K75 drum to disk brake conversion?
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3,268 Posts
K75 drum-to-disc conversion
You might check out www.ibmwr.org tech pages. They've been around a lot longer, and have a wealth of K75 knowledge there.
You might check out www.ibmwr.org tech pages. They've been around a lot longer, and have a wealth of K75 knowledge there.
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100 Posts
Ya know, I seem to remember that BMW went through at least 3 different versions of the rear brake rotor. I believe that they had problems with warping.
If you call MAX BMW in New Hampshire and ASK FOR RUSTY in parts I'd bet anything that he could help you. He's been a parts guy since the K bikes came out. I'm serious about that. He really knows his stuff. If anyone could help you with this project he can. Give him a call.
Not sure what you don't like about drum brakes but here are a few things to note.
The had lots of complaints about rear drum squeal.
There were some things done to the drum brakes in 1986-86. The shoe springs would vibrate and cause a squeal. To quiet this they came out with dampers for the springs. ( 34 21 1 457 602 55mm long or 34 21 1 457 572 70mm long) If that didn't work they had updated shoes with relocated spring attachment points. ( 34 32 2 242 401 and 34 21 1 242 402 ) These came out in 1986 and you can tell if you have it if your shoe is stamped with an 86 and 10 dots around it for the month of October. Supposedly these produced more spring pressure to the damping block. These were factory installed on the 1987 models.
If you mess with the drum brake shoes. Keep in mind that BMW didn't introduce asbestos free brakes shoes for the 1981 and up bikes until 1990. It was part number 34 21 2 310 523 and also included a rubber absorber for the rear return spring in order to reduce the vibration of the spring which caused a squealing noise during braking.
If you call MAX BMW in New Hampshire and ASK FOR RUSTY in parts I'd bet anything that he could help you. He's been a parts guy since the K bikes came out. I'm serious about that. He really knows his stuff. If anyone could help you with this project he can. Give him a call.
Not sure what you don't like about drum brakes but here are a few things to note.
The had lots of complaints about rear drum squeal.
There were some things done to the drum brakes in 1986-86. The shoe springs would vibrate and cause a squeal. To quiet this they came out with dampers for the springs. ( 34 21 1 457 602 55mm long or 34 21 1 457 572 70mm long) If that didn't work they had updated shoes with relocated spring attachment points. ( 34 32 2 242 401 and 34 21 1 242 402 ) These came out in 1986 and you can tell if you have it if your shoe is stamped with an 86 and 10 dots around it for the month of October. Supposedly these produced more spring pressure to the damping block. These were factory installed on the 1987 models.
If you mess with the drum brake shoes. Keep in mind that BMW didn't introduce asbestos free brakes shoes for the 1981 and up bikes until 1990. It was part number 34 21 2 310 523 and also included a rubber absorber for the rear return spring in order to reduce the vibration of the spring which caused a squealing noise during braking.
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76 Posts
Thanks for the advice.. I think the conversion to a disc rear brake might be a project when the rear fianl drive goes kaput..
Until then, I think the rear drum brake's peformance, even though less than dragging my feet on the pavement, will have to be sufficient.. brakes? I don't need no stinkin' brakes..
Until then, I think the rear drum brake's peformance, even though less than dragging my feet on the pavement, will have to be sufficient.. brakes? I don't need no stinkin' brakes..
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11 Posts
Yes, a conversion is possible. You are correct, you'll need the final drive, rear wheel, rear brake disc, caliper, brake pedal, rear master cylinder, rear brake line, rear brake switch, and possibly the right side footpeg plate, but I am not 100% sure on that. The rear disc brake on these bikes is not overly powerfull, but I suspect it is a little better than the drum. Good luck with the project!
Mike
Mike
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100 Posts
MAX BMW is having a big "garage sale" on the 12th in NY. 4000 sq ft of old bike parts
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