‘71 R75/5 poor front braking

[pomurchu1]

I am the new owner of a ‘71 /5 with just under 30K km. It’s in great shape cosmetically and fires up with no choke every time. There are some issues to be addressed but the first one I need to tackle is the front drum brakes.

The front has very little stopping power I adjusted them but even pulling them my hardest I can still rotate the front wheel fairly easily by just pushing on the handle bars with my legs on the ground. I am new to drum brakes but this seems very wrong. The back brake (also drum) has way better stopping power. I feel like I could lock it up.

I took a look at them when I changed the tires. Plenty of meat left in my opinion but are they glazed looking? Should I just buy a new set of pads?
Sorry about the poor quality pics. They are screen shots from a video I took but looks like I can’t post the video.

 

[ebeeby]

What instructions did you follow to make the adjustments? Did you grease the pivot points?

 

[omega man]

I don’t know much about Airheads but back in the day, for extra pressure on the brakes on a drum brake assembly……
Sometimes with a pull on the brake lever, we could still rotate the wheel- by hand.
Does it have the splined lever that the cable attaches to? We would move the lever on the splined shaft to increase cable pressure.
Sometimes a “cam” had gone too far and flipped over limiting the travel.
You mentioned the bike was new to you, a couple of things that you can check while waiting for better suggestions.
OM

 

[PGlaves]

If you are certain they are properly adjusted so that the shoes have full contact with the drum then it is time for new shoes. Those on the bike are most likely more than 50 years old and if so they have probably hardened beyond usefulness. If that were my bike I would try to find a brake shop that can reline the shoes with new material. I suspect anything in BMW's supply chain will be quite old.

 

[20774]

Brook Reams has a write up on refurbing the front brakes on a '73 R75/5. Worth a read:

34 BMW 1973 R75/5 Install Front Brakes

Now that I have the front forks aligned and installed, and you can read about how I did that here, 31 BMW R75/5 Install and Align Front Forks it’s time to put the front brakes back together a…

brook.reams.me

 

[pomurchu1]

Thanks all - and especially thanks 20774 for the link to the write up. The cams are way off for starters based on the template in the writeup - don’t even need to put it on the backing plate to see how far off they are. I guess I know what I’ll be doing for the weekend.

 

[20774]

Nice! Hopefully that will get you started in the right direction.

 

[pomurchu1]

I took off the wheel and drum. It was pretty clean inside so I didnt remove the springs (they are installed correctly based on the actuation described in Duanes article. I have a couple of questions.
1. Does anyone know where to find Duanes article that still has the pictures? I am using this one but the pic links are broken: https://w6rec.com/5-front-drum-brake-adjustment-and-repair/

2. With the backing plate off and on the bench I put the arm template up against the backing plate. The forward arm was way off - it was actually in the "Brake On" position- so I removed the forward arm and put it in the "Cable not connected" position. However - The locknit/4mm allen adjustment cam also influences the position of the arm. Should this adjustment cam be relaxed - ie not supporting the shoe while finding the correct position for the arm on the splines?

 

[20774]

1. Are you familiar with the Internet Archive or Wayback Machine? If you use it with that URL, you can find an archived page with pictures.

 

[pomurchu1]

1. Are you familiar with the Internet Archive or Wayback Machine? If you use it with that URL, you can find an archived page with pictures.

Never even heard of it but sure enough there was a version saved on Feb 6 2023 that has the pics. Thanks again!

 

[m_stock10506]

I think this link is correct. It should be a video on how to adjust the front drum brake. It was very helpful to me when I had to replace the front brake cable and set up the brake again.

 

[pomurchu1]

Thanks for the inputs all. After completely rebuilding the front drum and following the procedures and video recommended here my front brake is excellent now. I have to say it’s stopping power is on a par with my single front disk brake motorcycle. Amazing difference what a proper setup can do to these brakes.

 

[20774]

Yeah, the front brakes are the first generation of ABS braking!!