1975 R75/6 Refresh Projects

[20774]

One of our members, Mike V., has put together a discussion on his efforts to replace bearings in his snowflake rims:

http://forums.bmwmoa.org/showthread.php?46970-Wheel-Bearing-Replacement-Snowflakes

He's also working closely with Snowbum on this, so maybe in time, additional info will be released.

On the /6 wheels, you have the advantage of having steel innards...the snowflakes and /7 rims have aluminum. You can learn a lot about your bearings but reading what Duane Ausherman has written here:

http://w6rec.com/duane/bmw/wheel_bearing/

 

[mcrenshaw]

Brook, I know Mike V. pretty well and he's one of my go to guys. My R90/6 bikes both have wire wheels. I've read Snowbum and Duane's write ups a couple of times but still can't visualize everything I think I should. Did a search on Micapeak and no joy there either. So I'd be very interested in seeing your report when you do have a chance to write it.

 

[barryg]

As usual your thread is first rate. I really enjoy watching the progress and will continue to follow your progress. Probably my favorite thread. I gotta thing for 70's airheads. One question, did you acquire the bike with the lightened flywheel or did you lighten it yourself. Your opinion of it would be nice. Barry p.s. You've probably already discussed it and I missed it.

 

[20774]

MCrenshaw -

I suggest you look up Boxers by Bruce...he's only 30 minutes from you:

http://www.ntnoa.org/bruce.htm

See what he can do for you. He might not "teach you" but maybe you can watch and do the bearings yourself next time?

I was fortunate to get my /7 bearings done at a Tech Day in North Texas some years ago. Several good wrenches were there, including Bruce, who helped walk me through changing my bearings and setting the preload. I don't remember diddly from that session, but at least somethings left an imprint. One was how we had to heat my hubs...again, aluminum hubs on my /7. I'm not good with fire, so I'm glad people were watching and helping.

 

[mcrenshaw]

Kurt, I know Bruce very well and to bring you up to speed, he closed up shop at the end of January. Told me I could have his "Boxers By Bruce" sign over the door to his shop, but where ya gonna put it. I'm not sure if he's moved yet but he was pulling up stakes and moving to Las Vegas for his Golden Years. He's a good guy and we miss him. - Mike

 

[20774]

Mike, I did not know that. Bruce posts here every once in a while...always spot on with his posts. Hope things go well for him out west.

 

[brook.reams]

Lightened Flywheel

As usual your thread is first rate. I really enjoy watching the progress and will continue to follow your progress. Probably my favorite thread. I gotta thing for 70's airheads. One question, did you acquire the bike with the lightened flywheel or did you lighten it yourself. Your opinion of it would be nice. Barry p.s. You've probably already discussed it and I missed it.

Sorry for the tardy reply. As the site doesn't send email notices of new postings, I have to wander by to find them.

I raced the bike the summer after I bought it and lightened the flywheel to improve shifting at high RPM and low gears. It reduce the "thunk" and the tendency to upset the suspension when down shifting before heeling it over for a corner. IMHO, the shifting was smoother, particular down shifting, at high RPM. At "saner" RPM, the stock flywheel wasn't really a problem.

ASIDE:
In my first race at the track in Pueblo, CO, I bent the push rods when I downshifted a bit too soon and sent the RPM to about 8500. There was a nice "tat that tat that" on the ride all the way back to Denver at the end of the day. I installed racing push rods (titanium I believe) and I never bent one again. Perhaps I got a bit better at down shifts and avoiding over revs, but IIRC, there were a couple occasions the tach was pushing 8000. Ah, to be young and foolish again instead of the fool I am today

 

[brook.reams]

1975 R75/6 Project: Replace Left Handlebar Control Switch

Folks,

I had to replace this switch and decided to document "what wire goes where" inside the headlight shell on the circuit board and to the ignition switch and headlight relay.

I also explain how to map information found in various wiring diagrams to the labeled areas on the circuit board. There are some places where things got confusing for me in going between the various published wiring diagram(s) and the circuit board inside the headlight shell, so I hope this material helps others avoid being confused..

You will find this write-up here:

• 61 BMW R75/6 Replace Left Side Handlebar Control Switch

For those at "Das Rally", if you need to replace your switch, you won't need any of this information as you are surrounded by a vast store of Airhead knowledgeable folks. But, when you are on your own back home, ah, then this may come in handy.

Here are a couple pictures from the write-up.

<a title="Broken Switch" href="https://www.flickr.com/photos/brook-reams/28175020641/in/album-72157670243913412/"><img src="https://c2.staticflickr.com/9/8783/28175020641_dae0ed02c6_z.jpg" alt="Broken Left Side Headlight Switch" width="640" height="426" /></a>
Broken Left Side Headlight Switch

<a title="New Switch Assembly" href="https://www.flickr.com/photos/brook-reams/27972121590/in/album-72157670243913412/"><img src="https://c7.staticflickr.com/9/8728/27972121590_f09c9fbc17_z.jpg" alt="New Switch Assembly with (8) Wires" width="640" height="426" /></a>
New Switch Assembly with (8) Wires

[<a title="HeadlightWiringBoard-MAXBMW_Edit" href="https://www.flickr.com/photos/brook-reams/28045728730/in/album-72157670243913412/"><img src="https://c3.staticflickr.com/9/8569/28045728730_ba419f5831_z.jpg" alt="Wiring Circuit Board Inside Headlight Shell [Source: MAXBMW]" width="426" height="640" /></a>
Wiring Circuit Board Inside Headlight Shell [Source: MAXBMW]

<a title="Green/Black Wire Is A Ground Wire-Goes to Brown Section of Circuit Board" href="https://www.flickr.com/photos/brook-reams/28253124495/in/album-72157670243913412/"><img src="https://c8.staticflickr.com/8/7675/28253124495_87a709b639_z.jpg" alt="Green/Black Wire Is A Ground Wire-Goes to Brown Section of Circuit Board" width="640" height="426" /></a>
Green/Black Wire Is A Ground Wire-Goes to Brown Section of Circuit Board

 

[brook.reams]

1975 R75/6 Project: Install Wire Harness

Folks,

I have documented installation of the main wiring harness on this project and posted it here.

• 61 BMW R75/6 Install Wiring Harness

I made a short video to show the routing I used and where the front turn signal, neutral switch, voltage regulator, starter relay, coils, Dyna III electronic ignition, oil pressure switch, neutral switch and rear tail light/turn signal wires go.

It includes links to two other write-ups: The first describes the wiring connections to the diode board, alternator, points, and starter motor when I replaced the timing chain; The second write-up shows the details about the circuit board connection areas inside the headlight shell and how to connect the right handlebar switch inside the headlight shell.

• 11 BMW R75/6 Replace Timing Chain, Crankshaft Sprocket, Nose Bearing
• 61 BMW R75/6 Replace Left Side Handlebar Control Switch

My hope is that these write-ups will be helpful when you are installing these components and/or putting a wiring harness back into your bike.

Best.
Brook Reams.