R51/3 - updating brake system

[Micha]

The brakes are in a very poor shape and the drums are too thin to survive a re-bore in order to accept and machine new linings. It is too dangerous to ride her in such a condition and I parked her and froze the insurance, for now. I looked everywhere for new original or replica drums but could find none. So, a bit desperate and hopeless I am seriously starting to think about installing a non original, perhaps a bit more modern drum/hub brake assembly, and even an hydraulic one went through my mind. Let's say from an old Honda or so, something that will be much easier to source, and as a benefit, will supply her with much better stopping performance.
1. What do you think about such an idea?
2. Do you have any idea what brake assembly can fit? I will be glad to stay with the original rims, of course.
3. Anyone ever tried such an idea?
Thank you very much for any idea, input and so.

[808Airhead]

I think that is a horrible idea,you will "ruin" a beautiful machine that way. I have seen,on numerous occasions,perfectly good and usable drums on ebay.de. You can try to place a ad on www.ibmw.org ,I found someo0ne looking for a plunger rear fender on there,and sold it to them,so there are lots of buyers and sellers on there. Wait and find the RIGHT part instead of bodging you bike,history and your bike will love you for it.

[Darryl.Richman]

While I personally would not do this to my R51/3, it is your bike. If you want to ride the bike while you hunt for parts, perhaps you could just buy the whole front end from a smaller Japanese bike and fit it. Of course, it would be more obvious a retrofit than you are talking about, but also easier and possibly even cheaper. And you could have disk brakes. Make sure to get something for a bike that weighs at least the same as the /3, so it will be able to put up with the load. Good luck!

[Lincoln]

You might want to try one of the German parts suppliers. I've dealt with Uli's Motoradladen in Frankfurt several times for parts for my R69S. They've got a very good websites in English for both vintage and classic bikes. They provide excellent service and now that the euro is low their prices are very attractive, even including shipping. They respond promptly to emails in English and you can also telephone. Anyway, if you take a look at their catalog "BMW R24 to R69S - 1949 to 1969," p. 43, which you can download, it looks like they have what you need as part # 108 in the diagram. I assume, as on the /2 bikes, that the wheel hubs are interchangeable front and rear. But I may be wrong about this, as I haven't seen any of the plungers since 1964.

Hope this helps and doesn't send you off on a wild goose chase.

all best, Lincoln

[R68]

What you are proposing to do will only work if you use 1954 type plunger full hubs with the correct rear hub spline pattern, or Hoske hubs that are about unobtainable, but also with the proper rear hub spline. I could sell you a pair of ready-to-use '54 type full hubs/wheels, but I'd think the shipping to Israel would be too much money to be economical. I suggest as others above that you just keep looking for replacement half hub wheels. Incidentially, the Hoske's use a 4.5 wide shoe, the '54 hubs a 4.0 shoe (same as swing arm twin!), and the half hub 3.5cm...if you want to race your bike, with the Hoskes mounted STOP YOU WILL...

[808Airhead]

No,he is looking for the plunger 1/2 hubs,which are steel and hard to find I guess. I don't know if they repop these,but I know they have replacement splined centers available. As previously mentioned,I have seen some on German ebay.

[Micha]

Thank you all for your time and efforts.
Yes, I know that taking the bike through such a change will be a desecration of the bike, but as I mentioned before – I gave up in the run for replacement drums. Not on ebay.de they can be found or other parts suppliers in DE or Huggett at CH.
Anyways, the idea was only a thought, and I don’t think I will do it, finally.
There where semi drums once on eBay, but then again – I can not know for sure the condition and wall thickness, can I.
That’s the reason for looking after new ones.
Have a nice weekend all of you, and please jump in if any new ideas or so.

[Jim D 5112]

I thought you found someone who sold the drums and only need to have them riveted to the hubs. If so why don't you purchase them and have someone rivet them for you? I would think that finding the drums would be the hard part not the riveting.
Jim D.

[Micha]

The problem with the used drums is that “what you see is what you get”. They are mostly grit blasted and clean, but then again – I can not know the wall thickness. I also can clean and blast my original old ones and sell them on the web, but that would not be fair, would it.
Regarding the hubs – currently there’s no one over here in Israel that is skilled with riveting. Those guys disappeared from the landscape, unfortunately, and as these are my brakes where’re dealing with here, I can not take a chance.
I’m ok with complete items – drums riveted to hubs, if there are any out there I probably will purchase them immediately, but they have to be new items. NOS, replicas or AM – but new.

[jrapose]

If the drums are steel, how about metal spraying them ? it is a very common process and not terribly expensive.... the results I have seen look fantastic... or how about installing a sleeve ? they make them in all sorts of sizes and any good machine shop could install one, then grind it to the original size... just like they sleeve cylinders back to standard... just ideas... I sure would not ever replace the hubs with anything but original hubs....

Joel