apparently a plumber accessory. It rests nicely on the inside of the joint without touching the needles and it's long enough that you can hammer it without risk of hitting the top of the steering column. It then went down like butter. I used a heat gun but I am not absolutely convinced it was necessary."
  3. Drive it all the way to the bottom until it comes up nice and hard against the stop above the Gasket Ring.  You will both feel and hear it when it reaches that point, it sorts of goes CLANG rather than THUD.  (You’ll know).!
  4. Do NOT drive the bearing with the bottom of the SOFT Aluminium forks against something hard, straddle the forks OVER something that comes up against the MIDDLE of the LOWER fork brace.

Outer Race Replacement:

OK, these are relatively easy.

  1. Make sure the outer races have been in the FREEZER for a while.  Place in a bucket of ICED water until you need them if your freezer is at the other end of the House.
  2. Heat the Lower Frame at the Headstock around the Outer Race Location, Good and Hot.
  3. Take the Race and drive it into the LOWER Frame THICK END FIRST.  i.e.  Thin end facing YOU.  If you get it right (HOT & COLD), it should slip in.  I used the thick end of the old race to drive it in but it got stuck and took a bit of hammering to get it out.  Use a piece of pipe or something JUST smaller than the diameter of the thin end of the race, but not a drift unless it’s very BIG or it will damage the thin end of the race. Difficult, because the end of the race you drive is thin.  It will also go clang when it’s in all the way and seated against the flange.

    Jean #686 notes:
    To drive in both the lower and upper outer race I used a PVC pipe 1-1/2 in diameter and a foot long. I did not want to use anything that was made of steel because I did not want to damage the races. It took a lot of hammering but it went in (and the PVC pipe looks now like it's been chewed on by a Doberman).

    I used the torch but also a can of air duster (I used this technique on the outer races also - removing and installing) for cooling - it was hard to get the lower race in because of the working position. I also used some duct tape and taped the old race to the new one, only on the inside of the race so the tape didn’t get stuck in there so I could focus on hitting it with the hammer. Spakur, Sweden.
  4. The Upper Race is exactly the same, ALSO Thin End facing YOU.  i.e.  Thick end first.  Drive from the Top.

I had the forks off anyway for Fork Seals, I put the lower triple tree in the freezer overnight which worked very well. The bearing was then heated up and slid down with relative ease. A short length of suitably sized steel tube was used as a slide hammer to drive it home. Pat#1214

That’s your Bearings replaced!

Fork Replacement:

  1. First GREASE LIBERALLY the Lower Inner and Outer Bearing Races with Hi-Temp Bearing Grease. (BMW#10 or similar.)
  2. Insert Steering Shaft (With Forks Attached) in from the Bottom.  Get Someone to do this so you can Prop them with something under the bottom of the forks, so they stay put while you work on the top.  Make sure the Cluster of four nuts that lock the wheel shaft is on the RIGHT side and facing forward.  You cannot turn it later.!
  3. Grease the Upper Inner and Outer Bearing Races with Hi-Temp Bearing Grease and pop the Upper Inner Race (Needles i.e. thin end of the Taper goes Down) over the end of the shaft and tap gently onto the shaft. This bearing should go on fairly easily.
  4. Mine only had a lower Gasket Ring and so did Jean#636, but Mark #403 notes his had two, a lower and an upper. Perhaps rust protection.? At this stage the next item to go on is this Upper Gasket Ring, followed immediately by the Rubber Cover. Marty #436 provided this annotated Photo of the Sequence.
  5. Screw on the Slotted Nut HAND TIGHT only at this stage.  This will stop the forks dropping out.
  6. You’re not going to replace anything else at the moment, because we need to get the wheel back on so that we can get some weight back on the front of the bike, so that the correct adjustment of the Slotted Nut can be made.

Wheel and Cables & Lines Replacement.

  1. Fit the ODO connection back into the hub and ease the wheel between the forks.  Screw in the Wheel Axle Shaft. The threads are on the left side.  Torque the Shaft.  Don’t forget the Washer on the BRAKE side of the Wheel.  The Brake Disk goes on the left, odo on the right, both looking forward.
  2. Tighten the four 8mm nuts that clamp the Wheel Shaft.  These are safety nuts but they are very small.  Torque the TOP two first then the bottom ones.  There will be a GAP between the bottom shell and the fork frame after tightening these.  This is normal.  Don’t forget to Grease the ODO Connection and Shaft Before replacing.  Do not grease the part of the shaft under the 4 Nut Clamp.  Do NOT OVER TORQUE THESE TINY NUTS.!
  3. Spread the Brake pads apart with a screw driver so that they will fit over the Brake disc.  Only the Outer pad next to the Piston will actually move so lever that one against the other one.  Place the Brake over Piston and Torque the two Allen Bolts Holding it on.  (You can also fit the Brake and then the wheel into the Brakes, the way you do if you have a flat tyre and you remove JUST the wheel.)

