1976 R75/6 Troubleshooting

[Jimijam]

I recently acquired a 1976 r75/6 from a friend. It has only been sitting outside for a season or 2 but suffers from some corrosion. 1.does anyone know where I can obtain a shop manual? The owners manual is great but I need more information. 2.Yesterday I had the front tire off to fix the brakes because I couldn't move the tire, I cleaned up the pads with a wire brush and adjusted the calipers but now am having trouble getting the tire back on. On my parts list so far is new brake pads, new battery, and new fuel lines. 3.How do I find a stock seat?. I'm not super mechanical but am trying to learn as I go and would much appritate any instruction. When I first pulled the bike out I tried turning the ignition and the instrument cluster dimly lit, but it wouldn't start, I couldn't even hear the starter doing anything. Suggestions?

[Deleted User 62]

Needs a new battery, most likely. Haynes and Clymer manuals are both good. Good deals to be had on Amazon.com, with free shipping. New stock seats from BMW are expensive. There are several aftermarket options for roughly half the price.

[Ken in Oklahoma]

. . . 2.Yesterday I had the front tire off to fix the brakes because I couldn't move the tire, I cleaned up the pads with a wire brush and adjusted the calipers but now am having trouble getting the tire back on. . . .

Welcome to the forum Jimijam.

I'll deal with question #2. On your R75/6 you have a unique caliper, not seen on other motorcycles, which we around here usually refer to as a swinging ATE caliper, that is, it swings on the fork leg, the brand name is ATE, and, well, it is a caliper. I'm curious how you might have gone about "adjusting" it.

By removing a cap at the bottom of the caliper mount you will uncover a bolt head. Turning that head rotates an eccentric shaft. That is what you do to adjust the caliper. The idea is to adjust the eccentric until both caliper brake pads lie flat against the disk. Virtually all of the manuals, BMW or aftermarket, will have you marking the disk with a Marks a Lot, then squeezing the brake lever and inspecting how evenly the marks are removed as you turn the wheel. I don't like that way of doing it.

What I like to do is to squeeze the front brake lever and then hold the pressure with a large rubber band (made out of an inner tube) wrapped around the clutch lever and handlebar. Then go down to the bottom of the L/H fork tube and rotate the eccentric until you discover where the caliper "wants to be". Where it wants to be is with the brake pads flat against the disk, and that is exactly the right place for them to be. Put the cap back on the fork leg, remove the inner tube rubber band and you're good to go.

There's a lot to learn about your airhead, but there's a lot of knowledge out there on the internet to be had. Two of my favorite are our own Duane Ausherman's site at http://w6rec.com/ and snowbum's site at http://bmwmotorcycletech.info/

Ken

[Airbear]

What I like to do is to squeeze the front brake lever and then hold the pressure with a large rubber band (made out of an inner tube) wrapped around the clutch lever and handlebar.

Ken (probably feeling momentarily embarrassed in Oklahoma) meant to write 'brake lever' here.

Hullo Jimijam - welcome aboard.
To get the wheel back on you will probably need to pry the disk pads apart, pushing the caliper piston in so the disk fits in. Then go through Ken's procedure to adjust the brake. It will be worthwhile to remove that eccentric 'bolt' for cleaning and greasing, too. These brakes are troublesome, and frankly, are a very silly design - BMW's first attempt at a disk brake, using a hybrid cable/hydraulic system. You will need to remove the tank to top up the master cylinder or replace fluid, and you are likely to find that brake fluid has leaked all over the top frame tube. The kit to replace the sealing parts is expensive, the master cylinder may have suffered pitting, and when everything is perfect the braking is crap anyway. The good news is that you can replace the master cylinder with a handlebar mounted setup from a later model, and this is highly recommended.

Your situation is similar to mine in 2002, when I brought my 90/6 home in a trailer. It had issues that needed immediate attention - sticky forks, buggered front brake, tuning and electrical issues, and I knew almost zero about the care and feeding of old BMWs. The first thing I did was to order the Clymer and Haynes manuals. The Clymer is the better one - it is bigger, more comprehensive and has step-by-step procedures with pictures. The Haynes has much better wiring diagrams. Both manuals are known to contain errors.

The 75/6 is a great bike. It will make you grin when it is going (and stopping) properly. They are comparatively easy to work on - satisfying, too. Good luck with everything.

[Ken in Oklahoma]

Ken (probably feeling momentarily embarrassed in Oklahoma) meant to write 'brake lever' here.

Yikes! I can't believe I did that! And it gets worse. I think I might have sprained something trying to think of a fitting, funny, and uniquely clever retort. Normally that comes pretty easy to me. But all I'm getting is a headache now.

Does this mean I've lost my touch? And you, Airbear, you aren't helping with that gentlemanly, thoughtful, sensitive post.

And me being a gentleman too, I can't resort to disgusting crudities!

Sigh! It ain't easy being:

Ken in Oklahoma

[Jimijam]

Thanks y'all, I'll be posting more info tomorrow.

[Roy Gavin]

The old owners manuals actually give instructions for adjusting the front brake- least my R75/7 does.

First you remove and lube the caliper pivot pin to ensure it is turning freely.

Then you adjust it approximately with a screwdriver, the finish off the adjustment by applying the front brake as hard as you can, which should bring the pads into the required adjustment.

And if it doest,it is unlikely that the brake will work as well as it can.

[Jean]

Look for replacement parts, including a seat, on the IBMWR website; things for sale or classified or whatever...Lots of people list good stuff there.
What happened to the seat? Was it all torn-up?

[painter.724]

I will probably make a few people cringe on here , but when all else fails , a good search of EBAY can provide some decent parts and prices.

[Airbear]

Ken (probably feeling momentarily embarrassed in Oklahoma) meant to write 'brake lever' here.

Yikes! I can't believe I did that! And it gets worse. I think I might have sprained something trying to think of a fitting, funny, and uniquely clever retort. Normally that comes pretty easy to me. But all I'm getting is a headache now.

Does this mean I've lost my touch? And you, Airbear, you aren't helping with that gentlemanly, thoughtful, sensitive post.

And me being a gentleman too, I can't resort to disgusting crudities!

Sigh! It ain't easy being:

Ken in Oklahoma

Ah now Ken, you know I agonised about pointing that out. I could have left it. Anybody reading it would know it was a simple mistake, utterly trivial, not worth mentioning. But then I thought, "Hey, Ken doesn't make mistakes." What if Ken blunders upon this post at some time in the future and reads it for old time's sake - he would be deeply troubled, mortified, in fact. And he would be wondering why none of his imaginary friends here on the forum bothered to point out the discrepancy. It took courage, but I gritted the few remaining teeth and wrote the fateful words. Then with heart-pounding trepidation, hit the Submit button.

Ken, let me just say that your touch has definitely not been lost, in Oklahoma.

ps: I trust that our new member, Jimijam, will feel some pride in the knowledge that his first thread here experienced 'Boxerworks Drift' within the first few posts.