I already removed the fairing and front fender to repair them and send them out for paint so I have easy access to the handlebars, controls, steering stem and forks.
Remove Telefix Fork Brace
This bike has a Telefix fork brace installed which is an after market upgrade. It mounts to the top of the lower fork slider in place of the rubber bushing originally on the R100RS forks. The bike has the rubber fork gaiters installed which was a common change to prevent nicks and bug goo on the fork tubes that hasten fork seal leakage.
The brace consists of a center bracket and two outer semi-circular brackets that attach around the top of the fork slider using small Allan screws. I remove the hose clamp securing the fork gaiter, slide it up and then remove the four Allan head bolts securing one of the outer semi-circular brackets.
The center part of the brace consists of two pieces bolted together with two large Allan head screws. This allows adjustment of the distance spanned by the center section so it doesn’t pull or push the middle of the fork tubes together or apart which would increase fork stiction.
I slide the center part up one tube and rotated it to remove it, but I could also loosen the large Allan bolts or remove them if I had to.
The stock fork brace and fender mount, or “Bow” as BMW refers to it, is still attached to the fork sliders. It’s easier to remove this after I remove the fork sliders.
Remove Brake Calipers
I remove the steel brake line from the caliper and from the upper rubber hose where it connects to the steel line at the bracket on the top of the fork lower with an 11 mm wrench.
The brake calipers are attached to the fork slider by an eccentric pin that is under a cap nut screwed into the bottom plate of the fork lower the caliper pivots on. I remove the cap nut and the spring between it and the bottom of the eccentric pin.
The pin can be hard to remove. I use an M8 bolt and thread it into the center of the eccentric pin for a couple turns until it stops. I don’t force it any further.
I use a large expanding jaw pliers on the end of the bolt and a plastic hammer to hit the pliers to extract the eccentric pin. It’s a good idea to hang on to the caliper as it will fall out of the fork when the eccentric pin is removed.
The caliper is free and can be removed if it didn’t fall out from the upper and lower plates of the fork slider it sits between.
Remove Fork Sliders
The procedure for the 1977 R100RS is the same as for the 1973 R75/5 as shown here:
Another way to remove the nut securing the fork slider to the damper rod is with a cordless impact driver and a 13 mm socket. The fork springs provide enough friction on the damper rod to prevent it from spinning so this is a quick way to get the nut off the damper rod.
I keep the axle installed in the fork slider so I can slide them off together. I had to push up the damper rods into the fork tube a bit to have enough room to get the fork lowers off.
At the work bench, I remove the four large Allan bolts that secure the stock fork brace-fender mount and the brake line brackets.
The picture above shows the INCORRECT way to mount the brake line bracket. It should be on the other side of the fender brace next to the wheel, not in between the brace and and the fork slider. The way it was mounted by the previous owner will cause fork stiction making the forks less compliant and the suspension more harsh.
You don’t have to remove the controls if all you are doing is rebuilding the forks and steering stem. You can remove the bars and fold them forward to access the fork tube top nuts and the steering stem nut. Since I am stripping the bike to the frame I remove the controls.
This bike has heated grips so there are small screws that secure the heating element to the bar.
I removed the screws and also push the wires that enter the bar at the bottom, center of the handlebar toward the ends of the handlebar so there is enough slack to pull the grips off the bar.
To remove the right grip, I remove the throttle housing cover which frees the grip. Then I loosen the brake cable at the master cylinder under the gas tank so I can remove the cable from the right perch.
I remove the connector for the clutch switch before removing the left perch.
The left perch got twisted hard upwards and tore the top plate covering the clutch switch.
I know a fellow who is an excellent welder. The perch is made from pot metal and has a lot of zinc in it so it takes a bit of technique to weld it. Here is the repaired perch.
Note there are a few holes caused by metal boiling away. I fill those with body putty before I repaint the perches.
I remove the screws securing the perches to the handlebars leaving just the handlebars attached to the top plate.
I am going to repaint the levers so I remove the plastic bushing using a small diameter socket.
Remove Top Plate & Instrument Bracket
The top plate has four holes in a row. This permits the handlebar to be mounted more forward or rearward. When mounted forward, the instrument bracket is secured by the front studs of the handlebar clamps and the rear of the bracket is secured by two smaller bolts. When the handlebar clamps are moved to the rear, the large rubber bushing needs another bolt to secure the front the instruments bracket. On this bike, the handlebars were moved back. I remove the handlebar clamps and the front screws removing the handlebar and the instrument bracket.
The rubber grommets have steel bushing inserts. One of the larger ones is missing.
This is the top plate with the handlebars removed. I can now remove the fork tube top nuts and the steering stem top nut.
Remove Fork Tubes
The fork tubes are secured by a top nut and by the pinch bolts in the lower triple clamp of the steering stem. I use the pin wrench in the tool kit to remove the chrome caps on top of the fork top bolts.
I use a 36 mm socket that that I had ground flat to remove the bevel on the end of the socket. Since the fork top bolts are thin, the socket has to fully fit the edge of the bolt head or it will get rounded when I remove it.
You can get the forks out of alignment if you let the steering stem go to the steering stops while you loosen the fork tube top nuts. I use an old handlebar inserted in the opposite handle bar clamp from the top nut I am loosening and snug the handlebar clamp. Then I brace the handlebar with my stomach and loosen the top nut. I move the handle bar to the other handlebar clamp and repeat the procedure. Here is a picture of using the old handlebar when I did this work on the 1973 R75/5.
When the nut is loose unscrew it but cover the nut with a rag and keep your face away from it. The spring can launch it into you. I find pushing down on the nut as I near the last couple threads keeps it from launching.
I loosen the Allan bolts on the lower triple clamp while holding the fork tube so it won’t slide out and fall on the floor. If the fork tube won’t slide out easily, insert a large blade screw driver in the cut and gently tap it in until you can slide the fork tube out of the lower triple clamp.
Remove Steering Stem and Bearings
The procedure to remove the steering stem for the R100RS is the same as for the 1973 R75/5.
Remove Fork Lock
Since I am going to powder coat the frame, I remove the fork lock. The cover prevents the lock from coming out so I remove the cover.
I open the protective cover over the lock. I use a long shaft screw driver and put it against the inside of the cover and then tap the handle of the screw driver to push the cover and its pin out of the frame.
This exposes the lock tumbler.
I insert the key in the lock, turn it clockwise and pull the tumbler out of the frame with the key.
Now I can replace the steering head bearings and rebuild the front forks. I document that work in a separate write-up you will find here.
2021-10-09 Fix typos and grammar mistakes.