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Snowbum's BMW Motorcycle Repair & Information Website

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WHEELS, Wheel Spacers, Seals.
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Also contains information on swapping various years
and models of wheels (except Lesters).

Copyright 2020, R. Fleischer
article 54, section 3

Reference articles:   (wheel bearings servicing...IN DEPTH)   (tubes versus tubeless...IN DEPTH)   (all sorts of allied things)

I recommend that you read the wheel bearing article on Duane's website:

Certain 19" (ONLY 19") FRONT SNOWFLAKE wheels were RECALLED by the BMW Factory; and, are also in a formal government recall.  As far as I know, the Recall, under various titles, governments, BMW, etc., are applicable WORLD-WIDE. COMPLETE INFORMATION HERE:
BMW is probably going to run out of wheels for this recall, so DO CHECK YOURS, per that article. The wheels can break where the ribs meet the hub, under severe conditions.

1:   Early wheels, such as 1970-1978 (except 1978 REAR DISC snowflake wheels) have 100% aluminum hubs WITHOUT cast-in steel inserts. These early all aluminum hub wheel hubs MUST be heated to safely remove and replace a race and/or center assembly.  The 1978 REAR DISC wheel ...and later wheels ...all have cold-pressed-in races.  The early style that are supposed to be heated, WILL be seriously injured if NOT heated when withdrawing the innards assembly.    It is not a great idea to do a large number of heat and R/R cycles on the all-alloy hubs type that are to be heated.  I will have recommendations later herein on how to avoid that, as A VERY SIMPLE modification to an early hub parts (especially /5) can eliminate heating to R/R the left outer race for normal cleaning and re-greasing.

2:   For the early all-aluminum heated-type hubs withOUT steel insert wheels, FREEZE the outer races, bearings, sleeves, ETC., as a complete assembly, before replacing into the heated hub.

3:  The 1978 REAR DRUM snowflake wheel is an odd-ball, this can be identified by it being a snowflake, rear, drum,  and 5 bolts holding the seal retainer.   It has a NON-steel-insert hub, and must be heated for servicing the bearings, and is a POOR DESIGN. If the outer race has spun in the wheel, you may, or may not, be able to salvage the wheel.  That spun race situation also applies to all early wheels, whether snowflake cast wheels or wire wheels.

4:  BESIDES the method using spacers in the bearing preload measuring process, with a string and pull scale; there is a common method of checking preload, with the wheel on the bike, seals in, ready for riding, except that the wheel is off the ground, and the axle nut  loosened (and loosen the clamp if it is a front wheel).  One then slowly tightens the axle nut, while feeling the wheel bearing play.  Actually, this can be done without the wheel off the ground if one is careful, but best to have the wheel off the ground a wee bit.  This 'feel' method works fine, but takes some experience in knowing what the proper 'feel' is.  The wheel is generally wiggled with hands at 9 and 3 O'clock; and, 12 and 6.  Just barely no detectable play is correct.  Without experience, you can be way off doing this.  If normal axle nut tightness (typically 30 footpounds) reduces that play to noticeably no play and too much 'then some' ....and even MAYBE tight beyond that, you need to do preload spacer work.   This "shake" method is well-discussed on Duane Ausherman's website,   My method of using a spacer, string and string gauge, is vastly more accurate ...and, it will lead to VERY long bearing life if the bearings are cleaned and lubricated at regular intervals.

5:  BMW uses various brimmed spacers that I call top hat spacers.  BMW calls them Thrust Sleeves.   These spacers are tubular & thin-walled & made of metal, with a brim on one end.   In airheads prior to 1985, on twin shock models, at the rear wheel, these are used to space the wheel the appropriate distance in the swing arm.  They are also used in the swing arm to space it in the frame.    (I do NOT mean the many sizes available thick small 'preload' spacer used inside the pre-1985 wheels that do NOT have a HAT, and are often called the Wedding Ring).

