So you want better brake on your R100GS, why not a 4-pot Brembo????

One Less Harley · 10-01-2010, 07:30 PM

So you want better brakes on your R100GS??? Why not try something already available from BMW????

Like one of these calipers….

The mounting tab spacing of the R100GS caliper is the same as the left 4 pot Brembo from a R1100xx, K1100xx, or an early R1150GS (up to 11/2001). I can’t take credit for finding out that this works as there are a few references posted here on ADV Rider about the conversion. The only modification needed is to remove 0.158” off the caliper mounting tabs. This keeps the rotor centered to the caliper. I double checked the measurement and came within a few thousandths of and inch….good enough.

One thing that concerned me, was milling that much material would make the tabs too thin.

The stock 2 pot Brembo is 0.489” thick

The left 4 pot Brembo before milling tabs ( 0.609")

Area of material removed (0.158")

Thickness of tab after milling (0.451")

With 0.158" milled off the mounting tabs, the 4 pot Brembo is 0.038" thinner than the stock 2 pot Brembo.

I have 6 calipers, but only one has been modified. I need to double check the fit and centering of caliper to the rotor before having the other five milled.

I have a friend w/ a R100GS who is interested in trying the 4 pot caliper, but I'm waiting on an order of Galfer green pads to arrive. So look for more postings once it is installed. The bike will also (if he wants to spend the money) get a stainless line.
The five other calipers will be offered here with Galfer green pads and stainless lines.

fishkens · 10-01-2010, 07:40 PM

I'd love one of those fancy calipers since I probably won't be affording the billet unit anytime soon. Price?

Thanks.

One Less Harley · 10-01-2010, 07:47 PM

I don't know as of yet. I need to make sure the 1st caliper is machined correctly. Then need to get all the pads and stainless lines in, plus see what the total machining cost will be. The machinist is quite reasonable though.

fishkens · 10-01-2010, 07:51 PM

Ahh, so this'll be a turnkey solution. Nice. Keep us posted.

I haven't done a search but is there a preferred pad?

One Less Harley · 10-01-2010, 07:56 PM

I've read ( for what that's worth) the Galfer Green offers good braking. I'll post when converting my friends R100GSPD. I've never ridden a 2 pot Brembo on the GS. So I'll be relying on his impressions.

fishkens · 10-01-2010, 08:19 PM

I'm assuming that it'll be an improvement based on this thread (brief mentions of the Brembo arrangement v. the Nissin).

http://www.advrider.com/forums/showthread.php?t=75031

bereahorn · 10-01-2010, 09:23 PM

I made this mod to my '92GSPD and like the result. I think my caliper is from an R1100R and a friend milled the required amount from the caliper to center it over the disc. I think it's an effective and worthwhile mod. The stopping is much better. Of course the addition of a racetech gold valve contributed also.

fishkens · 10-01-2010, 09:30 PM

Okay, so now I'm thinking. Does it really need to be milled to be centered over the rotor? I mean, do the pistons really care if the guys on the one side of the are a little bit deeper in their bores and the fellows on the other side are a little bit prouder in their bores? We're talking about 1/16th of an inch on each side.

Hmmmm, just how much do the pistons care if they're all in the same relative position in the bores?

Am I misisng something?

ColininKodiak · 10-01-2010, 10:26 PM

Quote:

Originally Posted by fishkens

Okay, so now I'm thinking. Does it really need to be milled to be centered over the rotor? I mean, do the pistons really care if the guys on the one side of the are a little bit deeper in their bores and the fellows on the other side are a little bit prouder in their bores? We're talking about 1/16th of an inch on each side.

Hmmmm, just how much do the pistons care if they're all in the same relative position in the bores?

Am I misisng something?

Assuming the same piston diameter and bore, the pressure would be higher in one cylinder than the opposite side. I'd think this would cause the higher pressure side to wear the pad faster. Centering them causes each side to exert the same pressure and keep pad wear even. I'd also be leery of putting more pressure on one side of the disc as this has the potential to shear it off the hub (in extreme cases).

espressodrinker · 10-02-2010, 04:26 AM

Quote:

Originally Posted by ColininKodiak

Assuming the same piston diameter and bore, the pressure would be higher in one cylinder than the opposite side. I'd think this would cause the higher pressure side to wear the pad faster. Centering them causes each side to exert the same pressure and keep pad wear even. I'd also be leery of putting more pressure on one side of the disc as this has the potential to shear it off the hub (in extreme cases).

