23 BMW 1983 R100RS Rebuild Transmission Output Shaft

TRANSMISSION REBUILD WARNING:

Due to the complexity and numerous changes made by BMW in the airhead transmissions, I would recommend having access to an experienced mechanic who has worked on these transmission for guidance before attempting to work on yours. Increasingly, new parts are made from “unobtanium” and many are expensive so mistakes will be costly. It is also a critical drive-line component and sudden failure can be injurious. 

I previously rebuilt the transmission of my 1977 R100RS. This is the second time I have done this work. Therefore, I am not an expert, I am an amateur. I estimate I have invested around $700 in acquiring the necessary tools. This work requires a clean environment, precision measuring tools, multiple special tools, patience, skill and a close attention to detail. And, for both these rebuilds, I have access to long time, skilled airhead mechanics who are willing to support me with advice, part inspection and analysis, and answers to procedural questions.

If you don’t have all the above and you haven’t rebuilt multiple airhead motorcycles, I strongly advise you NOT TO DO THIS WORK. You should have it done by an expert mechanic.

Resources

In preparation for, and while doing this work, I used the following resources.

I shot a number of short videos about how the gears and shift cam mechanism work and part of the work I did on the 1977 transmission. You can find these on my YouTube site:

I was fortunate to have access to a respected, long time BMW airhead mechanic who provided invaluable support and advice.

You can read about how I disassemble the transmission and rebuild the shift cam assembly, input & intermediate shafts, and assemble the transmission here.

Tools

On the first transmission rebuild I did on the 1977 R100RS, I borrowed BMW transmission tools from a long time local mechanic and friend. This time, I borrowed the same tools, measured them and paid an experienced airhead and friend with a machine shop, Bill Lambert, to make copies of the tools for me. I plan to continue rebuilding transmissions on future projects, so I made the investment in owing these tools.

BMW Transmission Tools

Transmission Tools with Holder Machined For Me From BMW's Tools By Fellow Airhead Bill Lambert

Transmission Tools with Holder Machined For Me From BMW’s Tools By Fellow Airhead Bill Lambert

Transmission Rebuilding Tools

Transmission Rebuilding Tools

Drifts For Installing Input Shaft Seal (Two Pieces)

Drifts For Installing Input Shaft Seal (Two Pieces)

Input Shaft Seal Drift Parts

Input Shaft Seal Drift Parts

Drift For Removing Input Shaft Roller Bearing Inner Race

Drift For Removing Input Shaft Roller Bearing Inner Race

Drift For Removing Input Shaft Roller Bearing Inner Race

Drift For Removing Input Shaft Roller Bearing Inner Race

Drift For Removing Ball Bearings From Shafts & Install Gear Change Shaft Seal

Drift For Removing Ball Bearings From Shafts & Install Gear Change Shaft Seal

Sleeve For Removing Input Shaft Ball Bearing

Sleeve For Removing Input Shaft Ball Bearing

Sleeve For Removing Input Shaft Ball Bearing

Sleeve For Removing Input Shaft Ball Bearing

Sleeve For Removing Input Shaft Ball Bearing

Sleeve For Removing Input Shaft Ball Bearing

Drift For Compressing Input Shaft Torsion Shock Spring

Drift For Compressing Input Shaft Torsion Shock Spring

Drift For Compressing Input Shaft Torsion Shock Spring

Drift For Compressing Input Shaft Torsion Shock Spring

Drift For Compressing Input Shaft Torsion Shock Spring

Drift For Compressing Input Shaft Torsion Shock Spring

Hydraulic Press

To press the bearings off and on the shafts I use a Harbor Freight 20 ton hydraulic press.

Harbor Freight Hydraulic Press

Harbor Freight Hydraulic Press

Bearing Splitter

I use two different size bearing splitters to remove the bearings and also when I need to press on a shoulder to remove a part. The splitter has a dished face and a flat face. The dished face will fit between the bottom of a bearing outer race and the gear next to it to capture the bearing to remove it. The flat face works well against a shoulder when I need to press a part off the shaft.

Bearing Splitter Dished Face

Bearing Splitter Dished Face

Bearing Splitter Flat Face

Bearing Splitter Flat Face

Snap Ring Pliers

I use these to remove the lock rings on the output shaft.

Snap Ring Pliers

Snap Ring Pliers

Parts

I got all the parts for the rebuild from Tom Cutter at Rubber Chicken Racing Garage. He provided several kits with the needed parts. Here is a list of the BMW part numbers I used on this part of the rebuild.

