Snowbum's BMW Motorcycle Repair & Information Website

(1).  Obviously the first step is to remove ONE of the wheels from the motorcycle.
HINT:  If a front wheel, mark the hub "left" & "right" if so desired.  Nuts are on the left, as conventional standard..yes? ..no?
HINT:  If you have hydraulic brakes, NEVER EVER hang the calipers by the hose...you can kink the hidden inside thin plastic tube, causing big problems later-on.

Now that you have the wheel out of the motorcycle, remove any trim or cap (on some models), to gain access to the seals.  The seals will, on most later models, have a lipped spacer, called a top hat spacer, sticking out slightly from the seal.  The lip, or brim of that spacer is usually INside the seal. This is not so on some early models; but should be.   Main thing is that the spacer presses on the center part of the removable inner bearing.  It is probably a moot point, but a lip/brim on some of these top hat spacers can be put on the outside, for extra spray protection ...or some think so.   Engineering-wise, I prefer that the lip press on the inner bearing race.   Depending on the wheel type, use a round rod or large fairly blunt screwdriver to pry that lipped spacer out through the seal ...if the lip is inside.   This usually destroys the seal, but you are replacing it later anyway.  If you have the rarer big wide lip spacer, it may not easily come out, and the seal needs to be removed anyway.    Don't stick a seal removal tool in too far, don't scratch the inside of the hub, and REMEMBER that SOME wheels use different size spacers left and right, so mark them or keep notes!   There is an official seal removal tool at auto-parts stores you can buy if you really think you need another tool.  See my tools article for a photo, and part number.   I don't use a seal puller, some do, and even try to reuse seals, a POOR IDEA.   I replace seals, always.

Here are photos of how I remove the top-hat (brimmed) spacer, & then the seal, from a standard-assembled seal/spacer combination. When a spacer & seal are removed, the inner bearing can fall out ...so do things with the wheel flat on the ground (support the wheel/tire, if a dual-disc or doing the other side of the wheel shown).  Remove the inner bearing with a fingertip.  If it is a disc brake wheel, or twin disc front wheel, support the disc side by using wood 2 x 4's under the TIRE, as shown in a following photo.  DO NOT PRESSURE THE DISC!  DO NOT MIX UP THE INNER BEARINGS.

The below first photo show a block of thin wood to protect from nicks.   DO NOT insert the tip of the big screwdriver, as shown, too deep...otherwise you might gouge the hub (more likely on aluminum hubs without cast-in steel inserts). DO NOT use a block of wood that bears onto the disc! ...you could bend the disc.  The second photo shows the 2 x 4 pieces under the tire so as to not allow pressuring the brake disc.

MUCH LATER, when you install new seals, you will first install the lubricated top-hat (brimmed) spacer into the seal from the inside side of the seal; except some early wheels which can be reversed but I always do it from the inside anyway, unless the top hat is too wide and would pressure the bearing ...only the rotating bearing portion (see photo, inner race area) inner steel sleeve is to be pressured. On these tapered bearings, the inner sleeve that the bearing cage is around, is slightly wider, so it will be pressured, and not the larger diameter. See below photo.

New seals are tapped squarely into proper position by light use of a hammer or mallet and an appropriate size of socket ...the outside diameter of which is not more than about 3/16" smaller than the outside diameter of the seal.  Gently, slowly!  If the seal goes in cocked, tilt the socket.  Seat the seal to flush or tiny amount deeper. Do NOT hammer on that socket such that you damage the hub nor seal ...be sure the socket is not hitting the hub.  Some of the rubberized/plastic outer seals can be pushed into position with your fingers ...and if first solvent cleaned well, and thus not left oily on the outside seal rim, adding a drop or two of water around the seal rim can help the seal stay in place during insertion.

(2).  With the lip/brim spacer removed, you now need to remove the trashed seal.  Use a seal removal tool, or very carefully use a broad blunt large screwdriver.   If using a screwdriver, insert just barely far enough, not scratching the hub inside diameter, and give the tool a good angular whack, and the seal will go flying out.  DO protect the hub exterior from marks by using something like a piece of wood under your prying tool.

(3).  As soon as the seal is removed, the inner race assembly of the bearing is removable with your finger.   This is not so on the right side of some early wheels, so there are variations.

Here is a photo of a typical early 1980's type of hub, clearly showing the cast-in-place steel insert, & the outer wheel bearing race.  The plastic part you see, & its sleeve, are captive.  The 'wedding band spacer' fits into that hard-to-see cavity of the plastic/metal piece.  On some wheels it is not nearly as clear that there is a cast-in-place steel insert.  They are, however, magnetic.

(4).   Remove inner race bearing assembly with fingertip, inspect the rollers & the still captive outer race.  On early models with the more captive right side rear wheel bearing, at least FEEL the rotation.  Watch out for scoring or overheating (yellowish-brownish & overheated metal appearance).  These, and any roughness felt, are generally cause to replace the bearing which comes including the matching outer race.  NO roughness, however slight, must be felt.  I actually do the test before I remove the bearing for cleaning & greasing.   I then additionally carefully visually inspect the inner bearing rollers and the outer race for pitting or other damage.

