These instructions are aimed at the /5 owner. They're pretty close for later models, but there will be some differences. If something doesn't quit make sense on a later model, think /5. In any case, you should have a service manual handy, and when using these instructions on a later model, it'll really come in handy.
First off, it's probably best to remove the tank. It'll be safer well away from this work, plus it'll give you slightly better access. Not much, but a little. It's not really in the way of anything you're going to be doing.
Now disconnect the ground wire from the battery. You won't actually be working on the electrical system (aside from removing the front turn signals), but you'll be moving the headlight and the front of the wiring harness around, so it's for the best to make sure nothing is live.
If you have a fairing, remove it now. I use an 'S' fairing and to remove it I have to pull the turn signals off of their stalks. I *think* you could leave them on unless you want to rewire them, which I'll get to in the reassembly stage. In any case I think it would be easier to reroute the wire(s) on reassembly with the signals removed.
Now remove the steering damper. If you don't have a /5, read your manual here. If you do have a /5, unscrew the damper knob fully and withdraw it from the steering head. Then remove the Jesus clip that holds the lower disk of the steering damper to the lower triple clamp. Well what do you yell when one of these clips shoots across the room when you're trying to remove it? As Jesus clips go, the one on my /5 isn't too prone to flight.
Undo the bolt that holds the middle disk of the steering damper to the frame of the bike. It's right above the stock horn mount location.
All that should be left of the steering damper assembly now is the rubber washer that goes into the center of the steering stem. If this is rotted or missing, it can cause some weird parking lot handling problems, as the steering damper works/stops working at different bar positions. I just got a new one for about $2.00. I'd been making due with a piece of split fuel hose wrapped in tape. It worked fine, but the official part is easier to install.
When you put the steering damper back together, you'll need to lubricate it with something. I've used Permatex never-seize as well as wheel bearing grease mixed with the graphite powder sold for lubricating locks. The grease/graphite seems to work a little better.
Now remove the handlebars. To prevent damage, and to make the process a little less awkward, you might want to take off the mirrors first.
The bars are held on with four nuts under the upper triple clamp. With the nuts off, you can remove the upper handlebar clamps. The first few times I took the bars off, I was amazed by the way the clamp studs had corroded. Then one day I took the bars off one week after a ride in the rain. It hadn't rained at all during the intervening week, yet the studs were dripping wet. Apparently the bar clamps make a perfect water trap. Since then, I've been greasing the studs well each time I put the bars back on.
Now remove the front wheel. This is one of the areas where the /5 with its drum brake might make disassembly different from a later model. You maybe forgot about R60s with drum brakes?
First tie the center stand to the exhaust crossover pipe. Wouldn't it be a bummer for the bike to come off the stand while the front wheel and forks are missing? Better safe than sorry.
Remove the brake cable by unthreading the adjustor nut from the end. Pull the cable out from both levers. You'll probably need to remove the rubber boot, then pull the barrel shaped pin out from around the cable. There's a slot in it for this purpose. Make sure to remove the pin from the lower clamp as well. You're probably going to lose these pins, so you might want to put them in a baggy or something to delay the inevitable... :-)
Now take off the torque arm. This is the aluminum bar that runs from the brake backing plate to the fork brace/fender bracket. Take the upper bolt completely out to make this easier.
Loosen the pinch bolt that clamps the left fork around the front axle.
Put some sort of metal bar in the hole at the end of the front axle. This is on the left side, by the pinch bolt. While using this bar to prevent the axle from turning, remove the axle nut from the right side of the axle.
Remove the axle, using the metal bar that you put in the hole as a handle. This is where I always pinch my fingers between the bar and the axle.
Now roll the front wheel out from under the fender. The brakes and their backing plate are liable to fall on the floor at this point. Don't let them.
Now remove the front fender. It's held on by the fork brace and two other supports. Basically, you remove six nuts/bolts and both the fork brace and front fender are off as a unit. /6 and later models don't have the tubular fork brace that /5s do. Use your judgement and manual here.
Now, using the pin wrench in your tool kit, remove the fork caps. You don't have it? Neither do I. I use a sprocket cone wrench that I got for a bicycle years ago. Works perfectly. Later models (non /5s) don't use this sort of fork cap anyway, so you people don't worry.
Now remove the gland nuts that retain the the upper ends of the forks. Three potential problems here. They are (or should be) really tight. The socket you'll need if not using the official tool is big and expensive. I had one from another job, so all was cool. These caps hold the springs down. In theory, things could attain a rather high velocity real fast on the last turn or so of the nut. I got lucky, even with 3/4 inch spacers over my springs, there's only a few pounds of force as mine come out. Be careful though!
