This bike has 83,000+ miles on it and the wheel bearings are of unknown condition. So I replace them and set the wheel bearing preload. I also had the wheels powder coated after I removed the old bearings, so I had to also remove the disk brake rotors. I show how I remove, refinish and install the disk brake rotors in this document.

• 34 BMW 1983 R100RS Remove, Refinish, Install Disk Brake Rotors

Of course, you can remove the wheel bearings without removing the disk brake rotors.

Resources

The procedure for the 1983 R100RS is the same as for the 1977 R100RS that I document here. You should read the procedure below as it applies to this year bike.

• 36 BMW 1977 R100RS Wheel Bearings-Replace & Adjust Preload

One small difference is that the 1983 wheel does not have a drum brake using a rear disk brake instead. But all the rear wheel bearing parts are same for the two rear wheels.

Bob Fleischer has a number of sections of content about wheels, hubs, top hats, bearings and how to adjust the preload on the tapered roller bearings used in the wheels.

• Bob Fleischer: WHEELS, Wheel Spacers, Seals + Hints
• Bob Fleischer: Airhead Wheel Bearing Clinic, BMWMOA National Rally, July 2005
• Bob Fleischer: Wheel Bearings; preload & servicing

Duane Auscherman also has a good page about wheel bearings.

• Duane Auscherman: BMW motorcycle wheel bearings, 1956 to late 70s

The graph Duane shows of the tapered roller bearing life vs. preload setting was instructive. I conclude that lower preload values affect bearing life less than too high a value. And, the miles available from a preloaded bearing are “large” compared to the typical mileage expected for a BMW motorcycle, except when the preload is too high. Bob Fleischer points out that BMW’s recommendation of 21 – 42 inch-ounces of torque puts too high a value on the range. He recommends no more than 30 inch-ounces unless you have a side car attached. He is concerned with a bearing overheating if it has too much preload and that can lead to welding a bearing to the axle. I’m aware of one such incident, but I suspect the owner never lubricated the wheel bearings which certainly leads to bearing failure.

Parts

Here is the parts list for doing this work.

Part #	Description	Qty
07 11 9 985 005	TAPERED ROLLER BEARING – 40X17X14	4
Cycle Works	Wheel Bearing Adjuster Kit, 1970+	1
36 31 4 038 142	SLEEVE – 9,2MM, Rear Wheel, Right	1
36 31 1 230 322	COMPRESSION RING, 2 Front, 1 Rear Left	3
36 31 1 235 833	SHAFT SEAL – 40X22X5, Rear Wheel Right	1
36 31 1 240 238	SHAFT SEAL – 22X40X7, 2 Front, 1 Rear Left	3

I replaced the four “top hats” (part# 36 31 4 038 142 and 36 31 230 322)  that sit in the dust cover holes as the sides were scored and worn.

NOTE:
The right side rear wheel grease seal and “top hat” are shorter than the left side and front wheel parts which are the same length. But, if you decide to use a slightly oversize tire, there is longer top hat for the right rear that will increase the space on the right side so you can mount a 120/90 x 18 tire without it rubbing against the right side drive shaft tube.

I got two wheel bearing adjusting kits from Cycle Works. The kit includes two “wedding bands” and a number of shims so I can adjust the roller bearing preload without investing in various size wedding bands.

Tools

I need a blind bearing puller to remove the outer bearing races from the steel sleeve. I have a Cycle Works tool that removes and installs the swing arm roller bearing which is the same bearing used for the wheels.

• Cycle Works Swing Arm Bearing Puller 

CAUTION:
Only use the Cycle Works bearing puller, or an equivalent blind bearing puller, IF YOU HAVE THE STEEL SLEEVE VERSION OF THE SNOWFLAKE WHEEL. Using it on an all aluminum hub will ruin the hub.

I use a spring scale that measures in grams. The Cycle Works wheel bearing preload tool at 113 mm, it is too long for the snowflake wheels. For snowflake cast wheels I use a 1 inch diameter piece of steel pipe about 3-1/8 inch (80 mm) long and had a friend mill the ends flat and parallel.

• Wheel Tube /2 and /5

Video

Here is video that summarizes the procedure I use to replace the wheel bearings and set the bearing preload.

VIDEO: 1983 BMW R100RS Replace Wheel Bearings and Set Bearing Preload

Remove Rear Wheel Inner Bearing Races

The first thing to do is determine if the wheels have a steel sleeve press fit into the aluminum alloy wheel hub. I use a magnet to verify these wheels have steel sleeves.

