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Old 11-05-2008, 08:12 AM   #1
dukestodd OP
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Airhead Brake Upgrade

The following is a request for opinions from people who are smarter about Airheads than I am.


I have a relatively stock 78' BMW R100/7 with a dual front disk, ATE style brakes and an under tank master cylinder. I also have a set of 84' R100RT dual disk Brembo style forks and a set of Lester mag wheels that I plan to swap in this winter. At the same time I am swapping forks and wheels I would like to upgrade to a handle bar mounted master cylinder.


I know I need to purchase the following parts:
1. Dual front disks
2. Front brake calipers
3. Front brake pads
4. Braided steel front brake lines
5. Handle bar mounted master cylinder


What I need advise about is:
1. Is my list complete?
2. Can anyone recommend part numbers, manufacturers, and appropriate combinations?
3. Can anyone suggest suppliers of the necessary parts?


I sincerely appreciate any assistance or guidance you are able to provide.
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Old 11-05-2008, 11:20 AM   #2
CurlyMike
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wirewrkr is your man. need some throttle items as well...
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Old 11-05-2008, 01:02 PM   #3
crazydrummerdude
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Old 11-05-2008, 01:12 PM   #4
Wirespokes
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Well set-up Ate brakes can work as well as the Brembos.

All you need is one more disc to match what you've already got.

For the bar mount master cylinder, you'll need an early R65 or the later (86 -> on) perch (but not from the GS or R100R which are different) to keep the two throttle cables. 81-4 bikes used a splitter that ran one cable from the grip, to a splitter under the tank to each carb.

Get a 14mm master cylinder - it gives better feel than the 15 and larger that earlier twin disc models came with.

A good place to get new Brembo calipers is straight from the distributor - I believe some place in Colorado. I don't have a link to them at this time. They were something like $80 a few years ago. And then there are used ones for much cheaper. You're usually pretty safe with used ones.
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Old 11-05-2008, 01:27 PM   #5
Hawk Medicine
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I guess that Spokes beat me to it and covered the whole subject as well as anyone could.

But...

You'll have to find someone other than me to look up parts numbers for ya.

Thats too much work and it's your bike!
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Old 11-05-2008, 03:33 PM   #6
pommie john
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Wirespokes has got pretty well covered.

Just one thing.
Brembo callipers come with at least two different mounting hole spacings.
Measure the distance between the mounting lugs on your forks before you order new callipers.
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Old 11-05-2008, 05:24 PM   #7
mark1305
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For suppliers , I like to get Brembo specific stuff from Fred Renz at yoyodyneti.com, and all the ancillary parts like pads and hoses and rotors from cyclebrakes.com
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Old 11-06-2008, 10:36 AM   #8
dukestodd OP
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Thank you to everyone - I really appreciate your assistance.
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Old 02-07-2010, 08:12 AM   #9
eepeqez
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Ressurecting an old thread covering the same ground here;

I've got a 1984 (late twin shock) R65 with the original factory fitted single Brembo disk and 12mm master cylinder, which is weeping, as they do...

The m/cyl was stainless sleeved many years ago so I expect it needs a hone and seals. I haven't found a source of seals without the piston.

I've also got a second disk, opposite side caliper and 15mm master cylinder with no piston. This master cylinder would want sleeving and a piston and seals.


I had assumed that to fit the second disk I would have to go to the 15mm master cylinder, but from this thread and others I see people using smaller master cylinders. I actually had no idea there were more than 2 sizes to fit my throttle/switchgear etc.


A smaller master cylinder bore should provide higher line pressure for a given lever force, but displaces less fluid, so the lever needs to be pulled in further. Obviously the lever cannot be allowed to get to the bar!

Any opinions, experience? I can't see the 12mm cylinder being satisfactory but I could get it bored out to 13mm or 14mm if pistons are available and this is a better answer.

