Removing K75S ABS1 System

Wanna talk BMW K bikes? Here's your home.
Post Reply
Bill Smith
Posts: 18
Joined: Tue Oct 05, 2010 1:31 pm

Removing K75S ABS1 System

Post by Bill Smith »

The ABS on my 1991 K75S no longer works, and after getting three possible answers from three dealers, I've decided to remove the system and run standard brakes.

My question is in regard to replacing the brake lines. I'll keep the existing master cylinders and calipers, if anyone has done this, did you use stock, non-ABS brake lines, or was a custom set required?
Wobbly
Posts: 300
Joined: Mon Aug 07, 2017 8:48 pm

Re: Removing K75S ABS1 System

Post by Wobbly »

Not a fan of ABS, having worked on a 1100RS for 18 months now. Having replaced lots of BMW brake lines, please allow me to suggest a method...

You'll want to download a Fragola parts catalog from their site. (There are many other makers too, I just use Fragola.) Look at the section on AN-3 stainless steel covered Teflon PTFE hydraulic hoses and fittings. I suggest their hoses with black vinyl outer sheath. All BMWs use only 10mm x 1.00 threads.

Plan the shortest route from the master cylinder to the caliper, front and rear. The idea is to replace as many rigid steel lines with a single flexible hose. A single hose bleeds easier and flexes over a longer distance, thereby lasting longer. These hoses are much more pressure tolerant, thereby making a noticeable improvement in braking efficiency.

On my 1988 RS I was able to run a single hose from the front M/C all the way to the top of the caliper. That cut out 2 steel tubes and 2 flexible hoses. I left the steel tube that connects the 2 calipers in place. In hind sight, I should have run the new hose to the RH caliper, and moved the bleed nipple to the LH caliper. That would have reduced the hose length by 12" and made routing even easier.

Image

Image

My 41" hose was a special order AN-3 with black sheath, pn 312-1-3-41. Straight on one end, 3/8 banjo on the other. On the straight end (used at the handlebar M/C end) I screwed in a stock AN-3x3/8 banjo fitting, pn 650103. You can clearly see the longer and slimmer factory installed banjo worked great on the Brembo caliper end.

I ordered all this from Race Part Solutions at 561-375-6277.

I believe this gives me the exact hose I want at a price that typically saves me money over the pre-made brake line kits from motorcycle suppliers. And the black sheath makes it look completely stock. I'll gladly answer more questions on this subject.

All the best. ;)
After 20 years as a professional bike mechanic and 30 years as an engineer I know just enough to be dangerous !
Bill Smith
Posts: 18
Joined: Tue Oct 05, 2010 1:31 pm

Re: Removing K75S ABS1 System

Post by Bill Smith »

Thanks!
Post Reply