DANGER
These wheels have the steel sleeves in the hub. Earlier snowflake cast alloy wheels did not have steel sleeves and had all aluminum hubs. YOU DO NOT WANT TO REMOVE, OR INSTALL, THE OUTER RACES AS I SHOW HERE IF YOU HAVE ALL ALUMINUM HUBS. If use this procedure on all aluminum alloy hubs, you will damage the hub. The wheel bearing outer races will eventually spin in the bore and this can cause you to crash. Always verify if you have the steel sleeve hub using a magnet.

This is how I remove the rear wheel top hat, dust cover, inner bearing races and wedding band.

• Rear Wheel Top Hat, Oil Seal, Wedding Band and Inner Bearing Race

Remove Front Wheel Inner Bearing Races

This is how I remove the front wheel top hat, dust cover, inner bearing races and wedding band.

• Front Wheel Top Hat, Oil Seal, Wedding Band and Inner Bearing

Remove Outer Wheel Bearing Races

I use the Cycle Works tool to remove the outer roller bearing races from the rear wheel as described here.

• Remove Outer Bearing Races

Pictures & Comments About 1983 R100RS Wheel Bearing Removal

Here are pictures and some comments for the work done on the 1983 R100RS

Rear Bearings

These pictures summarize the work on the rear wheel bearings. All the details about the process are in the links above.

The rear wheel top hats and dust covers are not symmetric. The right side dust cap is 2 mm shorter than the left (5 mm vs. 7 mm) and the right top hat is shorter than the left (9.2 mm vs. 13 mm).

Front Bearings

The front bearings top hats and dust covers are the same thickness; top hat-13 mm, dust covers-7 mm. Therefore both front and the left rear top hats and dust covers are the same length.

The front inner and outer bearing races show wear. The inner race has been polished on the back and the outer race is scored. I’m glad I removed them as they are not happy looking front wheel bearings.

Powder Coat The Wheels

Due to the intricate pattern of the cast snowflake wheel, I have them powder coated. It’s hard to get complete, even coverage spray painting them.

NOTE:
There are two schools of thought about powder coating: It’s not a good idea;  It works well. One issue is what do you do when the powder coat gets chipped. I use matching paint to fill in the chip and that seems work well. The other thing to consider is powder coating on steel, when it chips, opens up a location for corrosion to start and if you neglect it, it will eat it’s way under the powder coat. Since I live in dry climate, and these are aluminum alloy wheels, corrosion is not the problem it would be with steel as aluminum oxide stops corrosion at the surface.

Since this bike is not a restoration, but a build staring from an RS and ending up with an RT, I’m taking some liberties with the paint and powder coat. I like the white wheels on the R65LS and I think white wheels lighten the stance of a bike. So, I had the wheels powder coated in matte white.

Install New Wheel Bearing Outer Races

DANGER
These wheels have the steel sleeves in the hub. Earlier snowflake cast alloy wheels did not have steel sleeves and had all aluminum hubs. YOU DO NOT WANT TO REMOVE, OR INSTALL, THE OUTER RACES AS I SHOW HERE IF YOU HAVE ALL ALUMINUM HUBS. If use this procedure on all aluminum alloy hubs, you will damage the hub. The wheel bearing outer races will eventually spin in the bore and this can cause you to crash. Always verify if you have the steel sleeve hub using a magnet.

I need to protect the disk brake disks from damage while I pound the outer races into the hub. I use two 2×4 and put towels on top and place the rim of the wheel on the towels. This raises the wheel enough to keep the brake disks off my work bench.

Outer Races Depth In Hub

The outer races are recessed into the hub, but not at the same depth on the front and rear, and the left and right side of the rear are also at different depths. To be sure I drive the outer race all the way into the hub, I measure the height of the outer race and the depth to the lip it rests on inside the hub.  Here are the measurements.

Outer Race Height: 11 mm

Front Wheel
Lip Depth (Both Sides): 22 mm
Distance From Top of Outer Race to Top Of Wheel Hub: 11 mm

Rear Wheel
Right Side, Lip Depth: 20 mm
Right Side Distance From Top of Outer Race to Top of Wheel Hum: 9 mm
Left Side Lip Depth: 23.5 mm
Left Side Distance From Top of Outer Race to Top of Wheel Hub: 12.5 mm

I marked the sides of the rear wheel with the lip depth and the distance to drive the outer race so I would not confuse myself.

