The Story of the Splines
or
How I Lubricated the Transmission Input Shaft Splines on a K75

By Bryan Lally

I'd heard recommendations for lubricating the transmission input shaft splines at many different intervals, including never, every 40 k miles, every 20 k miles, every other tire change, once a year, and probably a few others. Since this bike had spent the first year of its life not moving, and since I had the wheels off it for a tire change, and since I was basically interested in how it was put together, I started in on a transmission input shaft spline lube at 8200 miles, on a 2 year old bike, that had only been in service for about 8 months. The bike was a '94 K75S, with ABS. Other K-bikes should be similar, although K100s will have more bolts on the exhaust header. You may or may not have the belly pan, bag mounts, or the kickstand retraction linkage. It would have been slightly easier without the ABS, but not much. This is my story.

Tools and supplies that will be useful:

Parts that BMW says you should have:

This job turned out to be a lot easier than I had expected. The best advice I can give you is "have no fear." That said, realize that I am fairly mechanical, having grown up in a General Motors household in Detroit in the 60's and 70's, and had changed my first piston before I learned how to drive (it was in a Briggs and Stratton).

Most of the time involved removing all of the parts that are in the way. The transmission was off the motor for less than 10 minutes total! Total time was about 8 hours. I'm sure it would only take 5-6 hours the second time around. Here we go. We'll start with the easy stuff.

Wash the bike. It will be much nicer to work on, and better to get the dirt off than to have it fall into somewhere important.

Disconnect the battery ground lead at the frame.

Remove the belly pan.

Remove the left and right side covers.

Disconnect the connector to the fuel injection computer (insert a straight blade screwdriver in the hole in the tray under the seat above the connector to unlatch the connector) and then remove the tray with the FI computer. Remove the battery.

Remove the license plate holder/rear mud flap by removing the two phillips screws under the taillight, and loosening the 10 mm bolts inside the rear storage compartment aft of the seat. You might as well take the 10 mm nuts all the way off, as we'll have to later to remove the fender. Pull the license plate holder off to the rear.

Remove the rear wheel. I find it best to take the bike off the centerstand and have someone sit on the bike while I loosen the wheel bolts. Then put the bike back on the centerstand. Remove the bolts and the rear wheel. Don't lose the spacer.

Remove the exhaust system. Take the 6 bolts off the exhaust manifold, and then the 2 bolts at the back of the left footrest. Make sure you get the 3 copper seals out of the exhaust ports in the head. Some people have said you can just take the muffler off of the header, but I took the entire exhaust system off as a unit.

If you have the saddle bag mounts, remove them.

Remove the rear fender (2 more bolts under the seat).

Swing the coolant overflow tank out of the way and remove the battery mounting plate.

Remove the starter motor (2 mounting screws and one cable).

Remove the plastic alternator cover (right side) and the ignition coil cover (left side). The wire to the accessory outlet has a plug under the rubber boot. Not everyone has an accessory outlet here, it seems.

Remove the bolts that hold the ABS modulators to the footpeg plates (one for each modulator, and at the footpeg plates).

Support the swingarm so that it can not fall down, and remove the shock absorber. If the swingarm falls down, it will damage the rubber boot at the front of the swingarm, and you will have to remove the swingarm to replace it. Many people have been successful supporting the swingarm from below with wood blocks, or from above with a bungee cord. I found that it was easy to tightly wrap a nylon strap around the swingarm and the footpeg bracket. This supports the swingarm, and the swingarm and the footpeg bracket will move backwards as a unit later.

Remove the shock.

At this point, you could leave the rear drive and drive shaft attached, but you may as well lubricate the drive shaft splines at the same time, since you have things this far apart.

Clean around the speedometer sensor, and remove the speedometer sensor from the rear drive unit (one small bolt, and gently pry it out). Put a paper towel or rag in the hole.

Remove the rear brake caliper from the rear drive unit. Do not push the rear brake pedal from this point on. Tell your helper that. Remember which bolt goes where - mine had two different style bolts.

Remove the 4 bolts that hold on the rear drive unit, and wiggle the rear drive unit off. You may tap it off with a plastic or rubber mallet, or with a hammer and a block of wood. Gently ... Place it somewhere where it won't tip over and spill it's fluid out, and be careful to not damage the brake rotor.

