23 BMW 1983 R80ST Install Transmission

After removing the transmission, I disassembled it, had the case and rear cover vapor blasted, rebuilt the shift cam assembly, input, intermediate and output shafts and reassembled the transmission. You can read about that work here.

So, now I’m ready to install it. I also install the clutch throw-out lever assembly, foot shifter assembly, clutch cable and speedometer cable. The installation procedure for the 1983 R80ST is the same as the 1983 R100RS so I will link to parts of that documentation in this document as appropriate.

Tools

There is not enough room for a standard Allen key to fit on the left lower transmission bolt. The boss around the foot shift lever is too close to the bolt head. I cut off a 6 mm Allen key so it will fit on the bolt.

Standard 6 mm Allen Key Is Too Long For Lower Left Transmission Bolt

Standard 6 mm Allen Key Is Too Long For Lower Left Transmission Bolt

Cut-Off 6 mm Allen Key Fits

Cut-Off 6 mm Allen Key Fits

Parts

These are the parts I use. Euro MotoElectrics graciously donated them in support of my goal to auction this bike and send all the proceeds to the Motorcycle Relief Project.

NOTE:
I replaced the handlebars and the new ones have about a 3 inch rise instead of about an 8 inch rise on the original ones. So, I actual used a shorter clutch cable for a low handlebar R65 (part# 32 73 2 324 959) that is 1386 mm long (109 mm shorter) instead of the stock one shown in the table below.

Part #                 Description                                                                Qty
23 13 1 238 422  NEEDLE SLEEVE – 12X18X16, Throw Out Lever 1
23 13 1 241 833  BUSH, Throw Out Lever 1
23 13 1 241 849  SPRING, Throw Out Lever Assembly 1
23 13 1 464 167  PISTON, Throw Out Lever Bearing 1
32 73 1 237 694  CLUTCH CABLE – L=1495MM (See Note Above) 1
23 13 1 241 844  ROD, Throw Out Rod 1
23 13 1 338 731  CUP, Throw Out Lever Assembly 1
23 13 1 241 872  CLAMP – D=40, Throw Out Lever Assembly 1
23 31 1 232 097  BUSHING, Foot Shifter Rubber 1
23 41 1 241 595  SCREW – 33,5 (to 01/84), Foot Shifter Pivot Bolt 1

These are the clutch throw out lever assembly parts.

Clutch Throw Out Arm Parts

The needle bearing and bush in the throw out lever arm were rusted so I replaced them.

Clutch Throw Out Arm Bushing & Needle Bearing

Clutch Throw Out Arm Bushing & Needle Bearing

These are the foot shifter assembly parts.

Transmission Foot Shifter Parts

Transmission Foot Shifter Parts

Video

This is a summary video of how I install the 1983 R80ST transmission.

VIDEO: 1983 BMW R80ST Install Transmission

Prepare Transmission

Before I install the transmission there are some things I need to do to prepare it.

Install Clutch Throw-Out Rod

I install the throw-out rod before I attach the transmission to the engine block. It’s easier to push it gently past the seal in the rear of the input shaft. After I install the push rod, I put a small dab of Moly-60 paste on both ends to lubricate them as the clutch rod spins and one end fits in a hole in the clutch plate and the other end fits into a seal in the front of the combination piston-bearing.

Clutch Push Rod Gets Tiny Dab of Moly-60 On End The Fits In Hole In Clutch Plate And The Combination Piston-Bearing

Clutch Push Rod Gets Tiny Dab of Moly-60 On End The Fits In Hole In Clutch Plate And The Combination Piston-Bearing

End Of Clutch Push Rod That Goes To The Rear Of The Transmission And Fits In The Combination Piston-Bearing

End Of Clutch Push Rod That Goes To The Rear Of The Transmission And Fits In The Combination Piston-Bearing

Insert Clutch Throw-Out Rod Gently Into The Output Shaft From The Front Of The Transmission

Insert Clutch Throw-Out Rod Gently Into The Output Shaft From The Front Of The Transmission

Clutch Throw-Out Rod Installed At Rear Of Transmission In Hole That Holds Combination Piston-Bearing and Return Spring

Clutch Throw-Out Rod Installed At Rear Of Transmission In Hole That Holds Combination Piston-Bearing and Return Spring

Lube Input Shaft Splines & End Of Throw Out Rod

I apply Moly-60 paste to the transmission input shaft splines. I use a toothbrush to apply a light, even coat. I don’t over do the amount of paste applied to the splines as I don’t want it to get thrown off and contaminate the clutch plates. Moly-60 is sticky and stays put when it’s applied as a light coating.

NOTE:
Honda’s Moly-60 paste seems to be no longer available. A suitable replacement is MolyKote M77 paste.

