36 BMW 1983 R80ST Replace Wheel Bearings & Set Bearing Pre-Load

Before I install new stainless steel spokes and chrome plated brass spoke nipples, I replace the front wheel bearings. The rear wheel does not have wheel bearings. Instead it is mounted directly to the rear drive. Since the rear wheel does not have an axle, there is no need for wheel bearings.

Tools

I use the Cycle Works wheel and swing arm bearing tool to remove and install the front wheel bearings. Here’s a picture of the tool; “some assembly is required”. This is explained in the included instructions, and I’ll show you how it goes together.

DANGER
You MUST heat the front wheel hub to 225-250 F before pulling or installing the outer bearing race or you will damage the aluminum bore in the hub. 

Cycle Works Swing Arm & Wheel Bearing Puller Tool

Cycle Works Swing Arm & Wheel Bearing Puller Tool

I use a spring scale that measures in grams.

Spring Scale Measuring in Grams and 8 Feet of String

Spring Scale Measuring in Grams and 8 Feet of String

The Cycle Works wheel bearing preload tool is 113 mm, but it is too long for the axle on the R80ST front wheel. I use a 1 inch diameter piece of steel pipe about 3-1/8 inch (80 mm) long. I had a friend mill the ends so they are flat and parallel.

Bottom-Cycle Works Sleeve Fits Rear, Top-Shorter Sleeve Fits Front

Top-Shorter 80 mm Sleeve Fits Snowflake Wheels & R80ST Front Wheel, Bottom-Cycle Works Sleeve Fits Spoke Wheels On /5 and /6 models.

Resources

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.

Duane Auscherman also has a good page about wheel bearings.

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.

Parts

I got the new bearings and grease seals from Euro MotoElectrics who is supporting my charity build for the Motorcycle Relief Project with free parts.

Part #                   Description                                                                Qty
07 11 9 985 005  TAPERED ROLLER BEARING – 40X17X14, Front 2
36 31 1 240 238  SHAFT SEAL – 22X40X7 2

I got a wheel bearing adjusting kit from Cycle Works. The kit includes two “wedding bands”, in my kit they are 6.30 and 6.75 mm, with a number of shims that are 0.05 mm so I can adjust the roller bearing preload without investing in various size wedding bands.

Cycle Works Wheel Bearing Preload Adjustment Kit

Cycle Works Wheel Bearing Preload Adjustment Kit

Video

This short video summarizes how I do this work.

VIDEO: 1983 BMW R80ST Replace Wheel Bearings & Set Pre-Load

Remove Top Hat And Grease Seal

The wheel bearings are the classic two piece roller bearings with an outer race and inner race. The bearings are lubricated with bearing grease. There is a “top hat” on each side that fit into the grease seals. The top hats on the 1983 R80ST are the same length, 13 mm.

I use a screwdriver to pop out the top hat and the grease seal.

Grease Seal With Top Hat

Grease Seal With Top Hat

Prying Top Hat Out Of Grease Seal With Screwdriver

Prying Top Hat Out Of Grease Seal With Screwdriver

Top Hat Removed

Top Hat Removed

Both Spacers, aka "Top Hat", Are 13 mm

Both Spacers, aka “Top Hat”, Are 13 mm

Prying Grease Seal Out Of Hub With Screwdriver

Prying Grease Seal Out Of Hub With Screwdriver

Grease Seal Removed

Grease Seal Removed

Remove Inner Race, Center Pipe And Spacer, aka, The Wedding Band

I remove the inner bearing with my finger and pull out the center pipe. Next to the inner race on the other side inner of the wheel is a spacer, aka, the “wedding band”. It is used to set the pre-load on the wheel bearings.

Inner Bearing Race Removed

Inner Bearing Race Removed

Wheel Bearing Center Pipe Removed

Wheel Bearing Center Pipe Removed

Wedding Band That Adjusts Bearing Pre-Load Removed

Wedding Band That Adjusts Bearing Pre-Load Removed

The wedding band is 6.45 mm thick. BMW supplies them from 6.30 to 7.70 mm in 0.05 mm increments to set the preload on the wheel bearings.