Remove the drive shaft, by grabbing it gently with vise grips and gently tapping on the vice grips. It will pop out.

Snip the three cable ties on the right side of the frame that hold the cables leading to the footpeg bracket area. Disconnect the electrical cables that go to this area at their connectors near the top frame tube.

On each brake modulator is a ground wire that is attached to one of the bolts that hold the footpeg bracket to the transmission. Remove these ground wires from the modulators, leaving them attached to the footpeg brackets.

Using 2 more nylon straps, lift the brake modulators up until the modulator subframe is clear of the 4 mounting bolts on the top of the transmission. You can wrap the strap under the modulator, and through a hole in the frame near where the shock attaches (on the right side) and a matching hole on the left side.

Assemble the saw horses. Nail the legs into the brackets. Put one of the leg units on the long 2x4, very near one end. Slide this long 2x4 through the hole in the frame where the battery was, so that the legs are on the left side of the bike. The long 2x4 will have to angle down. Make sure that the legs are slightly outside of the shift lever. Put a towel or rag on the cross 2x4 to protect your frame.

Get a helper to steady the bike. The helper stands behind the bike and holds the passenger grab handles while you lift the free end of the 2x4, raising the bike slightly so that the centerstand is off the ground. Slip the other leg unit on the 2x4. Spread the legs (of the saw horse, not the helper) gently with a hammer to stabilize the saw horse.

Remove the clutch cable on the lower end.

If you have the auto-retracting sidestand, remove the pull rod attached to the kickstand linkage.

Remove the plastic mount for the belly pan from the kickstand console.

Remove the kickstand console by removing the 4 bolts. These are microencapsulated bolts and should not be reused. However, the BMW manual says that if you are going to reuse them, coat them with locktite 242 (blue, soft) before doing so (page 23-22.0). They are also quite tight, so have your helper steady the bike as you undo them - it would be bad if the bike fell on you at this point.

Remove the 6 Allen head bolts that hold the transmission to the clutch housing. They are all the same length.

Get your helper to return. The helper uses the right side foot pegs to stabilize the transmission. You support the transmission with the hydraulic jack and a piece of wood, and remove the two bolts that hold the transmission to the frame. Then gently slide the transmission backwards a few inches (my jack has wheels). Be careful to slide the transmission straight back, and to not over or under support it with the jack.

Clean the splines as best as you can, both the internal splines on the clutch, and the external splines on the shaft. Rags and a (curved) pick will be useful. Don't spray it with WD40 or anything like that. Then lubricate the splines using a toothbrush and BMW lubricant #10. Be thorough, but don't use too much grease. Excess grease can fling off and end up on your clutch plates. Lubricate the end of the clutch actuating pushrod. Also, apply a little grease to the locating dowels between the clutch housing and the transmission.

Push the transmission forward, and bolt it back on to the clutch housing, and the frame. Torque the bolts to spec in a cross pattern. Go have a beer and change CDs to another part of "The Ring." You are now in the reassembly phase, and the delicate part is done.

Put the kickstand back on, and then, using your helper, remove the saw horses. Again, torque carefully, with your helper in attendance.

Clean and thoroughly grease the splines on the drive shaft and rear drive. You can use plenty of grease here, as the excess won't hurt anything. Tap the drive shaft back into position (with a plastic or rubber mallet, or a block of wood) until it clips in.

Replace all the parts in approximately the same order as you took them off. Torque values are given below. All went according to plan on my bike, and I didn't have any leftover parts. Remember to put the license plate/mud flap back on before you tighten the rear bolts holding the fender on.

Adjust your clutch, if necessary.

Sit back, listen to Ride of the Valkyries for a few minutes, and then go for a careful test ride.

BMW says to replace the exhaust header seals (the copper rings) to prevent leaks. I didn't have any handy, so I reused them. It seems to have worked fine.

Torque Values Nm (ft-lb)
transmission to clutch housing 16 (11.5)
transmission to frame 45 (32.5)
rear drive to swingarm 40 (29)
rear caliper 32 (23)
kickstand console 41 (30)
starter motor 7 (5)
shock 51 (37)
rear wheel 105 (76)
exhaust manifold 21 (15)
muffler to footrest 9 (6.5)

Comments? Please send them to blally@concentric.net. I'd be happy to incorporate suggestions.

 

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Last Update: 05 October 2007