23 BMW 1983 R100RS Rebuild Transmission Input & Intermediate Shafts

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, output shaft 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

Modified M8 Allen Bolt

I modified an M8x50 Allen bolt to use as a drift for removing the input shaft top hat that the rear ball bearing runs on. I use a Dremel tool cut-off wheel to remove the threaded portion of the bolt leaving the unthreaded shank. It fits through the clutch rod seal that is install in the input shaft top hat so I can press the top hat off the input shaft.

Modified M8x50 Allen Bolt With Threads Cut Off To Use As A Drift

Modified M8x50 Allen Bolt With Threads Cut Off To Use As A Drift

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

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 21 1 235 449 CYLINDRICAL ROLLER BEARING,RADIAL – 47X38X26, Input Front 1
23 12 1 231 495 GROOVED BALL BEARING – 52X20X15, Input Rear, Intermediate Front 2
23 12 1 233 808 GROOVED BALL BEARING – 20X52X15, Intermediate Rear (With Cover) 1
07 11 9 933 516 SNAP RING – A20, Input Shaft 1
23 12 1 242 522 SHAFT SEAL – 8X14X4 (from 09/80), Input Shaft Clutch Push Rod Seal 1

NOTE:
BMW’s parts fiche is incorrect about the location of the intermediate shaft ball bearing (part# 23 12 1 233 808) that has a cover on one side. The bearing size is a C3 class, 52 x 20 x 15 size. The fiche shows this bearing used for the front intermediate shaft bearing when it is actually used for the rear intermediate shaft bearing (next to 1st gear).

The fiche also shows this bearing being used for the rear input shaft ball bearing, but that bearing does not have a cover and is actually part# 23 12 1 231 495. This bearing is also a C3 class, 52 x 30 x 15 size.

Video

Here is a video that summarizes the procedure for doing this work.

VIDEO: 1983 BMW R100RS Rebuild Transmission Input & Intermediate Shafts

Initial Inspection

This is the input shaft before I disassemble it.

Input Shaft Before Disassembly

Input Shaft Before Disassembly

Starting on the left is the rear ball bearing and baffle plate, the torsion shock spring collar, spring and lower yoke, the helical input gear and the inner race of the front roller bearing. I remove all these parts from the input shaft.

Before I start I look at the input gear to see which version it is. The earlier 5-speed transmissions used a helical gear with 15 degree helix. Later transmissions used a 17.5 degree helix. BMW marks the part with an “X” if it is a 17.5 degree helix and my input gear has the “X” so it’s the later version of the gear. Since the input gear meshes with the helical 5th gear on the intermediate shaft which meshes with helical 5th gear on the output shaft, all three helical gears mush have the same helix.

Input Gear with "X" Denoting 17.5 Degree Helix

Input Gear with “X” Denoting 17.5 Degree Helix

This input shaft uses a small seal inside the rear ball bearing shaft to seal the clutch push rod. The clutch push rod fits inside a hole in the input shaft and engages the clutch diaphragm spring to disengage the clutch and engine from the transmission input shaft. I have a new seal to replace it.

Location of Input Shaft Clutch Rod Seal Inside Rear Ball Bearing Shaft

Location of Input Shaft Clutch Rod Seal Inside Rear Ball Bearing Shaft

Input Shaft Clutch Rod Seal

Input Shaft Clutch Rod Seal

New Input Shaft Clutch Rod Seal

New Input Shaft Clutch Rod Seal

Disassemble Input Shaft

I replace the two input shaft bearings; the front roller bearing and the rear ball bearing. I replace the small clutch push rod seal inside the rear ball bearing shaft and the snap ring that secures the collar on the torsion shock load spring.

Remove Rear Ball Bearing

I start by removing the input shaft rear ball bearing. I slide the transmission tool that fits around the outer race so the shoulder inside it fits against the race.

Transmission Tool Sleeve Slides Up The Input Shaft

Transmission Tool Sleeve Slides Up The Input Shaft

Transmission Tool Sleeve Installed On Input Shaft Rear Bearing

Transmission Tool Sleeve Installed On Input Shaft Rear Bearing

I place the transmission tool on the press plates to support it.

Tool And Input Shaft Rear Bearing Supported By Hydraulic Press Plates

Transmission Tool With Input Shaft Rear Bearing Supported On Hydraulic Press Plates

I use a socket that fits on the shaft and is small enough to slide through the bearing and a drift to press the shaft out of the bearing using the hydraulic press.

