Brembo brakes on a vintage cafe racer

[M900]

I am putting together a cafe racer out of a 1979 Honda CB 650.  It needs both front and rear brakes and I can't help but notice that the Brembo brakes from a parted-out Ducati is less expensive than the rebuild kits...  Is there any reason why I couldn't use a pair from a Duc and adapt the right side front brake and use it for a rear brake, with both being controlled by the handlebar MC?  I think I can get the bracket adaptors milled at a machine shop for both front and rear calipers to be mounted, and I can get a longer stainless steel line made to connect the rear wheel with the MC, and essentially operate both the same as operating the twin front brakes --except one set of calipers will clamp down on the rear brake...  I have not seen anyone try to do this, and I am wondering if I will unleash somebad juju from an engineering standpoint.

[dlearl476]

Two things:  One, if you're doing this to race, check the sanctioning bodies first, it may not pass muster.  Second, I think you may need some sort of proportioning valve between the F/R calipers.  Old Moto Guzzi's do this, but backwards.  The hand lever accentuates one disc on the front, the foot brake accentuates the rear brake and the second front disc.  IMO, the pressure you could put on the rear disc would want to be less than the disc.

[M900]

Two things:  One, if you're doing this to race, check the sanctioning bodies first, it may not pass muster.  Second, I think you may need some sort of proportioning valve between the F/R calipers.  Old Moto Guzzi's do this, but backwards.  The hand lever accentuates one disc on the front, the foot brake accentuates the rear brake and the second front disc.  IMO, the pressure you could put on the rear disc would want to be less than the disc.

Not racing -- I picked up a CB650 for $150 and I'd lke to get it up and running as a cafe without pouring too much money into it.  Oddly enough, a set of brakes off a Duc is less expensive than a CB650 kit for teh front and back -- and it'll even have the added bonus of actually stopping the bike!

Do you think the longer line to the rear brake would act to bleed off some of the pressure?

[brimo]

Not really a good idea, varying riding conditions require different input to the front and rear brake,  buy the front and rear sets and only use one of the calipers on the front.

[brimo]

Do you think the longer line to the rear brake would act to bleed off some of the pressure?

No, remember too that disc thickness may be different between the honda and the duc. Some of those old bikes had pretty thick discs.

[M900]

No, remember too that disc thickness may be different between the honda and the duc. Some of those old bikes had pretty thick discs.

Eyeballed, the disc thickness seem to be similar between the Monster and the CB.  I'll measure it with calipers at some point.

Not really a good idea, varying riding conditions require different input to the front and rear brake,  buy the front and rear sets and only use one of the calipers on the front.

If I took the slave cylinder for the front, can I use the foot-activated master ?  Also, if I used the handlebar-mounted master for just one disc, would it work?

[brimo]

The slaves and masters are really designed as a set, the master moves a given amount of fluid forward to move the piston on the caliper (or calipers)
When you disconnect one caliper you are moving a larger amount of oil in proportion to the size of the caliper pistons that you want to move.
This results in brakes that can have very little feel.
If you used the existing honda master on the brembo caliper on the rear you may find it's not moving enough fluid to operate the pistons sufficiently to give you enough braking.
Best all round to bite the bullet and refurb the existing brakes, put in some decent pads and some new braided lines.
So unless you can get a full set cheap I'd be going that way, if you do really want brembos, try a full set from a monster dark, I'm pretty sure they only had a single disc on the front.

[M900]

Best all round to bite the bullet and refurb the existing brakes, put in some decent pads and some new braided lines.
So unless you can get a full set cheap I'd be going that way, if you do really want brembos, try a full set from a monster dark, I'm pretty sure they only had a single disc on the front.

thanks for the info.  Part of why I wanted to run both the front and the rear with the handlebar MC is because I thought just connecting one brake to a MC designed for two calipers wouldn't work.  You confirmed my suspicion...

I'd love to get a set from a Dark or an old 750 Monster, but they're few and far in between.  If I do find one that's priced reasonably, I'd def pick it up. 

Realistically speaking, I'd probably wouldn't save much buying the parts, then adapting the Brembos to the CB, but I'll wind up with superior brakes...

Do you think the foot activated MC from a Ducati work with one of the front calipers?  I can buy a set and split it up -- use one on the for and one on the rear wheel -- the only thing I'd need to find is ahand-perated MC for the bars and a pedal-activated one for the rear brake...

[brimo]

Remember about the front brake ending up with little feel or worse being very grabby and spitting you off, I'm not sure if the front and rear calipers are the same but I would suspect that they are, a little more research re part numbers may be in order.

[dlearl476]

thanks for the info.  Part of why I wanted to run both the front and the rear with the handlebar MC is because I thought just connecting one brake to a MC designed for two calipers wouldn't work.  You confirmed my suspicion...

I'd love to get a set from a Dark or an old 750 Monster, but they're few and far in between.  If I do find one that's priced reasonably, I'd def pick it up. 

AFAIK, all 600's have single front discs.