My 1981 R100 has interesting transmission characteristics. Maybe it's me... It seems that I can hit a lot of false-neutrals when downshifting at lower speeds. The shifter seems to move past the next gear (especially when going from 5th to 4th) and will stay there unless I shift again. Shifting "up" goes back into 4th which doesn't have much drama. Downshifting again crunches into 3rd. At higher speeds it doesn't seem to happen (at least not as much.) Are there any adjustments to be made? Any common wear issues I should learn about? I'm comfortable with trannys in Japanese bikes but have never worked on a Beemer. The thing probably has at leat 50K miles on it... thanks
The simple things to check... 1. Is the gear lever loose? That can cause fudgey shifts. It doesn't need to be very loose. 2. I find synth oil helps shifting. 3. Do you use preload on the lever when up shifting? That definitely helps. 4. Do you blip the throttle when downshifting? That helps. 5. I have found that unfamiliar boots don't help smooth shifts too. They're all setup and technique easy things to sort, and I apologize now if you've been riding these things for years and years and do it already. Otherwise, I'm guessing the trans may need a look inside.
Hi BB81: It's okay to list the obvious things; upshifting usually works okay, it's downshifting where things don't work out that well. It's very easy to give a push down from 5th and end up between 3rd and 4th. I'm developing a technique that helps but am afraid parts may be worn. Again, I'm not familiar with airhead trannys, guess I'll have to do some reading.
If that's the case, ensure you blip the throttle on the downshift, and also just a tap of the gear lever to move down a gear. They aren't an intuitive trannie to use, and do have a quirk or two.
Dodgy downshifts can be a symptom of input shaft splines that needed cleaning and lubricating. The clutch disk hangs up on the dry input shaft and interferes with the process of getting the gears and shafts turning the same speed so it slips into the lower gear. It is something that may need doing every 10 or 15,000 miles on original splines. This maintenance might clear up your problem without opening the transmission.
My 81 RS hits a lot of false neutrals on the downshift as well. BMW did offer an upgrade kit that goes inside the transmission to fix the problem. There is a plate inside that has detents that index things between shifts (no idea what it's called) and the upgrade has steeper ramps between the detents so that the thingamajig that settles into the detents doesn't hang up in between them. There! That's nice and technical, huh? Sorry, I know VERY LITTLE about transmissions. I've pretty much decided to live with it until my transmission needs to come apart for some other reason. I did have to rebuild the trans in my 81 G/S and the shop did do the upgrade. It virtually eliminated any false neutrals.
Those kits are NLA from BMW and very, very expensive to buy as parts... that said Motobins out of the UK does have them at a very good price.
More good info! I've pretty much decided to live with it for now and will deal with it sometime in the future. I will keep an eye out for the kit. Thanks everyone.
Sounds like your shift plate or the shit rollers are worn. When you pull the clutch in take a deep breath- exhale then shift
I'll be wanting to look at that! I have an '82 trans that has the old style shift cam etc.. The detents for the rollers are ....unimpressive. I was comaparing it to a later model 5 speed and the differences are obvious and large.