Part #                  Description                                                     Qty
23 12 1 338 795 GROOVED BALL BEARING – 62X17X17, Output Front 1
23 12 1 231 495 GROOVED BALL BEARING – 52X20X15, Output Rear 1
23 21 1 232 299 BUSH, Output 1st Gear 1
07 11 9 934 100 LOCK RING – 17X1, Output 5th Gear 1
23 21 1 235 006 SNAP RING, Output 5th Gear 1
07 11 9 934 186 LOCK RING – 28X1,5, Output 2nd Gear 2

In addition, Tom includes a thin shim that fits under the lock ring that secures the front ball bearing next to 5th gear onto the output shaft as shown on the left in the picture below.

Output Shaft New Shim, Snap Ring and Lock Ring To Secure Front Bearing Next to 5th Gear

(Left to Right) New Shim, Snap Ring and Lock Ring To Secure Output Shaft Front Bearing Next to 5th Gear

This ensures that the lock ring securely presses on the ball bearing to keep it from moving on the output shaft.

NOTE:
Tom provided me this information about how to obtain the output shaft shim.

The transmission output shaft shim that you see on my page was supplied by Tom Cutter at Rubber Chicken Racing Garage. You can order those shims, Part Number RC008, at the PAY NOW button on Tom’s website RubberChickenRacingGarage.com or use the handy link below.
The shims are $9.90 each, plus $10.20 USPS Priority Mail postage, total $20.10 USD for one shim. To order additional shims just add another $9.90 each. (Only pay postage once.)

To make payment click here: PAY NOW. In the Payment Description box, put “RC008 SHIMs“.

Video

I shot a video summarizing the procedure I use to rebuild the output shaft.

VIDEO: 1983 BMW R100RS Rebuild Transmission Output Shaft

Initial 5th Gear Inspection

Before I dissemble the output shaft to replace the 1st gear bushing, ball bearings and lock rings, I inspect it. I take a measurement of the distance between the ends of the two ball bearings. When I reassemble the shaft with new ball bearings, the distance should be almost the same–within a 0.001 inch (0.02 mm)–and if it’s not, I made a mistake.

I start by pushing 5th gear to see if it will move and/or rock on the shaft. It moves axially about 0.4 mm and rocks. This means the bearing and shaft have worn. This is often caused by incorrect gear lube used in the transmission; either the wrong weight or synthetic gear lube, or getting water into the transmission via a leaking speedometer shaft rubber seal. This is not an uncommon situation for 5th gear on the output shaft.

Output Shaft 5th Gear Moves Axially about 0.4 mm and Rocks On The Shaft

Output Shaft 5th Gear Moves Axially about 0.4 mm and Rocks On The Shaft

I do a more through inspection of all the parts as I disassemble the output shaft. I put all that information in the Inspection section below. I send the photos to an experienced mechanic for his evaluation of the condition of  the output shaft.\

Disassemble Output Shaft

I remove all the bearings and gears from the output shaft using the transmission tools and the hydraulic press. This section is organized in the order I remove the parts.

Remove Front Ball Bearing Next To  5th Gear

I start by removing the front ball bearing next to 5th gear which is the gear with the helical teeth. I remove the lock ring with my snap ring pliers and lift out the snap ring that fits in the chamfer of the bearing race next to the output shaft. BMW uses this snap ring to provide more surface for the lock ring to press on to keep the front bearing from moving on the shaft. Since 5th gear is a helical gear, when it is engage, there is a large axial force pushing on the front bearing so it needs to be secure on the output shaft.

Output Shaft Rear Ball Bearing Secured By Lock Ring

Output Shaft Rear Ball Bearing Secured By Lock Ring

Remove Output Shaft Rear Ball Bearing Snap Ring That Is Under The Lock Ring

Remove Output Shaft Rear Ball Bearing Snap Ring That Is Under The Lock Ring

Output Shaft Rear Ball Bearing Lock Ring and Snap Ring-I Replace Both Of Them

Output Shaft Rear Ball Bearing Lock Ring and Snap Ring-I Replace Both Of Them

Now I can push the output shaft through the front bearing using a bearing separator, an M8 bolt and the transmission tool short drift. I put the M8 bolt in the hole in output shaft to protect it when I push the shaft out of the ball bearing. I attach the bearing separator so the dished side is under the face of the ball bearing. I tighten the nuts on the bolts that push the two halves together to tighten push the knife edge of the separator between the bearing face and the face of 5th gear. Before I tighten up the nuts I verify the knife edge is not contacting any of the helical teeth on 5th gear so I don’t damage 5th gear.

