1971 R75/5 clutch pushrod leak

Hello All,

New to me 1971 R75/5

Approx 50k on the clock..

Clean and neat as a pin....aside from this leak.

Bike has sat for approximately 2 weeks without being run (Michigan).

Note the puddle on the floor.

Pics show where the leak is coming from.

Definitely gear oil (as per the smell)

Just wondering if this is a fairly easy fix (new seal ?)

Or if it's going to require separating the gearbox (not really an issue as the bike is being stored in a heated pole barn over the winter).


Thanks for any and all advice !

Dan

Welcome to the forum, Dan! Should be able to deal with this without pulling the transmission. See this picture from RealOEM:

http://www.realoem.com/bmw/enUS/showparts?id=0260-EUR-01-1971-2476-BMW-R75_5&diagId=21_0071

Everything from #3 on back can be removed from the back for inspection. Probably you'll need to replace #6.

I had a /6 that leaked there, yours looks the same. I was able to replace the seal on the piston in about 1/2 hour. Easy fix. Cheers. Good luck.

While apart would it wise to replace both #2 (feltring) as well as #6 (gasket ring) ?

edit: And at that point just do #7 (cup) ?

Thanks.

The felt ring can't be replaced from the rear i believe, to do that the trans will have to come out. I would just replace the seal and inspect the T.O. bearing. You should be good to go. Really a simple job. Chunk.

Anyone have a quick and dirty procedure ?

I have adjusted the clutch as per: http://www.vintagebmw.org/v7/node/7410#comment-12917

I am imagining that I'll loosen the adjuster screw and locknut until I have sufficient slack to remove the clutch cable from the clutch arm.

Remove the "c" clip and pin to drop the clutch arm away.

Remove (and replace) the "cup"

Then ? am I just "prying the old (21521020109) gasket ring out with a pick and pushing in the new one ?

Thanks !

After you remove the arm, grab the piston (#5) and pull it out rearward. The seal (#6) goes on the piston in the recess on it, see the diagram. From memory, i think my clymer manual advise to grease all the bits well, eventually i think the transmission gear oil will do that, but it will take time to migrate to all the bits. I did this some time ago so a check of manual is advisable. Cheers.

chunk said:

o so a check of manual is advisable. Cheers.

Click to expand...

No manual or Clymers...so I suppose a purchase of one is in my future...

You have several choices for manuals -

I think that the Haynes manual seems a bit easier to follow, and in many instances offer suggestions for alternate tools -
https://www.amazon.com/2-Valve-Hayn...2382718&sr=8-4&keywords=bmw+motorcycle+manual

The Clymer manual has more photos, but there are errors regarding some procedures. I don't know if there is an on-line errata. -
https://www.amazon.com/through-R100...2382718&sr=8-1&keywords=bmw+motorcycle+manual

The BMW factory manual is comprehensive, but assumes that one has been to the factory school. One vendor is Capital Cycle, although their price seems high. I thought that Re-Psycle BMW was selling someone's reproduction of the factory manual for around $40, but my knowledge might be a few decades old. NOTE: a number of the torque values in the factory manual have errors in the conversion from N-m to ft-lbs. I believe that the N-m values are correct.
https://www.ebay.com/itm/BMW-Book-R...h=item43bccd4d58:g:Z9sAAOSwKfVXIO7b:rk:1:pf:0

Re-Psycle BMW has lots of used airhead parts. You will need to call and inquire about manuals, parts, advice, etc. -
https://re-psycle.com/

There is a parts catalogue available from Capital Cycle, but I find the on-line parts fiche from vendors (i.e., MAX BMW) to be more useful.
https://www.ebay.com/itm/BMW-Parts-...h=item461029586a:g:APkAAOSwiYFXIPC0:rk:2:pf:0
https://shop.maxbmw.com/fiche/PartsFiche.aspx

One of the airhead gurus, Snowbum, has an extensive amount of on-line tech info. It might take a few readings of some subjects to absorb his advice -
http://bmwmotorcycletech.info/index.html
Here is Snowbum's info on the airhead clutch throwout bearing -
http://bmwmotorcycletech.info/clutch.htm

Another airhead guru, Anton L., frequents this forum and he also has a growing amount of tech info that seems quite clear and well illustrated -
http://www.largiader.com/

In the early days of the web, a number of folks participated in the Internet BMW Riders email discussion. From this grew a number of procedures -
https://ibmwr.org/index.php/airhead-tech-articles/

And finally, I would recommend that you consider joining the Airheads club. This club frequently have tech days at various locations where one can help or get help with many maintenance procedures. There are a number of documented procedures available on the on-line website. The monthly newsletter has a very useful tech column -
http://www.airheads.org/

Perfect illustration: http://www.largiader.com/articles/throwout/

I've got it now.

Along with Snowbum's advice to possibly replace the clutch arm pin (11 and/or 12 and 13) with a shoulder bolt and nylock nut.

Is that really an issue to be concerned with ?

Thanks.

Directly below the center boss for the clutch actuation rod and lever assembly you can see a smaller boss which is the location of the ‘axle pin’ for the kickstart idler gear. The outside face of the pin should be flush with the back of the boss. Yours is recessed just a bit which means the pin and idler gear are getting loose from using the kickstarter and working their way into the transmission. Keep your eye on that and make sure it doesn’t move inward any more. In fact, I’d recommend you not use the kicker at all. There are reasons for and solutions to this issue. To much to go into here.

danielzink said:

Perfect illustration: http://www.largiader.com/articles/throwout/

I've got it now.

Along with Snowbum's advice to possibly replace the clutch arm pin (11 and/or 12 and 13) with a shoulder bolt and nylock nut.

Is that really an issue to be concerned with ?

Thanks.

Click to expand...

I just used a new clip and made sure it was seated correctly in the groove, never had a problem. Cheers.

A bolt and nylock nut are insurance. If the pivot pin comes loose and gets away from one of the cast aluminum ears that they are fitted in, the other one will break. Your 4 speed has a cotter pin that holds the pivot in place. It is drilled through the pivot ear and shows in your 3rd photo. When you pull that pin and extract the pivot pin, you will find a groove machined in the pin. This is where the cotter pin engages the pivot pin to hold it in place. When correctly assembled, it is fail safe.

Also, if you are not already a member, please consider joining the Airheads Beemer Club. http://www.airheads.org/

It would be the best $30 you ever spend to learn how to care for your "new" bike.

Na Cl K9 said:

Directly below the center boss for the clutch actuation rod and lever assembly you can see a smaller boss which is the location of the ‘axle pin’ for the kickstart idler gear. The outside face of the pin should be flush with the back of the boss. Yours is recessed just a bit which means the pin and idler gear are getting loose from using the kickstarter and working their way into the transmission. Keep your eye on that and make sure it doesn’t move inward any more. In fact, I’d recommend you not use the kicker at all. There are reasons for and solutions to this issue. To much to go into here.

Click to expand...

So....

You were right as well...

Replacing the seal on the clutch pushrod solved that leak....

Unfortunately this morning I came back out to the barn to find another "puddle"....albeit a much smaller puddle...but gear oil nonetheless...

Referencing 'axle pin' mentioned above...

I can manually push the pin into the transmission..

I realize that sated above you really don't want that pin moving forward as I did...but...

it's so loose I could take my magnet tool and draw it back towards the rear wheel to be flush with the case as it's supposed to be.

And upon laying there and watching carefully - I can watch gear oil build up around the the pin and start to form a small "drop"...

What's my next step ?

Thanks, Dan