(5).  At this point, if NOT doing a preload measurement, and assuming your bearings & races are OK, you force grease by hand or use a bearing greasing tool, throughout the bearing, add some to the race & cavity (clean out any hardened or dirty grease you can easily, first).    Now install the oiled or greased lipped spacer from the seal inside & install the seal/spacer via the proper socket, squarely, and to flush or faintly below flush.    Do the other side of the wheel, reassemble the wheel to the bike, properly doing the bounce test after the axle nut is tight, tighten the axle clamp bolts, check things over, including trying to wobble the wheel, must be NO detectable play; go for a ride.   Early 'heated type' wheels with captive right side bearing can be modified for a custom made internal lubrication tool.  You will need to grind the finned inner spacer diameter slightly as has been noted in this article earlier. Doing this makes the parts removable without removing the left side outer race (but you have to do this once, this first time, by using the heating routine).  /5 and /6 wheels are like that, in general.

Once you have your wheel apart, all this talk in this article will be vastly clearer to you!! ....really!

(6).  IF you are doing the FULL preload job, you will be cleaning the bearing outer races with a slightly solvent dampened rag, and cleaning the inner race bearings by soaking them in something like kerosene or other grease dissolving/cleaning liquid.  The FULL preload check is done withOUT seals in place, & the bearings already cleaned of grease in a solvent, & are then wiped of excess solvent ....and then OILED.   Install the bearings in the proper side of the wheel (you did NOT mix them up??, I engrave L and R on them), together with all spacers, etc., that you may have removed.   The only parts not to be installed are any trim pieces & the grease seals.

The early wheels are shown in the books as being serviced by heating the hub and totally removing the entire 'works'.  I consider this a so-so idea, that is, constantly heating & removal/replacement over the years, with the possibility of long-term damage, so I have recommended the minor modification of the finned spacer & use of a special greasing tool for the remaining captive bearing on the right rear wheel.   The modification on the inner finned spacer that I have described for these EARLY wheels will enable cleaning & greasing without disassembly in the future ...although the RIGHT REAR WHEEL  bearing will need a tool to grease it (cleaning not being easily possible, which will be OK).  NOTE, again ....The 1978 REAR DRUM SNOWFLAKE is an odd-ball orphan, this can be identified by being a snowflake, rear, drum, and 5 bolts holding the seal retainer.  There is NO steel-insert in the hub, and all must be heated for servicing the bearings.

(7).  To avoid any confusion, I will emphasize, again, about wheels generally before 1979. While spacers & string & pull-scale CAN be used with stock original stack parts, there is more room for accumulation of errors. Hence, my advice to modify the finned spacer, & then do the preload checking by feel, or external spacers made up & do it somewhat like is described below, as done on the later wheels, like the 1983-1984 that were used for this article.   I am also fine with you using the feel method, that Duane calls the shake-wheel method, just do it right. See Duane's article for more depth.

(8).  At this point I will describe the preload in more detail, how it is basically measured, & the 1 or 2 special adapter tools needed for such as a 1983 or 1984 bike, that was used for making much of this article.  We are talking here of the FULL procedure, an ACTUAL measurement ...NOT the FEEL/SHAKE procedure. With proper width spacer(s) present in the wheel, & the wheel mounted normally in the motorcycle, the axle nut, when tightened, squeezes all the parts in the hub together.  A very tiny amount of 'free play' must exist when the nut is tightened to specifications (~30+ foot-pounds) to allow the wheel to turn without substantial friction and allow the bearings proper running clearance.  That freeplay should not be enough to be feelable.   You also do not want too little, as the friction in the bearings will be increased, which is bad for them.   BMW specifies a certain preload, and this is generally 21-42 inch-ounces.  I believe that 42 is considerably too high and I generally try to set the preload towards the lower side of that specification ...but see later herein.

For those thinking about measuring with other methods: It is DIFFICULT to measure the preload, seals removed or not, with the wheel in the motorcycle.  Some have proposed doing it by pulling on the tire circumference ...this can be done, but I say to forget it ...as the tire is very large in diameter compared to my 1.5" adapters (or, using the axle for wrapping the string around), so the force using the tire circumference is then quite low, & difficult to measure, all things considered.  Using a very sensitive click type or even gauge type torque wrench is additionally going to be difficult, due to the "break-away force".  You can also call that the "initial starting to turn force".  The preload specification is based on RUNNING (constantly rotating) torque.  My method with the string gauge works very well.  If anal, you could purchase a torque wrench of the specific type designed for rotating loads, as mentioned in this article....and, here is the information on those special torque wrenches:

There is another way of measuring the preload on the tapered wheel bearings. The factory method used after the early heated-hubs wheels (which are done by feel but CAN BE done with my methods) was to use a torquemeter. Simplified, this is a torque measuring tool that could be adapted to the end of an axle (such as to a socket over the axle nut), with the axle through the wheel and appropriate spacers made to take up the space of the swing arm or front forks. These measuring tools are PRICEY, and you still need spacers of some sort. I have elected to not show this method in this article, as my methods are accurate, much cheaper generally, etc. If interested in these torquemeters, do an Internet search for these, and similar: Proto 6104; Snap-On TQSS-025-FU; etc.

