Airhead Tech Pages


I Be Doin' Dat Pawl Spring Thang..., part 1

(or how to open a transmission on an R65LS)
by Dave Thompson (davet@spyglass.com)

After about 4,000 miles and four months of riding my '82 R65LS, I was sitting at a stop light waiting for the green. I took off from the stop light and then shifted into second gear. A moment later, pulled in the clutch, shifted to third but it wouldn't go. Tried again and I was still in second. Down shifting didn't work either. stuck in second...

I posted a note on the net and got back 6 unanimous replies that my pawl spring in my transmission had broken. The part costs about $1, but I've heard estimates of $200 to $600 for labor. Being about 2 hours away from my local dealer and no way to get it there except by riding it all the way in 2nd, I took this as an excellent educational opportunity!

Both Haynes and Clymer describe how to remove the tranny by moving the engine forward in the frame. This requires removing the exhaust system which I didn't really want to do because 1) I don't have an exhaust wrench and 2) I have this fear that my exhaust nuts are so corroded on there that removing them might damage my pipes. Don Eilenberger gave me the idea that I could remove the tranny by removing the swingarm instead and leave the engine in place. I opted for the swingarm method.

  1. removed the gas tank. I noticed that the harness is chaffing in one spot. The electrical tape that is wrapped around the harness had worn away. The wires were fine. I wrapped more tape onto the harness in that area. The harness isn't as well secured to the frame as my R100GS's is. I'll have to strap it down.
  2. removed the battery and case.
  3. removed the left and right carburetor. The rubber tubes leading to the head intake on mine were cracking, so I'll probably take the opportunity to replace them. Also, I noticed that the lower throttle cables are not looking to healthy and should be replaced. I ordered two of these.
  4. removed the air box. There are three bolts that hold this box to the transmission. The left and center bolts are easy to get to. On the right side is a nut that needs to be removed. To get at, one must first remove one of the pure air intake devices. This requires a 24mm wrench.
  5. removed the speedometer cable and ground cable.
  6. removed the clutch lever. Be sure to remove the rubber boot. It contains a spring that holds the clutch pushrod. I didn't and found it more difficult to remove the transmission due to the rod getting in the way while trying to remove it from the frame.
  7. disconnected the shifter rod from the transmission.
  8. removed the left foot peg so that it wouldn't get in the way when removing the transmission.
  9. loosened the forward portion of the drive shaft boot, and slid it back. There are four 12 point bolts that connect the driveshaft to the transmission. These bolts are use once, so once they are removed, they will have to be replaced with new ones.
  10. removed the rear brake lever and rod. This is necessary when removing the swing arm. I actually just disconnected it from the frame, and brake drum lever with out removing. This gave me enough room to pull out the swing arm.
  11. removed the rear wheel.
  12. support the swingarm and then remove the left and right shock. remove the left shock first, then remove the top bolt of the right shock. Slide the top of the right shock out and lift the final drive. This way the lower right bolt will clear the exhaust pipe and the right shock may be removed with the exhaust in place.
  13. to remove the swing arm, one needs a 27mm socket. Not being a common socket, I had to look around. I found one at Sears. However, a 1 1/16 socket just happens to be 26.99mm. You'll likely need to grind the outside edges of the socket. For me, on the right side of the bike, the socket fit snug. For the left side, I needed to grind down the socket. I went to the store (menards) and picked up a nice 1/2 HP no name Chinese built grinder for $32. I cleaned and then repacked my swingarm with that new anticorrosive BMW #10 general purpose red grease. The R65LS has sealed bearings, and so I didn't need an oil seal.
  14. There are three bolts and one nut that hold the transmission to the engine. One of the bolts and the nut are removed when the the air box is taken off. The other two are located on each side near the base of the transmission. The lower left bolt also holds a grounding wire for something in place. I removed the remaining two bolts.
  15. There are two connectors to the neutral switch located at the bottom center of the transmission. I disconnected these as I pulled out the tranny.
  16. patted myself on the back.
  17. I checked out the inner clutch splines that everyone has been in fear of not having enough lubricant... My '82 R65LS with 20k miles still had some grease on the clutch splines, but not much. I put some BMW #10 lube, which is what BMW is recommending now over the Staburags 30 PTM, on the clutch splines and clutch pushrod pressure point where it contact the pressure plate. I also put a light coating on the flywheel splines since those were dry. Fortunately all of the splines looked fine. I don't think these splines have ever been lubed during that last 12 years this bike has been in use. I think the once a year lube job that clymer recommends may be a bit overkill.

Opening the tranny...


To open the transmission, you'll need an output flange holder/extractor. Clymer lists this tool as #234 and #232 which doesn't seem to have much meaning to the rest of the world. BMW lists this tool set as 88 88 6 231 700. It has a price tag of $128.83 to $143.15 depending where one shops. I couldn't see spending this kind of money for a one shot deal. I improvised using some suggestions in the Haynes manual. I picked up a flat metal rod from the hardware store. I drilled two holes and used my new grinder to grind a small area that would fit around a 24mm socket. I bolted my new tool (output flange holder) to the output flange. Then using a 24mm socket wrench (breaker bar) with an extender I undid the output flange holder nut. It took a couple taps with a hammer. The nut is held on there at 200-220Nm!