    IMPORTANT: When you replace the Front Brake Calliper, make sure the Bolt threads are clean and there are absolutely NO bits of Aluminium or any other dirt or swarf jammed in the threads. If there is, use a fine screwdriver and a wire brush to clean them thoroughly. In addition check there are no bits of Aluminium in the threads of the Calliper itself. Test that it can be wound all the way in BY HAND before tightening. If it jams going in by hand, take it out and check it and clean it again until you CAN screw it in BY HAND.

    The reasons should be apparent, however any small amount of Aluminium in the thread will start the bolt jamming. If you tighten it further with a socket or spanner, it can't screw in any more and starts ripping threads out. Then with more Aluminium now jammed in the threads, as you back it out it rips even more Aluminium out. You do not want this to happen. Really Bad Karma. Do not exceed the specified torque.
  4. Reattach the Plastic Fork Brake Cover.
  5. Reattach the Splash guard.  Reattach the Cable & Brake line connections on the lower fork legs and underneath the Splash Guard under the Front Fairing.  Re-attach the HORN Electrical Spade Connector.
  6. Jean #636 notes: "It was difficult to make sure that all the cables were nicely back in place such as the odo cable in between the fork legs, not outside the right one (when seated on the bike), the brake line going under the ignition solenoid, and the throttle cable that goes under the tank in between the fork leg (not outside...) That may sounds stupid but when you get it wrong you have to undo the triple tree to (replace them right.". So true.! So look first before you undo it. Marty #436 provided this annotated Photo of the Cable Routing.

Triple Tree & Handlebar Clamp Replacement:

  1. First you have to adjust the play in the Steering Bearings.  There should be “No Play”, but this doesn’t mean cranking up the Slotted Nut with an Almighty Force.  The Steering must be Free to turn without Jamming, but should still have NO PLAY.  So remove all the props under the bike and allow the weight to go back on the front wheel.  Rock the steering back and forth a couple of times to seat.  Tighten the Slotted Nut with the C-Spanner or a screwdriver in one of the Grooves, just Until it’s Little Finger Strength Tight but NO FORCE.  Test it a few times to feel if it Jams or if it is free.  (You can also adjust the Slotted Nut later on, it’s just a bit of a PITA to take off the handlebars again.) Some folks may like to put the Handlebars on first before tightening, to get the feel of the Steering, I just found it easier to get to without AND you need the BMW Socket to do this.
  2. Place the Triple Tree over the Steering Shaft AND the Forks and Torque the 30mm Nut down onto the Slotted Nut.  Make sure the Triple Tree IS over the Forks before tightening the Nut.  The 30mm NUT MUST be tightened FIRST before the two fork leg clamps (marked with yellow splodge), or you will stress the Triple Tree.  Some folks use LOCTITE 248 (The removable one) on this Nut.  Not a Bad idea, but if you want to adjust it later you will need to reapply it. NOTE: Strictly speaking, it should be the LOWER Fork Clamps that you should undo, if you want to maintain EXACTLY the 3mm Upstand between the Top of the Fork Plug and the Triple Tree. But IMHO the movements are so small, (But that doesn't mean the induced bending stress is small) so I just undo the upper ones.
  3. Torque the two fork leg clamps (RHS). (Allen Key Bolts). Here's the other one (LHS). Also (marked with yellow splodge).
  4. Untie the Handlebars from the Windshield and Replace on the Handlebar Mounts.  Use your old marks for height.  Torque the Allen Keys down, rear ones first then the front (This is an opinion).  Replace the plastic covers.
  5. Feed the Cables back into the retainers.  They should all be nice and loose on Full Lock, both ways.
  6. Squeeze the Handbrake a few times to get the Pressure back on the Front Brake System.  (To avoid giving yourself a Heart attack when you drive off.)

Tank Replacement:

See the Gas Tank Removal-Replacement FAQ for photos and details.

That’s IT.!

Go for a Ride and Go WOW, Like New!..!  Then Go Have a Beer or 3 and feel very very satisfied with yourself.

Readjusting Play:

If you didn’t get it quite right you can readjust the play later on.  In this order:

  1. Remove the handlebars (or if you have the BMW Socket just Loosen the triple Tree Nut under the bars, this is where the BMW Tool IS Useful), and Loosen Only the 30mm Nut with a Socket. 
  2. Loosen the Fork Clamps (Allen key Bolts) at the Top of Each Leg,  NOTE: Strictly speaking, it should be the LOWER Fork Clamps that you should undo, if you want to maintain EXACTLY the 3mm Gap between the Top of the Fork Plug and the Triple Tree. But IMHO the movements are so small, (But that doesn't mean the induced bending stress is small) so I just undo the upper ones.
  3. Then adjust the Slotted Nut with a C-Spanner or by tapping in the Groove with a Screwdriver.  SMALL INCREMENTS. 
  4. Check Play.  The Steering must be Free to turn without Jamming, but should still have NO PLAY. 
  5. IMPORTANT.  Torque the 30mm NUT up first BEFORE the 2 Leg Clamp Bolts or you will put a bending stress into the triple tree.
  6. Torque the 2 Leg Clamp Allen Key Bolts.