(9).  On a practical basis, for the FULL ACTUAL MEASURED procedure, the wheel has to be out of the bike.   Since the wheel is no longer in the forks or swing arm(s), some means for keeping proper side to side pressure on the bearings, hub parts, etc., must be had.  This is done with spacer tools, often one for each side of the wheel or one on one side, as appropriate for the particular wheel.    These spacer/tools can be of different dimensions than what I am specifying herein, and you should determine what you want, after taking a look at your wheels, their outer hub areas, axles, etc.    These spacer/tool(s) really should be made on a lathe.   This is a very simple job for any machinist.  It is possible to use pieces of 3/4" steel pipe, but that CAN create problems from canting, due to the too large inside hole, even if the ends are quite flat and parallel, & they work best if centered.  The inside diameter is never what you really want (always too large) ...and they must be visually aligned to be centered anyway. Can be done though, if very careful.

(10).  The type of wheel used for this article's specific procedure was a cast aluminum wheel called a Snowflake, from the early 1980's.  These types of wheels are MUCH improved, as far as servicing goes, compared to earlier heated-hub types.  These later wheels have a steel insert done during the casting process, thus no heating is required to service the bearings nor wedding band shim.  Another huge improvement was that the ends of the hubs are counter-bored, in such a way to leave a substantial shelf.  The outer races are pressed (no heat needed, as you are pressing a steel race into a steel insert) into the wheel. The outer races are prevented from being pressed in too far, as there is that shelf for them to bottom-out against.   If you ever replace a bearing on one of these wheels, be sure the bearing cavity is very clean right into the very bottom edges, & that the new outer race is pressed fully home.   Since there is a shelf, there is NO NEED for the very large cylindrical spacer used on early  hubs.   That also means that shimming is done entirely by the wedding band thickness (width). Another advantage to these later wheels is that the inner race portion of both bearings can be removed from their respective wheel sides, easily with fingers, once the seal is removed.  That means easy cleaning & re-greasing ...and, actually, rather easy pre-load checking.

You will remember that on the older style wheels with no internal wheel shelf for the outer races (that is, they are the heated hub type), the whole internal 'pack' is assembled on the bench, out of the wheel.   So, for those, there is a considerable difference in procedure from the later wheels, like the early eighties type I used for this article; ...BUT THE IDEA IS THE SAME, and there are a lot of similarities in what  you do to check and set preload.    Some do the push or shake test as described by Duane Ausherman on his website.  Others may fashion a string & string gauge something as I have described for these later non-heated hubs. For those early hubs you could put the string around the very large internal spacer sleeve, or have that stationary and pull on the axle.  Same basic idea as for the later wheel I describe below.

(11).  When I made up steel spacers for use with my 1983 and 1984 R100RT bikes, I made them with a central bore of 0.670", tolerance +.002", -0; length 2.125" to 2.250" for one of them & 2.75" to 3.00" for the other.  I used 1.5" diameter steel material.  You COULD use nearly any size, & even 2.0 inch is OK, will work against the bearing properly, and the calculations are easy with those also.   Do NOT make the spacers too large in diameter, at least not at the part of the end touching the bearing (sure, you could use a machined step at the end), as they MUST bear onto the correct part of the bearing.  I say it that way, and mention making a step, because some have made the spacer main body larger than the portion of the spacer contacting the bearing inner race area, which works fine.  The spacer should be a very smooth easy sliding fit on the oiled axle, with NO excessive play on that cleaned and oiled axle. Scan the below sketch with your mouse, left-right-left, if you have to.  BTW ...if your axle is a bit rough, DO SAND IT, or, wire brush it.

(12).  The below sketch is right out of my notebooks. It is for 1.5" outside diameter adaptors, & indicates an ideal value to go for of 757 grams.   I think most of you should go higher, perhaps 900 or 950; and, 25 inch-ounces is 945 grams.  See item (16), well below, for some additional information.

My two spacer tools.  Some longish time ago I also made a set that had a larger outside diameter, and I machined a step into the spacer ends, for properly fitting up to the inner race.   You can make up almost anything that properly fits, squarely, and is a smooth easy push through by the axle, oiled.

Below is a photo of one of the above steel adapter-spacers I made on my lathe, being used with a length of string, & one of my pull-type gram gauges.  The cheaper string gauges recommended in this article are OK for this job.  While the photo shows that the string, gauge, and spacer-tool are being used on the left side of the rear wheel with axle inserted from the left; it makes no difference if you want to insert the axle from either direction.  You can also measure from either side. Not shown is that the nut and washer are in place and torqued to 30ftlbs on the other side of the wheel.  Note that the spacer is tight to the axle ....there is a stock STEP on the AXLE, that is not seen here ...look at YOUR axle!  It is that step that is against the steel adapter in the photo.