Use Transmission Tool Drift and Socket To Drive Shaft Out Of The Input Shaft Rear Bearing

Use Transmission Tool Drift and Socket To Drive Shaft Out Of The Input Shaft Rear Bearing

When the bearing is removed, the “top hat” that is pressed onto the end of the input shaft is exposed along with a baffle plate.

Input Shaft Rear Bearing Baffle Plate Fits On Top Hat and Under Bearing

Input Shaft Rear Bearing Baffle Plate Fits On Top Hat and Under Bearing

Input Shaft Rear Bearing & Baffle Plate Removed Exposing "Top Hat"

Input Shaft Rear Bearing & Baffle Plate Removed Exposing “Top Hat”

Remove Torsion Shock Load Spring Collar & Snap Ring

I use the transmission tool spring compressor sleeve to push the torsion shock spring down to expose the snap ring so I can remove the snap ring.

Torsion Shock Spring Collar Retaining Ring Fits In Groove In Collar and Input Shaft

Torsion Shock Spring Collar Snap Ring Fits In Groove In Collar and Input Shaft

Install Transmission Tool Torsion Shock Spring Compression Sleeve

Install Transmission Tool Torsion Shock Spring Compression Sleeve

Torsion Shock Spring Collar Compressed To Expose Snap Ring

Torsion Shock Spring Collar Compressed To Expose Snap Ring

I use a couple screw drivers to pry the spring out of the groove in the input shaft and push it up the shaft. Then I release the hydraulic press to let the torsion shock spring and collar move up the input shaft.

Use Screw Drivers To Push Snap Ring Out Of Groove In Input Shaft

Use Screw Drivers To Push Snap Ring Out Of Groove In Input Shaft

Spring Collar Retaining Ring Moved Up The Input Shaft

Spring Collar Retaining Ring Moved Up The Input Shaft

Remove Top Hat

To remove the input gear, yoke, spring, spring collar and snap ring, I remove the top hat. I use a bearing splitter and a modified M8x50 Allen bolt as a drift.

I push the snap ring all the way up the input shaft past the groove at the top of the shaft so it’s resting against the shoulder of the top hat. I don’t want the snap ring to engage in the groove when I press the top hat off the shaft.

Input Shaft Spring Collar Snap Ring Pushed Past Groove At Top Of The Shaft Against The Shoulder Of the Top Hat

Input Shaft Spring Collar Snap Ring Pushed Past Groove At Top Of The Shaft Against The Shoulder Of the Top Hat

I use the spring retaining collar to support the top hat as I push the input shaft out of the top hat. I install the bearing splitter with the flat face against the shoulder of the spring retaining collar.

Torsion Shock Spring Retaining Collar Pushed Against Top Hat Shoulder

Torsion Shock Spring Retaining Collar Pushed Against Top Hat Shoulder

Flat Face Of Bearing Splitter Installed Under Shoulder Of Spring Retaining Collar

Flat Face Of Bearing Splitter Installed Under Shoulder Of Spring Retaining Collar

I cut the threads off the M8x50 bolt with my Dremel cut-off wheel. I can slide the shank through the seal so the end of the bolt butts up against the input shaft. I use an Allen socket with an extension mounted in the Allen bolt for the anvil of the hydraulic press to push against.

M8 Allen Bolt Head Will Pass Though The Hole In The Top Hat

M8 Allen Bolt Head Will Pass Though The Hole In The Top Hat

Use An M8x50 Allen Bolt With Threads Cut Off As Drift

Use An M8x50 Allen Bolt With Threads Cut Off As Drift

M8 Bolt Fits Inside Input Shaft Clutch Push Rod Seal

M8 Bolt Fits Inside Input Shaft Clutch Push Rod Seal

Input Shaft Drift Assembly For Removing Top Hat-M8 Allen, Socket & Extension

Input Shaft Drift Assembly For Removing Top Hat-M8 Allen, Socket & Extension

I mount the input shaft with the bearing splitter resting on the plates of the hydraulic press. I carefully center the M8 Allen bolt head on the face of the seal and make sure the edge of the bolt is not going to contact the top hat. I center the socket extension under the anvil and press the input shaft off the top hat.