Output Shaft Rear Ball Bearing with M8 Allen Bolt In Bearing Splitter

Output Shaft Rear Ball Bearing with M8 Allen Bolt In Bearing Splitter

Pressing Output Shaft Off Rear Ball Bearing

Pressing Output Shaft Off Rear Ball Bearing

Remove 5th and 3rd Gears

I put the output shaft in my wood plate with the hole for the output shaft taper so it’s easier to work on it.

Output Shaft Mounted On Wood With Hole For Tapered End Of Shaft With 5th Gear Side Facing Rear Ball Bearing

Output Shaft Mounted On Wood With Hole For Tapered End Of Shaft With 5th Gear Side Facing Rear Ball Bearing

I lift 5th gear off the output shaft. There is a flat washer on the face of 5th gear with the shift dog teeth. This washer has a side with a chamfer around the hole in the washer and the other side has a flat edge around the hole in the washer without a chamfer.

Output Shaft 5th Gear Washer Side With Chamfered Hole Goes Against Splines On Shaft

Output Shaft 5th Gear Washer Side With Chamfered Hole Goes Against Splines On Shaft

Output Shaft 5th Gear Washer Side With Flat Face Goes Against 5th Gear

Output Shaft 5th Gear Washer Side With Flat Face Goes Against 5th Gear

The side of the washer with the flat face goes against 5th gear and the side with the chamfer around the hole goes against the splines on the output shaft that secure 3rd gear on the shaft.

Output Shaft 5th Gear Face That Goes Next To The Front Bearing

Output Shaft 5th Gear Face That Goes Next To The Front Bearing

Output Shaft 5th Gear Face With Dog Teeth Has A Flat Washer

Output Shaft 5th Gear Face With Dog Teeth Has A Flat Washer

There is an “X” mark stamped on the the dog teeth face of 5th gear indicating this one has a 17.5 degree angle. The earlier transmissions used a 15 degree angle on the helical gears of the input, intermediate and output shaft and you can not mix 15 and 17.5 degree gears.

Output Shaft 5th Gear "X" Indicates 17.5 Degree Helix

Then I pull 3rd gear off the shaft. The face of 3rd gear facing 5th gear has slots in it to engage with the dog teeth on 5th gear. There is also a slot for one of the shift forks. The other face of 3rd gear is smooth and faces 2nd gear.

Output Shaft With 3rd Gear Side Facing 5th Gear Has Slots For Dog Teeth To Engage

Output Shaft With 3rd Gear Side Facing 5th Gear Has Slots For Dog Teeth To Engage

Output Shaft 3rd Gear Dog Slots

Output Shaft 3rd Gear Dog Slots

Output Shaft 3rd Gear Shift Fork Slot

Output Shaft 3rd Gear Shift Fork Slot

Output Shaft 3rd Gear Face Next to 2nd Gear

Output Shaft 3rd Gear Face Next to 2nd Gear

Remove Rear Ball Bearing Next To 1st Gear

The 2nd gear is secured to the shaft with two lock rings on either side of the gear. So I can’t remove it until I remove the rear ball bearing, 1st gear and 4th gear.

Output Shaft 2nd Gear Secured With A Lock Ring On Each Side

Output Shaft 2nd Gear Secured With A Lock Ring On Each Side

I use the bearing splitter to remove the rear ball bearing as I did to remove the front bearing. I opted to use the nut that secures the output flange to the threaded end of the output shaft to protect the threads from damage by the hydraulic press anvil before pressing the output shaft through the rear bearing. I thread the nut on backwards so the shoulder faces the anvil and keep it even with the end of the output shaft so the threads don’t take all the load from the press.

Using Flange Nut To Protect Output Shaft Threads

Using Flange Nut To Protect Output Shaft Threads

Press Rear Bearing Off Output Shaft with Hydraulic Press

Press Rear Bearing Off Output Shaft with Hydraulic Press

Rear Ball Bearing Removed-Inside Face Towards 1st Gear

Rear Ball Bearing Removed-Inside Face Towards 1st Gear

Rear Ball Bearing Removed-Outside Face Towards Taper

Rear Ball Bearing Removed-Outside Face Towards Taper

Remove 1st Gear

First gear has a flat washer that I remove. The washer on this side of 1st gear is wider than the one on the other side. One side of the washer has a chamfered edge around the hole and the other side has a flat edge without a chamfer. The chamfered side of the washer faces 1st gear. The chamfer accommodates the bushing that goes on the output shaft inside 1st gear.