Outer Race Installation Procedure

I freeze the outer races and use my heat gun to heat the inside of the hub to make it a bit easier to install the race. I use the old outer race to help start driving the new race into the hub. When the outer race is going in straight, I use the hammer directly and tap all around the perimeter of the race to drive it into the hub. When the top of the outer race is flush with the hub, I use the the rectangular aluminum block from the Cycle Works swing arm bearing kit to drive the race all the way into the hub until it is seated on the lip. The I use my depth gauge to measure the distance from the top of the outer race to the top of the hub to confirm it’s seated on the lip.

Oops, I Forgot To Install The Center Pipes In The Wheel Hubs 🙁

So, at this point I realized that when I installed the outer bearing races, I forgot to install the center pipe inside the hub after installing the first outer race and before I installed the second outer race. The plastic sleeves on the center pipes have ridges that are too large to pass through the outer bearing races.

I could remove one outer race on each wheel and install the center pipe and reinstall the outer race. But I really don’t want to disturb the outer races now that they are installed.

Tom Cutter, at the Rubber Chicken Racing Garage, and Bud Proven, at The Nickwackett Garage, both long time airhead mechanics, told me I can remove the plastic sleeves from the center pipe. Then I can deform the ribs enough to push them through the outer bearing race. Then I insert them into the center pipe while they are inside the hub.

Before I start I note the orientation of the rib on the sleeves; The rib is off center with the shorter end of the sleeve pointing to the inside of the center pipe.

The right side plastic sleeve is pushed down the center pipe exposing about 5 mm of the pipe. The left side plastic sleeve is proud of the end of the center pipe to create a pocket for the wedding band. There is a ridge on the plastic sleeve the wedding band butts against and it is 5 mm below the end of the plastic sleeve on the end of the plastic sleeve the wedding band fits into.

I adjust my bench vice so the jaws are under the lip of the plastic sleeve and the the center pipe can slide between the jaws. I use a socket that fits on the center pipe and will pass through the sleeve, mount it on an extension and use my plastic hammer to drive the center pipe out of both sleeves.

I insert a sleeve and force it past the outer bearing race. Then I insert the pipe and line it up with the hole in the plastic sleeve.

Set Wheel Bearing Preload

The wheel bearings are tapered roller bearings. For long bearing life, they need to be under axial load, or what is called preload. Preload is set by measuring the torque needed to spin the wheel bearings. The target torque is 20-30 INCH-Ounces. That’s a small value to measure. The tools for doing it are a spring scale that measures in grams, about eight feet of string, and a metal sleeve. Due to the different lengths of the front and rear axles I need two different length sleeves.

Computing Range Of Bearing Preload Force

Torque is a measure of force applied at right angles to a lever arm. If you have 500 ounces of force and apply it at right angles to an arm that is 1 inch long, you will create a torque of 500 INCH-Ounces. If you shorten the arm to 1/2 inch, the torque is reduced to 1/2 as much, or 250 INCH-Ounces.

The complicated part is figuring out how to convert the torque setting BMW recommends to the force I can measure on the spring scale. To do this requires knowing the diameter of the sleeve and converting from ounces to grams. This is explained in Bob Fleischer’s material, shown above in the Resources section, that I summarize here.

1. I measure the diameter of the sleeve, mine is 1.1 inches.
2. I divide this by 2 to get the radius, or 0.55 inches.
3. Bob Fleischer recommends a range of 20 – 35 INCH-ounces, but the upper end, 30-35 inch-ounce, is only applicable if you have a sidecar. Since this bike does not have a side car I use 20 – 30 INCH-ounces as the acceptable range of torque.
4. My scale measures in grams so I convert ounces to grams. There are 28.35 grams in 1 ounce.  I convert the lower and higher torque values of the range to INCH-grams by multiplying the values by 28.35: that gives a lower value 567 INCH-grams and an upper value to 850 INCH-grams.
5. To compute the force on the pull scale, I divide the torque by the actual radius of the sleeve. The sleeve radius is 0.55 inches, therefore the spring force range is:
   Lower: 567/0.55 = 1,031 grams;
   Upper: 850/0.55 = 1,546 grams.
6. For simplicity, I’ll use a range of 1,030-1,550 grams of force.

How Bearing Preload Is Applied

Inside the wheel hub is a tube. On each end is a plastic sleeve that keeps the tube centered in the hub so it’s easy to install the axle through the tube. One of the plastic sleeves has a shoulder inside that holds a spacer known as a “wedding band”.

One inner race butts up against one end of the tube and the other inner race butts up against the wedding band on the other end of the tube.

By adjusting the thickness of the wedding band, you adjust how close together or far apart the two wheel bearing inner races are. If the inner races are closer together, they fit tighter in the outer races and there is more force, or preload, on the rollers in the bearing. It they are farther apart, then the preload force on the rollers is less.