Wedding Band - 6.45 mm

Wedding Band – 6.45 mm

Here are the wheel bearing parts with the exception of the outer races that I still have to remove in the order they go together.

Wheel Bearing Components With Exception Of Outer Bearing Races

Wheel Bearing Components With Exception Of Outer Bearing Races

Remove Outer Bearing Races

The front wheel is an aluminum alloy. There is no steel sleeve installed in the hub as was done on the later model snowflake cast rims. I verified that with a magnet which did not stick to the inside of the hub since it is aluminum, not steel.

Magnet Shows Hub Is Not Magnetic So It Does Not Have Steel Insert

Magnet Shows Hub Is Not Magnetic So It Does Not Have Steel Insert

Therefore I have to heat the hub to about 225-250 F before removing and installing the outer races to avoid damage to the aluminum hub.

DANGER:
If you don’t heat the hub to 225-250 F, you will damage it removing/installing the outer bearing races.

I use the Cycle Works tool to remove the wheel bearing outer races.

Cycle Works Swing Arm/Wheel Bearing Puller Kit

Cycle Works Swing Arm/Wheel Bearing Tool Components

The following pictures show how to assemble the tool.

16 MM Bolt with Lock Nut-Faces Aligned

16 MM Bolt with Lock Nut-Faces Aligned

Four Screws In Plate

Four Allen Screws In Plate

Four Screws at Same Depth

Four Screws at Same Depth

Screw Plate with 16 MM Bolt and 4 Screws

Screw Plate with 16 MM Bolt and 4 Allen Screws

Long Screws Cage The Large Bolt And Lock Nut

Long Allen Screws Cage The Large Bolt And Lock Nut

Long Screws Cage The Large Bolt And Lock Nut

Long Screws Cage The Large Bolt And Lock Nut

Insert Threaded Rod into Screw Plate

Insert Threaded Rod into Screw Plate & Tighten To Expand The Six Allen Bolt Heads Under The Edger Of The Outer Race

I insert the puller plate with the six Allen bolts surrounding the larger bolt with lock nut and the long Allen bolt into the hub so the edges of the six Allen bolts are below the bottom edge of the outer race.

Install Puller Plate With 6 Allen Bolts Into Hub

Install Puller Plate With 6 Allen Bolts Into Hub

Tighten Long Allen Bolt To Expand Puller Under The Edge Of The Outer Race

Tighten Long Allen Bolt To Expand Puller Under The Edge Of The Outer Race

Install Puller Sleeve On Top Of Hub

Install Puller Sleeve On Top Of Hub

Install Top Plate And Thread Nut On Long Allen Bolt

Install Top Plate And Thread Nut On Long Allen Bolt

NOTE:
Since the outer races are pretty deep inside the hub, I can’t use the large flat washer under the nut.

Tighten Nut To Extract Outer Race

Tighten Nut To Extract Outer Race

Loosen Long Allen Bolt To Remove Outer Race From Puller

Loosen Long Allen Bolt To Remove Outer Race From Puller

There is a shoulder with four ribs underneath the outer race that act to position the race inside the hub.

Wheel Bearing Shoulder Ribs Inside Hub Locate The Outer Race Inside The Hub

Wheel Bearing Shoulder Ribs Inside Hub Locate The Outer Race Inside The Hub

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 an 80 mm long, 1 inch diameter metal tube.

Top-Shorter 80 mm Sleeve Fits Snowflake Wheels & R80ST Front Wheel, Bottom-Cycle Works Sleeve Fits Spoke Wheels On /5 and /6 models.

Top-Shorter 80 mm Sleeve Fits Snowflake Wheels & R80ST Front Wheel, Bottom-Cycle Works Sleeve Fits Spoke Wheels On /5 and /6 models.