Ready To Drive Top Hat Off Input Shaft-Make Sure Edge Of Allen Bolt Will Clear The Edge Of Top Hat Hole

Ready To Drive Top Hat Off Input Shaft-Make Sure Edge Of Allen Bolt Will Clear The Edge Of Top Hat Hole

As the input shaft is pushed out of the top hat, the seal is pushed down the top hat but not all the way out. This destroys the seal, but there is no way to save it when you remove the top hat. To completely remove the seal, I put the brim of the top hat on the jaws of my vice and tap it out with a hammer using the Allen Socket attached to the M8 bolt.

After I remove the top hat, I can remove the torsion shock spring collar, the spring, the yoke and the input helical bearing off the input shaft.

Torsion Shock Spring Collar Removed

Torsion Shock Spring Collar Removed

Torsion Shock Spring Removed

Torsion Shock Spring Removed

Yoke Removed

Yoke Removed

Input Gear Removed

Input Gear Removed

Here are the input shaft parts removed except for the roller bearing inner race which I remove next.

Input Shaft Disassembled Except For Roller Bearing Inner Race

Input Shaft Disassembled Except For Roller Bearing Inner Race

Remove Roller Bearing Inner Race

I use the transmission tool long sleeve to push the inner bearing race off the shaft. The inside of the sleeve is sized to just fit over the splines on the input shaft without damaging them and butt against the tapered end of the inner roller bearing race.

Transmission Tool Long Drift Removes Input Shaft Roller Bearing Inner Race

Transmission Tool Long Drift Removes Input Shaft Roller Bearing Inner Race

Transmission Tool Long Drift Slide Over Splines

Transmission Tool Long Drift Slide Over Splines

I put the spline end of the shaft on a press plate and push the long sleeve down the input shaft with the anvil of the hydraulic press until the inner race is pushed down past the shoulder onto the narrower part of the shaft the input gear spins on.

Orientation To Push Roller Bearing Inner Race Off Input Shaft

Orientation To Push Roller Bearing Inner Race Off Input Shaft

Input Shaft Parts Inspection

I inspect the parts looking for damage. I use a wire wheel to clean the input shaft splines so I can inspect them. They are not chipped, cracked or worn down. The shaft splines are not chipped or damaged. There is some discoloration where the top hat mounts on the ball bearing end of the shaft and I’ll polish that to remove it.

Input Shaft Splines Cleaned with Soft Wire Wheel Show No Damage

Input Shaft Splines Cleaned with Soft Wire Wheel Show No Damage

Input Shaft Splines Don't Look Worn

Input Shaft Splines Don’t Look Worn

Input Shaft Splines Don't Show Signs Of Damage Or Excessive Wear

Input Shaft Splines Don’t Show Signs Of Damage Or Excessive Wear

Input Shaft Splines Are In Good Condition

Input Shaft Splines Are In Good Condition

Ball Bearing "Top Hat" End Of Shaft Is A Bit Discolored

Ball Bearing “Top Hat” End Of Shaft Is A Bit Discolored

The input gear teeth are not chipped or damaged and the saddle does not show signs of abuse although there is one small nick in the edge and there are is only minor wear on the saddle that mates with the yoke.

Input Gear Teeth Are Not Chipped Or Cracked-Note "X" Indicating 17.5 Degree Helix

Input Gear Teeth Are Not Chipped Or Cracked-Note “X” Indicating 17.5 Degree Helix

Input Gear Saddle Has One Small Chip

Input Gear Saddle Has One Small Chip

The edges of the yoke are not chipped or cracked. There is wear on the peaks of the yoke but it’s not significant.

Input Shaft Yoke Edges Are Not Chipped or Cracked

Input Shaft Yoke Edges Are Not Chipped or Cracked

Input Shaft Yoke Edges Are Not Chipped or Cracked

Input Shaft Yoke Edges Are Not Chipped or Cracked

The spring does not show damage but the spring collar has some rust spots that I’ll clean.

Input Shaft Torsion Shock Spring Is In Good Condition

Input Shaft Torsion Shock Spring Is In Good Condition

Input Shaft Torsion Shock Spring Collar Has A Bit Of Rust

Input Shaft Torsion Shock Spring Collar Has A Bit Of Rust

Input Shaft Torsion Shock Spring Collar Has A Bit Of Rust

Input Shaft Torsion Shock Spring Collar Has A Bit Of Rust

Here is the torsion shock spring collar and the ball bearing baffle after I cleaned and polished them.