36-31-4-038-142:  This spacer is the stock one used at the rear wheel of twin-shock Airheads (that is, all models EXCEPT Monolever and Paralever models).  It is typically 0.359" wide (height, usually with slight variances seen) fact I have seen them from 9.0 to 9.2 mm.  It is generally just referred to as the stock 9.2 mm rear wheel spacer.  It is common to see this stock right side top hat spacer replaced by the 10.7 mm wide one, 36-31-2-301-737, that BMW offers just for moving the rear wheel over slightly to the left (especially pre-1982), to allow a wider rear tire.

Once in awhile an even wider spacer is used: 36-31-1-230-322:  This top hat spacer was made in two styles with the SAME part number! BOTH have a width (height) of 12.9 to 13 mm.  An early version was extra wide on the top hat portion; diameter of 31.95 mm nominally.  The "seal' surface of this spacer measures an O.D. of 21.95 mm.   Sometimes one must add flat spacers or move the rear disc brake arm slightly, when dealing with certain types of tires.

BMW modified the SPOKE wheels long ago for the /5 and for the G/S and ST, to fix tire to swing arm interference.  BMW changed them to offset the wheel slightly.  Information is in other areas of this website.  But, here are the basics.  BMW went to the 2.15" x 18" rim during /5 production, and some bikes had rubbing, particularly at speed, between the swing arm and the tire.  BMW then offset the rear wheels by aligning spokes, by 1.5 mm to the left.   This moving the wheel over was done for the same reasons on the R80ST, by 3 mm, on the 2.5 inch rear wheels.

6:  For the rear wheels on twin-shock models, and all pre-1985 front wheels, wheel seals are damaged during normal removal for servicing of bearings for greasing, preload work, etc.  DON'T even think about trying to reuse a seal!   Keep some new wheel seals on hand.  Greasable bearings (pre-1985) should be re-greased at each tire change, and the preload should be checked every few tire changes.  Any modern thin feeling NON-FIBROUS grease is likely OK.   I suggest you select grease specified for disk brake wheel bearings if you are not sure about the grease characteristics.  Modern greases have high melting-flowing temperature characteristics, and high resistance to water wash-out.  Use of these modern 'thin' greases CAN allow for fairly close preload adjustment withOUT the need for cleaning, oiling, checking preload, then cleaning again and greasing.  BUT, some experience in this regard is a good idea.  Chevron UltraDuty EP in NLG1 or NLG2 (both very good), StaLube SL3161 (excellent), BMW Red #10, Quaker State, etc.

7:  In 1985, BMW began using non-regreasable sealed ball bearing units.   The discussion herein on preload does NOT APPLY.  Those ball-bearing units are NOT serviceable.   There is an exception to that 1985 date.   The R65LS was manufactured from January 1981 to October 1985, and its FRONT wheel may use a 36-31-1-242-854 BALL bearing that is sized 17 x 40 x 12 ...the same size, but not same bearing, as the taper bearings used prior to 1985.

8.  The wheel bearing seals, etc., are a bit complicated.  Be aware that some parts are interchangeable, and some are just updated versions, and that variations exist between drum and disc brake models, & even between left & right parts on the same wheels in a few instances.

***Part numbers get superceded all the time.  Your dealer has the latest numbers, or, go on-line to an on-line fiche, such as here:

9.  Seals:

Seal, 1970-1977, spoke wheels, rear, left; 1970-1977 spoke wheels, drum brake, front, left;  1974-1977 spoke wheels, disc brake, front, left and right:   36-31-1-230-334.  NOTE:  Left sides same early and late /5, and very early 1978 cast wheels rears.

Seal, late 1972-1977, all spoke wheels, right, rear; late 1972-1977, front, shoe brake, right side:  36-31-1-231-701.  NOTE:  this seal can be used to replace the 36-31-4-038-155 felt, and the 36-31-4-038-157 retainer, in the 1970-early 1972, but one must enlarge the seal bore on a lathe.

