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Old 01-02-2012, 09:22 AM   #1
ishirock OP
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Bmw r60/6 frone drum brakes

I'm in the process of restoring a 1974 BMW R60/6 airhead. The r60 uses 2 return springs of different tension on the front drum brakes so the brakes can be adjusted properly. Does anyone know if it matters which spring goes where? One side of the drum has an adjusting cam and the other side does not.
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Old 01-02-2012, 09:31 AM   #2
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http://www.realoem.com/bmw/showparts...02&hg=34&fg=11

does this help?
If so let us know which spring is which.
You can plug in your own chassis# for the best accuracy.
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Old 01-02-2012, 09:55 AM   #3
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Thanks for the link. I will see if i can see a difference in the spring design as shown in the diagram.
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Old 01-02-2012, 10:09 AM   #4
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It is very important which spring goes where-- the brakes are self-energiziing duplex shoe type and with the wrong springs situated the won't work right.

I don't recall off the top of my head, and the factory manual makes no sense: "fit strong springs on the lower and upper front brake shoes and weak springs on the lower and upper rear brake shoes ". Sometimes things get lost in translation...

Check Duane's website, he has a section on drum brakes:

http://w6rec.com/duane/bmw/index.htm

Or just order new return springs and note which # goes where. I'm thinking that the black (strong) spring goes to the front, but not sure.
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Old 01-02-2012, 10:47 AM   #5
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Thanks, found this on duanes website that explains installation and proper adjustment. Next time i will pay more attention when disassembling

Examination of the BMW motorcycle front drum brakes.

This is where I always start.* Slowly pull the front brake lever while watching the right side of the drum brake.* A few things should be observed.* The two arms should move about the same amount.* They should move easily and without any jerky motion.* The rear arm should move forwards first and when it stops, the forward arm should move rearwards.* You may find that one arm doesn't move.* The arm is sticking in the "on" position and that is not uncommon.* Reach down and try to move it by hand.* Move it away from the other arm.*

If you find that the front arm moves first and then the rear arm, that is because the springs are installed backwards.* That is not uncommon.* This observation tells you that in order to make the front brake work properly, you must take it apart and assembly it correctly.* It probably needs it anyway, so don't fret.

If you had the brake backing plate off and were to examine the front brake springs you would see that they are of a different diameter of wire.* The larger wire spring is stronger.* The rear arm moves first, because it's spring is weaker.* When that shoe contacts the drum, it stops moving and then the front lever with the stronger spring begins to move.* So the two levers move at different times to pull the shoes up against the drum.* One before the other.* The cam is the stop, or resting point of the lower shoe.* This cam determines the distance that you must pull before you get brakes.* It won't change the amount of braking action that you get, but it will change the amount of play and your perception of the brake.
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Old 01-02-2012, 04:14 PM   #6
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Old 01-03-2012, 04:30 PM   #7
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I was impressed with that old leading-shoe brake once I got it dialed in.... I can chirp the front tire easily... Mind you, not a 100mph brake, but certainly adequate for the riding I do (well, with the exception of rain+drumbrake, which can be scary for the un-initiated...keep that brake dried out as best you can!)

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Old 01-03-2012, 04:49 PM   #8
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I would add to that advise that is important to position the brake arms on the cam splines so that both arms are as close to almost 90 degrees as you can get them when the brakes are full on. I hope that makes since. That is the position that the brake arms offer the most leverage and it is entirely a mechanical system. Every bit of leverage you can get helps.

They can be set up to work pretty well if you don't expect to be able to moderate them like disc brakes. Drums are comparatively like an on/off switch. Especially twin leading shoe brakes. It's inherent in the way they work. Twin leading shoe drums overheat very quickly. Once they start to fade they are only going to get worse big time until they cool off.
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