The pressure in a hydraulic system HAS to be the same all over the piping.

I agree I can't see what diffs it would make for the disk to be off-centre.

B.Curvin · 10-02-2010, 04:58 AM

Quote:

Originally Posted by ColininKodiak

Assuming the same piston diameter and bore, the pressure would be higher in one cylinder than the opposite side. I'd think this would cause the higher pressure side to wear the pad faster. Centering them causes each side to exert the same pressure and keep pad wear even. I'd also be leery of putting more pressure on one side of the disc as this has the potential to shear it off the hub (in extreme cases).

For future reference, there are no stupid questions, but there are stupid answers.

Did you just make that up as you typed?

Quote:

Originally Posted by espressodrinker

The pressure in a hydraulic system HAS to be the same all over the piping.

I agree I can't see what diffs it would make for the disk to be off-centre.

Yeppers.

C Squared · 10-02-2010, 05:11 AM

For future reference, there are no stupid questions, but there are stupid answers.

Did you just make that up as you typed?

Hey you syole my reply. I just wanted to know how the pressure would be greater in one side over the other? I'd love to read the rational. Maybe there is a new field of physics that I am un aware of?

B.Curvin · 10-02-2010, 05:42 AM

Quote:

Originally Posted by C Squared

Hey you syole my reply.

I saw I had been quoted and thought for sure someone was going to bash me for being an asshole.

ipanemaguy · 10-02-2010, 06:09 AM

Quite correctly several have stated that in a hydraulic system the pressure equalizes, hence the inner and outer pistons will have the same pressure if they are driven from the same master.
I will suggest that the problem arises at some off-center differential that the pads on one side may retract insufficiently to completely clear the rotor and result in brake drag, overheating (and consequent warping) of the rotor.
Some difference may be OK, too much is harmful - as is everything else in life.

One Less Harley · 10-02-2010, 06:31 AM

I doubt you could get the pad in the caliper on one side.

10-01-2010, 07:30 PM	#1
One Less Harley ^OP OH.THAT'S GONNA HURT Joined: Nov 2006 Location: Bowling Green, Ky Oddometer: 3,923	So you want better brake on your R100GS, why not a 4-pot Brembo???? So you want better brakes on your R100GS??? Why not try something already available from BMW???? Like one of these calipers…. The mounting tab spacing of the R100GS caliper is the same as the left 4 pot Brembo from a R1100xx, K1100xx, or an early R1150GS (up to 11/2001). I can’t take credit for finding out that this works as there are a few references posted here on ADV Rider about the conversion. The only modification needed is to remove 0.158” off the caliper mounting tabs. This keeps the rotor centered to the caliper. I double checked the measurement and came within a few thousandths of and inch….good enough. One thing that concerned me, was milling that much material would make the tabs too thin. The stock 2 pot Brembo is 0.489” thick The left 4 pot Brembo before milling tabs ( 0.609") Area of material removed (0.158") Thickness of tab after milling (0.451") With 0.158" milled off the mounting tabs, the 4 pot Brembo is 0.038" thinner than the stock 2 pot Brembo. I have 6 calipers, but only one has been modified. I need to double check the fit and centering of caliper to the rotor before having the other five milled. I have a friend w/ a R100GS who is interested in trying the 4 pot caliper, but I'm waiting on an order of Galfer green pads to arrive. So look for more postings once it is installed. The bike will also (if he wants to spend the money) get a stainless line. The five other calipers will be offered here with Galfer green pads and stainless lines. __________________ 2004 BMW R1150RS 1984 BMW R80G/S (wrenching index) 2003 Suzuki DRZ 400S (TAT Prep) One More DRZ does the TAT (Ride Report) One Less Harley screwed with this post 10-01-2010 at 07:58 PM

10-01-2010, 07:40 PM	#2
fishkens Further... Joined: Nov 2009 Location: Seattle, WA Oddometer: 5,146	I'd love one of those fancy calipers since I probably won't be affording the billet unit anytime soon. Price? Thanks. __________________ Forging ahead, down a false trail.

