ADVrider

Go Back   ADVrider > Bikes > Old's Cool > Airheads
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 02-21-2014, 11:17 AM   #1
op48no1 OP
Studly Adventurer
 
op48no1's Avatar
 
Joined: Jan 2014
Location: Boston, MA
Oddometer: 640
I bought some K1100RS calipers for my monolever.

Was poking around on eBay yesterday and decided on impulse to buy a pair of four-piston calipers from a 1996 K1100RS. My understanding is they'll fit in the same mounting bosses as the stock 2-piston calipers. The two main issues are the different rotor offset, and the need for a 20mm master cylinder.

Based on Googling, it seems there's a K75 rotor with wider spacing that's close enough to use without machining anything.

WRT master cylinders, it would be cool to use a Brembo RCS type lever assembly. I don't mind losing the stock controls. Another issue is to get a matching cable-pull clutch assembly.

Was wondering if other people have successfully undertaken this project. Worse comes to worse, I can put the calipers in the junk box for a future project.

-Henry
__________________
1988 BMW R100
2012 Ducati Monster 1100 Evo
op48no1 is online now   Reply With Quote
Old 02-21-2014, 12:49 PM   #2
Mobiker
Beastly Adventurer
 
Joined: Apr 2003
Location: Missouri
Oddometer: 1,473
I put one on I bought from One Less Harley. He machined it for proper centering. I just bolted it on using the stock master cylinder. Seems to work ok to me.
__________________
'88 R100GS
'76 xl350
"Don't Panic"
Mobiker is online now   Reply With Quote
Old 02-21-2014, 08:48 PM   #3
op48no1 OP
Studly Adventurer
 
op48no1's Avatar
 
Joined: Jan 2014
Location: Boston, MA
Oddometer: 640
Quote:
Originally Posted by Mobiker View Post
I put one on I bought from One Less Harley. He machined it for proper centering. I just bolted it on using the stock master cylinder. Seems to work ok to me.
I suspect with a dual-disk setup, the 13mm master cylinder would give too soft a lever feel... Standard is 18-20mm for this application.

-Henry
__________________
1988 BMW R100
2012 Ducati Monster 1100 Evo
op48no1 is online now   Reply With Quote
Old 02-22-2014, 05:48 AM   #4
Mobiker
Beastly Adventurer
 
Joined: Apr 2003
Location: Missouri
Oddometer: 1,473
Quote:
Originally Posted by op48no1 View Post
I suspect with a dual-disk setup, the 13mm master cylinder would give too soft a lever feel... Standard is 18-20mm for this application.

-Henry
Didn't realize you were running dual discs. I do like the caliper on my otherwise stock single disc set up. Been very pleased with it.
__________________
'88 R100GS
'76 xl350
"Don't Panic"
Mobiker is online now   Reply With Quote
Old 02-22-2014, 10:03 PM   #5
op48no1 OP
Studly Adventurer
 
op48no1's Avatar
 
Joined: Jan 2014
Location: Boston, MA
Oddometer: 640
Quote:
Originally Posted by Mobiker View Post
Didn't realize you were running dual discs. I do like the caliper on my otherwise stock single disc set up. Been very pleased with it.
Yeah, dual disk. Was perusing the fiche today and the dual-disk setup on the R100R used a 15mm master cylinder. K1100RS used 20mm, IIRC.

-Henry
__________________
1988 BMW R100
2012 Ducati Monster 1100 Evo
op48no1 is online now   Reply With Quote
Old 02-23-2014, 03:45 AM   #6
r60man
Gnarly Adventurer
 
r60man's Avatar
 
Joined: Mar 2013
Location: Robesonia PA
Oddometer: 332
Quote:
Originally Posted by op48no1 View Post
Yeah, dual disk. Was perusing the fiche today and the dual-disk setup on the R100R used a 15mm master cylinder. K1100RS used 20mm, IIRC.

-Henry
The K1100RS also has ABS, does this not play into the mix at all? I have a K1100RS, love the thing, great bike. Never thought about putting the brakes on my airhead. hmmmmmm...
__________________
K1100RS, R75/6