BMW sells a large variety of wedding bands in 0.05 mm (0.002 inches) increments of length. The shortest wedding band is 6.30 mm and the longest is 7.70 mm. That’s a lot of different wedding bands to cover the adjustment range. The front wheel has a 7.00 mm wedding band while the rear wheel has a 6.70 mm wedding band.

I use the Cycle Works wheel bearing preload adjustment kit. It comes with two different wedding band sizes, 6.30 and 6.75 mm, and ten 0.05 mm shims. This is an affordable way to adjust wheel bearing preload.

I’m going to start with the original 7.00 mm wedding band for the front wheel and the original 6.80 mm wedding band on the rear wheel.

Configure Axle & Bearings For Preload Measurement

The wheel bearings normally are packed with grease. However, to measure the bearing preload force, they have to be completely clean, dry and then lubricated with some light oil, not engine oil. My bearings are new, but I use carburetor cleaner to clean the inner race roller bearings and then apply 3-in-One oil to the rollers.

For the front wheel I use the 80 mm sleeve on the left side of the axle with the threads. The sleeve will push on two inner races establishing the preload force taking the place of the two fork tubes.

I mount the front wheel in my bench vice using rubber jaws and some shop towels to protect the rim.

I put the 7 mm wedding band into the plastic sleeve on the left side. I insert the axle and an inner bearing race from the right side. Then I put the second inner bearing on the left side of the axle followed by the the 80 mm sleeve, the flat washer and the axle nut. I torque the axle nut to 25 FT-Lbs which is the specified torque for the axle nut.

Measure Preload On Front Wheel Bearings

To make the preload force measurement for the front wheel bearings, I wrap the eight feet of string evenly around the 80 mm sleeve. I attach the spring scale to the loop on the end of the string. Then I walk back from the wheel pulling at a steady rate and read the scale when it settles down to a steady reading.

The stock 7.00 mm wedding hat made the bearings too tight. I added 0.05 mm shims. With three shims, it took about 2,000 grams to spin the bearings and with four shims, it dropped to about 800-850 grams.

Consequently, the preload I need is somewhere between three and four shims. So, what do I do?

Since four shims makes the inner bearing races too far apart, I can fine tune the preload, by shortening the wedding band. I use 400 wet dry paper and sand the faces of the 7.00 mm wedding band to reduce its thickness. I start out sanding each face 10 times in a figure-eight pattern. Then I install the wedding band with four shims and measure the preload force. I repeat this process until I get the preload within the range of 1,030-1,550 grams. After about 30 laps on each face, the preload force is 1,200 grams on the front wheel bearings.

Measure Preload on Rear Wheel Bearings

The process is the same for the rear wheel as the front. However, the rear axle is longer than the front and my sleeve is too short to work. So I put the front axle in the rear wheel so I can use the sleeve to preload the bearings.

I mount the rear wheel with the left side, that has the disk brake rotor, facing me so it’s easy to get the wedding band and install any of the 0.05 mm shims if I need to. I start with the original rear wheel wedding band that is 6.80 mm. It’s way too tight. I add shims and find that three shims are pretty close to the range of 1030-1550 grams. I sand the band as I did the front and end up with 1300-1350 grams for force to spin the rear wheel bearings.

I lay out the parts for installing the inner bearing race, the wedding band, the three shims, the grease seals and the top hots. The right side uses a thinner grease seal and shorter top hat while the left side uses the same sizes as the front wheel.

Install Inner Bearing Races & Dust Seals

I pack the bearings with high pressure red grease. I have a large socket the fits over the grease seal so I can drive the seals into the hub if they won’t go in by hand.

I start on the front wheel, left side, where I install the wedding band and the four 0.05 mm shims. I stick the shims into the grease on the face of the inner bearing and put the bearing inside the hub. I put a bit more grease on top of the bearing. I install the top hat so the brim is on the back side of the grease seal. I can press the grease seal into the hub by hand. I repeat this procedure for the other side.

The rear wheel is different than the front wheel as the right side has a shorter grease seal and top hat.

The right side has the drive gear for the wheel. I start with that side and follow the same procedure as I did on the front wheel. But, I can’t press the right side steel shell grease seal in by hand, so I use the large socket to drive it into the hub until it is flush.

Then I install the left side with the wedding band and three 0.05 mm shims. I had to use the socket to get the left grease seal to go all the way into the hub.

Here are the powder coated wheels with new wheel bearings and refinished disk brake rotors.