Spring Scale Measuring in Grams and 8 Feet of String

Spring Scale Measuring in Grams and 8 Feet of String

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 1.0 inches.
  2. I divide this by 2 to get the radius, or 0.50 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 0.50 inches, therefore the spring force range is:
    Lower: 567/0.50 = 1,134 grams; say 1,150 grams.
    Upper: 850/0.50 = 1,700 grams.
  6. For simplicity, I’ll use a range of 1,150-1,700 grams of force.

How Bearing Preload Is Applied

Inside the wheel hub is a pipe. The wedding band typically goes on the left end of the pipe up against the left inner bearing race.

(LEFT)-Wedding Band; (RIGHT) Pipe

(LEFT)-Wedding Band; (RIGHT) Pipe

Left Inner Race Goes Against The Wedding Band

Left Inner Race Goes Against The Wedding Band

Left Inner Race Goes Against The Wedding Band

Left Inner Race Goes Against The 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.

How Inner Races, Wedding Band & Pipe Go Together Inside The Hub

How Inner Races, Wedding Band & Pipe Go Together Inside The Hub

How Inner Races, Wedding Band & Pipe Go Together Inside The Hub

How Inner Races, Wedding Band & Pipe Go Together Inside The Hub

By adjusting the thickness of the wedding band, you adjust how close together or far apart the two wheel bearing inner races are from the outer races. 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 6.45 mm wedding band.

Front Wheel Wedding Band - 6.45 mm

Front Wheel Wedding Band – 6.45 mm

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 a number of 0.05 mm shims. This is an affordable way to adjust wheel bearing preload.

Cycle Works Wheel Bearing Preload Adjustment Kit For One Wheel

Cycle Works Wheel Bearing Preload Adjustment Kit For One 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.

Clean Inner Bearings with Carburetor Cleaner

Clean Inner Bearings with Carburetor Cleaner

Use Light Oil to Lubricate Inner Bearings

Use Light Oil to Lubricate Inner Bearings

Here is the order of the front wheel bearing components that are installed in the hub when setting the bearing pre-load. I don’t install the grease seals or the top hats.

Front Wheel Bearing Parts Order For Setting Bearing Pre-Load-Grease Seals & Top Hats Are Not Used

Front Wheel Bearing Parts Order For Setting Bearing Pre-Load-Grease Seals & Top Hats Are Not Used

From left to right side of the wheel:

  • Axle Nut,
  • Thin Flat Washer (not the stock thick one),
  • Inner Bearing Race;
  • Wedding Band;
  • Pipe;
  • Axle Spacer
  • Inner Bearing Race

For the front wheel I use the 80 mm sleeve on the left side of the axle that has the threads and substitute the thin washer for the stock thick axle washer. The sleeve compresses the two inner races when the axle nut is tightened establishing the preload force. I also include the axle spacer that goes on the right side of the axle.

Parts Order For Setting Bearing Pre-Load-80 mm Pipe Goes On Left Against Inner Bearing

Parts Order For Setting Bearing Pre-Load-80 mm Pipe Goes On Left Against Inner Bearing With Thin Flat Washer Under Axle Nut

Front Wheel Bearing Configuration For Setting Bearing Pre-Load

Front Wheel Bearing Configuration For Setting Bearing Pre-Load

Since I am replacing the spokes, I don’t have the wheel assembled. So I mount the front wheel hub in rubber jaws in my vice and also use shop towels to cushion the hub to avoid scratching it. Of course you can mount the assembled wheel in the vice if you have removed the front tire and tube.

Front Hub In Rubber Jaws Of Vice With Shop Rags

Front Hub In Rubber Jaws Of Vice With Shop Rags

I insert the axle with the axle spacer and an inner bearing race from the right side of the hub.

Insert Inner Bearing Race & Axle Spacer On Right Side Of Hub

Insert Inner Bearing Race & Axle Spacer On Right Side Of Hub

Then I insert the pipe, the original 6.45 mm wedding band, and the inner bearing race on the left side of the hub.