Graham in Melbourne
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Old 02-07-2010, 09:29 AM   #10
dilandau
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radial

hey, i put a radial master on my r100 - dual disk. they come in various piston sizes and you wont have to worry about hitting the bar, as you can adjust them out to fit. (they adjust radially - in and out from the bar to fit your reach and wanted pull)

its not very period correct - but it was a vast improvement over the stock if you want to go that way.
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Old 02-07-2010, 10:23 AM   #11
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Radial Master

Quote:
Originally Posted by dilandau
hey, i put a radial master on my r100 - dual disk. they come in various piston sizes and you wont have to worry about hitting the bar, as you can adjust them out to fit. (they adjust radially - in and out from the bar to fit your reach and wanted pull)

its not very period correct - but it was a vast improvement over the stock if you want to go that way.

Pictures??? Would love to see that set up!
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Old 02-07-2010, 10:51 AM   #12
dilandau
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Laugh

currently its functionally good, but still not aesthetically squared away. i wanted to make it work before i worried about being pretty.

straight forward though-- i just tore out the under the tank master-- and stuck on the radial master with some stainless lines to my oh so awesome ATE calipers. i did a fake rebuild of those as well, just took apart, replaced seals and home honed the cylinders with a soft sanding wheel. the disks are semi-floating from "braking USA" and i used the stock brake hubs ( had to cut the rivets off). new pads, and some alignment and wow!

i have brakes!!!!!!! nearly as good as a honda. but actually, yeah, two fingers no problem. its a heavy bike, but the brakes will dive the front end right to the ground.



i just ground off the old lever mount so i could fit it. i need to take it back off and grind more and then paint to make it look nice. and get a little something better than zip ties to hold up the reservoir.

if someone wants to do it- i just called up spiegler and they built the lines to fit, and of course 10x1 banjo bolts all around and a double banjo for the master. the master comes with a bleeder valve on the top, which made bleeding very doable. i also put in the braided lines for the rear just for kicks, but i cant tell any difference there. i just used a string to estimate the length of the lines and it worked out alright. a little long on the far one.. but if i tuck it up inside it looks ok.

i suspect the semi-floating is making a big difference, as the Achilles heal of the ate caliper is alignment, and having disks that can adjust a little to fit snug is making a big difference ( I suspect)
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dilandau screwed with this post 02-07-2010 at 11:02 AM
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Old 02-07-2010, 02:26 PM   #13
pommie john
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Quote:
Originally Posted by eepeqez
I had assumed that to fit the second disk I would have to go to the 15mm master cylinder, but from this thread and others I see people using smaller master cylinders. I actually had no idea there were more than 2 sizes to fit my throttle/switchgear etc.


A smaller master cylinder bore should provide higher line pressure for a given lever force, but displaces less fluid, so the lever needs to be pulled in further. Obviously the lever cannot be allowed to get to the bar!

Any opinions, experience? I can't see the 12mm cylinder being satisfactory but I could get it bored out to 13mm or 14mm if pistons are available and this is a better answer.

Graham in Melbourne
Brembo master cylinders come in three sizes of piston. 12, 14 and 15mm.

The 12 is designed for a single disc, and the 14 and 15mm for twin discs. Obviously the 15mm gives a more solid feel and the 14mm a softer feel but more stopping power for a given lever pressure.
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Old 02-08-2010, 05:40 PM   #14
eepeqez
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Quote:
Originally Posted by pommie john
Brembo master cylinders come in three sizes of piston. 12, 14 and 15mm.

The 12 is designed for a single disc, and the 14 and 15mm for twin discs. Obviously the 15mm gives a more solid feel and the 14mm a softer feel but more stopping power for a given lever pressure.
Thanks for this. Sounds like ideally I'd choose the 14mm, but since I've already got a 15mm, thats the way to go. Unless of course I can get it sleeved down to 14mm when it is stainless steel sleeved.... hmmm
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Old 02-09-2010, 05:25 AM   #15
jtwind
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Personally I like to leave airheads as stock as possible. Your bike with dual ATE's will stop just fine if you rebuild the mc, rebuild the calipers, and install a ss line and new shoes. Up to brembos? not sure but close and for less money and it's till original.
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