I am in the process of rebuilding airhead transmission. The bike is a 1989 r100gs. The output shaft fifth gear has about the same amount of play as the one in your video. So as a precaution I would like to replace it. The fifth gear has an outer diameter of 58.8 mm, it has 21 helical teeth. And no “X” stamp. In addition the output shaft does not have a groove on the engine side to accept a circling retainer for the bearing. When I go to euromotoelectric or siebenrock sites. Both state that after 1982 the fifth gear helical gears were set at 17.5 degrees and the fifth gear on the output shaft has 20 helical teeth. Question: post 1982 did BMW ever go back to 21 teeth and 15 degree fifth gear? I’d like to replace the fifth gear on the output shaft and would appreciate your insight.
I'm not certain, but I believe when BMW went to 17.5 degree helical gears they stayed with that design. BTW, Siebenrock sells a "tall" 5th gear that has one more tooth. Perhaps someone previously rebuilt the transmission and used that gear. BMW removed the retaining ring for 5th gear, which was a mistake. 5th gears moved on the shaft without the retaining ring. You might want to have the groove cut on the shaft. I'd contact Tom Cutter at rubber chicken racing garage about this. (rubberchickenracing@gmail.com)
Wish someone would 3d print 7speed Fitchel&Sachs trans from Hercules motorcycle from the1970's, very compact design. Wonder how it would compare to BMW GS 5speed in the real world? Just a thought, nice video.
When you changed the 5th gear with a smaller one did you had to change the other one on the input shaft? and what is the part number for the new 5th gear?
Manny, no you only need to change the output shaft gear with the gear for a taller 5th gear. It has one more tooth than the stock gear. Contact Tom Cutter, www.rubberchickenracinggarage.com for the taller 5th gear. BMW does not supply it so it does not have a BMW part number.
Hi Sylvain, No, my friend is not in the business of making tools for sale. He does have a machine shop in his garage and was willing to do this project for me
Those tools and the press made a much easier go of it than using the bearing pullers I've seen on the B2V videos for the same procedure. Nice work
A very very nice and clear explanation. The best ever seen. Thank you!
Thank you for the kind words Massimo.
Thank you Brook for your excellent videos! Very precise and with great explanation on how to. Very inspiring indeed!
You're welcome Mike.
Very good - looking forward to the next video!
Thank you Peter.
I am in the process of rebuilding airhead transmission. The bike is a 1989 r100gs. The output shaft fifth gear has about the same amount of play as the one in your video. So as a precaution I would like to replace it. The fifth gear has an outer diameter of 58.8 mm, it has 21 helical teeth. And no “X” stamp. In addition the output shaft does not have a groove on the engine side to accept a circling retainer for the bearing. When I go to euromotoelectric or siebenrock sites. Both state that after 1982 the fifth gear helical gears were set at 17.5 degrees and the fifth gear on the output shaft has 20 helical teeth. Question: post 1982 did BMW ever go back to 21 teeth and 15 degree fifth gear? I’d like to replace the fifth gear on the output shaft and would appreciate your insight.
I'm not certain, but I believe when BMW went to 17.5 degree helical gears they stayed with that design. BTW, Siebenrock sells a "tall" 5th gear that has one more tooth. Perhaps someone previously rebuilt the transmission and used that gear. BMW removed the retaining ring for 5th gear, which was a mistake. 5th gears moved on the shaft without the retaining ring. You might want to have the groove cut on the shaft. I'd contact Tom Cutter at rubber chicken racing garage about this. (rubberchickenracing@gmail.com)
Wish someone would 3d print 7speed Fitchel&Sachs trans from Hercules motorcycle from the1970's, very compact design. Wonder how it would compare to BMW GS 5speed in the real world? Just a thought, nice video.
When you changed the 5th gear with a smaller one did you had to change the other one on the input shaft? and what is the part number for the new 5th gear?
Manny, no you only need to change the output shaft gear with the gear for a taller 5th gear. It has one more tooth than the stock gear. Contact Tom Cutter, www.rubberchickenracinggarage.com for the taller 5th gear. BMW does not supply it so it does not have a BMW part number.
@@BrooksAirheadGarage thank you... with the taller 5th gear did you see some improvement on the highway revs/mph?
@@fan-ew4zi It's about 5% difference based on the change in the number of teeth.
Really nice Job Brook
Do you know if your friend who made your tools have a website to sell this set of tools?
Thanks
Moum’s from france
Hi Sylvain, No, my friend is not in the business of making tools for sale. He does have a machine shop in his garage and was willing to do this project for me
Brook's Airhead Garage lucky guy!
18:26 - the bevel should be facing the shoulder, not the bushing.
Jacob, you are incorrect. The bevel provides relief for the gear lube to exit the bushing.