23 BMW 1983 R80ST Remove Transmission

The transmission on this 1983 R80ST is serial number Z 078854. According to Robert Fleischer’s article on transmissions, the range of transmission serial numbers in 1983 was from Z 074700 to Z 084299, so mine is the original transmission as it is within the range for 1983.

Transmission Serial Number Z 078854

Transmission Serial Number Z 078854

Video

Here is a short video that summarizes how I do this work.

VIDEO: 1983 R80ST Remove Transmission

What To Remove Before Removing The Transmission

In preparation for removing the transmission, I removed the battery and battery box; the swing arm, rear drive and monoshock; and the air box and pulse air components.

Battery Box Removed

Battery Box Removed

Rear Drive, Monoshock & Swing Arm Removed

Rear Drive, Monoshock & Swing Arm Removed

Air Box With Pulse Air And Crankcase Rebreather Components

Air Box With Pulse Air And Crankcase Rebreather Components

Air Box Removed

Air Box Removed

Drain The Transmission Gear Oil

I remove the transmission fill plug and the drain plug. Unfortunately water comes out with a very thick goo of gear lube. The speedometer cable is missing from the bushing on the rear of the transmission. Although some cloth was put in the hole in the bushing, since the bike did sit outside, water got into the transmission through that bushing.

The Speedometer Bushings (Black With White Material Inside) Is To The Right Of The Wrench

The Speedometer Bushing (Black With White Material Inside) Is To The Right Of The Wrench

Transmission Has Water In It :-(

Transmission Has Water In It 🙁

Remove Clutch Throw-out Arm

On the back of the transmission is the throw-out arm that works the clutch. I need to pull the transmission backward off the clutch splines to remove it so I need all the clearance between the transmission and the frame I can get. The clutch throw-out arm on the back of my transmission is caked with hardened gear lube and dirt so I clean it with engine cleaner before I start work. It is likely the seal inside the transmission input shaft (part# 23 12 1 242 522) that is supposed to seal the push rod was leaking.

The Clutch Throw-Out Arm On The Rear Of Transmission Is Filthy With Gear Lube and Dirt

The Clutch Throw-Out Arm On The Rear Of Transmission Is Filthy With Gear Lube and Dirt

Much Cleaner

Much Cleaner

On the 1983 transmission, the throw-out arm is secured with a bolt, nut and washer. It pivots in a boss cast onto the back cover of the transmission.

Clutch Throw-Out Arm Secured By Bolt and Nut Through A Bushing

Clutch Throw-Out Arm Secured By Bolt and Nut Through A Bushing

Clutch Throw-Out Lever Secured By Bolt and Nut Through Bushing

Clutch Throw-Out Arm Secured By Bolt and Nut Through Bushing

Clutch Throw-Out Lever Bolt Has Nut And Wave Washer On The Bottom

Clutch Throw-Out Arm Bolt Has Nut And Wave Washer On The Bottom

I remove the 6 mm bolt, nut and washer to release the clutch throw-out arm from the boss.

Removing Clutch Throw-Out Arm Bolt

Removing Clutch Throw-Out Lever Bolt

Clutch Throw-Out Arm Hardware Detail

Clutch Throw-Out Arm Hardware Detail

An adjusting bolt on the clutch throw-out arm fits into a rubber bellows. The bolt is used to adjust the free play of the clutch lever on the handlebar. The adjusting bolt presses on a bearing assembly that in turn presses on the clutch throw-out rod. The clutch throw-out rod presses on the center of the clutch diaphragm spring to separate the clutch plate from the clutch disk.  I remove the throw-out arm adjusting bolt from the rubber bellows.

Clutch Throw-Out Arm Adjusting Bolt Fits Into Rubber Bellows

Clutch Throw-Out Arm Adjusting Bolt Fits Into Rubber Bellows

Pulling Clutch Throw-Out Arm Adjusting Bolt Out Of Rubber Bellows

Pulling Clutch Throw-Out Arm Adjusting Bolt Out Of Rubber Bellows

Clutch Throw-Out Arm Removed From Rubber Bellows

Clutch Throw-Out Arm Removed From Rubber Bellows

The rubber bellows is secured by a metal strap that I remove. Under the bellows is the clutch return spring. Mine is bent so I will replace it

Clutch Throw-Out Arm Rubber Bellows Secured With Metal Strap

Clutch Throw-Out Arm Rubber Bellows Secured With Metal Strap

Rubber Bellows, Return Spring and Retaining Strap

Rubber Bellows, Return Spring and Retaining Strap

I use a magnet to remove the throw-out bearing cup and the ball bearing race under it. Since the clutch throw-out rod rotates, the bearing allows it to do so with out damage to the stationary throw-out arm.

Magnet Pulling Out Clutch Throw-Out Bearing Cup

Magnet Pulling Out Clutch Throw-Out Bearing Cup

Clutch Throw-Out Ball Bearing Race And Front Cup

Clutch Throw-Out Ball Bearing Race And Front Cup

Remove Transmission Foot Shift Mechanism

The foot shift mechanism consists of an adjustable linkage that attaches to the transmission shift lever and the foot shifter.