If steering head bearing play is:

"too loose" you'll feel vague handling at high speed.

"too tight" you'll feel the bike feels "drunk" and "staggers around" at slow speeds.

"barely too tight" you'll feel like it has a steering damper on (Just right). Marty #436



I can’t remember the total time exactly, because I did it over several days, initially after work, under lights, munched by mosquitoes.  The first night I took off the tank and the forks.  With ALL the Tools at Hand:


This assumes you have or can borrow (At least the Torque Wrench) all the Tools, including Allen Keys, Sockets, Ring Spanners, Torque Wrench, C-Spanner, Drift. Thanks to Mark #403 who was the first to use the FAQ and Jean #636 who was the second, both of whom came back with some great comments, as well as parts numbers.


Steering Head Check and Bearing Relube (NOT Replacement)

by Langlois


The F650s are known for being underlubed so I am adding this to the 6K service, here are the photos.


Pop off handlebars, hang to the left side with the upper triple clamp. Move tank back on frame or remove.

Upper bearing race, not bad, needs grease.

Lower bearing, has lube, does not look bad, just needs some grease.

Lower bearing re-greased. (after wiping the race and bearing of the nasty old lube, not that there was much!)

Upper bearing, greased. This grease is either Mobil 1 or the Castrol equivalent, I keep a grease gun full of each handy. I have had very good luck with the Mobil 1 grease with other high wear applications and really like the stuff. I also use the Castrol and like it as well.

All buttoned up and ready to assemble. Note anti-seize liberally slathered on threads,  I love the stuff, you should too. I find the F650 notoriously "dry" when it comes to thread lube.


Total time, messing around, dawdling, taking my time added an hour to the service.


More Detailed Steering & Wheel Bearing Information

Flash #412, Hombre Sin Nombre, Mark #403, Haakon #636

Steering Head Bearings


The box for a Timken 30205 will read as 30205 #92KA1or 30205M #90KM1. The "M" stands for through hardened steel as opposed to case hardened steel that the 30205 #92KA1 is. Both are valid part numbers with Timken however the 30205 is currently superseded by the 30205M.


At 13K miles my OEM steering head bearings gave out on my '99. Upon disassembly they were the expected Bulgarian models. I couldn't find suitable substitutes locally, and had a friend in California looking for a specific model of Timken. Unable to find what I wanted, or a good substitute, he went to the BMW dealer to buy my new seal rings. He checked on what they had available, knowing that I did not want to use the OEM Bulgarian models. I was pleased to find that the new replacement bearings in the dealers stock, in BMW boxes with BMW part numbers, are SKF's made in Germany (SKF 30205 J2/Q) and cost less than $10 each. Hopefully these should be much better than the original bearings, at a very reasonable cost. So if you need to replace your Bulgarian bearings, don't be afraid to see what your dealer has available before you go to additional trouble to search out an alternative source for something other than the original Bulgarian bearings.


I wonder if we could find a slightly thinner bearing or with a different tapered race? The Timken catalogs won't let me search by dimensions.  The reason I mention this is because originally on my bike, I discovered that the upper seal ring did not fit down into the recess for the race, not providing a full seal. Lifting the flexible rubber cover, I could see the bearing rollers. I think the original race was fully seated, but the Bulgarian bearing in its race was almost 1mm thicker overall than the new SKF bearing. The new race is fully seated (I inspected it with a mirror), and the seal ring almost, but not completely, seats inside the race recess. Much better seal, but I wish the seal ring seated entirely within the race recess, as it would with a slightly thinner bearing. I also note that the upper lip of the race recess is NOT in true alignment with the bottom of the race recess, the welded ring/lip that the race bottoms against, almost 1.5mm of difference - very poor QC on the part of whoever made the frames - it would matter less if I could get the ring to seat deeper inside the lip. And I WISH there were room for zerks, however there just isn’t the space.


Through vs. Case Hardened Bearings


Steel alloys' molecular structure will arrange itself differently depending on how it is heated and cooled. Take a materials science course to learn all about metal phases. "Through hardened" means that the entire part has the same hardness throughout. If you took a cross section of the item and tested the hardness in the center, it would be identical to that of the outside surface. "Case hardened" means that, sort of like a Twinkie, the soft center is surrounded by a harder exterior covering.


The difference between through hardened and case hardened can be considered analogous to the difference between solid gold and gold plated.


