brake caliper interchange

[stevenm]

Will the Brembo calipers from a 94-01 BMW R1100RT, R850RT, with dual pistons, well actually four pistons, fit the forks and discs of a 1983 R65? Anyone hear of this transplant being done, and if so, was it successful?

Thanks

[BubbaZanetti]

do a search for "oilhead brake" or "brake swap airhead" or something like that here (http://www.advrider.com/forums/forumdisplay.php?f=35)

i couldn't find anything in the history here

[bikerfish1100]

just talking off the top of my head, i would tend to think "no". or at least, "not easily".
here's why- The early 80's R65 is a bike much unto itself; it shares few parts with other airheads of similar vintage, let alone bikes from an entirely different configuration and decade (or 2).
ABS that (likely) existed on the oilhead bike would not adapt over to the airhead at all.
rotor thickness and diameter is likely different, so the entire system would have to come over. axle diameters are different, likely leading to rotor mountings being different. again, not sure of how things mic out, but points to consider.
job one is to look at caliper mounting possibilities. the lower fork legs are vastly different, so the calipers and rotors have to come over to the R65 and mount up to what you already have. If things don't readily line up, now you're talking machining work.
handy with CNC or custom fabrication work? if not, i suspect that the differences are too vast to justify the expense. some have grafted K bike front ends onto earlier airheads- that might be a more feasible possibility. but again, the R65 is something of a strange duck in the BMW flock (which is itself something of a strange flock in teh larger world of bikes).

[BubbaZanetti]

just talking off the top of my head, i would tend to think "no". or at least, "not easily".
here's why- The early 80's R65 is a bike much unto itself; it shares few parts with other airheads of similar vintage, let alone bikes from an entirely different configuration and decade (or 2).
ABS that (likely) existed on the oilhead bike would not adapt over to the airhead at all.
rotor thickness and diameter is likely different, so the entire system would have to come over. axle diameters are different, likely leading to rotor mountings being different. again, not sure of how things mic out, but points to consider.
job one is to look at caliper mounting possibilities. the lower fork legs are vastly different, so the calipers and rotors have to come over to the R65 and mount up to what you already have. If things don't readily line up, now you're talking machining work.
handy with CNC or custom fabrication work? if not, i suspect that the differences are too vast to justify the expense. some have grafted K bike front ends onto earlier airheads- that might be a more feasible possibility. but again, the R65 is something of a strange duck in the BMW flock (which is itself something of a strange flock in teh larger world of bikes).

from what i've seen, between threads on adv and friend's bikes, if you have a good micrometer, a vision and a way to get some metal fabricated, you can put whatever caliper you want on whatever bike you want, but that doesn't mean it's necessarily going to be all that much more effective than what's currently on there.

my friend put a 6 pot Tokico calipers on this 99' Triumph Thunderbird Sport. he did the research, figured out the swept area and had something fabricated. that may or may not work for you. from what i recall, the angle that the oilhead calipers have to be mounted to the airhead rotor, even with a special bracket, actually reduce the pad contact area and result in braking not much better than the old brembos. but then again, someone might have figured a work around.

[AnnapolisAirhead]

Another thought is to install 6-piston Tokico calipers (I think Kaw and Suzuki's use them). The is an article in the December 2008 Airmail issue of it being fitted to an Airhead GS. A guy named Guy (no pun) Henderson made a bunch of adapter kits to mount a left sportbike (back side of fork) caliper onto the right leg of a GS (front side). I just got off the phone with him ordering another product and he told me he made what he thought was a lifetime supply...until the Airhead article came out. His stuff generally is GS centric and he has no plans to made more (I'm thinking he has much bigger projects).

Anyway, custom things like this are possible but I would think there are huge liability concerns preventing a lot of commercialization of products. YMMV.

[boxermaf]

The R65 isn't strange or that different from the other airheads of the same vintages. The Brembos on the R65 are like the Brembos on the R80/R100 of the same years. The fork lowers are a bit different, so the mounting bushings and spacers aren't likely to be identical/interchangeable. Many of the R65 fork parts from the 81-84 era are the same as the R80ST forks, but there ARE differences. The R65 had 18 inch wheels when the other bike were still using 19 inch front wheels, so there are definite differences

I would say that if you can adapt the brakes from an oilhead to an 80's vintage R80 or R100, you could just as easily do it to an R65. That said however, I don't think this could be easily done for any of them. The airheads appear to have thicker rotors and no provision for the clearance needed for the ABS "gear" that is mounted with the brake rotor.

