Shep -
Welcome aboard !

OEM rotors warp on a steady basis, and BMW charges an outrageous price for them. Luckily there is an option, and with a beginner's tool kit and a little luck you can do all the work yourself. I highly recommend this, because you'll get to know your bike even better. And it's VERY important that you get to know the front stoppers really good, because your life may depend upon this quirky, yet ingenious design.

Your front brake is a highly out-dated, first-generation, single piston ATE, but it is capable of near modern stopping power if you'll do ALL the following....

• Buy a new rotor AND pads from British maker EBC. These are easily had from Ebay and Amazon sellers. It's not that the BMW version is "bad", it's that the EBC version is light years ahead and less expensive. And when we talk about brakes, being really better is a good thing. Download the on-line EBC catalog and be sure and get the correct EBC part numbers because they all look so similar.

The new rotor simply bolts to the wheel with the existing bolts. Torque of the holding bolts is important, but if you don't have a torque wrench, then simply try to get them all equally tight.

• Remove the fuel tank from the bike and behold the totally ignored brake master cylinder (m/c). It's quite normal for these to leak corrosive brake fluid all under that tank. Highly suggest a bath with hot soapy water at this point for everything under the tank. Not only do you want to buy the BMW m/c rebuild kit, but while it's removed you want to sand down all the rust on the frame and master cylinder body, and then protect the frame and m/c body with a nice coat of new black paint.

• You want to closely inspect the front brake cable for any signs of damage or fraying. If there is ANY, then the cable has to be replaced.

• Then you want to replace the stock flexible flat black rubber brake hose. You'll want the modern "stainless steel" reinforced flexible hose to take its place. These are very popular and the bike may already have one of these, so you'll want to inspect closely. If the hose is soft and rubbery, then then look online for "stainless steel" replacement hoses. Spiegler is one company that makes a good product. Spiegler USA Link You can get the new lines in black, but they'll be glossy in color and cannot be pinched closed with the fingers.

• Last repair part is to disassemble the caliper. One brake puck is held in by a safety pin looking clip which you may wish to replace. The single piston is removed by blowing compressed air through the brake fluid line. As with the m/c, wash all parts in hot soapy water and allow to dry in the sun, or until ALL water is GONE. You most probably do not need a repair kit for the caliper.

• The last bit (selection of brake fluid) is a personal choice. You can choose DOT4 (the OEM fluid) or the purple DOT5 Silicone.... BUT NOT BOTH. They absolutely will not mix ! The DOT4 is really good, but will eat the paint off anything it touches and will need replacing once a year forever. The DOT5 Silicone non-corrosive to paint and metal, and will not need annual services. Take your pick.

Before you can re-assemble either the caliper or m/c, all the internal parts MUST be wetted with the brake fluid of choice. Never re-assemble any hydraulic part dry.

I've found that "dry" systems do much better by being filled from the bottom, with the fluid being pump into the caliper "bleed nipple". This can be easily done with a new (clean) pump-type oil can ( Oil Can Link ) and a 4" length of 1/8" ID hose.

Total time for such a rebuild with all parts present is about 6 hours. Consult your workshop manual for dis-assembly, re-assembly and fastener torque details. If you have issues or questions we're always glad to help you, but please realize that most questions about details are best asked with a photo attached.

Hope this helps.

Wobbly - thank you for the step by step - parts are ordered. Dealer this year - myself next.
Thanks Shep65

Dealer this year - myself next.

Glad to help you all I can. I used to work in several dealership shops. Let me tell you about it. They are not in the business to loose money.

• The problem is that the mechanics doing the work weren't even born when that machine was made. The present BMW product line bares no resemblance to your bike, and so it doesn't matter how many times they've been to "BMW school" they've never seen anything like it before. So basically you'll be paying those guys to learn, and they can burn up a lot of clock learning. What's their hourly rate, $75 ?? $85 ??
• They are probably not allowed by the dealership lawyers to rebuild brake master cylinders and calipers (although valid, it's a 70's thing), so you'll get brand new units from BMW. That may total $450 just for parts.
• There's no way a dealership is going to offer you the optional use of DOT5, unless they sell Harleys. And BMW dealers don't.
• And if they do all the detail work I outlined, your bill will easily equal the purchase price of the machine.

If you cap the work at $600Can, only half the work and parts is going to get done. Then the bike is still not going to stop very good. So you'll end up finishing the job at home anyway.

The root issue is you don't own a "motorcycle", you own a 43 year-old "vintage vehicle". You might as well be taking a Model T to the local Ford dealership !! It's exactly the same scenario. The extreme age of the vehicle works against you.

Certainly wish you good luck, brother.

thanks again
turns out the managing mechanic is old school and spent this past winter resto mod - cafe style on an R80 thats in the shop on display - and - i know him from years ago. He recommended that I purchase the parts needed to avoid mark up etcetc. so at least there is some hope here. Need the dealer as its a safety issue at the moment and will look to setting up the garage for future works. Its a long road of knowledge required I know. Suggested using for part Motobins in the U.K. vs. the basket of U.S. suppliers not sure why.
D.

OK. Like was said, we wish you the very best of luck, and certainly hope all the repairs turn out with a happy ending.

Just so you know... These bikes were designed just so all the work could be done by the owner, generally using only the tools found in the tool kit. There's 1 or 2 updates on the parts, and some repair techniques that are almost lost to time, both of which the Club can supply. Other than that, 1970's BMWs are the easiest motorcycles to own and maintain.

You should also look up your local Airmarshal, even if he's across the border. Attending a Tech Event will definitely be an eye opener for you, and hopefully encourage your interest.

Above all else, please stay in touch, because we'd like to hear the end of this story.

IMHO, stick with dot 4-fluid! Read Snowbum on ATE brakes. I am rebuilding a dual disk ATE with handlebar mounted master cylinder for my old drum brake R60/6. It's already a mongrel with R75 engine so I'm not worried about sticking to original. I just want better brakes with the spoke wheels. Otherwise wobbly's advice is good.