Despite the presumably negative effects (more moving mass in particular) I would like to explore the possibility of adding a disc brake to a 4-lug monolever (or 3-lug for that matter). I could imagine that using the dual-shock beveldrive housing with a plugged thru-hole should work, it has all brackets for the rear m/c. The brake disc attachment is to the ring gear I presume, so the 4-lug ring gear (in my case) would need to be modified accordingly. Can the rear drum stay where it is? Or does the attached brake disc moves it out too far? Do you need to lace the rear rim to the right to compensate for it? Or worst case, do you need to machine a special hub to allow spoked wheels AND disc brake? Can you take the dual-shock ring gear and weld/bolt an adapter to it for the brake disc and the drumbrake hub? I would love to explore the possibilities from a "Sure, it can be done" perspective first. For general information regarding the subject, I first need pictures of the rear disc brake setup of the 81-on RS's and RT's (and may be others) that show the setup from all possible angles. Email works for me. My Dad had a 1983 RS with that setup but I never bothered looking at it in detail. Call me nutz, you know I'm good for it.
Iffen it had been anybody else, my first comment woulda been... w h y ? But I have learned not to ask......... just wait and see........
There is a thread somewhere with instructions... I want to say that the K bike internals can be put onto the para final drive with little trouble...
I must be missing something here. The twinshock housing doesn't hold the bearing sizes to support the wheel loads. There are all kinds of incompatibilities between the monoshock/Monolever and twinshock internals. What exactly do you mean?
That IS indeed the type of discussion I need: so the twin-shock housing can't be used as it hasn't got provisions for the big bearings. That is killing the deal for the twin-shock beveldrive housing ... until proven that the housing can be modified to accept the big bearing. There must be enough material to machine the seat for the bearing. Pictures of open twinshock beveldrive anyone?
If the bolt patterns match, I would look at using a K75 disk brake cover on a mono housing. If not, but the swingarm bolt-up matches, you may be able to put your old gearset into the K housing. Or have the K pinion modified and use the whole K final drive. I don't have a mono housing here to compare. I have twinshock, K, all sorts of Paralever and even an R1200C housing.
Good evening from Germany! Now this IS a very interesting conversion project! I have been considering this for a while, since I saw pictures of mono housings modified to accommodate a rear disk brake. I have tried to put a K-drive onto a mono swingarm, but the bolting pattern does not fit. The K disk brake cover does not fit on a mono housing, either. One ingenious bloke (German of course ) modified the mono swingarm to the bolt pattern of the K housing, and some clever Japanese guys (ritmo-sereno) race an R 80 which in its initial stage had a Brembo rear caliper attached to a modified mono housing carrying a 4.5 x 15 cast wheel (the one used on the R 1100 and The K 1100)- however, their pictures do not reveal the exact dimensions of the home-made adapter for the Brembo caliper. I have also seen pictures of a heavily modified Guzzi which had a BMW mono swingarm plus mono rear housing carrying a disk brake arrangement plus the above mentioned BMW 3-spoke wheel. Conclusion: It can be done! Why do it? in a street bike you will get a rear brake that works, and you have a very special motorbike. Looking foward to continuing this thread! Alfons
From another source I got this in a nutshell: - use R-4-lug-monolever as directed (!) - add K75 rotor (plug 'n play) - weld bosses for rear m/c to R-bevel - use R1100GS rear wheel due to bolt pattern and hub width - go ride (with a couple of tiny little problems with e.g. rear brake pedal etc) Now that sounds way too easy but comes from a guy that refurbishes R- and K-beveldrives for a living! Another very weird idea: bolt a swingarm extension to the R-swingarm that is wide enough to accommodate a second u-joint and go from there. Now THAT goes towards a paralever design approach which, if I really wanted it badly, would do via GS paralaver and R1100GS disc brake cover etc, the NORMAL way! I am not planning to do any of the above. I built my bike purposely with a monolever. I also like the drum brake. But if it was a simple bolt-on I certainly would have tried, just for the education.
I agree, but this mono conversion is more challenging in more than one way, might involve less weight and in my opinion it looks better than the bulky paralever rear drive. I have a paralever with a rear disk brake, and it is the question of technical feasibility that has kept me busy with the idea on modifiying a mono. lots of greetings Alfons
I love my rear disc and think its one of the best mod ive done. It does highlight how weak thw front is then but thats easily curable. I ride a lot two-up so powerful brakes are the go. On my last big trip prior to doing the mod my archiles tendon started giving me grief. I put this down to the amount of force required to get any power out of the drum.
Iv've seen a race BMW with a K arm and mono disc setup http://pagesperso-orange.fr/curves.speed/magnov04.htm I've discussed with the owner, this is a K100RS swing arm shortened to enter the frame rails
BTW here is the thread where PP describes his brake project: http://www.advrider.com/forums/showthread.php?t=432979 I've been thinking about it and it looks like there are two basic ways: K100 way and R1100 way. The R1100 cover has larger holes for the larger bolts, but otherwise it's a bolt-up. The fiche shows both the large and small bolts for the K-bikes; I don't know if they changed at some point but the only K FD I have (K75C drum) is small-bolt like the GS. I guess what we'd really want is a Paralever housing with the shock mount (GS/R and 4V K only) but without holes for brake rod (rules out Airheads) or the speed sensor (rules out K-bikes). The shock mount is in the place of the ABS hole so that's not a factor. I think I don't have a non-ABS R11 cover, unfortunately. I have an R1100RS cover but that bike uses the K-type caliper, and I have three ABS covers. PP, the R11 rotor is always very close to the boot, like nearly touching. If I go ahead with this I'll probably try to just use a regular BMW wheel shim if I need clearance.
Hi, consulted online catalogue and had a look at the various parts involved: the early K bikes had their covers bolted on with 8 mm bolts, later the factory used 10 mm bolts. So one would have to find the cover from a pre-October 1983 bike. Then we could actually bolt on our K-bike brake caliper and disk. However, I am not sure whether the K cover fits onto the monolever housing: The K cover is sealed on the housing by use of an o-ring while the monolever cover has a gasket. Unfortunately I do not have the BMW parts in my garage to get first-hand experience. Will continue to find information on this issue best wishes Alfons
I am absolutely intrigued by this conversion that was mentioned before (found on Micapeak): What I like: - use of the stock 3-lug hub (if I knew the internals I would know whether use of a 4-lug hub would be doable too - only added mass seems to be the caliper and the disc, offset that with the drumbrake components -> very interesting - Phreaky Phil has got the mods for the rear brakelever and m/c position I couldn't find the name again of the guy that did this. Anybody?
I dont know, that looks like it will offest the wheel to the left, or you will need to dish the wheel plus hat caliper bracket looks not really up to the task. I've never found the rear brake to be lacking (if set up right) on any of my drum braked airheads. And i've found that the disc on my guzzi rear end set up right (brembo) doesn't feel as good.
Same here, that wasn't the reason for initiating this thread. "Hypothetically feasible?" was the reason behind it ... at this stage!
If the excess was machined off the outside of the backing plate could you utilize the backing plate mounting bolts for a bolt on caliper mounting plate ?