Felt, 1970-early 1972, front and rear:  36-31-038-155

Retainer, right only, combination seal, two parts, OIL the felt; 36-31-4-038-157

Seal, all cast wheels, front and rear, 1978 and later, pre-1985:  36-31-1-235-836.   There are many versions of this basic -836 seal, and inside the seal you may see molded-in markings of -832, -832-4, -837, etc.  These molded-in markings may well NOT conform exactly to the BMW dealer stocking part number.   Note that numbers on most anything on a BMW may well be dissimilar to the stocking part number.    MOST of these seals are interchangeable, even though some parts books may show slight dimensional changes, especially in width.   For the most part, -832 is used on cast wheels, and are interchangeable with -836, others are likely usable on all cast wheels except early 1978.

Seal, exception to the above, this is for early 1978 cast rear, where the -334 and -701 are used.

Look at the internal molded printing on your seals.

10.  NEVER EVER point a high pressure water source at your wheel seals when washing the bike.

11.  In production year 1975, BMW changed the diameter of the front axle from 14 mm to 17 mm.  It IS possible to remove bushings inside the wheel on most earlier wheels, and fit the 17 mm axle.  More on this later NOTE 12-g.

12.  Swapping wheels from one year to another, one style to another, etc:
This can get quickly complicated.  BMW used several sizes of front and rear rims in snowflake, regular cast alloy, wire, and GS type external wire spoked.   I cannot list every combination or swap here.  You may have to put #1 eyeball on your proposed modification. But, here are a few ideas:

a.  A front wire wheel can be put into an early 80's airhead (that came with snowflake wheels).   Use an R80ST front wheel; or use a front hub from a R65 or R80ST and lace to a 19" rim.  You could also machine a hub from a 1975-1980 spoke wheel bike, which is narrower, as the 1975 to 1980 hub is too wide and spokes will contact the Brembo calipers.  Use R65, not R65LS, discs, or make spacers.

b.  As above, but for the rear wheel, use any 1970-1980 spoke wheel.

c.  A snowflake front wheel can be put on a very early bike, let us say a 1974 /6.  You need a 1974 R90S front end, with dual disc. This is a hassle, but can be done.  The tube spacing is different, you need the triple clamps.  You need a 1975-1980 dual disk ATE lowers, with 17 mm axle holes, and you need the 17 mm axle of course.  You CAN use the ATE calipers.

d.  /6 Airheads had a narrower fork brace (fender mount).  If needed for your metric or oversize tire size, you can use a 1977-1980 brace from a /7,  46-61-1-234-907.

e.  If converting single disc ATE to dual-disc, ATE, let us say a 1978, use the 1979 parts:  new right slider, caliper, disc.

f.  Watch out for cracking rear rims on 1974-1975 bikes, these cracks develop at the spoke hole area; the fix is to use later heat-treated rims.  TAP the spokes on the proposed 74-75 rim, and if any are quite dull sounding, there may be a hidden problem at the nipple/rim.

g.  In 1975, BMW changed to 17 mm axles on the R90S.   BMW then continued with 17 mm axles.  Swapping wheels from one year to another, can be somewhat complicated.  The 14 mm axle wheels can be modified to fit a 17 mm axle bike.  This can get more complicated if you try to swap into a much later bike, but for the /6, for example, it is not all that bad.  For the front wheel, remove the size reducing sleeve in the wheel and install the larger ID wedding band spacer (that sets the preload) used on any later model up to and including 1984.    This spacer is used on both front and rear wheels of later models.  There is a cast-in web on the old wheel that held the smaller spacer captive.  Drill it out, to a bit larger diameter than the later wedding band spacer's O.D.   To install the wheel you will need the top-hat spacers .   You may have to fiddle with things a wee bit.  Do the usual preload work before installing the wheel.