Output Shaft 1st Gear Washer Next To Rear Ball Bearing-Sharp Side Faces Away From 1st Gear

Output Shaft 1st Gear Washer Next To Rear Ball Bearing-Flat Side Faces Away From 1st Gear

Output Shaft 1st Gear Washer Next To Rear Ball Bearing-Chamfered Side Faces 1st Gear Bushing

Output Shaft 1st Gear Washer Next To Rear Ball Bearing-Chamfered Side Faces 1st Gear Bushing

The face of 1st gear that fits against the rear bearing is smooth and the other face has dog slots that fit the dog teeth on 4th gear.

Output Shaft 1st Gear Detail-Face Toward Rear Bearing

Output Shaft 1st Gear Detail-Face Toward Rear Bearing

Output Shaft 1st Gear Detail-Face Toward 4th Gear With Six Shift Dog Slots

Output Shaft 1st Gear Detail-Face Toward 4th Gear With Six Shift Dog Slots

The busing inside 1st gear slides off the shaft exposing the other flat washer that is not as wide.

Remove Output Shaft 1st Gear Bushing

Remove Output Shaft 1st Gear Bushing

Output Shaft 1st Gear Bushing Detail

Output Shaft 1st Gear Bushing Detail

Output Shaft 1st Gear Washer Next To 4th Gear-Sharp Edge Faces Toward 4th Gear

Output Shaft 1st Gear Washer Next To 4th Gear-Flat Side Faces Toward 4th Gear

Output Shaft 1st Gear Washer Next To 4th Gear-Chamfered Edge Faces 1st Gear Bushing

Output Shaft 1st Gear Washer Next To 4th Gear-Chamfered Side Faces Toward 1st Gear

Remove 4th Gear

Fourth gear slides off the shaft. It has dog teeth on both sides. The side facing 1st gear does not have the slot for the shift fork.

Output Shaft 4th Gear Shift Dogs Facing 1st Gear

Output Shaft 4th Gear Shift Dogs Facing 1st Gear

Output Shaft 4th Gear Face With Shift Fork Slot Faces 2nd Gear

Output Shaft 4th Gear Face With Shift Fork Slot Faces 2nd Gear

Output Shaft 4th Gear Shift Dogs Facing 2nd Gear

Output Shaft 4th Gear Shift Dogs Facing 2nd Gear

Remove 2nd Gear

With all the other gears removed from the output shaft, I can access the two lock rings that secure 2nd gear to the shaft and remove the gear. I use the snap ring pliers to remove the lock rings. Under each lock ring is a flat, slotted washer. The slotted flat washers are the same and so are the two 2nd gear lock rings.

Output Shaft 2nd Gear Lock Ring and Washer Go On Both Faces Of 2nd Gear

Output Shaft 2nd Gear Lock Ring and Washer Go On Both Faces Of 2nd Gear

The face of 2nd gear that faces toward 4th gear has dog slots in it and the other face is smooth.

Output Shaft 2nd Gear Lock Ring and Washer Go On Both Faces Of 2nd Gear

Output Shaft 2nd Gear Lock Ring and Washer Go On Both Faces Of 2nd Gear

Output Shaft 2nd Gear Lock Ring and Washer Go On Both Faces Of 2nd Gear

Output Shaft 2nd Gear Lock Ring and Washer Go On Both Faces Of 2nd Gear

I tie wrap the slotted flat washers and lock rings to 2nd gear so they are against the face they came from. That way they will go back together the way they were originally installed.

Output Shaft 2nd Gear Parts Wrapped Together In Order Removed

Output Shaft 2nd Gear Parts Wrapped Together In Order Removed

There is a bushing for 2nd gear on the output shaft. It is nice fairly tight on the shaft and I don’t remove it as I’m not going to replace it.

Output Shaft 2nd Gear Bushing

Output Shaft 2nd Gear Bushing

Output Shaft Parts Inspection

As disassembled the output shaft I inspected the parts. I put all that information together in this section in the order the parts fit on the shaft starting from the front of the shaft.

Front Ball Bearing

With the front ball bearing removed, I inspect the inside face. I can see a wear pattern on the face of the inner race created by the wobble and axial movement of 5th gear on the output shaft.