Moly-60 For Lubricating Transmission Input Shaft Splines

Moly-60 For Lubricating Transmission Input Shaft Splines

Use Toothbrush To Apply Moly-60 To Transmission Input Shaft Splines

Use Toothbrush To Apply Moly-60 To Transmission Input Shaft Splines

Transmission Input Shaft Splines with Thin Coat Of Moly-60

Transmission Input Shaft Splines with Thin Coat Of Moly-60

Apply A Dab Of Moly-60 On End Of Transmission Push Rod

Apply A Dab Of Moly-60 On The Front End Of Transmission Push Rod That Fits Into The Clutch Assembly

Dab Of Moly-60 On Rear End Of Clutch Push Rod That Fits Into The Bearing/Piston Assembly

Dab Of Moly-60 On Rear End Of Clutch Push Rod That Fits Into The Bearing/Piston Assembly

Protect Frame

I tape some plastic packing sheets around the frame tubes to protect them from being scratched when I install the transmission.

Foam Padding To Protect Frame

Foam Padding To Protect Frame

Attach Neutral Switch & Oil Pressure Sub-harness

I attach the BROWN and BROWN-Black wires of the sub-harness to the terminals of the neutral switch. Since the switch is on the bottom of the transmission, it’s easier to connect the wires to the switch terminals before I install the transmission in the frame and attach it to the engine block.

Low Oil Pressure Sender & Neutral Switch Sub-harness

Low Oil Pressure Sender & Neutral Switch Sub-harness

Neutral Switch Wires Installed On Neutral Switch Before I Mount The Transmission On The Engine Block

Neutral Switch Wires Installed On Neutral Switch Before I Mount The Transmission On The Engine Block

After I attach the transmission to the engine block I will attach the BROWNGreen wire to the oil pressure sending unit on the left side of the engine block.

Attach Transmission To Engine Block

I used the following hardware to attach the transmission to the engine block. On the 1983 R80ST, the airbox is attached using the transmission top stud and bolt to secure it along with a center bolt that screws into the top of the transmission. So I will mount the airbox at the same time I mount the transmission.

Transmission Mounting Hardware

Transmission Mounting Hardware

Starting from the left, the nut wave washer and thick washer go on the upper right stud in the engine block; the bolt and thick washer go on the top left of the transmission; the second bolt with washer and wave washer goes on the bottom left of the transmission; the long bolt with nut, wave washer and flat washer goes on the bottom right of the transmission; the short bolt with thick washer secures the center of the air box to the top of the transmission.

NOTE:
The MAX parts fiche shows two thick washers (part# 13 72 1 337 205) used on the top transmission bolt and stud to mount the airbox to the transmission; one the outside and one on the inside of the airbox. This is incorrect. Only one thick washer is used on the inside of the airbox.

I carefully maneuver the transmission so I can hang it on the top right engine stud. Then I rotate the transmission input shaft with a finger until the splines on the input shaft line up with the splines on the clutch plate so I can push the transmission input shaft into the splined hole in the clutch plate.

Rotating Input Shaft In Small Increments To Align Splines With Clutch Splines

Rotating Input Shaft In Small Increments To Align Splines With Clutch Splines

I make sure the transmission fits into the bell housing of the engine block and the ears on the front of the transmission slide past the edge of the bell housing so the front of the transmission fits flush with bell housing. Sometimes this takes some wiggling of the transmission to get the ears to slide into the bell housing. I don’t force the ears or hammer on the transmission because I don’t want to damage them.

NOTE:
If you can’t get the transmission to line up correctly to slide into the bell housing it’s likely the clutch plate is off center and you will need to center it. I used a clutch centering tool when I assembled the transmission. If you have to re-center the clutch plate, you can loosen the clutch bolts until you can slide the clutch plate. Then align the clutch plate splines so they mate with the splines on the transmission input shaft. Then move the transmission until you can slide it into the bell housing and it fits flush with housing. Carefully remove the transmission so you don’t disturb the clutch plate and tighten the clutch bolts. Install the output shaft in the clutch splines and the transmission should fit flush with the bell housing.

I install the bottom left bolt and install the ring terminal of the oil pressure and neutral switch sub-harness on the bolt before finger tightening the bolt. Then I install the lower right bolt, flat washer, wave washer and nut and finger tighten the nut. Then I push the transmission into the bell housing to be sure the ears on the sides of the transmission slide into the bell housing. Then I snug up the two lower transmission mounting bolts alternating between them so I pull the bottom of the transmission squarely into the engine bell housing.

Lower Left Transmission Bolt Includes Oil Pressure-Neutral Switch Ground

Lower Left Transmission Bolt Includes Oil Pressure-Neutral Switch Ground

Install Right Bottom Transmission Mounting Bolt, Washers and Nut

Install Right Bottom Transmission Mounting Bolt, Washers and Nut

Cut-Off 6 mm Allen Key Fits On Lower Left Bolt Which Gets Sub-Harness Ground Wire Ring Terminal

Cut-Off 6 mm Allen Key Fits On Lower Left Bolt Which Gets Oil Pressure and Neutral Switch Sub-Harness Ground Wire Ring Terminal

There is a torque for the bolts and top right nut of 15 FT-Lbs, but it’s impossible to get a torque wrench on them, so I use “good  and tight” force on my Allen key to tighten the bolts.