Speed doesn't kill anyone, suddenly becoming stationary, that's what gets you - Jeremy Clarkson
r60man is offline   Reply With Quote
Old 02-23-2014, 04:16 AM   #7
beemerphile
Beastly Adventurer
 
beemerphile's Avatar
 
Joined: Jan 2006
Location: Danielsville, GA USA
Oddometer: 1,670
I did this on my monolever by milling the proper offset on the calipers. As far as the master cylinder, I used a 13mm and it was a soft lever, but it never touched the bar if properly bled. Mine were dual disk. A 14mm would have been better. I think 20mm is way out of range for this. It would have a nice hard lever feel, but less leverage and thus less braking force for a given input. My 13mm M/C had great progressive feel if you could get by the lever travel going nearly to the bar. If I had it to do again I would use 14mm. 15mm max.
__________________
ΜOΛΩΝ ΛΑΒΕ - Lee
Amateurs practice until they get it right, professionals practice until
they never get it wrong
beemerphile is offline   Reply With Quote
Old 02-23-2014, 08:20 AM   #8
rbm
Adventurer
 
Joined: Mar 2011
Location: Toronto, CANADA
Oddometer: 54
Using 4-pot calipers from an ABS-equipped or non-ABS-equipped K-bike will not matter; either will function in a non-ABS application.

To mount the calipers on your forks without modifying either part, you could manufacture a set of adapter plates, similar to what is pictured below:
http://specialks.net/index.php?super...enres=1280-800

Changing from 2-pot to 4-pot calipers on BMW K75's and K1002V's has been done before. People who have successfully done this have found that the 16mm front master cylinder from a BMW R80R/R100R "Mystic" 1991-1995, ETK No 32 72 2 314 022 provides the minimum size MC capacity to give good feel to the front brake lever for a pair of 4-pot calipers and, at the same time, eliminates the need to re-engineer the throttle assembly.

Read through these threads and PDF document to get more ideas.

http://www.bmwmoa.org/forum/archive/...p?t-33917.html

http://www.k-bikes.com/forums/showthread.php?t=18156

http://k-technik.pytalhost.com/pdf/bremsenumbau.pdf
__________________
- Robert
rbm is offline   Reply With Quote
Old 02-24-2014, 07:30 AM   #9
op48no1 OP
Studly Adventurer
 
op48no1's Avatar
 
Joined: Jan 2014
Location: Boston, MA
Oddometer: 640
Quote:
Originally Posted by rbm View Post
Using 4-pot calipers from an ABS-equipped or non-ABS-equipped K-bike will not matter; either will function in a non-ABS application.

To mount the calipers on your forks without modifying either part, you could manufacture a set of adapter plates, similar to what is pictured below:
http://specialks.net/index.php?super...enres=1280-800

Changing from 2-pot to 4-pot calipers on BMW K75's and K1002V's has been done before. People who have successfully done this have found that the 16mm front master cylinder from a BMW R80R/R100R "Mystic" 1991-1995, ETK No 32 72 2 314 022 provides the minimum size MC capacity to give good feel to the front brake lever for a pair of 4-pot calipers and, at the same time, eliminates the need to re-engineer the throttle assembly.

Read through these threads and PDF document to get more ideas.

http://www.bmwmoa.org/forum/archive/...p?t-33917.html

http://www.k-bikes.com/forums/showthread.php?t=18156

http://k-technik.pytalhost.com/pdf/bremsenumbau.pdf
Thanks for the info. Yeah, I scoured the web for articles on the subject, didn't find much more than what you posted here.

I was wrong, the R100R uses a 15mm piston. I was considering buying a Brembo RCS16 master cylinder and this cool cable clutch perch to match on the other side:



I am also planning to rewire the bike with the Motogadget M-Unit, and would replace the stock switch gear with their M-Button parts. The M-Buttons and the Brembo lever parts are actually cheaper than switching over to stock BMW controls and switches.

-Henry
__________________
1988 BMW R100
2012 Ducati Monster 1100 Evo
op48no1 is online now   Reply With Quote
Old 02-26-2014, 08:44 AM   #10
op48no1 OP
Studly Adventurer
 
op48no1's Avatar
 
Joined: Jan 2014
Location: Boston, MA
Oddometer: 640
Bad news here. I thought the K75 and 1988 R100 brakes were the same. Turns out that's not the case. The K75 rotors have 31.5mm offsets while the R100 rotors have 28.0mm offsets. The fellow with the K75 cited above was able to solve his problem by switching to R100R rotors, but my rotors and the ones on the R100R are the same, so no luck there.

I compared calipers this morning and there's definitely an offset issue. I think the best solution will be to machine down the caliper mounting bosses. The K1100 calipers are a lot beefier than the R100 calipers, so I don't think there would be a strength problem.

I'm thinking because of the extraordinary cost of changing master cylinders and switch gear that I will put the bike back together stock and leave this as an upgrade for later.

-Henry
__________________
1988 BMW R100
2012 Ducati Monster 1100 Evo
op48no1 is online now   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


Times are GMT -7.   It's 08:30 AM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014