For the 1983-1984 Airheads that I used for this article:
The spacer tool length must be such that they replace the width of the forks, or somewhat anyway, and yet are not so long that when in use you cannot fit the axle and axle nut through the entire wheel assembly.    The inside diameter of the spacer/tools must be the same as your axle ...PLUS about a thousandth or two or so. See #11, above, for the actual specifications.  IT IS NOT ALL THAT CRITICAL.   You want the clean and oiled axle to be easy to insert & easy to remove in the spacer tool, but not loose enough to allow the spacer tool to cant sideways, yet not tight enough to grab the axle.  A nice reasonably easy slip fit; ....if you held the axle upright, the spacer would slide down the axle by itself.  You need to supply your machinist with your axle ...and that axle should be cleaned with steel wool or wire wheel, etc., before giving it to him. Tell your machinist you want an "easy, non-cocking slip-fit, axle oiled", spacer to fall of its own accord if vertical ...but not excessive clearance. If the spacer the machinist makes for you just falls of its own weight down the OILED & SMOOTH CLEAN AXLE held vertically, and cannot be canted, that is likely perfect.    In addition, the end faces of these spacer/tools must be flat & square to the bore and to each other. If done on a lathe, they will be that way.   Make these tools of common steel, not aluminum.  Information on my spacer inner diameter is also in the wheel bearing clinic article 54, subsection 9.   https://bmwmotorcycletech.info/wheel-bearing-clinic.htm. Note that you can use your spacer tool with any top hats or axle sleeves that you may already have that are not in use for the wheel under discussion; this extends the versatility of the spacer tool.  This has been particularly helpful if you have more than one Airhead, with different spacer tool length needs.

Note also that you might decide to make the spacer with a diameter larger than 1.5".  I'd suggest keeping within the range of values I show in this article.  There is nothing at all wrong with making the spacer out of somewhat larger than 1.5" material; and then, on a lathe, having a short end area with the diameter being smaller, so that end fits the bearing INNER RACE AREA properly, see the photo of a tapered bearing inner.

One specification is the spacer's main outside diameter, that the string will be single-layer wound on. I have mentioned 1.5 and 2 inches.     This needs a wee bit of thought & discussion, for these reasons:

a.)  The correct diameter means easier mathematical calculations for preload.

b.)  The correct diameter at the end of the spacer tool must be such that the end of the spacer/tool presses against the inner bearing at the proper place. See c.) however, regarding a top hat/brim spacer.

c.)  The inner bearing (called an inner race or cage) sticks out of the outer race a bit, so the spacer/tool, if used directly against the bearing, can be larger than the diameter of the inner bearing portion.  This is self-explanatory when you look at your wheel bearing, hub, & lipped spacer.  BUT:  If you tried to use a 2" spacer tool directly against the bearing, you would need to machine a smaller diameter on the spacer/tool at its end, otherwise it would contact the wheel hub.   If you wished-to, you could use one of your top hat spacers, and a shorter adaptor, & doing so would avoid machining a step into one end of the tool.  But; the top hat type of spacer is not the best thing to press against the bearing cage.  I considered these various things.  That is why I made my spacer tools 1.50" in diameter.  They need no 'step'.  An added advantage is that you don't have to do calculations, as my figures, below, and in the notebook sketch above, all directly apply!   Thus, while I have complicated the explanations here to include a stepped end on the spacer, I suggest you use 1.5" steel material, no step, and do it all my way!   Everything will fit, easy calculations, etc!

d.)  For reasons noted, and also because of the bearing inner cage size, I selected a spacer/tool diameter of 1.50 inches, & one of mine is 3-1/8" long, the other is 2-1/4" long ...& these are the one's I used for the 1983-1984 wheels in this article.  YOU should make the lengths as required for YOUR bike(s).  You might consider making them such that they are universal, for early & later wheels, & front & rear wheels.  All you really have to do, for determining the length of any one spacer, for any one wheel, is to insert your axle into the assembled wheel, and see what spacer length you need, that allows the axle nut and washer to be installed and be able to be torqued to squeeze the innards.  Obviously, nothing very critical about the length beyond that.  Be able to engage at least 4 full threads, that's all.  I have one spacer tool for the rear wheel, one spacer tool for the front wheel.  You could certainly make them so one is for one wheel, and use both for the other wheel.  Nothing is critical here except for the fit to the inner cage bearing, and that you are able to torque the axle with all the parts on it, including the wheel if using that setup, as opposed to the earliest heat-only type of hub.

e.)  It is possible to use some old steel/iron water pipe & make adapters from pipe.  One must be careful in doing/using this method.  You want repeatable measurements.  I recommend against using common pipe, unless the ends are flat from being made on a lathe, and you are quite careful in their use, to be centered, squarely, etc. on the axle and against the bearing (or, top hat as spacer).   Standard pipe sizes that will work will likely have a center hole considerably larger than your axle, allowing CANTING under pressure if off-centered, ...and that will possibly lead to unreliable measurements.

(13).  In checking the preload with the wheel, hub parts, axle, spacer/tool(s), axle nut, & without the wheel seals, remember, this procedure is for the 1983-1984 wheels I used for this article.  Your wheels and axle will vary, so check for what YOU need for a spacer for each wheel.