Output Shaft Rear Ball Bearing Face Next To 5th Gear Wear Pattern

Output Shaft Rear Ball Bearing Face Next To 5th Gear Wear Pattern

The edges of the outer race show discoloration and scuffing which is also evident in the bearing bore of the transmission case.

Output Shaft Front Bearing Discoloration and Scuffing

Output Shaft Front Bearing Discoloration and Scuffing

5th Gear

Before I disassembled the output shaft I could move 5th gear axially on the shaft about 0.4 mm and I can rock 5th on the output shaft so there’s wear on both the shaft bushing and the inside of the hole in 5th gear. The outside face of 5th gear that is against the front bearing shows some wear due to the wobble.

Output Shaft 5th Gear Rocks On The Shaft

Output Shaft 5th Gear Rocks On The Shaft

Output Shaft 5th Gear Wear From Rubbing Against Front Bearing

Output Shaft 5th Gear Wear From Rubbing Against Front Bearing

The shift dog teeth are uniformly shiny on one side which means the wobble was not so bad that some of the teeth took all the load. That’s a good sign. The shiny side is the driving side of the dog teeth that engage 3rd gear when accelerating and at speed so they wear more than the other side of the dog teeth which engage under deceleration or when coasting.

Output Shaft 5th Gear Dog Tooth Face "Shiny" Side on Acceleration Side Of Tooth

Output Shaft 5th Gear Dog Tooth Face “Shiny” Side on Acceleration Side Of Tooth

Output Shaft 5th Gear Dog Tooth Face On Deceleration Side Of Tooth-Not So Shiny

Output Shaft 5th Gear Dog Tooth Face On Deceleration Side Of Tooth-Not So Shiny

The gear faces show no chips or cracks.

Output Shaft 5th Gear Teeth Are In Good Condition

Output Shaft 5th Gear Teeth Are In Good Condition

3rd Gear

The gear teeth show no signs of abnormal wear. The shift fork slot is worn a bit but not damaged. The shift dog slots are not cracked or chipped.

Output Shaft 3rd Gear Dog Slots Are Not Abused

Output Shaft 3rd Gear Dog Slots Are Not Abused

Output Shaft 3rd Gear Shift Fork Slot and Gear Teeth Are In Good Condition

Output Shaft 3rd Gear Shift Fork Slot and Gear Teeth Are In Good Condition

2nd Gear

The gear teeth have a slight helical wear pattern. The dog slots are not cracked or chippped.

Output Shaft 2nd Gear Teeth Show Some Helical Wear Patterns

4th Gear

The gear faces and both sets of shift dogs on 4th gear show no abnormal signs of wear, chips or cracks. The shift fork slot has some wear but no signs of damage.

Output Shaft 4th Gear Teeth And Shift Fork Slot Are In Good Condition

Output Shaft 4th Gear Teeth And Shift Fork Slot Are In Good Condition

Output Shaft 4th Gear Shift Dog Teeth Facing 1st Gear Are Not Damaged

Output Shaft 4th Gear Shift Dog Teeth Facing 1st Gear Are Not Damaged

Output Shaft 4th Gear Shift Dog Teeth Facing 2nd Gear Are Not Damaged

Output Shaft 4th Gear Shift Dog Teeth Facing 2nd Gear Are Not Damaged

1st Gear

The teeth on 1st gear show a helical wear pattern. The shift dog slots show no signs of chips or cracks.

Output Shaft 1st Gear Teeth Have A Helical Wear Pattern

Output Shaft 1st Gear Teeth Have A Helical Wear Pattern

Output Shaft 1st Gear Detail

Output Shaft 1st Gear Detail

Rear Ball Bearing

There is some minor scuffing on the outer bearing race but no discoloration.

Some Scuffing On Outer Race of Rear Bearing Next To 1st Gear

Some Scuffing On Outer Race of Rear Bearing Next To 1st Gear

The inside face of the ball bearing next to 1st gear does not show wear indicating the 1st gear bushing is not loose allowing the face of 1st gear to rub on the face of the inner race.

Rear Ball Bearing Removed-Inside Face Does Not Show Any Wear From 1st Gear

Rear Ball Bearing Removed-Inside Face Does Not Show Any Wear From 1st Gear

Output Shaft

The taper of the input shaft has two scores. These were caused by the machining of the taper on the output flange which left some vestigial machining marks that scored the output shaft taper.

