bmw master cylinder suggestions???

i dig boogers · 01-13-2011, 02:43 PM

i have a '76 r90/6 that has a dual disc setup on it. the master is leaking severely and upon inspection is pitted beyond honing.
i was thinking of...

(1) having it re sleeved (locally $120) but to go with 17mm or 14mm (word is that size works better?) new piston is the question there. plus its a lot of $ for not giving an upgrade.

(2) getting a post '85 (what i heard was the easiest swap?) handlebar mount master. if someone has more specific suggestions for which model to use for the swap that would be helpful.

(3) finding a used master that isnt pitted

(4) finding a used single cylinder (14mm?) master and have it tapped for a second line (not sure of cost or if its a possible home job)

ive been researching for a while and havent come up with a very good solution yet considering this bike has nickel and dimed my resources but this is the last (fingers crossed) issue i have to deal with so i may just put whatever i need on a card and deal with it later! (aka the american way).

any input would be greatly appreciated, thanks,
-idb

SOLO LOBO · 01-13-2011, 02:57 PM

Regardless of what option you dp pick, it may be worth your time checking out motobins in the UK, they have great prices for new parts and ship fast.

I got a new master cylinder for my '81 G/S for something like $120, and it delivered in less than a week.

blaine.hale · 01-13-2011, 03:00 PM

I'll second the motobins suggestion. Buy a new one for roughly the same price as getting that one re-sleeved and you'll have piece of mind. That fluid will destroy your frame (it pitted min really bad.)

vacantstare · 01-13-2011, 03:06 PM

I posted part numbers in this thread:
http://www.advrider.com/forums/showt...ht=agonizingly

for a bar mount master cylinder and some of the other parts you'd need if you decide to go this route.

wirewrkr · 01-13-2011, 06:11 PM

Quote:

Originally Posted by SOLO LOBO

Regardless of what option you dp pick, it may be worth your time checking out motobins in the UK, they have great prices for new parts and ship fast.

I got a new master cylinder for my '81 G/S for something like $120, and it delivered in less than a week.

Yeah, but that's just for the master portion itself.
He will need the whole enchilada as he currently has the under tank style.
Quite a bit more $$$.

i dig boogers · 01-13-2011, 07:31 PM

hmmm, when i looked up the current under tank m/c from motobins it is $354, the handlebar mount kit with a hose and splitter is $380. where are these $120 ones?!?

@vacantstare good info and research. btw how much was your bmw bar mounted m/c and what year/mocel is it too?

anyone ever put on a single throttle pull jap m/c and lever then use a cable splitter? seems the only issue would be finding correct ratio unless those splitters dont perform well.

boxerboy81 · 01-13-2011, 09:17 PM

Another option...look for 2nd hand from a mono 800...13mm mc.
Ss lines while you're at it.

SOLO LOBO · 01-13-2011, 09:25 PM

Quote:

Originally Posted by i dig boogers

hmmm, when i looked up the current under tank m/c from motobins it is $354, the handlebar mount kit with a hose and splitter is $380. where are these $120 ones?!?

ell, if you look at the R80G/S ones you will find the $120 ones...

Quote:

Originally Posted by i dig boogers

anyone ever put on a single throttle pull jap m/c and lever then use a cable splitter? seems the only issue would be finding correct ratio unless those splitters dont perform well.

bgoodsoil did on his G/S that has a Suzuki front end... perhaps not the answer you were looking for.

i dig boogers · 01-13-2011, 11:14 PM

Quote:

Originally Posted by boxerboy81

Another option...look for 2nd hand from a mono 800...13mm mc.
Ss lines while you're at it.

would that be an f800? and whats the consensus on going with a lower mm piston? in the mean time im thinking of just picking up a single caliper m/c and tap it until i save up or make a better informed decision

boxerboy81 · 01-13-2011, 11:27 PM

Quote:

Originally Posted by i dig boogers

would that be an f800? and whats the consensus on going with a lower mm piston? in the mean time im thinking of just picking up a single caliper m/c and tap it until i save up or make a better informed decision

R80 85-87 or the other R100 mono variants. They had 13mm mc, then part way thru '89 they changed to 14mm.

The higher the number, the shorter the lever movement, but the more abrupt the braking. This is a twin disk, handlebar setup.