>>>For earlier wheels, like the /5 & /6 heated type hubs, these do not have a bottoming shelf for the outer bearings and you will assemble the entire innards onto the axle, & use a somewhat different method.   You COULD, if you want to, apply the string scale method to these earlier wheels with a bit of thinking & looking.  There was additional information in the articles by Gary L. Smith in BMW-MOA magazine in 2004; & as delivered our jointly done Seminar at the BMW MOA National Rally in Spokane in 2004 ...& published elsewhere's as well.     Duane's article will also be of help. But, you really do not have to read & know about those things, you will easily see that the bearing assembly is such that you can use a string around the large outer spacer, and clamp the axle, perhaps to a vice; or, you could use the string around the large step diameter of the axle, and hold the outer sleeve with your other hand ...you don't want to clamp that in a vice.<<<

(14).  Assemble the cleaned and oiled bearings into the wheel, and the wedding band, without the seals.   Tighten, using the one or two spacer/tool adapters (and, if helpful, a top hat spacer) as required and the axle and axle nut.   Tighten to near spec.  About 20 to 25 foot-pounds is enough however, although 30 can be used.    For a heated hub type, DO tighten to full specification.  You should be able to rotate the axle assembly SMOOTHLY.  If it seizes up as you increase the torque, then stop and find the problem, if a new bearing is being used, then the spacing between bearings is not correct, and preload needs to be lessened.  Think about this, and, remember that in these wheels INcreasing the distance between the bearing inner races will DEcrease preload pressure ...and, vice versa, of course.

(15).  Wind a piece of light string around a spacer/tool, perhaps a dozen or 20 turns, in ONE layer (overlap the first few turns or use tape, so the string stays in place).  Attach a spring scale, cheap ones are fine, see Ohaus and others for such as the Ohaus model 8004 spring scale, to the end of the string.   Hold the wheel upright, that is, normal position, and pull on the string scale SMOOTHLY and CONSTANTLY, as best you can.  The spring scale will jerk around some, especially as it starts the rotation, but hopefully not excessively. If the scale shows very excessive jerky-ness, you may have poorly made adapter tools or another problem to be looked-into (you ARE using OILED bearings?).   READ the scale during the smooth part of the pulling as the axle spacer turns.  You are not interested in the START reading, but the reading DURING the smooth rotation of the axle assembly.

>>>If you have the earliest wheel type, and have modified the finned spacer, you can do the feel test before reinstalling the assembly into the heated hub....OR....you can simply reinstall into the heated hub and since you have, with finned spacer modification, easy access to the wedding  band spacer, you can change its thickness, thinner, or additive by adding Duane's (Scotties) thin shims. With that last method, you can use my adapters method with a string and pull gauge! The only problem with doing it with the string method is that once the hub is re-heated and innards installed, then you can't modify the large spacer tube inside the hub.   I consider that hardly of much interest, because you DO have access to the wedding band (finned spacer must be modified as I've noted).  NOTE that if doing the push type test, the interface between central large tube and the bearings must be oily.<<<

Assuming you are using the string method, and the assembly is torqued, mathematically convert the spring scale reading as required, & change or modify the wedding ring spacer as required (note my information in this article on the early hubs ...about the large outer spacer, which can be sanded if helpful) & repeat measurement & modification, until within YOUR desired specifications.

(16).  Specifications are, by the book, 21-42 inch-ounces.  If you see official figures in the various metric numbers, you may see this as 1.5-2.5 CMKp or 15-30 Ncm.  As noted previously, I think anything close to 42 inch-ounces is too high, & such can lead to scorched bearings.  My advice is to not go over 35 inch-ounces, nor under 20 inch-ounces, for a motorcycle.  I suggest 30-35 inch-ounces for a sidecar rig.

Tapered bearings have an OPTIMUM preload.   If the preload is considerably less (more looseness), the life of the bearing DEcreases from road irregularities  "pounding".  If the preload is near or beyond the 42 inch-ounce specification, the super-thin layer of grease may be forced out considerably, and temperature inside the bearing will increase, this becomes an event that feeds on itself, so things get worse and worse ...and the bearing may fail early, disastrously, even by welding.

(17).  As described previously in this article, many BMW shop mechanics, and others, do not measure the preload, they do it by experienced feel, as they slowly tighten-up the axle nut, bit by bit.  The feel test works pretty good for the early heated-type wheels, not so good for the later NON-heated wheels unless you have a good touch/feel.  The feel test is applicable with the bearing pack out of the wheel; but best used with the wheel in the bike.  This feel test is, perhaps, not necessarily for the first-timer, without an expert showing them the feel; but, read Duane's description, and you could be OK.  No matter how good that mechanic is, his results are unlikely to be as good as my pull string method.  Preciseness and CLEAN GREASE means LONGER bearing life.   Duane's article describes the feel method quite well.

(18).  Unless the spacer/tool is exactly 1.50 inches in diameter, you must convert the spacer/tool diameter (For 1.5 inch diameter I've already done the math for you) to the equivalent, mathematically.   So, for other than 1.5" diameter spacer tool, using the figures on my sketch, you need a multiplying factor. This is rather easy!    The inch-ounce specification divided by the RADIUS (half the diameter) of the spacer/tool is the factor.