Scoring On Taper Of Output Shaft Caused By Vestigial Machining Marks On The Output Flange

Scoring On Taper Of Output Shaft Caused By Vestigial Machining Marks On The Output Flange

The end of the output shaft the front ball bearing runs on shows some discoloration as does the bushing under 5th gear.

Output Shaft Rear Bearing Bush Discoloration

Output Shaft Rear Bearing Bush Discoloration

Output Shaft Discoloration On 5th Gear Bushing

Output Shaft Discoloration On 5th Gear Bushing

Output Shaft Parts Condition Assessment

I sent the pictures to an expert mechanic for his assessment of the condition of the output shaft parts. He suggested that I replace 5th gear with a new one. There is an option to get a taller 5th gear (one less tooth than the stock gear). The gear has a slightly tighter hole which should reduce the rocking and axial movement of the gear on the shaft and it reduces RPM at highway speed. Since I installed high compression pistons that give me about 5% more torque and horsepower, I opted for the tall 5th gear.

The other parts were all judged serviceable.

Assemble Output Shaft

Before assembling the shaft, I cleaned all the parts in my parts washer. I cleaned and polished (AutoSol Metal Polish) the input shaft bushings to remove the discoloration, dirt and debris. I used a wire tube brush to clean up the inside of the output shaft in my parts washer. This is the passage for gear lube to reach the 5th, 2nd and 1st gear bushings so having it nice and shiny clean is a good idea.

Use Brass Tube Brush To Clean Bore Of Output Shaft

I didn’t remove the 2nd gear bushing. But if you do, it’s critical when you install it to be sure the hole in the shaft and the hole in the bushing line up so the bushing gets lubricated. You can use a small drill bit to ensure the bushing is installed so it’s aligned with the hole in the shaft.

Ensure 2nd Gear Bush Hole Is Over Hole In Shaft

Ensure 2nd Gear Bush Hole Is Over Hole In Shaft

Using Small Drill Bit To Ensure 2nd Gear Bush Hole Is Aligned With Hole In Shaft

Using Small Drill Bit To Ensure 2nd Gear Bush Hole Is Aligned With Hole In Shaft

I laid out all the parts in order on my work bench (left 1st gear to right 5th gear) and replaced the old parts with the new ones so I wouldn’t accidentally install an old part.

Output Shaft Parts In Order From 1st Gear (Left) to 5th Gear (Right)

Output Shaft Parts In Order From 1st Gear (Left) to 5th Gear (Right)

This is the new front ball bearing which is a larger diameter than the rear ball bearing along with the new parts used to keep it from moving on the output shaft: the shim, the snap ring and the lock ring.

Output Shaft 5th Gear Ball Bearing with Hardware To Secure Bearing On Shaft

Output Shaft 5th Gear Ball Bearing with Hardware To Secure Bearing On Shaft: (Left to Right) Shim, snap ring and lock ring

This is the new tall 5th gear and the original flat washer that goes on the face of the gear with the dog teeth.

New Output Shaft "Tall" 5th Gear & Original Washer Which Goes On The Other Face Of The Gear (Note "X" at Bottom Of New 5th Gear Indicating It Has A 17.5 Degree Helix)

New Output Shaft “Tall” 5th Gear & Original Washer Which Goes On The Other Face Of The Gear (Note “X” at Bottom Of New 5th Gear Indicating It Has A 17.5 Degree Helix)

This is 2nd gear with the original slotted washers and new lock rings.

Output Shaft 2nd Gear with Original Slotted Washers and New Lock Rings

Output Shaft 2nd Gear with Original Slotted Washers and New Lock Rings

This is 1st gear with the new bushing and original flat washers.

Output Shaft 1st Gear With New Bushing And Original Flat Washers

Output Shaft 1st Gear With New Bushing And Original Flat Washers

Install 2nd Gear

I start by installing 2nd gear on it’s bushing securing it with the two slotted washers and new lock rings.

Output Shaft with 2nd Gear and Hardware

Output Shaft with 2nd Gear and Hardware

The dog slots on 2nd gear face the tapered end of the shaft. I put some gear lube on the bushing so it will be lubricated until gear lube can move up the shaft to lubricate it.