For the output flange extractor, I borrowed from a friend a harmonic balancer steering wheel puller which can be picked up at most auto parts stores (or Sears) for $20. I had to pick up 2 8mm x ~3inch fine threaded bolts to attach the puller to the output flange. Using this tool, one can pull on two of the four output flange holes at once. Last week, someone posted a note saying they screwed up their output flange using only two holes. Others + the Haynes manual said it could be done. This person said that he had to buy a rebuild that was pretty costly to fix his problem. I've priced how expensive a screw up is, and actually consider the cost/risk factor cheaper than buying the special tool. A new output flange is about $90. If the output shaft were damaged, which I'm not sure how this could easily happen, it would set me back about $150 for a new one. Determined to be an other, I let the output flange soak in liquid wrench for 36 hours. With the help of a friend (Terry Mclaren), Here is the repetitive process we followed:

  1. Insert the 8mm bolts into the output flange counting the threads so that each 8mm bolt will have equal amounts of tension.
  2. While Terry held the flange from spinning, I tightened the puller with a wrench until it slipped from his gloved hands.
  3. Then I gave a sharp couple taps on the puller with a hammer to help loosen the flange.
  4. We attempted to turn it again. If it didn't turn, we took the puller off and put it on the other two bolts repeating the process from step 1.

We repeated the whole process about 4 times. On the fourth time when we tapped on the puller with the hammer, the output flange came free. Just like the manual had said, "When the output flange releases, there is a loud crack like metal breaking. This is normal." I'm glad I had read that. It's a bit of a shocker when it finally breaks free.

There are nine alan screws that hold the cover into place. After removing them I bopped the cover a couple times with my rubber mallet hoping I would get lucky and the cover would just pop off. no such luck. The repair manuals say it may need to be heated to 80-100 Celcius. The two methods I've heard to remove the cover are to bake it in the oven, or use boiling water. I opted for baking. There was a note on the net from someone concerned about leaving the oven smelling like hypoid oil afterwards. no problem. However, I made sure that the tranny didn't touch the oven nor would any oil drip onto the oven if it should leak out.

I put the tranny in a baking pan lined with tin foil and then stuck it in the oven for 40 minutes at 225 checking on it periodically. It takes a while to heat up all that metal. Pulling it apart wasn't easy. The rubber mallet helped separate it enough so that I could apply a little gentle prying force. In the end though, I had to persuade the cover to come off with my rubber mallet. The sharp edges of the tranny cover shredded my rubber mallet and left rubber shavings everywhere. I'll have to remember to wash out the tranny with some hypoid oil to make sure I got out all the little rubber bits. The bearings on the input, output and intermediate shafts fit into the cover and are what hold the cover tightly closed. Since the tranny took so long to heat up in the oven, much of the heat may have transferred to the bearings reducing the thermally caused gapping between cover and the bearings. Next time, I might try putting some boiling rags on the middle of the tranny cover where the shaft bearings mount. (later addition here:) with hindsight, experience, and asking some experienced mechanics I would suggest carefully using a propane torch to apply an even heat across the cover despite what Haynes and Clymer say. The cover does not need to get above 100 Celcius and probably shouldn't.

The net diagnostic was correct. The pawl spring had broken. the coil of the spring was still wrapped around the pawl axle. However I haven't located the broken portion of the spring. I'm hoping it drained out with the oil. I'll be checking for this.

I removed the two bolts that hold the gear shifting mechanism in place. Everything on the gear shifting mechanism is held in place by circlips and e-clips. My needle nose plyers weren't quite small enough to remove the circlips. Without the right tool, it's a drag. I picked up a circlip removing tool at the hardware store. It took me 5 minutes to dissemble the whole gear shifting mechanism... amazing what the right tool for the job does.

Noemi Berry mentioned a gear shifting upgrade kit that I ordered for $70. Also, she said that Cal BMW recommended replacing the nylon roller on the shift mechanism with the metal roller that is installed on the K bikes. The upgrade kit comes with the two cam plates, shifter lever, pawl and pawl spring. It's intended for bikes from '74 to '84. I've been told that this was stock in the 1983 and later R65LS. I compared the shift kit with what came with my bike and found that the output shaft cam had deeper shifting recesses for the roller which I guess would make it more difficult to slip out of gear. The intermediate shaft cam looks identical to the original. The shifter lever looks stronger. The pawl looks a bit different. The new one has an extra run of metal along the back which looks like it would prevent it from flexing back too far where it could hit the intermediate shaft cam. This may save the pawl spring from being over flexed and breaking again! I noticed that the Clymer blow out drawing of the shifting mechanism has the old pawl while the photos are of the new pawl. The cause of all my troubles, the pawl spring, is being replaced with a thicker gauge spring that looks like it should be more durable.

I noticed that the rear intermediate shaft bearing doesn't spin as freely as the other bearings, however, there isn't any roughness. Haven't decided yet if I should replace it.

Fortunately I have another bike (the R100GS) and am not in a hurry. Due to other things going on, I've only had about an hour every other night to work on this. This works well when one has to rely on mail order for parts. I started taking this apart about 2 weeks ago. However, it probably would have taken me about a full day to get this far, less if I didn't have to make some tools and run to the hardware store. I'm taking my time studying the parts as I go...

For the next two weeks it looks like the bike will be sitting in pieces in the garage until I get some free time to put it back together again.


Dave Thompson
davet@spyglass.com (http://www.spyglass.com/~davet)
'82 R65LS
'92 R100GS
'81 R80G/S
Champaign, IL


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Last Update: 11 September 2010