You can forget about calculating for the string diameter (unless truly anal), just do not use rope, instead, use light thin cotton or thin nylon packaging twine or inner parachute cord twine.  For your reference purposes (??), 16 ounces is 454 grams and 1 ounce is 28.35 grams.

In my shop I have pull scales graduated in grams.  For the 1.50 inch diameter spacer/tools, the pull force I prefer is 567-943 grams.  For the original factory specification of 21 to 42 inch-ounces, the force would be 794 to 1588 grams.   See the sketch, above. Convert if you have ounce scales.  The Ohaus #8004 scale reads in the values you need.  There are other similar INexpensive ($9-$15) spring scales from other brands, such as Sargent Welch, etc.  You can use an spring scale that reads a maximum of 1000 or 2000 grams if you are using a 1.5" spacer adaptor, unless you intend to go to the BMW high specification (NOT recommended by me).  Divide the inch-ounces you want, by the radius of the spacer tool, then multiply by 28.35.  You now have the number of grams to read out on your spring scale.

(19).  WIDENING the wedding band spacer (or, adding a shim) will DEcrease the pull force, as the bearings are now held farther separated from the captive outer races.  Change wedding bands, or modify them on a surface plate as noted previously, or add one of the proper shims from Duane Ausherman, etc.  Early heated hubs can ALSO have the large diameter inner spacer modified slightly in length.    Use your micrometer as needed to be sure of your work.

If this is an early wheel, of the type where you must heat the wheel for the entire bearing pack to be removed ...& what your measured need is for a slightly WIDER wedding band, & you do not have one (or, none of Duane's shims), you can REDUCE the width of the very large round tube-like spacer inside the wheel hub that distances the OUTER bearing races.  That spacer is NOT present in the later wheels that have an outer race bearing shelf.

(20).  Once things are within the specifications you want, you must remove the bearings, use solvent to remove the oil, dry them a bit (I recommend you do not spin-dry wheel bearings that you solvent cleaned with an air hose unless quite careful.   It is possible to spin the rollers to rather high speeds, which is not good for them) and then clean up the outer races of oil too.  Then, grease the bearings & install them, with some extra grease on the inside, and a bit on the outside, & install new seals after inserting the greased lipped spacer in the seal (from the inside).   Keep the spacers/tools in the box you keep your wheel bearing grease, wedding bands, string gauge, adapters, & other such wheel service items.

(21).  You can now put the wheel back on the motorcycle. Lightly grease the axle, so it slides into the bearing pack and the swing arm nicely.   It is a good idea to do the wheel feel test as you slowly take up the axle nut.  REMEMBER that the axle CLAMPING bolt(s) is/are NOT tightened UNTIL after the axle nut is fully torqued.

(22).  Your first ever wheel bearing preload will go slowly.  The next one will go much faster as you learn.  You will find that doing the preload checking takes a quite modest amount of extra time during a tire change after some experience.

>>>(23) I suggest that you do tire balancing while the seals & lipped spacers are OUT & the bearings OILED.   That allows the conical balancer tools to fit the bearings; AND, you get the best balance due to reduced friction.

Nerdy:   The URAL sidecar wheel bearings are oppositely installed ...ask me about those sometimes over a brewski!

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TOP HAT SPACERS AND SPECIAL GREASING TOOLS:

Top Hat or brimmed spacers may be called thrust sleeves by BMW.  Some literature calls them thrust washers, or compression washers or compression rings.   If you were to measure the large -322  13 mm tall spacer, see in the middle of the photo below, you would probably find it measures ~12.9 (tall) x ~21.95 x ~31.95 mm.  The important part is the "13mm" nominal size (you will find it measures ~0.508" to ~0.512" tall; close to 13mm & thus comes that 12.9 mm).  BMW may ship this 36-31-1-230-322 with a smaller brim, closer to appearance as the 10.7 spacer in the photo and that smaller brim as shipped is OK for use.   This spacer is used on the LEFT SIDE OF THE REAR SNOWFLAKE DISC WHEEL.  If, by mistake, you use the 9.2 mm or 10.7 mm top hat spacer on the LEFT of such wheels, & it is a disc brake model, the disc screws/rivets may rub the Brembo caliper. Don't put that narrow spacer on the left of the rear wheel.

9.2 mm is .362"; I find the parts to measure ~ 0.357"; the part number is 36-31-4-038-142; same as used in the swing arms bearings area. This is the part that sets spacing of the wheel cup splines into the rear drive splines.  It works fine on all twin-shock models for standard specification 4.00x 18 tires.  The 10.7 mm spacer is used for 120 size tires; & sometimes for 110 tires.  BMW changed specifications on the twin shock swing arms ~1980 or 1981.  After which there is a wee bit more clearance for the wider tires.  Often the 10.7 spacer is still needed.

10.7 mm is 0.421"

When contemplating how long to make YOUR spacer-tools, keep in mind that you can use existing top hat or sleeve spacers already on your axles, OUTside of the hubs, if you need more versatility with your tools.

There are anomalies in some wheels, such as the earliest /5 having a smaller right side bore for use with a smaller seal.