Output Shaft 2nd Gear Orientation-Dog Slots Face Tapered End Of Shaft

Output Shaft 2nd Gear Orientation-Dog Slots Face Tapered End Of Shaft

Put Some Gear Lube On 2nd Gear Bushing

Put Some Gear Lube On 2nd Gear Bushing

Output Shaft 2nd Gear Slides On Bushing

Output Shaft 2nd Gear Slides On Bushing

Then I install the slotted washer and lock ring on each end of 2nd gear to secure it the output shaft.

Output Shaft 2nd Gear Slotted Washer

Output Shaft 2nd Gear Slotted Washer

Output Shaft 2nd Gear Slotted Washer Installed

Output Shaft 2nd Gear Slotted Washer Installed

Output Shaft 2nd Gear New Lock Ring

Output Shaft 2nd Gear New Lock Ring

Output Shaft 2nd Gear Secured With Slotted Washer and New Lock Ring-Same On Other Side

Output Shaft 2nd Gear Secured With Slotted Washer and New Lock Ring-Same On Other Side

Install 4th Gear

I put the output shaft in the wood plate with the taper end (1st gear end) facing up to install 4th gear and 1st gear.

Output Shaft 2nd Gear Installed & In Hole In Board with Spline End Facing Up

Output Shaft 2nd Gear Installed & In Hole In Board with Spline End Facing Up

Output Shaft 4th Gear (Left) and 1st Gear (Right) Go On Next

Output Shaft 4th Gear (Left) and 1st Gear (Right) Go On Next

Fourth gear has shift dog teeth on both sides of the gear and a slot for the shift fork on one side. The shift fork slot faces 2nd gear.

Output Shaft 4th Gear Face With Slot Faces 2nd Gear

Output Shaft 4th Gear Face With Slot Faces 2nd Gear

Output Shaft 4th Gear Orientation-Sift Dog Teeth Face 2nd Gear

Output Shaft 4th Gear Orientation-Sift Dog Teeth Face 2nd Gear

Install 1st Gear

I start by sliding the flat washer on the shaft with the side with the chamfered hole facing up. If you are not sure which is the chamfered side of the washer, put it on the shaft and look at the inner diameter of the washer next to the shaft. The side with the flat face will have almost no gap next to the shaft and the side with the chamfer around the hole will have a noticeable gap.

Output Shaft Washer Side with Sharp Edge-Note Small Gap Next To Shaft

Output Shaft Washer Side with Flat Face-Note Small Gap Next To Shaft

Output Shaft Washer Face With Chamfer-Note Larger Gap Next To Shaft

Output Shaft 1st Gear Washer With Narrow Ring Has Chamfer Side Facing Toward 1st Gear-Note Larger Gap Next To Shaft

Then I put some gear lube on the shaft and the inside and outside of the new 1st gear bushing so it will have some lubrication until the transmission can push gear lube up the inside of the output shaft to lubricate the bushing and slide the 1st gear bushing on the output shaft.

Output Shaft 1st Gear Bushing Installed

Output Shaft 1st Gear Bushing Installed

NOTE:
Since the 1st gear bushing can spin on the shaft with 1st gear, the holes in the shaft and the holes in the bushing don’t line up all the time.

I install 1st gear with the face with the dog slots facing the dog teeth on 4th gear.

Output Shaft 1st Gear Dog Slot Face Goes Next To 4th Gear Dog Teeth

Output Shaft 1st Gear Dog Slot Face Goes Next To 4th Gear Dog Teeth

Then I install the wider flat washer with the flat side facing up so the side with the side with the chamfer around the hole faces the bushing.

Output Shaft 1st Gear Orientation

Output Shaft 1st Gear Orientation

Output Shaft Wider 1st Gear Washer Face With Sharp Edge Points Outward

Output Shaft 1st Gear Washer With Wider Ring Has Flat Side Pointing Away From 1st Gear

Install Rear Ball Bearing Next To 1st Gear

The smaller diameter ball bearing slides on the 1st gear end of the shaft.

Output Shaft 1st Gear Ball Bearing Is Smaller Diameter Than 5th Gear Bearing

Output Shaft 1st Gear Ball Bearing Is Smaller Diameter Than 5th Gear Bearing

I use the long drift I used to remove the input shaft roller bearing inner race to push the bearing onto the shaft using the hydraulic press.

Pressing Output Shaft 1st Gear Bearing Onto Shaft with Transmission Tools Long Drift

Pressing Output Shaft 1st Gear Bearing Onto Shaft with Transmission Tool Long Drift

Output Shaft 1st Gear Ball Bearing Installed

Output Shaft 1st Gear Ball Bearing Installed

Install 3rd Gear And 5th Gear

I flip the output shaft over so the taper end is in the hole in the board and install 3rd gear. Third gear slides onto the output shaft. The face with the slot for a shift fork faces 2nd gear.