13.  ALL of the 1981 R100S polished (spokes) wheel models were recalled, at the importer level, during the time of shipment from Germany.  This was NOT a federally mandated recall.  Cast wheels were installed LATER, those  FRONT cast wheels plus all other models having cast 19 inch front wheels, up to a certain casting date, were recalled! ....see the information on this website:

14.   Earliest snowflake rear disc brake wheels on later airheads, interference with bolts on rear drive:
I have run into this problem myself, and thought I would mention the situation, and one type of fix.   The earliest of the snowflake REAR disc brake wheels castings (these 2.75" width ones came out in 1978 on the R100S and the R100RS; and 1979 those and the RT) are not exactly the same as the later castings.  For the easiest way to identify a very early one, look at the INside of the right side dish cavity of the snowflake wheel.  If you see quite a few 'nubs' (one of which probably is stamped with the casting date) that are part of the casting, near the outer edge of the 'dish', then this wheel will NOT fit the later rear drives without modifying the wheel.  If you try to mate up the wheel, those nubs will grab onto the bolts of the later model rear drives.   The fix is to laboriously (wear respirator) use a burr grinder (or, lathe, if you have a huge one available) and remove the nubs entirely, leaving a nice smooth surface, which is important.

15.   Snowflake disc brake wheels with wider tires (not necessarily meaning an officially marked oversize tire!):
This problem was seen more on wheels before 1980 or 1981 or 1982, depending on the model.   Some tires are much wider than you might expect.  In one very egregious situation, I wanted to use a 4.00 x 18 Metzeler Enduro rear tire on a 1983 rear drive on a 1983 R100RT.  The 1983 swing arm has the fix from BMW for many wider rear tires; BUT,  that tire is so wide that it rubs the swing arm BADLY, fully inflated, and worse if deflated!  While that Enduro tire was a particularly nasty case,  many 120 ROAD tires may rub!   MOST 110 ROAD tires will not rub.    Rubbing can occur at high speeds even if not rubbing at lower speeds. The fix, for road tires, is to install the available wider top-hat spacer on the right side of the wheel. Doing so has no effect on the bearing preload.    That wider spacer is usually only needed on 1981 and earlier models, as later models have a slightly changed swing arm, not easily visible.   The wider spacer is 36-31-2-301-737.   It is 10.7 mm wide. Install with the hat INSIDE the seal.  SOME tires will let you know about tire expansion at speed, by the smell from the tire rubbing against the swing arm....or at the disc brake mount flat metal stay.     It varies with tires, wheels, etc.     Earlier mention and part number for an even wider spacer:  see NOTE 5, well above!

The drum brake rear drive has the same basic dimensions as the disc brake rear drive, and in fact it is easy to modify a drum brake rear drive to fit, although one must be careful about which rear drives are being interchanged, as some (later) have narrower shoes, earlier have wider shoes, and the wheel drum may have a narrow shoe ridge to be dealt with.

Changing or modifying the spacing at the brake stay is not complicated, as usually one can just move its point of attachment to the caliper support casting, to the outside of the attaching boss ....or, it is easy to see how to move the stay away from the tire, by moving the stay over to the left, or modifying it at its rear bonded washer, or some other means.

It is possible that the rivets on the disc could be a bit proud of the surface, and interfere with the caliper.  Simply adjust the spacing slightly, with a washer, or whatever method you prefer.  For the rivets interference, I usually make up a spacer washer, that fits between the caliper support casting and the left wheel bearing.

In one of the conversions I did, the cast disc wheel was from the late seventies, and the bike was an early eighties, both were RT's, I THINK.  In installing the earlier disc brake wheel THE initial problem (after I removed all the old wheel nubs) was how to move the wheel over to the left.   One could add a separate spacer to the right side, except that one can NOT get that spacer into the area once the wheel is on the bike!!   One could MAKE a wider top hat spacer on a lathe, I suppose or try the alternator extra wide one that I have mentioned.    Not having a lathe at my disposal at the moment, I pondered on what to do.   I decided it was not any special help to move the hat to the outside, although maybe a bit easier to attach a washer.  I decided to solder a shim ring to the top hat side of that top hat spacer, doing this very carefully and cleaning it all up to be very flat and square, and have the shim and hat side on the INside of the seal, although it certainly could be on the outside.  Having it on the inside was OK with the SEAL, and being on the inside, had less tendency to get pulled out of the seal, as the wheel was R/R, and it would not get lost, nor would it be likely to get soldering cracks.