There is a special greasing tool that was made and sold by Chuck Walus back in the late 70's & into the 80's, that is very handy for greasing bearings in your hand ...and for flushing and/or greasing bearings even on the captive right side ones.   It was described in the June 1978 BMW Owner News, on pages 23 and 24.  It uses a zerk fitting & your grease gun.  You could make one.   The cone type of hand-greasing-tool, cheap at an auto-parts store, does an adequate job.  So does a THOROUGH hand-packing job.  When greasing a bearing, especially if it was not solvent washed first, it is very important for the new grease to completely force out the old.

AFAIK, the only person selling the tool for greasing the inner captive bearing, and I have not seen this one, is from http://cycleworks.net.

The greasing tool I am familiar with is this below one; the only trick is to get it into the bearing to the correct depth.  It does a FAIR to OK job.

>>>Various NON-brimmed spacers are used with various wheels, models, years.  The fiche will list the part numbers, and usually NOT the dimensions.

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MISCL:

DO NOT use "moly" greases in wheel bearings ....yes, I know SOME are OK.  Best to just not use them.
See https://bmwmotorcycletech.info/chemicalsetc.htm for information on greases.

I used to have full and specific information here on how to deal with an early wheel, particularly a /5 rear wheel, that has 'spun' its outer race, particularly the left side outer race. The information was misused.  Some folks decided they could 'get away with ...xxxx' without following-up; and IN PARTICULAR they did not put rear wheel shake tests on a VERY REGULAR TO-DO LIST.   I removed all the information.   While there were no 'incidents', I thought there might be, eventually, from foolish people who refuse to take advice, no matter how strongly given.    If you want information on how to deal with a spun outer race on early wheels, I will provide my input on the Airheads Mailing List, the internet-based list.  Methods for 'fixing' wheels include:
a.  Machining & installing a sleeve of some sort.
b.  A sleeve without machining.
c.  A new wheel.
d.  Measuring diametrical clearance & oblongitivity & determining if Loctite #638 or slightly thinner #640 will, perhaps, work.

You may want to look into how Speedi-Sleeves are used.  If properly done that METHOD can work well, be preferable to some other methods.  An expensive lathe-turned full sleeve & machining of the hub could be used if it fails.  Other advantages are that the METHOD can work when the diametrical clearance is so large that Loctite should not be considered; and, the method can be used with irregular shaped hub outer race recess area; ...elongated, for instance.  All-in-all, a Speedi-Sleeve MIGHT be my first choice these days ...unless I had free access to a large lathe & the value of my time was negligible. I have seen at least two articles on how to use a Speedi-Sleeve, and am not overly happy with the articles, finding them to have errors in MY opinion at least.

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Wheels from 1985 (a few exceptions to earlier, see the dealership's microfiche or on-line fiche):

The R65LS was produced between January 1981 & October 1985.  The FRONT wheel of that model uses a BALL bearing, part 36-31-1-242-854, a common bearing type number 6203 which is the same size as the taper bearings, 17 x 40 x 12 mm.  Look carefully at what is engraved on your R65LS bearings.  The R65LS has a built-up front wheel called a Compound Type, which is quite different from the old spoked rims & the snowflake rims.

All the other models changed, not at the same time in 1985 (a few as early as 1983), to common 6005 bearings which are 25 x 47 x 12 mm, 36-31-1-450-859. THAT NUMBER IS OBSOLETE.  So is 36-31-1-469-265.  The latest number is 36-31-1-450-967.    Supposedly the changeover for these occurred at: R80, R80RT in 1985; R65 in 1986; all the rest in 1987.   The crossover on the R65LS was supposedly in the 1985-1986 era.   The on-line fiche may show some few models having the change earlier.  The bearing is a common one, 6005 type, graded C3, and SEALED.   For SKF brand, 6005-2RSH/C3.   Tom Cutter suggested NKE 6005-2RS2-C3.   Use a QUALITY, name brand bearing, is my advice.

These front wheel ball bearings on the late Airheads models are the same as the bearing used on the Y spoke K models & the K11 series left bearing.

For models with ball bearings, the bearings are to be replaced when noticeable free play exists.  These bearings are lubricant-sealed for life.   Life may be long, but not as long as a properly taken care of tapered bearing type of the earlier models.  I think about 40,000-70,000 miles is typical for the ball bearings, but some go a lot further.

One reference book says that the 1985+ ball bearings are replaced by heating the wheel hub to close to sizzle temperature & using an internal expanding puller to remove the bearing, & then, while the wheel is still quite hot, tap in the new bearing to flush depth. Another describes late bearings as being cold pressed.   The problem is that there are different wheels & methods ...and I will not do cold pressing on any of them.   These various sources of 'information' are often WRONG!  Ask about yours on the Airheads List, if you want to.

Use Kukko adaptor 21/4 with the Kukko puller. Any decent blind hole puller will likely work OK.

(1):  Remove the wheel from the bike and then LOOSEN the brake rotor bolts.

(2):  Heat the hub around the outside area of the bearing.  A good spit or water sizzle is about right (about 250°F for the more anal, which is a bit OVER sizzle).

(3):  Pull the bearing with the Kukko or other quality blind-hole puller, after all is hot.

(4):  Remove the center spacer, which falls right out.  You can now use any old piece of wood to push out the other bearing.