Output Shaft 3rd Gear Has Slot For Shift Fork

Output Shaft 3rd Gear Has Slot For Shift Fork

Install Output Shaft 3rd Gear With Shift Fork Slot Toward 2nd Gear

Install Output Shaft 3rd Gear With Shift Fork Slot Toward 2nd Gear

Next I install the 5th gear flat washer so the face with the chamfer around the hole goes against the splines on the output shaft and the flat face without the chamfer goes against 5th gear.

Output Shaft 5th Gear Washer Chamfered Face Goes Against Splines On Shaft

Output Shaft 5th Gear Washer Chamfered Face Goes Against Splines On Shaft

Output Shaft 5th Gear Washer Flat Face Goes Against 5th Gear

Output Shaft 5th Gear Washer Flat Face Goes Against 5th Gear

Output Shaft 5th Gear Washer Flat Face Points Up

Output Shaft 5th Gear Washer Flat Face Points Up

I slide 5th gear onto the output shaft with the face with the dog teeth facing 3rd gear. I try rocking 5th gear and can feel that there is much less rocking due to the new gear being a tighter fit on the output shaft bushing.

Output Shaft 5th Gear Slides On The Output Shaft

Output Shaft 5th Gear Slides On The Output Shaft

Install Front Ball Bearing Next To 5th Gear

The front ball bearing is larger than the rear. I push it onto the output shaft using the drift for installing the input shaft seal to push the gear onto the shaft with the hydraulic press.

Transmission Tools Input Shaft Seal Drift Used For Driving Output Shaft 5th Gear Bearing

Transmission Tool Input Shaft Seal Drift Used For Driving Output Shaft 5th Gear Bearing

Driving Output Front Bearing Onto Shaft With Hydraulic Press

Driving Output Front Bearing Onto Shaft With Hydraulic Press

When the front ball bearing is pressed on the output shaft, I secure it with the snap ring, shim and locking ring, in that order.

Output Shaft New Shim, Snap Ring and Lock Ring

Output Shaft New Shim, Snap Ring and Lock Ring

Output Shaft 5th Gear Bearing Snap Ring Goes On First

Output Shaft 5th Gear Bearing Snap Ring Goes On First

Output Shaft 5th Gear Bearing Shim Goes Over Snap Ring

Output Shaft 5th Gear Bearing Shim Goes Over Snap Ring

Output Shaft 5th Gear Bearing Lock Ring Fits On Top Of Shim

Output Shaft 5th Gear Bearing Lock Ring Fits On Top Of Shim

Output Shaft 5th Gear Bearing Secured To Shaft

Output Shaft 5th Gear Bearing Secured To Shaft

The lock ring is a tight fit into the groove. I use a flat screw driver blade and tap around the circumference of the lock ring to ensure it is seated in the groove. Then I push on one ear of the lock ring to rotate the lock ring in the groove on the output shaft to verify it is seated correctly.

A visual inspection shows the distance from the top of the lock ring to the end of the output shaft is uniform all the way around.

Verify Output Shaft 5th Gear Bearing Lock Ring Is Uniformly In The Groove

Verify Output Shaft 5th Gear Bearing Lock Ring Is Uniformly In The Groove

Verify Output Shaft 5th Gear Bearing Lock Ring Is Uniformly In The Groove

Verify Output Shaft 5th Gear Bearing Lock Ring Is Uniformly In The Groove

The axial movement of 5th gear has been reduced almost in half to about 0.25 mm and the gear barely rocks on the shaft which is a good thing.

 

Rebuilt Output Shaft Ready To Install In Transmission

Rebuilt Output Shaft Ready To Install In Transmission

Revisions

2023-07-06 Add note from Tom Cutter about how to order the output shaft shim kit.

2 thoughts on “23 BMW 1983 R100RS Rebuild Transmission Output Shaft

  1. Hi. It’s nice to find new information along with your projects. Keep it up! 🙂
    I wonder if you happen to remember or have written down the dimensions of the shim you use together with the lockring and the snapring?
    Regards
    Philippe

    • Philippe,

      No, I don’t have the dimensions. But, if you go to MAX BMW parts fiche, they commonly provide dimensions in the parts description.

      Best.
      Brook.

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