10-01-2010, 07:47 PM	#3
One Less Harley ^OP OH.THAT'S GONNA HURT Joined: Nov 2006 Location: Bowling Green, Ky Oddometer: 3,923	I don't know as of yet. I need to make sure the 1st caliper is machined correctly. Then need to get all the pads and stainless lines in, plus see what the total machining cost will be. The machinist is quite reasonable though. __________________ 2004 BMW R1150RS 1984 BMW R80G/S (wrenching index) 2003 Suzuki DRZ 400S (TAT Prep) One More DRZ does the TAT (Ride Report)

10-01-2010, 07:51 PM	#4
fishkens Further... Joined: Nov 2009 Location: Seattle, WA Oddometer: 5,146	Ahh, so this'll be a turnkey solution. Nice. Keep us posted. I haven't done a search but is there a preferred pad? __________________ Forging ahead, down a false trail.

10-01-2010, 07:56 PM	#5
One Less Harley ^OP OH.THAT'S GONNA HURT Joined: Nov 2006 Location: Bowling Green, Ky Oddometer: 3,923	I've read ( for what that's worth) the Galfer Green offers good braking. I'll post when converting my friends R100GSPD. I've never ridden a 2 pot Brembo on the GS. So I'll be relying on his impressions. __________________ 2004 BMW R1150RS 1984 BMW R80G/S (wrenching index) 2003 Suzuki DRZ 400S (TAT Prep) One More DRZ does the TAT (Ride Report)

10-01-2010, 08:19 PM	#6
fishkens Further... Joined: Nov 2009 Location: Seattle, WA Oddometer: 5,146	I'm assuming that it'll be an improvement based on this thread (brief mentions of the Brembo arrangement v. the Nissin). http://www.advrider.com/forums/showthread.php?t=75031 __________________ Forging ahead, down a false trail.

10-01-2010, 09:23 PM	#7
bereahorn Beastly Adventurer Joined: Mar 2002 Location: North Coast (Lake Erie) Oddometer: 1,054	I made this mod to my '92GSPD and like the result. I think my caliper is from an R1100R and a friend milled the required amount from the caliper to center it over the disc. I think it's an effective and worthwhile mod. The stopping is much better. Of course the addition of a racetech gold valve contributed also.

10-01-2010, 09:30 PM	#8
fishkens Further... Joined: Nov 2009 Location: Seattle, WA Oddometer: 5,146	Okay, so now I'm thinking. Does it really need to be milled to be centered over the rotor? I mean, do the pistons really care if the guys on the one side of the are a little bit deeper in their bores and the fellows on the other side are a little bit prouder in their bores? We're talking about 1/16th of an inch on each side. Hmmmm, just how much do the pistons care if they're all in the same relative position in the bores? Am I misisng something? __________________ Forging ahead, down a false trail.

10-02-2010, 05:11 AM	#12
C Squared Now with TURBO! Joined: Mar 2008 Location: FDL WI. Oddometer: 5,534	For future reference, there are no stupid questions, but there are stupid answers. Did you just make that up as you typed? Hey you syole my reply. I just wanted to know how the pressure would be greater in one side over the other? I'd love to read the rational. Maybe there is a new field of physics that I am un aware of? __________________ A fight to the death between zombies has a few inherent problems.

10-02-2010, 06:09 AM	#14
ipanemaguy Many bikes & little time Joined: Jun 2007 Location: Rustbelt, USA Oddometer: 76	It's not the pressure it's the gap Quite correctly several have stated that in a hydraulic system the pressure equalizes, hence the inner and outer pistons will have the same pressure if they are driven from the same master. I will suggest that the problem arises at some off-center differential that the pads on one side may retract insufficiently to completely clear the rotor and result in brake drag, overheating (and consequent warping) of the rotor. Some difference may be OK, too much is harmful - as is everything else in life.

10-02-2010, 06:31 AM	#15
One Less Harley ^OP OH.THAT'S GONNA HURT Joined: Nov 2006 Location: Bowling Green, Ky Oddometer: 3,923	I doubt you could get the pad in the caliper on one side. __________________ 2004 BMW R1150RS 1984 BMW R80G/S (wrenching index) 2003 Suzuki DRZ 400S (TAT Prep) One More DRZ does the TAT (Ride Report)

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