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R90/6 trans trouble

Posted: Wed Oct 05, 2011 10:08 am
by beemersanducs
Hi all, returning from a ride Sunday the Cafe didn't want to down shift,lever would move but not catch after a few tries it worked, BUT about 2 blocks from home I could not down shift at all. My question is, is there a spring that goes bad or could it be something else?

Re: R90/6 trans trouble

Posted: Wed Oct 05, 2011 10:20 am
by Garnet
What year is your /6 trans? The 1974 kickstart 5 speed is quite different from the 75 to 77 5 speed.

Re: R90/6 trans trouble

Posted: Wed Oct 05, 2011 10:32 am
by beemersanducs
Bike is a 1976.

Re: R90/6 trans trouble

Posted: Thu Oct 06, 2011 12:43 pm
by mattcfish
beemersanducs wrote:Bike is a 1976.
I've got a known good 75-76 tranny if you end up needing one. I can't give it away....but it could be substantially cheaper than trying to repair yours. PM me if interested.

Re: R90/6 trans trouble

Posted: Thu Oct 06, 2011 4:46 pm
by RickR90s
your shifter return spring has more than likely snapped. Very, very common on early 5 speed boxes. Happened to my '74 R90s and my buddy's R90/6, albeit at different mileages.

So if you're stuck in a certain gear, but the lever moves, that's probably it.

Tranny will need to be removed. Most guys install a shift kit which is an updated spring (stronger) and re-designed pawl to eliminate false neutrals. (My R90s has it after mine broke). I'm pretty certain that BMW only sells the newer spring anyway.

RickR90s

Re: R90/6 trans trouble

Posted: Sat Oct 08, 2011 11:05 am
by John Falconer
Rick is right, I believe, about only getting the newer spring.

However ... the new spring can fit too tight on some of the earlier boxes so check it for movement. Also, as others have said, installing the "shift kit" can be a very nice upgrade. There are three different cam plates - you really want the newest one. You'll also probably find the plastic roller that follows the track in the cam plate is toast.

As long as no gears are broken it is worth repairing - IMHO.

John Falconer

Re: R90/6 trans trouble

Posted: Sat Oct 08, 2011 5:38 pm
by beemersanducs
Is the "shift kit" a dealer item? if not where can I get one?

Re: R90/6 trans trouble

Posted: Sat Oct 08, 2011 5:58 pm
by George Ryals
I think the shift kit is NLA.

http://bmwmotorcycletech.info/transmission.htm About .7 way down on this page is all the information you could ever want about the shift kit and ita parts. Scroll down to NOTE!!!!!!!!!.....the shift kit......

Re: R90/6 trans trouble

Posted: Mon Oct 10, 2011 6:46 pm
by Dave Backmarker
I'm about three quarters complete with rebuilding a R90S transmission. I'd suggest taking a look at http://www.cycleworks.net for transmission and flywheel tools and parts. Dan offers an excellent video that will take much of the guess work out of the job. The video goes into detail on removing and fitting new springs and pawls on the shifter mechanism. The video is $50 and will be money well spent as you'll see if you want to do this job. I've been a gear-head for 41 years and if you haven't taken apart a transmission before, this video will walk you through the process and also show you exactly what tools and jigs you'll need. And, if you pull the transmission, you may want to remove the clutch (special tools) to check on the diaphragm spring condition and clutch disc thickness and if you're doing that, you should pull the flywheel (read snowbum's work first) and check the main seal and oil pump seal.

I am not associated with Cycleworks. I'm a customer of Dan's machining work, parts and tools and have a great respect for his machining and welding skills.

DaveM
1975 R90S
2000 R1100RT

Re: R90/6 trans trouble

Posted: Wed May 30, 2018 1:06 am
by rapide
''
Most guys install a shift kit which is an updated spring (stronger) and re-designed pawl to eliminate false neutrals. ''
In 2006 .... i had my tranny rebuilt by Oak. the COST for the ' SHIFT KIT ' was upwards of $6-700.oo just for the HARD to FIND PARTS. He machined the end cover and made a threaded plug to seal up the now completely removed K/S gears and ALL associated bits. these things are now very hard to get parts for R90 transmissions .

I suggest ........... remove the K/S bits