Loosen the clamps that hold the upper ends of the gaiters on. Slide the gaiters down so that you can get a good grip in the upper fork tube. You might be able to skip this step, but it'll probably make things easier since you'll be able to grab the upper fork tubes directly.
Now it's time to remove the forks. Undo the pinch nuts on the lower triple clamp. Slide the fork tubes out one at a time. I had to pry the clamps apart slightly. This is where you can show some skill and judgment by not mangling the soft aluminum of the clamp. :-)
When the forks are out, put all the caps back on to keep the insides clean. Remember that they're full of messy oil, so store them in an upright position just in case.
Now would be a good time to do any fork maintenance that you've been thinking of.
Now remove the upper triple clamp. The sheet metal one. First remove the big nut that holds it to the steering stem. This will probably be very tight. I used the same socket and breaker bar that I used to remove the fork gland nuts. I sat on the bike to ensure stability and used the steering lock (not the fork lock) to hold the assembly in place.
With the nut off, lift the upper triple clamp off.
The headlight assembly will probably want to fall forward now. Put some sort of large bucket or box upside down in front of the bike to set the headlight and handlebar assembly on. The bars and their cables will have to be threaded over the remaining steering head parts to do this. Be careful not to stress the wires and control cables.
Now remove the nut that applies tension to the bearing assembly. That's the adjuster nut right under the upper triple clamp. It may be one of two types. According to my service manual, the /5s used a split nut with a locking bolt, and later models used a round nut with notches in it. I had the later nut on my /5. The split nut is turned with a metal rod (supposadly found in the tool kit, while the notched nut is turned with a "C spanner". Which didn't come with my bike.
While the nut was off, I made a wrench to fit it. A piece of mild steel strapping proved perfectly adequate. I traced the shape of the nut onto the metal and used a die grinder with a cutoff wheel and some other attachments to cut away the excess metal. Then a bit of work with a file and some of that really cool aluminum paint, and I had a wrench.
With the upper nut and the little stamped cover it holds in place off, the steering stem, lower bearing, and lower triple clamp may be withdrawn from the bottom of the steering head. I've heard of people having trouble here, but mine came right out with a few gentle raps with a rubber hammer.
Lift the upper bearing out of the top of the steering head.
Now the lower bearing has to be removed from the steering stem. It's pressed on and it's quite difficult to get a grip on it. There have been many methods discussed on the BMW lists to do this. Some sound good. Some concern me a bit. Some convince me that I don't want *that* person to work on my bike.
Which did I use? None of them. I just took my assembly to the local non-official BMW shop (plug: Moody Cycle Sales in Kokomo, IN -go there if you're in central Indiana!) and had the bearing removed for almost nothing. I had to go there to pick up the parts as well, so it didn't even cause any delay. It's nice to have a good relationship with a local shop.
If you are going to remove this bearing yourself, it comes off over the threaded end of the steering stem. The lower triple clamp does not have to be removed from the steering stem to do this job. Some disagree with me, but I'd never do it that way. Ever. No way. I'd destroy the bearing removing it first, like I did with the races (see below) (hey, it's bad anyway, or I wouldn't be changing it!)
When the new bearing is being installed (I did that myself), use a piece of pipe to drive it on. I used some oil to lubricate it, but I didn't use any heat/cold. It went on easily. Firm, but no heroic measures were needed.
OK, now you have to remove the bearing races that are left in the steering head. This is likely to be the most difficult step in the procedure. My Haynes book says, "Outer races must be pulled with an internally expanding bearing puller". I took this to mean a slide hammer with an internally expanding collet. I've got such a slide hammer. I guess when all you have is a hammer, then all problems seem to call for nails...
In any case, it didn't work. With a little work, I could grab the bearing races but the slide hammer wouldn't budge them. Since then, a few people have suggested that a tool something like a gear puller exists that could do the job. Well, I don't have one of them.
At this point I would have taken the job to the shop, except that this would have meant carrying the bike onto the trailer and then off of it again. Remember that there are no front wheels or forks at this stage. I didn't have enough volunteers for this. Basically I had one volunteer and I figure this is a four man job.
So here's what I did. I got out the die grinder again and scored the bearing races deeply. Not all the way down to the metal in the steering head, but close. Well I tried for close, but I did nick the steering head under the upper race. Not enough to worry about though.
You could use a Dremel Moto-Tool here. I used an Ingersoll-Rand air grinder with a 1/4 inch collet and a Dremel brand cut-off wheel and mandrel.