Input Shaft Torsion Shock Spring Collar & Ball Bearing Baffle Plate After Cleaning and Polishing

Input Shaft Torsion Shock Spring Collar & Ball Bearing Baffle Plate After Cleaning and Polishing

I shared these pictures with an experienced mechanic and his conclusion is the input shaft is in good condition. I only need to replace the bearings, and the top hat I broke.

Assemble Input Shaft

Here are all the input shaft parts. Input Shaft Parts Ready For Assembly

I replaced the front roller bearing, the torque shock spring collar snap ring, the top hat I broke, the clutch push rod seal that goes inside the top hat and the rear ball bearing. I wire brushed the input shaft splines and the torsion shock spring collar to clean them. I used AutoSol metal polish to remove all the discoloration on the roller bearing bushing, input gear bushing, top hat bushing, the torsion shock spring collar and the ball bearing baffle plate. A clean transmission is a happy transmission.

Install New Clutch Push Rod Seal In Top Hat

I use an M8 Allen bolt to push the seal into the top hat. I support the top hat in the jaws of my vice, but I don’t clamp it as I don’t want to scratch or score the outside of the top hat that the roller bearing inner race spins on.

Use Vice Jaws To Support Top Hat But Not Clamp It

Use Vice Jaws To Support Top Hat But Not Clamp It

I heat the top hat with a heat gun to expand it a bit to make it easier to start the seal.

Heating Top Hat With Heat Gun

Heating Top Hat With Heat Gun

I start the seal using a plastic mallet to get it square in the hole. Then I invert the M8 Allen bolt so the head is on the front face of the seal to drive it into the top hat. I stop with the inside edge of the seal is just exposed on the other end of the top hat.

 

Driving Clutch Push Rod Seal Into Top Hat Using Inverted M8 Allen Bolt

Driving Clutch Push Rod Seal Into Top Hat Using Inverted M8 Allen Bolt

Clutch Push Rod Seal Installed in Input Shaft Top Hat

Clutch Push Rod Seal Installed in Input Shaft Top Hat

Install Roller Bearing Inner Race

NOTE:
In setting up for several of the pictures below, I oriented the roller bearing inner race backwards on the input shaft. I note that mistake in the pictures below. The race has a collar and a chamfered end. The chamfered end goes against the splines as shown in the picture below.

Correct Orientation Of Roller Bearing Inner Race On Input Shaft

Correct Orientation Of Roller Bearing Inner Race On Input Shaft

I use the input gear and the yoke to drive the roller bearing inner race onto the input shaft. The yoke has a shoulder that I insert into the flat face of the bearing splitter so I can use the hydraulic press to push the input shaft down through the inner race until the edge of the race butts up against the edge of the splines.

Using Input Shaft Gear & Yoke To Push Roller Bearing Inner Race On Shaft

Using Input Shaft Gear & Yoke To Push Roller Bearing Inner Race On Shaft

NOTE:
In the picture above and the one below, I show the inner roller bearing race backwards on the shaft. One end of the race has a collar and the other end has a chamfer. The chamfered end goes against the end of the splines.

I put some 3-in-One oil on the input shaft busing to help the inner race slide into place as its a very tight fit on the shaft.

Light Oil To Aid Pushing Roller Bearing Roller Bearing Inner Race On Shaft

Light Oil To Aid Pushing Roller Bearing Roller Bearing Inner Race On Shaft

I put a flat washer on the end of the splines so the anvil of the hydraulic press doesn’t damage them.

NOTE:
The two pictures below were taken after I pressed the roller bearing inner race on the input shaft. You can see the chamfered end of the race is against the splines and the shoulder is against the input gear.

Flat Washer To Protect Input Shaft Splines

Flat Washer To Protect Input Shaft Splines

Flat Washer To Protect Input Shaft Splines

Flat Washer To Protect Input Shaft Splines

Then I install the assembly on the plates of the hydraulic press and press the shaft through the roller bearing inner race until it’s flush with ends of the splines.

NOTE:
The picture below also shows the inner race backwards on the input shaft. The collar of the inner race should be on the bottom and the chamfered end of the race on top. I staged the picture, but didn’t notice the error. I pressed the race on correctly as shown below.