(5):  Do a VERY careful cleaning-up of the bearing bores in the wheel.  They must be left clean, nick-free.  While you are cleaning the wheel bores, put the new bearing sets into your freezer.   When the wheel bores are finished, and you've reheated the hub area, insert a bearing into one side, and be sure it is fully inserted.  You must install it squarely, and you can use the front axle as a tool to help do this.  Let it sit a bit to be sure it is going to not come out ...you can use an old socket, etc.   ...and turn the wheel upside down on it ...the bearing will then remain in place.

(6):  Insert the previously removed spacer; & since the hub is still hot, you can install the other bearing from your freezer.   Be sure the bearings stay in place during cooling ...I use the axle, spacer(s), washer, nut.

While use of the axle is a help, one can use any proper diameter socket for the tool to drive in the new bearing (with the hub hot, bearings frozen, they go in easy anyway) ...be sure that the socket bears ONLY on the bearing OUTER portion.  BE SURE THE BEARING GOES IN STRAIGHT AND SQUARE.

DO NOT FORGET to retighten the brake rotor bolts after the assembly has cooled.

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Revisions:
10/03/2002:  Addendum #1.
05/10/2003:  Add link for Duane's site.
09/15/2003:  Some clarifications, and add PART 4:
02/26/2004:  Editing and adding references; simplification notes, etc.
05/23/2004:  Re-edited slightly.
05/23/2004:  Updated considerably.
05/24/2004:  Edit information on R65LS front bearing information.
06/21/2004:  Addendum #2.
11/23/2004:  Clarify using magnet to detect cast-in steel insert; very minor other things.
06/04/2005:  Some update and clarifications.
07/26/2005:  Expand information on the later ball bearing models.
03/01/2006:  Add more Kukko information, and reference to Ed Korn.
02/23/2007:  Minor editing.
05/04/2007:  Clarifications, and add Ohaus #8004 part number at several places.
10/01/2007:  Add, in last paragraph, the superceded number and the grade+.
05/28/2010:  Recheck article, clarify ball bearing installation, + very minor other things.
05/03/2011:  Update & clarify & incorporate old "overview" article, which WAS section 54, subsection 2, as the Introduction here.
06/25/2011:  Some cleanup, re-arranging, and clarifications.
02/29/2012:  Cleanup; fix how article displays in various resolutions. Clarify a few minor details.  Emphasis added here and there.
09/07/2012:  Update article as Duane's wheel bearing article now incorporates some things I was doing; & his article has been greatly expanded.   Add QR code; change Google ads structure; other changes for clarity.
04/15/2013:   Re-write 8b; the spacer tool fits against the INNER bearing; explain it better, etc.
04/17/2013:   Add list of 14mm and 17mm wedding bands to the website; make it in .gif format; add hyperlink to it in the above article, and edit slightly that area. Add pull-string sketch later this same day.
04/19-??? :    Remove separate wedding bands page .gif & its hyperlink; make table, expand to ALL wedding band spacers available from BMW, put into article.  Add table for wheel seals & felts.  Add photo of spring scale.  Move some sections to earlier in article.  Clarify some details. More photos and descriptions, editing. 
06/25/2013:   Add note on 1985+ wheels to use Kukko adapter 21/4.
06/28/2013:   Additional information to Part 4, about the R45 wheel bearings.
09/09/2013:   Commentary changed on the link to the Speedi-Sleeve article.
05/07/2014:   Updated the article in numerous places.  NO errors corrected, weren't any.
10/19/2014:   Fix wheel-bearing-preload-sketch1.gif so is fully displayed.
01/25/2015:   MINOR cleanup.
08/14/2015:   Fix a hyperlink
12/09/2015:   Update meta-tags; increase article font to minimum 14 point; decrease width, justify left, etc.
01/31/2016:   Add second link to the speedi-sleeve article.
03/02/2016:   Add quick basic section.
03/25/2016:   Meta-codes update.  Go completely through article.  Improve explanations, reduce use of fonts & color changes, increase basic font size for readability, change layout.  Make attempt to shorten article by reducing redundancies; yet expand some to differentiate wheel innards & have better information on the heated versus not-heated hubs.  Add sketches of wheel parts, tools, etc.  Improve clarity/ability to display better on small screens.
10/06/2016:  Update information on source for Duane Ausherman's wheel preload shims.
10/24/2016:  Metas, scripts, layout, fonts, simplify much HTML.
01/14/2017:  Add information on the spring scales, taken from my wheel bearing clinic article, slightly edited.
01/19/2017:  Add additional, if minor, information on the ball bearing part numbers/details.
02/26/2017:  Edit #18 to remove reference to 1 inch diameter, to avoid confusion.
03/01/2017:  Revise (12) and (16) slightly, to try to reduce possible confusion.
04/16/2018:  Revise article.  Reduce excessive html, colors, fonts. Reduce or eliminate a few redundancies. Add 10pxl margins.  Improve layout.  Clarify a number of details, and emphasize differences and how to deal with heated versus not-heated hubs. Remove bad hyperlinks.

© Copyright 2020, R. Fleischer

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Last edit/check: Saturday, August 27, 2022