Alternate Calipers. In fact brakes in general

[Tony Smith]

I was looking at a 2000 year R1100 this morning that had some very tasty looking 4 spot Brembos on it.
 
Now I didn't have a tape measure or a vernier in my back pocket (I was on my way to do something for my day job) but my calibrated eyebrow reckoned that they would go very close to fitting the R65 fork leg.
 
The spacing on the front wheel looked pretty similar too (again note absence of any precision measuring instruments before shooting me down).

Does anyone have actual knowledge of how close they go to fitting? Or more to the point, can they be fitted by modifying the caliper only (that is no mods to fork leg).

If they do fit, I reckon a pair would look very trick on an R65 and would usefully improve braking.

My second flight of fancy is that I have accumulated virtually an entire spare rear disc brake setup for an R100. I also have a nice gold R100 disc rear wheel.

By now you can see where I am going with this.  Now I am here to tell you that having ridden both drum rear braked BMWs and disc rear braked BMWs that over all I reckon the drum works well enough and it probably less overall hassle than a disc set up. But, I've got the bits and it would look a bit different.
 
Last silly question from me today. The last time I needed new disc rotors for the R100 (in about 1984 or thereabouts), the local council storage yard suddenly found itself missing a very nice 100 year old meonite cast iron manhole cover and shortly thereafter my R100 had new disc rotors. Sort of magic in a way.

The last couple of days I have been looking for replacement rotors as I need at least 1, and if I decide to go dual front discs 2, and if I carry out my silly plot to go with a rear disc, 3 rotors. The world seems to have gone mad with the price of the things. My carriers are perfectly usable, all I need is the rotor - ebay seller want US$245 each. Motobins is almost as silly, but at least theirs is a complete unit. Does anyone have a source for good old cast iron disc rotors? Making my own is not really an option this time as I nolonger have access to a mill or a shaper capable of doing the job and the finish of cast iron off a lathe is simply not going to be good enough.

[Bob_Roller]

One of our members here Julio, went through this on another model BMW bike calipers, can't remember which one it was .

He couldn't make it work without having the mounting area on the caliper machined down to around half it's original thickness .

The brakes on the R65 is the only area, where I think a great improvement could made with the right combination of calipers and master cylinder .

When I go from my oilhead to one of the R65's, the brakes aren't confidence building .

[Tony Smith]

The last time I needed new disc rotors for the R100 (in about 1984 or thereabouts), the local council storage yard suddenly found itself missing a very nice 100 year old meonite cast iron manhole cover and shortly thereafter my R100 had new disc rotors.

A friend of mine has pointed out that the correct term is "Meehanite" and that it was originally invented by a company still in existence today (http://www.meehanite.com ) to make cast iron pistons for cars.
 
Thing is I clearly remember that the cast iron manhole cover I liberated said "meonite" and was cast by the Imperial Foundry, Toowoomba in Queensland. Now the Imperial Foundry no longer exists, in fact 10 minutes research suggests it ceased to exist shortly after WWII. I suspect the naughty fellows were making meehanite cast iron (which is correct for manhole covers that have traffic over them) and not paying royalties to the inventor.
 
For what it is worth meonite/meehanite is prized for disc brakes because of its ease to machine (relative to most cast irons of course) and its friction characteristics. When you score a nearly 100 year old manhole cover you can be reasonably sure that the casting as done all the stress relieving its going to and that your new disc rotors are not about to crack on you the first time you sue them.

[Tony Smith]

I did PM Julio, but have not yet got a reply.
 
I have however been reading Snowbum's website and I now know that the 4 spot calipers from (at least) a 2000 year model oil head will fir the mounts on an R65. with two pre-conditions.

The calipers need to be reversed, i.e. left caliper goes on right fork leg.
Approximately 4mm needs to be machined from the mounting pads to bring the calipers central to the discs.
[/list]

Snowbum makes the point that whilst these brakes will (when matched to the correct master cylinder bore) greatly improve braking on an R65, that due to the reversing of rotation and placing the small piston in the "lead" roll, that strange wear patterns on the pads may result.
 
I've had a think over the weekend and have decided that what I really need is a mill. Making a pair of 4 spot calipers is not difficult , if I proceed I will have a look around for some cheap and readily available automotive disc pads and make some alloy calipers to suit.
 
Along the line I will make the decision whether to machine from billet or proceed by way of a casting - if by way of casting then that at least raises the possibility of a small production run.
 
First I need a mill, second I need to retain enthusiasm.

[Burt]

Tony,  

Try Metalgear in Brisbane.  metalgear.com.au

I have not used them but others have.  

Cheers, Dave.  

[Julio A.]

Hi Tony Smith, I sent you a message.
Sorry I wasn't able to reply as quickly. I'm kinda caught up with term end finals in Strength of Materials, Fluid Dynamics and freakin' Theology.

I actually already have the resources I need for fabrication, I just need a little downtime to mock up the adapter plates. But since I'm really busy in school work and I'm using my R65 almost everyday, I just really don't have the time to do it right now.

When I'm taking Machine shop this year; I'll have lots of quality time with the school's CNC machine. I'll use the adapter plate design I have in mind for my term project.  

[montmil]

Julio, Don'tcha just love it when a plan comes together!