Then, using a small cold chisel, I split the races. The upper one came out in lots of tiny shards, the lower one split in one place and was easy to pull out. If you can, what you want to do is crack all of the way through the race, leaving one piece with a split in it. There will be no tension holding it in anymore and it will slide right out. Worked perfectly on the bottom one, the top was, shall we say, somewhat more experimental...
I was surprised by how brittle the metal was. I expected hard and brittle, but this was sort of like hitting glass with a chisel and hammer.
If you decide to do this, wear a full face shield. At least I did and was glad for it. Goggles might be enough, but when those metal shard fly, they do so with a lot of force. We don't want anyone to lose an eye here.
If you did nick the metal of the steering head, use a small file or stone to remove any burrs. You should clean any remaining grease out of the steering head at this time.
Now put the new races in. This is a lot easier than removing the old ones. Many people chill the new races and heat the steering head, but others do not. When I asked on the list, I got perhaps a 50:50 response. I decided to keep it simple and not bother.
The upper race is the easiest. When it is installed the upper part of the race is flush with the upper part of the steering head. I used a block of aluminum and a hammer to drive it in. Just make sure it's square the whole way. Use a little grease on the back of the race.
The lower race is harder since it's recessed into the steering head. I used the block to drive it in until it was flush, then used the old lower bearing race to drive it the rest of the way.
Make sure the races are driven in as far as you can get them. Even so, they probably won't be all the way in. After you've ridden a few hundred miles, your steering head will probably be loose. Adjust it. You may have to do this several times. The first time I changed steering head bearings (on a Yamaha) I had to adjust the steering head perhaps four times. It's been about three weeks since I got the /5 back together and I only had to do it once. I did again yesterday "just in case", but it wasn't really needed.
Now grease the new bearings thoroughly. I'm not even going to discuss what grease is best. I used wheel bearing grease. Plain old buy-it-at-Wal-Mart wheel bearing grease. I always have and it works fine for me.
Now put the lower triple clamp and bearing in from below. Insert the upper bearing and its dust cap. Put the adjuster nut back on.
At this point you may want to add a ground wire to the turn signals. I always used to have trouble with the front turn signals not working. There was power making it to them, but there was no good ground. The ground was through the stalks which touched the lower triple clamp which was grounded through the steering head bearings. It worked some of the time...
I've seen boxers at rallys that had a ground wire attached to the turn signal clamp nut and then running inboard to a better ground. I suppose intermittent turn signals are a common problem.
I ran another wire from the reflector (my reflector even had a terminal for this wire, Bosch must have expected me to do this some day), through the stalk and the fork tube cover, and out through the grommet in the side of the fork tube cover. I ran mine to the main wiring harness and back to one of the bolts that holds the coils in place. This is where the wiring harness is grounded to the frame, so it had better be a good ground!
Now you can pretty much put everything back the way it came off.
Before you tighten the upper triple clamp nut, adjust the steering head bearings. While I have heard people quote a torque in lb-Ft for this nut, my Haynes book simply suggests tightening it until all play is removed.
I tighten it until I feel resistance at the wrench handle, then just a little more. If the front end won't fall freely to the side when pushed off center, the bearing's too tight. If you can grab the forks and feel play in the bearings, they are too loose. Expect to try this a few times if you don't already have experience adjusting steering head bearings.
The lower triple clamp pinch bolts should still be loose while you are adjusting the bearings.
When you get the steering damper back together, make sure that the clip which holds the lower disk in place isn't abrading the wiring harness. Mine was.
When you are putting the front axle in, don't tighten the pinch bolts until the nut at the right end is tightened. I wouldn't tighten the fork brace until after the triple clamps are back together and the axle is in. The axle may not go in as easily as it usually does BTW. Without the fork brace holding the lower fork tubes in alignment, you may have to slightly compress one by hand to get the axle holes to line up.
You can find torques for the various critical bolts and nuts in your service manual.
Don't forget that the front brake will need to be readjusted now. Unless the throttle cables wind up in exactly the same position they used to be in, they might have to be adjusted as well. The same goes for the clutch, but it seems less likely.
When it's back together, go for a ride. If the front end wobbles or shakes, you've probably got something loose (most likely the steering head bearings). If the bike handles as if you are "aiming" it instead of steering it, either the steering head bearings or the steering damper are too tight. Don't be surprised if all is well at first, then the steering head bearing needs to be readjusted after a few hundred miles. As mentioned above, something probably wasn't seated quite all the way...