A through hardened steel race has a (more or less) uniformed hardness through the entire cross section of the race - basically, it's the same hard metal inside and outside. Because this is actually a cheaper priced bearing, I'm guessing it's a special proprietary alloy. (Bearing mfg's are SERIOUSLY into special alloys and metal treatments.) The race may be very hard and strong, but will be more brittle, possibly subject to certain types of cracking, before it warps. Tensile and ductile strength may be higher, while yield strength may actually be lower. (Harder usually means more brittle.) A case hardened steel race is usually also homogeneous metal throughout, but it has been hardened after manufacturing. Usually this is surface hardening, the depth varying depending upon intended application. Think of it as similar to "tempering" the surface of the metal. While the basic alloy of the metal is the same throughout, the molecules on the surface may be re-arranged, either mechanically, or thru ion exchange, or have additional elements, such as other metals, or in the example of case hardening, usually carbon. This is usually accomplished by additional treatment processes after basic manufacturing. The surface (sometimes to a considerable depth) can be made MUCH harder than the original alloy. Since it's all one single piece of metal, and the original underlying alloy can be more ductile, the overall effect can be a race that is less brittle, and less damaged by warpage, and possibly even harder than the through hardened type M bearing. I don’t know which bearing surface is actually harder in this case, probably proprietary Timken info.


Detailed Bearing Information & Resources

by Haakon #626.


For other alternative Bearing Parts Numbers refer the Bearing Schedule.


In the Wheel Bearing Replacement FAQ the section with the GS/Dakar Sprocket Carrier the 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.


You can have the same nominal size e.g. 18x24x16 needle bearing in different formats, for instance,

  1. Loose: a group of individual loose needles, no carrier or shell, just loose needles.
  2. Caged: needles held in a plastic or metal cage, usually with inner and outer bearing surfaces exposed (plastic cages might not have been as popular in your 1984 index) and
  3. Shell: needles held inside a tube (usually metal) with narrowed or crimped ends that retain the bearings. Usually there are 1-2 less needles for the same size bearing, because of the shell. Similar to a "cage" but only the inner bearing surface is exposed, the outer bearing surface is contained inside the shell, which is inserted as an assembly when installed.


  1. If the bearings were loose needles (not used much today due to cost- then you have to use hardened and ground surfaces on both the "axel" and inside whatever "housing" you have) only the diameter and length is used.
  2. Same as (1) expensive to use, size given as Inside Diameter-ID/ Outside Diameter-OD and Width-W.
  3. This is what I BELIEVE is used by BMW. An outer shell and the needles held in place with a cage (to be honest it was also the only type I found with the right sizes) The use of a cage inside the shell is to prevent the needles to accumulate where there is the least pressure, and "opening" a gap where the pressure is. That does not matter a lot when the bearing turning. In the linkage and rear- swingarm we have a more or less static load and then it is not good. Of course, without a cage you get to use more needles = more bearing surface.

Some Alternative Bearing #'s.

Classic Feedback

Please note there is very little Feedback on this item because this was one of the first FAQs and at that time "Feedback" was not taken. It doesn't mean it didn't happen and that there wasn't a problem on the Classic. It does happen and it IS a problem. You can see from the FAQ above at least 10 people did by themselves. If you have done it or had it done, please email  The FAQ so we can record it here. Thanks, ed


See the Survey Section for early feedback.

Differences for the GS


So far there have been very few reported cases of the SHB notchiness on the GS. The procedure is very similar to the Classic, once you get the Panels off the bike. If you have the answers to any of these questions, please contact The FAQ

  1. Has anyone out there done the SHB on the GS/Dakar? Any significant changes from the FAQ apart from the plastic-related stuff?

  2. What's the fall-apart curve on the SHBs? In other words, will they rapidly degrade from here on in, or will they last 10,000 miles before they get really bad? Are we talking safety hazard here, or

  3. Has anyone paid a shop to do this? If so, how much did they get screwed for the work?

GS Feedback

Are SHB Warranty Work?
by Marty #436-Chicago-97 F650F

My SHBs are notched at 29K miles. I'll probably replace them myself, but as long as I was at "Chicago BMW" this morning I asked them if it would be covered under warranty. They said "No, it's a normal wear item.". Have people here had any luck replacing SHBs under warranty? Raymo #1173, Chicago, 2001 F650GSA

Look at the warranty page in your owners booklet. It will tell you that BEARINGS are considered normal wear items. My wheel bearing was toast at 13K...sorry, no warranty. My SHBs were toast at 25K (out of warranty), so sounds like you did OK on mileage. Be sure to use QUALITY BEARINGS from a bearing house and a QUALITY, WATER-WASHOUT RESISTANT GREASE that is rated for HIGH-TEMPERATURE (Classics only) and, preferably, good against fretting wear as well. (Unlike BMWs OEM stuff). You should do much better on mileage with the quality stuff.