I went from a 15mm on my '82 RS to a 13mm and like the improvement in feel.

i dig boogers · 01-14-2011, 05:36 PM

any advice on tapping a single caliper m/c? thanks for all the input to far!

brentde3 · 01-14-2011, 05:42 PM

+another for motobins. I got a magura handlebar mounted master cylinder for my '76 r90/6. It came with a splitter, so one assumes that it could be made to work with a dual-disc setup.

http://www.motobins.co.uk/bmw-parts....20valve%20Twin

Use the dropdown menus to select brakes and handlebar master cylinder kits. Their currency converter says it's $381. Spendy, but cool.

01-13-2011, 02:43 PM	#1
i dig boogers ^OP Adventurer Joined: Nov 2010 Location: san diego Oddometer: 20	bmw master cylinder suggestions??? i have a '76 r90/6 that has a dual disc setup on it. the master is leaking severely and upon inspection is pitted beyond honing. i was thinking of... (1) having it re sleeved (locally $120) but to go with 17mm or 14mm (word is that size works better?) new piston is the question there. plus its a lot of $ for not giving an upgrade. (2) getting a post '85 (what i heard was the easiest swap?) handlebar mount master. if someone has more specific suggestions for which model to use for the swap that would be helpful. (3) finding a used master that isnt pitted (4) finding a used single cylinder (14mm?) master and have it tapped for a second line (not sure of cost or if its a possible home job) ive been researching for a while and havent come up with a very good solution yet considering this bike has nickel and dimed my resources but this is the last (fingers crossed) issue i have to deal with so i may just put whatever i need on a card and deal with it later! (aka the american way). any input would be greatly appreciated, thanks, -idb

01-13-2011, 03:00 PM	#3
blaine.hale Beastly Adventurer Joined: Feb 2009 Location: Atlanta, Ga Oddometer: 2,293	I'll second the motobins suggestion. Buy a new one for roughly the same price as getting that one re-sleeved and you'll have piece of mind. That fluid will destroy your frame (it pitted min really bad.) __________________ 1974 BMW R90 /6 1968 Bultaco Matador MK3 1973 BMW R75 /5 Toaster LWB 1969 Bultaco Bandido MK2 2013 Husqvarna Terra TR650

01-13-2011, 03:06 PM	#4
vacantstare Gnarly Adventurer Joined: Dec 2009 Location: Around the Sound Oddometer: 284	I posted part numbers in this thread: http://www.advrider.com/forums/showt...ht=agonizingly for a bar mount master cylinder and some of the other parts you'd need if you decide to go this route. __________________ 1971ish 'AmbassaRado' (a work in progress) 2008 Moto Guzzi Norge

01-13-2011, 09:17 PM	#7
boxerboy81 Stay Horizontal Joined: Jul 2009 Location: Oz, Australia Oddometer: 1,600	Another option...look for 2nd hand from a mono 800...13mm mc. Ss lines while you're at it. __________________ R100RS Gallery, over 800 pictures...

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01-13-2011, 07:31 PM	#6
i dig boogers ^OP Adventurer Joined: Nov 2010 Location: san diego Oddometer: 20	hmmm, when i looked up the current under tank m/c from motobins it is $354, the handlebar mount kit with a hose and splitter is $380. where are these $120 ones?!? @vacantstare good info and research. btw how much was your bmw bar mounted m/c and what year/mocel is it too? anyone ever put on a single throttle pull jap m/c and lever then use a cable splitter? seems the only issue would be finding correct ratio unless those splitters dont perform well.

01-14-2011, 05:36 PM	#11
i dig boogers ^OP Adventurer Joined: Nov 2010 Location: san diego Oddometer: 20	any advice on tapping a single caliper m/c? thanks for all the input to far!

01-14-2011, 05:42 PM	#12
brentde3 Should be outside Joined: Apr 2010 Location: Oneonta, NY Oddometer: 447	+another for motobins. I got a magura handlebar mounted master cylinder for my '76 r90/6. It came with a splitter, so one assumes that it could be made to work with a dual-disc setup. http://www.motobins.co.uk/bmw-parts....20valve%20Twin Use the dropdown menus to select brakes and handlebar master cylinder kits. Their currency converter says it's $381. Spendy, but cool.