[vanzen]

The question is not so easily answered.
BMW provided 4-piston calipers in a number of configurations.
The first item to check is the spacing of the mounting tabs on the sliders –
108 mm for the old F08 Brembos.
Some later calipers as used on BMWs have this spacing, some do not.
The second consideration will be center to center width –
The caliper must be perfectly centered over the rotor.
Often the caliper 'mounting ears' will need either machining or spacers to accomplish this.
Finally, 4-pots are intended for larger diameter rotors,
the concerns presented above by BubbaZanetti must be considered,
and very likely will involve designing and fabricating mounting adapters.

ABS hardware can be removed, but ...
If the use of later 285 mm rotors is considered, the bolt pattern to fix them to the wheel is different (4 vs 5).
By 1990 – rotors were larger yet, and mounted to the outer edge of the (spoked) wheel hub
or the "spokes" of a cast wheel.
IMO, re-fitting any of the later rotors to the R65 wheel will be impractical at best.
If the use of wheel and rotors is considered, the differences in axle diameters will make it an impractical swap.
You'll find that it would be much simpler to swap an entire later model telescopic forks assembly.

For the ambitious, any caliper can be fit to any bike –
but then it's all about the amount of personal involvement to make it happen vs the results.

An example (http://www.r100.net/content/view/38/43/) of 2-pot to 4-pot conversion
on a (Mono) airhead with a 285 mm rotor. (sorry, it's in German, use babel-fish or the like if needed)

[lkchris]

Will the Brembo calipers from a 94-01 BMW R1100RT, R850RT, with dual pistons, well actually four pistons, fit the forks and discs of a 1983 R65? Anyone hear of this transplant being done, and if so, was it successful?

Oh, it's easily answered.

Not a chance.

Calipers are designed around the diameter of the rotor they clamp.

Early Airhead rotor diameter is not same as current BMW models, nor in fact the same as '85-on Airheads.

[CTellman]

My PO changed from double Brembo calipers to four pot Brembo Calipers. It was a dual caliper setup before the change. The original plumbing is used. To make it work he had to machine the flanges on the calipers where they bolt to the struts so they would be centered on the rotors. I do not know where the four pot Brembos came from but the brakes work great.
FWIW
Campbell Tellman II
'93 R100RT
:thumb

[vanzen]

HARRISON (http://www.billet.co.uk/index2.html?home.html~mainFrame) makes a 6-pot caliper for BMWs with a 280 mm rotor diameter.
However, their "application page" (http://www.billet.co.uk/index2.html?home.html~mainFrame) specifies "83-94".
Not sure why – from 1981 - 1983 rotor, caliper, and forks were the same.

Calipers are designed around the diameter of the rotor they clamp.

84 (?) saw a 5 mm increase in rotor diameter –
but the SAME F08 Brembo caliper was fitted ...
Fact is that Brembo F08s were fitted to various makes from Ducati to Moto Guzzi –
and a variety of rotor diameters.
In spite of the fact that a larger diameter rotor provides more "stop"
and sheds heat better than it's smaller counterpart,
diameter of the rotor is not so critical –
Even as swept area and placement of the caliper is.

Having said that, the great advantage of multi-pot calipers
is not the addition of pistons or an increase of piston area
but rather will be that a larger diameter rotor with a narrow swept area can be used

– which means a significantly lighter weight rotor and less unsprung mass –

To provide the same stopping force with a single-pot
will require a rotor with a wide swept area – and the additional weight of it.
Besides all the fitting and alignment issues,
swapping multi-pots to the old 280 mm does none of this.

IMO. The best way to improve braking on the old boxers:
Quality pads.
New hoses.
MC in perfect condition.
Careful adjustment of the calipers (if ATE).

and then, if you want to throw money at it ...
Iron rotors.
And a change of MC size.

[boxermaf]

I will add that swapping the (admittedly old) rubber brake lines for new braided stainless steel on my LS made a BIG difference in stopping power. I've got some new organic pads in to try next..

[AntonLargiader]

Oh, it's easily answered.

Not a chance.

Calipers are designed around the diameter of the rotor they clamp.

Sounds great on paper but it's unsupported by reality. The R100R caliper for its 285mm rotor is the same part as the R1100RS caliper for the 305mm rotor.

The real problem with the proposed conversion is the bolt spacing on the fork leg which is greater on those earlier bikes.