Now I install the airbox on top of the transmission.

Airbox Mounts On Top Of Transmission

Airbox Mounts On Top Of Transmission

I insert the engine breather hose into the large hole on the front of the airbox. Then I hang it off the top left engine stud, install the thick flat washer and nut finger tight, install the top right bolt and the thick flat washer finger tight and then the center bolt and thick flat washer. Then I tighten the nut and two bolts “good and tight”.

Air Box Mounts On Top Of Transmission With Left Bolt & Right Nut-Engine Breather Hose Fits Into Hole Toward Right Side Of Airbox

Air Box Mounts On Top Of Transmission With Left Bolt & Right Nut-Engine Breather Hose Fits Into Hole Toward Right Side Of Airbox

I check the seam between the transmission the bell housing of the engine block to be sure there is no gap. There is a small gap at the very top of the transmission that is past the bell housing mating surface, but that’s how it should be.

Left Side Transmission Seam Is Tight

Left Side Transmission Seam Is Tight

Right Side Transmission Seam Is Tight

Right Side Transmission Seam Is Tight

Install Clutch Throw-Out Lever

Before I install the clutch throw-out lever, I replace the needle bearing and bush since they were rusty. I used a Allen socket to drive out the needle bearing after heating around it with a heat gun.

Rusted Clutch Throw Out Arm Bushing & Needle Bearing Removed

Rusted Clutch Throw Out Arm Bushing & Needle Bearing Removed

Allen Socket Used To Drive Needle Bearing Out Of Heated Clutch Throw Out Arm

Allen Socket Used To Drive Needle Bearing Out Of Heated Clutch Throw Out Arm

I show how to install the clutch throw-out lever assembly in the 1983 R100RS document. Here is the link.

Install Speedometer Cable

I show how to install the speedometer cable in the 1983 R100RS document. Here is the link.

Here is how I routed the speedometer cable on the 1983 R80ST.

R80ST Speedometer Cable Routing

R80ST Speedometer Cable Routing

R80ST Speedometer Cable Routing

R80ST Speedometer Cable Routing

R80ST Speedometer Cable Routing

R80ST Speedometer Cable Routing

R80ST Speedometer Cable Routing

R80ST Speedometer Cable Routing

R80ST Speedometer Cable Routing

R80ST Speedometer Cable Routing

Install Clutch Cable

I install the clutch cable starting at the left clutch lever. I insert the end of the cable into the barrel that fits into the hole in bottom of the clutch lever. I lubricated the barrel with a little Gun Snot, that Tom Cutter supplies. Here is how I route the clutch cable.

Clutch Cable Barrel Installed In Bottom Of Clutch Lever

Clutch Cable Barrel Installed In Bottom Of Clutch Lever

Clutch Cable Routing

Clutch Cable Routing

Clutch Cable Routing

Clutch Cable Routing

Clutch Cable Routing

Clutch Cable Routing

Clutch Cable Routing

Clutch Cable Routing

Clutch Cable Routing

Clutch Cable Routing

Adjust Clutch Cable

I show how I adjust the clutch in the document showing how I install the handlebar perches, switches and cables on the 1983 R100RS.

Install Foot Shift Mechanism

I install the foot shift mechanism.

Transmission Foot Shifter Parts-Top to Bottom: Foot Shift Lever, Rubber, Pivot Bolt, Shift Linkage Retaining Pins, Shift Linkage

Transmission Foot Shifter Parts-Top to Bottom: Foot Shift Lever, ,Foot Rubber, Pivot Bolt, Shift Linkage Retaining Pins, Foot Shift Linkage

The pivot bolt screws into a tapped hole on the lower left frame tube. I apply some wheel bearing grease to the shank of the pivot bolt to lubricate it and apply some blue loctite to the threads of the pivot bolt so it won’t vibrate loose.

NOTE:
The MAX parts fiche shows two rubber O-rings: one under the pivot bolt head and the other next to the bushing in the frame. These just squeezed out when I tightened the pivot bolt. After 01/1984 there is a change in the design of the bushing inside the shift lever so it is shorter. I suspect the rubber O-rings only work with that later version. I removed them and used a flat washer against the bushing in the frame. It seems to work fine.

Install Foot Shift In Tapped Hole In Frame

Install Foot Shift In Tapped Hole In Frame

Screw In Foot Shifter Pivot Bolt

Screw In Foot Shifter Pivot Bolt

The foot shifter linkage attaches to the ball on the end of the transmission shift lever and a second ball on the back side of the foot shift lever. I put some grease in the cups of the linkage. It is secured onto each ball with a wire bale that fits into a small hole on the side of the cup and then swings around to fit in a groove beneath the cup.

Install Foot Shift Linkage

Install Foot Shift Linkage

All Done

Here is what I started with and here is the refinished, rebuilt and installed transmission.

Transmission Condition As I Found It

Transmission Condition As I Found It

Transmission Condition As I Found It

Transmission Condition As I Found It

Transmission Installed

Transmission Installed

Transmission Installed

Transmission Installed

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