Transmission Foot Shifter Adjustable Linkage Attaches To Transmission Shift Lever

Transmission Foot Shifter Adjustable Linkage Attaches To Transmission Shift Lever

The foot shifter is attached to the frame with a pivot bolt.

Transmission Foot Shifter Connects To Other End Of Adjustable Shift Linkage

Transmission Foot Shifter Connects To Other End Of Adjustable Shift Linkage

Transmission Foot Shifter Pivot Bolt

Transmission Foot Shifter Pivot Bolt

The linkage has a cup on each end. The transmission shift lever and the foot shifter have a bolt with a ball on the end. The cup fits over the ball and is retained with a wire clip.

I remove the wire retaining clip from the cup on the transmission shift lever ball with a screw driver. The wire pivots out of it’s groove and then I pull it down out of the small holes drilled into the side of the cup on the linkage.

Removing Cup And Ball Retaining Clip With Screwdriver

Removing Cup And Ball Retaining Clip With Screwdriver

Removing Cup And Ball Retaining Clip

Removing Cup And Ball Retaining Clip

Cup And Ball Retaining Clip

Cup And Ball Retaining Clip

I use a screwdriver to pry the cup off the ball.

Prying Cup Off Ball On Transmission Shift Lever

Prying Cup Off Ball On Transmission Shift Lever

Transmission Foot Shifter Linkage Removed From Transmission Shift Lever

Transmission Foot Shifter Linkage Removed From Transmission Shift Lever

Next I remove the pivot bolt so I can access the other end of the adjustable shift linkage that is attached to the back of the foot shifter.

Transmission Foot Shifter Allen Pivot Bolt

Transmission Foot Shifter Allen Pivot Bolt

Remove Transmission Foot Shifter Pivot Bolt With Allen Socket

Remove Transmission Foot Shifter Pivot Bolt With Allen Socket

Transmission Foot Shifter Pivot Bolt Detail-Note Bushing Inside Foot Shifter Hole

Transmission Foot Shifter Pivot Bolt Detail-Note Bushing Inside Foot Shifter Hole

I remove the other end of the adjustable shift linkage from the back of the foot shifter in the same way I removed the adjustable shift linkage from the transmission shift lever.

Transmission Adjustable Shift Linkage Mounts On Back Of Foot Shifter

Transmission Adjustable Shift Linkage Mounts On Back Of Foot Shifter

Transmission Foot Shift Hardware Detail

Transmission Foot Shift Hardware Detail

Remove Transmission Mounting Bolts

I already removed the upper left bolt and upper right nut when I removed the air box.

I remove the bottom left Allen bolt and wave washer with a cut-down 6 mm Allen wrench as its a tight fit between the bolt and the boss for the transmission shift lever.

Removing Lower Left Transmission Bolt With Cut-Down 6 mm Allen Wrench

Removing Lower Left Transmission Allen Bolt With Cut-Down 6 mm Allen Wrench

Lower Left Transmission Bolt Hardware Detail

Lower Left Transmission Allen Bolt Hardware Detail

The bottom right transmission Allen bolt goes through the engine bell housing and is secured by a nut and wave washer. There is a flat washer under the bolt head

Lower Right Transmission Allen Bolt Extends Through Engine Bell Housing

Lower Right Transmission Allen Bolt Extends Through Engine Bell Housing

Removing Lower Right Transmission Allen Bolt And Nut

Removing Lower Right Transmission Allen Bolt And Nut

Lower Right Transmission Allen Bolt Hardware Detail

Lower Right Transmission Allen Bolt Hardware Detail

Remove Transmission From The Frame

The transmission is loose from the engine. I pull it back and expose the clutch push rod. I push the clutch push rod back into the transmission and pull it out of the back of the transmission. Then I remove the transmission through the left side of the frame.

Transmission Ready To Slide Back And Lift Out Of The Frame

Transmission Ready To Slide Back And Lift Out Of The Frame

Clutch Push Rod Exposed

Clutch Push Rod Exposed

Clutch Push Rod With Front Bearing Cup Rusted To The Rod

Clutch Push Rod With Front Bearing Cup Rusted To The Rod

Transmission Removed

Transmission Removed

The transmission input shaft has splines that mate with splines on the clutch plate. These need to be lubricated with a molybdenum disulfide sticky grease–Honda Moly 60, which is no longer available, or Honda Moly 77–to ensure the splines move smoothly when the clutch engages.

Clutch Assembly On Crankshaft

Clutch Assembly On Crankshaft

Splines On Clutch Disk

Splines On Clutch Disk

Splines On Transmission Input Shaft

Splines On Transmission Input Shaft

Here’s what the bike looks like now. I just have to remove the engine from the frame. To make that a bit easier, I’ll remove the top end of the engine first to reduce the weight.

Transmission Removed

Transmission Removed

Revisions

2022-01-26  Added missing YouTube summary video link.

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