The twist grip became progressively harder to turn then finally seized because the bevel gear teeth broke. I replaced the throttle tube, cam disc and throttle cables. A Morgan Carb Tune was employed to synchronize the carburetors.
One of the aftermarket Progressive rear shocks was leaking fluid and a new pair of YSS Bravo shocks was installed. The Progressive shocks were ~3/4" longer than the original Boge shocks and the YSS shocks are same length as the Boge shocks. Steering trail is increased and the bike no longer over-steers in sharp corners at low speeds. YSS shock's spring rate more closely copies the Boge shocks and the ride is softer without any floating feeling.
The twist grip became progressively harder to turn then finally seized because the bevel gear teeth broke. I replaced the throttle tube, cam disc and throttle cables.
It sounds more likely that the bevel gears finally broke when the twist grip became too hard to turn, i.e. the cables became too hard to pull. Regular lubrication of the grip, gear set, and both cables is required maintenance.
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Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
It sounds more likely that the bevel gears finally broke when the twist grip became too hard to turn, i.e. the cables became too hard to pull. Regular lubrication of the grip, gear set, and both cables is required maintenance.
I periodically greased the bevel gears but never lubricate the control cables or throttle cables. Item #5 on the attached link from Snowbum states: 5. "Lubricating BMW cables....lubrication attracts abrasive dirt and may swell the liner (a nylon-like material). Only the very earliest original-as-shipped /5 cables were not lined."
What is the cable lining material?
1) My cable set did not seem to be lined, and lubrication helped. But there is no way for me to know if these are factory cables, since they came with the bike.
2) Somewhere in the archives is a reference to reduced tension throttle return springs. This also helps.
3) The liner is typically PTFE tubing (Teflon).
4) You also need a protective layer of grease between the chrome handlebar and the alloy twist grip tube. If not, a white, chalky form of galvanic corrosion takes place that makes the twist grip hard to turn, and impedes spring return of the throttle.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
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