Ready To Press Input Shaft Roller Bearing Inner Race On Shaft-Note Flat Washer On Top Of Splines To Protect Them

Ready To Press Input Shaft Roller Bearing Inner Race On Shaft-Note Flat Washer On Top Of Splines To Protect Them

NOTE:
The picture below proves I oriented the inner race correctly when I pressed it onto the input shaft 🙂

Input Shaft Roller Bearing Inner Race Installed Flush With Splines

Input Shaft Roller Bearing Inner Race Chamfered End Installed Flush With Splines

Assemble Input Gear, Yoke, Spring, Spring Collar and Snap Ring

Now I can slide the input gear, yoke, spring and spring retaining collar on the input shaft.

Input Shaft Parts Order That Hold The Input Gear and Torsion Shock Spring Components On The Input Shaft

Input Shaft Parts Order That Hold The Input Gear and Torsion Shock Spring Components On The Input Shaft

I push the ring onto the shaft using my snap ring pliers to get it started and then walk it down the shaft with two screw drivers.

Ready To Push Input Shaft Torsion Spring Collar Snap Ring Onto The Input Shaft

Ready To Push Input Shaft Torsion Spring Collar Snap Ring Onto The Input Shaft

Input Shaft Torsion Spring Collar Retaining Ring Pushed On Shaft

Input Shaft Torsion Spring Collar Retaining Ring Pushed On Shaft

I put the transmission tool on and compress the spring collar until the groove in the output shaft is exposed. I walk the snap ring all the way down the input shaft until it slides into the groove in the shaft.

Transmission Tool To Compress Input Shaft Torsion Shock Spring And Collar

Transmission Tool To Compress Input Shaft Torsion Shock Spring And Collar

How Tool Fits On Spring Collar

How Tool Fits On Spring Collar

Ready To Compress Input Shaft Torsion Shock Spring And Collar

Ready To Compress Input Shaft Torsion Shock Spring And Collar

Use Screwdriver To Work Snap Ring Down Input Shaft Into Groove

Use Screwdriver To Work Snap Ring Down Input Shaft Into Groove

Snap Ring Seated In Input Shaft Groove

Snap Ring Seated In Input Shaft Groove

The snap ring has to compress until the ends are closed. Here is my first try when I just pushed down on the snap ring while releasing the pressure on the hydraulic press. I didn’t get the ends to compress completely. This is NOT how the snap ring should look when installed.

Input Shaft Torsion Shock Load Spring Retaining Ring INCORRECTLY Installed-Ring Is Proud Of Collar and Ring Ends Don't Touch

Input Shaft Torsion Shock Load Spring Retaining Ring INCORRECTLY Installed-Ring Is Proud Of Collar and Ring Ends Don’t Touch

To do that I use two flat blade screwdrivers on either side of the ends of the snap ring and wedge them against the side of the window of the transmission tool to leverage the ends of the spring closed. While holding them with one hand, I release the pressure on the hydraulic press so the spring will slide the collar up and capture the spring. If it’s installed correctly, the top of the spring is flush with the top of the collar.

Use Two Screwdrivers To Compress Snap Ring Until Ends Close

Use Two Screwdrivers To Compress Snap Ring Until Ends Close

This is what I got the second time. The ends of the snap ring are closed, but the ring is not seated correctly in the groove and its proud of the spring collar.

Input Shaft Torsion Shock Load Spring Retaining Ring INCORRECTLY Installed: Ends Meet But Snap Ring Is Proud Of Spring Collar

Input Shaft Torsion Shock Load Spring Retaining Ring INCORRECTLY Installed: Ends Meet But Snap Ring Is Proud Of Spring Collar

So I tried again. This is what success looks like. The top of the snap ring is slightly below the top of the spring collar.

Spring Collar Retaining Ring

Install Top Hat, Ball Bearing Baffle and Rear Ball Bearing

I press the top hat onto the shaft using one of the transmission tool drifts to press the collar onto the shaft. It’s a tight fit.

Input Shaft Roller Bearing Collar Fits On End Of Input Shaft With The Collar's Shoulder At Bottom

Input Shaft Roller Bearing Collar Fits On End Of Input Shaft With The Collar’s Shoulder At Bottom

Using Input Shaft Seal Inner Drift To Press Ball Bearing Collar On Shaft

Using Input Shaft Seal Inner Drift To Press Ball Bearing Collar On Shaft

Pressing Top Hat On Input Shaft

Pressing Top Hat On Input Shaft

I put the baffle plate on the top hat so the side with the ridge in the center points toward the face of the ball bearing. I press the ball bearing onto the shaft using a transmission tool drift that clears the shaft.

