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.

• 23 BMW 1983 R80ST Remove Transmission
• 23 BMW 1983 R80ST Disassemble, Rebuild, Assemble Transmission

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.

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.

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

These are the foot shifter assembly 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.

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.

Protect Frame

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

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.

After I attach the transmission to the engine block I will attach the BROWN–Green 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.

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.

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.

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.

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”.

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.

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.

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

• 23 BMW 1983 R100RS Install Transmission
  • Install Clutch Throw-out Mechanism

Install Speedometer Cable

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

• 23 BMW 1983 R100RS Install Transmission
  • Attach Speedometer Drive Cable

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

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.

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.

• 32 BMW R100RT Install Handlebar Perch Assemblies
  • Adjust Clutch Cable

Install Foot Shift Mechanism

I install the foot shift mechanism.

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.

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.

All Done

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