The wheel and setup I have discussed, above, is the WORST CASE. You will be UNLIKELY to have all these minor problems, normally just changing the spacer to the -737 is enough.

16:  Re-spoking:   See Buchanan's (see URL list).  see  if YOU want to do it.   BMW rim centers are centered with respect to the bearings.  This is only important to know if you are re-spoking.  Lots of hints and information in that link.

17:  The dual-disc front wheels can be reversed accidentally; after all, most look ALMOST exactly the same, side to side.  This can make for improper braking action until the pads re-break-in, and some other problems can be had, depending on year and model, etc.   By accepted convention, the NUTS holding the DISC CARRIER(s) are on the LEFT side of the wheel, as you sit on the bike.    Some wheels are not marked by BMW as for direction, nor some carriers (or discs).   Many folks mark a L or R on the wheel hub, or wherever.  See 18, below, for a more definitive bit of information, deeper than just 'nuts on left  side'.

18.  BMW used a JIG to machine the wheels for the valve stem hole.  The valve stem hole is LIKELY NOT CENTERED between the snowflake wheel ribs.  Typically the hole has a bias towards the leading edge of the nearest spoke, as the wheel rotates in the normal direction.  Here is how I will state this:   "The proper installation of the front snowflake wheel is, by convention, either by means of the directional arrow on the rim; or on the disc or disc carrier; or it may be noted that the valve stem (hole) is closer to the cast spoke ahead of it as the wheel rotates in the normal direction ....than the following cast spoke".

19.  Duane Ausherman, ,, long ago, had $$$ dies made.  Up until perhaps 2015 (?) Duane used them to make thin shims in assorted thicknesses.  He sold a small set of them quite reasonably. These can be very handy in adding a small amount of thickness to an existing wedding band spacer; or, using a narrower wedding band and adding to it, etc.   Use of these shims can greatly cut down any need to have a large selection of wedding bands for your bike.  Duane has transferred the shim business to Scottie Sharpe.  (408) 475-2696.  Scottie is selling packages of assorted shims for $15, and has both axle hole sizes available, for fitment to the /2 as well as 14 and 17 mm axle Airheads needing them.

20.  Wheel and tire balancing information is here:


03/07/2006:  Incorporate all prior updates, plus add #29, plus make quite a few changes in the entire article, bringing it up-to-date.
01/06/2008:  Remove hyperlink for as it is dead.
08/19/2009:  Minor updates.
12/05/2009:  Add R1200C type 5/10 gram weight strips p/no.
02/25/2010:  Minor clarifications.
05/22/2011:  Expand #14, in line with my other articles.
09/20/2011:  Edit #10, adding information that was already in Section6.htm, on the extra-wide spacer.
09/23/2012:  Add language button; QR code; Google code update; some editing for clarity.  Remove language button, 2013.
04/17/2013:  Add more to balancing information, including the edited response I did.
11/02/2014:  Add paragraph and link re: pressures; to note 7 and 23.
05/29-30/2015:  Moved things to the tire repair article, etc., and re-arranged this article.
06/01/2015:  Finished editing above changes, making a few more re-arrangements.  DONE!
08/14/2015:  Fix a hyperlink.
04/28/2016:  Update metacodes, horizontal lines, basic layout, fonts, colors, scripts....etc.
10/06/2016:  Add 19.
01/15/2017:  Metas, scripts, layout, fonts, colors, simplify excessive HTML, general cleanup.
02/04/2017:  Add missing numeral 1 in spacer, located in item 5:  36-31-1-230-322.
01/11/2017:  Add #20.
01/02/2018:  Complete cleanup.
06/10/2018:  Expand #6 a bit.

Copyright 200, R. Fleischer

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Last edit/check : Saturday, December 19, 2020