Orientation Of Input Shaft Rear Ball Bearing Baffle-Raised Shoulder Around Shaft Faces Bearing

Orientation Of Input Shaft Rear Ball Bearing Baffle-Raised Shoulder Around Shaft Faces Bearing

Use Input Shaft Seal Outer Race To Press Rear Ball Bearing On Input Shaft

Use Input Shaft Seal Outer Race To Press Rear Ball Bearing On Input Shaft

Input Shaft Rear Ball Bearing Pressed On

Input Shaft Rear Ball Bearing Pressed On

Input Shaft Rear Ball Bearing Baffle Plate

Input Shaft Rear Ball Bearing Baffle Plate

This is how the clutch push rod fits through the input shaft and the seal inside the top hat on the rear of the input shaft.

Clutch Push Rod Goes Through The Input Shaft and Seal In Top Hat

Clutch Push Rod Goes Through The Input Shaft and Seal In Top Hat

Replace Intermediate Shaft Bearings

There are no replaceable parts on the intermediate shaft. BMW only sold the entire shaft which is no longer available. So I only need to replace the two ball bearings on the ends of the shaft. The front ball bearing is the same size as the rear ball bearing on the input shaft. The intermediate shaft rear ball bearing is the same size as the front, but has a plastic cover on one side of the ball bearings. This cover faces you when you install the bearing onto the intermediate shaft.

I inspected the condition of the intermediate shaft before I removed the two ball bearings.

Inspect Intermediate Shaft

After I removed the intermediate shaft from the transmission I inspected the gears and the bearings for abuse and excessive wear.

The teeth of 5th gear were not worn, chipped or cracked.

There were no signs of damage to shift the dogs that engage 3rd gear on 2nd gear nor the slots they engage with on 3rd gear on the intermediate shaft. The dogs on 2nd gear and the slots they engage with on 4th gear also show no signs of damage.

There are some helical wear patterns on the faces of the gear teeth on 4th gear.

There is some scuffing and some discoloration on the outside of the rear bearing but none on the front bearing.

When I shared the pictures with an expert mechanic for his opinion on the condition of the intermediate shaft, the verdict was the shaft and gears are quite serviceable.

Remove Ball Bearings

Before I remove the ball bearings, I measure the distance between the ball bearing outer races from the outside face of the bearings. I will check that distance when I reinstall the bearings and they should be very close to the same distance.

I use the bearing splitter with the flat face of the splitter under the bearing and tighten the nuts on the bolts tightly to force the blade between the gear face and the bearing. However, I verify that the blade is not touching the gear teeth before I tighten the bolts as I don’t want to damage the gear teeth.

Bearing Splitter Installed On Intermediate Shaft Ball Bearing

Bearing Splitter Installed On Intermediate Shaft Ball Bearing

Ready To Press Intermediate Shaft Ball Bearing Off The Shaft

Ready To Press Intermediate Shaft Ball Bearing Off The Shaft

I put the intermediate shaft between two puller plates with the bearing splitter sitting on the plates. I use the drift for installing the gear change seal to push the input shaft out of the bearing with the hydraulic press.

Pressing Intermediate Shaft Through The Ball Bearing

Pressing Intermediate Shaft Through The Ball Bearing

Intermediate Shaft Front Bearing Removed

Intermediate Shaft Front Bearing Removed

Install Ball Bearings

When I get the old bearing off, I press the new one on the shaft using a transmission tool drift.

Intermediate Shaft New Front Roller Bearing Installed

Intermediate Shaft New Front Roller Bearing (Next to Helical 5th Gear) Installed

Intermediate Shaft New Rear Roller Bearing (Next To 1st Gear) with Cover Installed

Intermediate Shaft New Rear Roller Bearing (Next To 1st Gear) with Cover Installed

After I installed the two new bearings I measured the outside distance between the outer races of the two ball bearings. I got 146.25 mm before disassembly and 146.26 mm after installing the new bearings. That leads me to believe that the bearings are correctly installed on the intermediate shaft.

 

 

 

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