Insert Pipe Into Left Side Of Hub

Insert Pipe Into Left Side Of Hub

Insert Inner Bearing Race And Wedding Band On Left Side Of Hub

Insert Inner Bearing Race And Wedding Band On Left Side Of Hub

Then I install the 80 mm sleeve, the thin flat washer and the axle nut centering the sleeve on the inner bearing race. Then I torque the nut to 25 Ft-Lbs using a screwdriver in the right side axle hole to keep the axle from turning.

80 mm Sleeve, Thin Flat Washer & Axle Nut Installed On Left Side

80 mm Sleeve, Thin Flat Washer & Axle Nut Installed On Left Side

Torque Axle Nut To 25 Ft-Lbs

Torque Axle Nut To 25 Ft-Lbs

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.

String Wound Evenly Around Sleeve

String Wound Evenly Around Sleeve

Scale Attached To Loop On End Of String

Scale Attached To Loop On End Of String

Pulling Scale To Spin Front Wheel Bearings To Measure Required Force

Scale Attached To Loop On End Of String

The original 6.45 mm wedding hat made the bearings so tight I couldn’t turn the axle. So I tried the 6.75 mm band that is included in the wheel bearing shim kit from Cycle Works. That was too loose only requiring about 200 grams of force.

I went back to the original 6.45 mm wedding band and begin adding 0.05 mm shims from the Cycle Works shim kit. The shims go against the narrow side of the inner bearing and will butt up against the wedding band when I install the inner race. I check the force on the spring scale as I add each shim.

Shims Go Against The Narrow Face Of The Inner Bearing Race

Shims Go Against The Narrow Face Of The Inner Bearing Race

Original Wedding Band Needs 4 Shims For Proper Bearing Pre-Load

Original Wedding Band Needs 4 Shims For Proper Bearing Pre-Load

At three shims the force required was close to 2,000 grams and at four shims it was about 800 grams. So the preload I need is somewhere between three and four shims.

Since four shims makes the inner bearing races too far apart resulting in too low a pre-load, I fine tune the preload by reducing the thickness of the wedding band. I use 320 wet/dry paper and sand the faces of the 6.45 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 1,150-1,700 grams. After about 30 laps on each face, the preload force is 1,200-1,300 grams on the front wheel bearings. So I called that good.

Install Inner Bearing Races, Grease Seals & Top Hats

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.

Ready To Install Inner Bearing Races, Pipe, Wedding Band, Shims, Grease Seals, Top Hats

Ready To Install Inner Bearing Races, Pipe, Wedding Band, Shims, Grease Seals, Top Hats

The top hat fits into the grease seal so the brim of the hat is on the inside of the seal.

Top Hat Detail-Brim On Right

Top Hat Detail-Brim On Right

Top Hat In Orientation In Rear Face Of Grease Seal-Brim Goes Behind The Seal

Top Hat In Orientation In Rear Face Of Grease Seal-Brim Goes Behind The Seal

Top Hat In Orientation In Front Face Of Grease Seal

Top Hat In Orientation In Front Face Of Grease Seal

I pack the inner bearing races generously with Sta Lube, Sta-plex Extreme Pressure Premium red grease.

Inner Bearing Races Packed With Sta Lube, Sta-Plex Extreme Pressure Premium Grease

Inner Bearing Races Packed With Sta Lube, Sta-Plex Extreme Pressure Premium Grease

I use the large socket and tap the right side grease seal with top hat into the hub until it is even with the face of the hub.

Large Socket To Drive Grease Seal

Large Socket To Drive Grease Seal

Right Side Of Hub Inner Race, Grease Seal And Top Hat Installed

Right Side Of Hub Inner Race, Grease Seal And Top Hat Installed

I flip the hub over and I install the center pipe and the wedding band inside the hub. I stick the four shims into the grease on the narrow face of the left side inner race and install it into the hub. Next I install the grease seal with top hat. I marked the left side of the hub so when I install the wheel, that side of the hub will be on the left.

Left Side Of Hub With Grease Seal, Top Hat, Inner Race, Shims, Wedding Band and Pipe Installed

Left Side Of Hub With Grease Seal, Top Hat, Inner Race, Shims, Wedding Band and Pipe Installed

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