How to retrofit dual front brakes?

[drewboid]

I have a 1984 R65 and want to add a second front disk.  I have a right side Brembo and the second rotor - any advice on how to go about this or is it as straight foward as I think?  I know I need a splitter for the second brake line ( or should I daisy chain them?) as well as additional brake lines.  any recommendation on changing the 12mm master cylinder to a larger one?  

Thanks,
Drew

[Bob_Roller]

Normally you would use the larger master cylinder (14 mm I think), but I have heard of riders using the 12 mm master cylinder. You could try the retrofit with the old master cylinder, and if it isn't to your liking, then replace it with the larger master cylinder.

[Justin B.]

Some people claim they like the 12mm MC better.  They say it gives them better control and a better "feel" for the front brakes.  I have scrounged and rebuilt a 12 mm MC for my LS project but can't comment yet 'cause I can't find the freaking banjo bolt!

[Jon_P]

the only thing in using a 12mm master cylinder is that it will be softer than what you have now. it will work. it wont have that give it a little pull brake, it will have a real easy brake that you will have to pull more before it works like the single.

if it where me (i live with my front brake) i would get a bigger master cylinder

[Justin B.]

That's the reason why some folks say they like the smaller cylinder, more of a "progressive" long pull...  

[thrang]

The jobs pretty straight forward, but for a real improvement on the front breaks fit a set of braided hoses (Goodrich etc) and a set of after market disks. Motobins & Motorworks offer a reasonable exchange deal for your old disks.  
Tony

[Semper Gumby]

Hi Drewboid,

I did this with my 1980 R65.  Some minor differences.  I have the ATE brakes.  I scrounged a RH side caliper from the attic at Bluemoon in Atlanta.  Then I bought the longer bolts (five) that run through the hub for the added width of the extra disk.  

Instead of the extra bmw disk, I bought two EBC full floating disks from www.cyclebrakes.com in Calyfornia.  I tried using my 12mm master cylinder but it wasn't enough.  I bought the last 15mm round reservoir master cylinder from BMW north america.  The feel is fine and in a panic,  the lever doesn't bottom out against the grip.  For your 1984 I think you need the larger 15mm (or 16mm) rectangle resevoir master cylinder.

Its expensive but you end up with "great" brakes.  For pads I use the Galifer Kevlar also from cyclebrakes.  This combination will not fade in the dry and sqeegees a bit when wet and prevents me  from locking up the front in the slippery wet.

There is one other possible combination for R65 brakes.  It involves a single four piston caliper from a British company.  The parts are not R65 specific (I think you have to use the R80ST parts to make this work but you would be a testpilot/mechanic on this one)

Good luck.

[msbuck]

There is one other possible combination for R65 brakes.  It involves a single four piston caliper from a British company.  The parts are not R65 specific (I think you have to use the R80ST parts to make this work but you would be a testpilot/mechanic on this one)

So, are you saying to keep one disc and just change out the single caliper for the four piston?  Should that be make a big enough difference or are you just speculating?

[Semper Gumby]

The four piston caliper is extremely expensive  ($500+).

When I saw the price I looked away...

Ah Here is the link.  Harrison in the UK.  They have a four piston and a six piston Caliper.  If you want to do Stoppies on your R65's single disk then THIS is the caliper.

http://www.billet.co.uk/gallery.htm#bmw

Also...

http://www.billet.co.uk/index2.html?home.html~mainFrame

On this page they list a caliper for the 280mm rotors.

Un fortunately you will have to do your own engineering as it is not R65 specific.  The fitment comes close but some engineering/machining will probably be required unless you want to put the R80 front end on your R65.  I decided to go with stuff that I wouldn't have to machine....hence the second ATE Caliper and the dual EBC full floating Rotors.  BTW I also had to use a shim to get the RH side caliper to center on the second rotor.  I had to go one size larger.  I did it by "eye".

TTFN,

[Ed Miller]

My bike came with dual front disks, but there are two draw backs.  The front wheel is obviously a bit heavier, and there is an extra step in removing the front wheel.  You have to remove one of your calipers and hang it up out of the way before you can get the wheel off.  I don't mean to disuade you, I just thought I should point these out.

Good luck,