951 Cup brake master cylinder
08-11-2002, 09:32 AM
#1
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951 Cup brake master cylinder
Hi all,
I have new calipers(Brembo calipers) for my 951 Cup for the front with bigger pistons (48/40 instead of 44/36),using the same discs, which I would like to install. However I have a few questions:
1-Master Cylinder? is the one in my car big enough for the new volume of the pistons? I have the 951S unit.
Will the MC from a 928 GTS fit? Is it bigger?
2-Brake bias. How will I fare with the 30/28 rear calipers? I have a pair of 38/36 mm calipers in store, will they go better with the new fronts?
3-Brake bias valve. I know there are a few options there, I have the numbers. What do those that have gone this way use?
Any insight from the Brake gurus is more than welcome here.
Thanks, GeorgeK
I have new calipers(Brembo calipers) for my 951 Cup for the front with bigger pistons (48/40 instead of 44/36),using the same discs, which I would like to install. However I have a few questions:
1-Master Cylinder? is the one in my car big enough for the new volume of the pistons? I have the 951S unit.
Will the MC from a 928 GTS fit? Is it bigger?
2-Brake bias. How will I fare with the 30/28 rear calipers? I have a pair of 38/36 mm calipers in store, will they go better with the new fronts?
3-Brake bias valve. I know there are a few options there, I have the numbers. What do those that have gone this way use?
Any insight from the Brake gurus is more than welcome here.
Thanks, GeorgeK
08-11-2002, 11:55 AM
#2
Drifting
I am intewrested in this type of info as well, as I miss the feel of my brakes before I upgraded from '86 951 to 89 S4-spec calipers...
What have you big red guys done to retain pedal "feel"?
What have you big red guys done to retain pedal "feel"?
08-11-2002, 02:44 PM
#3
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i have never understood why this isnt a mjor bitch with Big read users, but you are correct that the stock small bore master does not adequate front circuit volume for the BR caliper.
The stock early car master is a 19/21 diameter staggered bore. I fought with a soft pedal when i upgraded my 86 to BRs...my solution was to get a 19/23 bore master from an 89 (there are bores up to 25mm on mercedes part numbers) and adding the hardlines from the master to the left front corner from the same car....presto, adequate pedal height and the kind of hard pedal that you need in a race car.
I would STRONGLY encourage anyone with a non S car to plan on a master and line upgrade when you add BRs to the car...if you dont, you will have a low soft pedal with too much travel.
Vendors...come on...tell people they need this when thye pick up a BR kit from you, and they will be much happier. For me this made the difference between acceptable brakes, and confidence inspiring and predictible ones. Its really important.
The stock early car master is a 19/21 diameter staggered bore. I fought with a soft pedal when i upgraded my 86 to BRs...my solution was to get a 19/23 bore master from an 89 (there are bores up to 25mm on mercedes part numbers) and adding the hardlines from the master to the left front corner from the same car....presto, adequate pedal height and the kind of hard pedal that you need in a race car.
I would STRONGLY encourage anyone with a non S car to plan on a master and line upgrade when you add BRs to the car...if you dont, you will have a low soft pedal with too much travel.
Vendors...come on...tell people they need this when thye pick up a BR kit from you, and they will be much happier. For me this made the difference between acceptable brakes, and confidence inspiring and predictible ones. Its really important.
08-11-2002, 04:03 PM
#4
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Thread Starter
Hi Mumzer,
Do you have details on the Mercedes benz master cylinder. I was looking into that, because I like the short travel and harder pedal on my cars, but there are too many choices in the ATE catalog online for master cylinders (WWW.ate.de).
Do you know from which car the 25/xx mm MC would come from?
regards, GeorgeK
Do you have details on the Mercedes benz master cylinder. I was looking into that, because I like the short travel and harder pedal on my cars, but there are too many choices in the ATE catalog online for master cylinders (WWW.ate.de).
Do you know from which car the 25/xx mm MC would come from?
regards, GeorgeK
08-11-2002, 09:26 PM
#5
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[quote]Originally posted by GeorgeK:
<strong>Hi Mumzer,
Do you have details on the Mercedes benz master cylinder. I was looking into that, because I like the short travel and harder pedal on my cars, but there are too many choices in the ATE catalog online for master cylinders (WWW.ate.de).
Do you know from which car the 25/xx mm MC would come from?
regards, GeorgeK</strong><hr></blockquote>
george...i'll track it down, but i really would encourage you to try the 19/23 first...it puts the pedal high enough that at full brake I can just get the throttle in a heel-toe gearchange...more like toe-toe actually... i think if you went with the larger version, you would have to rework the brake pedal lever itself to reposition it.
<strong>Hi Mumzer,
Do you have details on the Mercedes benz master cylinder. I was looking into that, because I like the short travel and harder pedal on my cars, but there are too many choices in the ATE catalog online for master cylinders (WWW.ate.de).
Do you know from which car the 25/xx mm MC would come from?
regards, GeorgeK</strong><hr></blockquote>
george...i'll track it down, but i really would encourage you to try the 19/23 first...it puts the pedal high enough that at full brake I can just get the throttle in a heel-toe gearchange...more like toe-toe actually... i think if you went with the larger version, you would have to rework the brake pedal lever itself to reposition it.
08-12-2002, 12:33 PM
#7
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[quote]Originally posted by StanUK951:
<strong>Mumzer - when you fitted your BR's did you use a kit for the 86 model or go through the hassle of changing spindles etc...??</strong><hr></blockquote>
i actually have a pretty strange car...ite was purchased to be raced...no sunroof, no headlight washer system, no AC, and the prior owner installed all the turbo S chassis pieces he could find....transaxle, spindles hubs, front a-arms and subframe, rear cotnrol arms hubs and halfshafts...
my front brakes consist of Big reds on an aluminum hat with a coleman 13" gray iron rotor...the caliper is mounted dirctly to the spindlesmall billet shims were neceessary to accomodate the additional rotor diameter, but they took about 3 mins each to spit out of the lathe.
<strong>Mumzer - when you fitted your BR's did you use a kit for the 86 model or go through the hassle of changing spindles etc...??</strong><hr></blockquote>
i actually have a pretty strange car...ite was purchased to be raced...no sunroof, no headlight washer system, no AC, and the prior owner installed all the turbo S chassis pieces he could find....transaxle, spindles hubs, front a-arms and subframe, rear cotnrol arms hubs and halfshafts...
my front brakes consist of Big reds on an aluminum hat with a coleman 13" gray iron rotor...the caliper is mounted dirctly to the spindlesmall billet shims were neceessary to accomodate the additional rotor diameter, but they took about 3 mins each to spit out of the lathe.
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08-12-2002, 12:56 PM
#8
Race Director
Interesting. Not exactly the same, but I put 928S4 calipers and stainless steel lines on my car (with the stock 951 bias valve) and my pedal feel is just the same as it was before the upgrade. Still feels fine with the same master cylinder. I haven't done any "spirited" braking yet, I guess I'll find out at my next auto-x..
Tifo
Tifo
08-18-2002, 05:39 PM
#9
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Thread Starter
Bump,
Mumzer, I could still use some help there. The guys at the part shop and at MB want more details, as there are at least three different part numbers for the same diameter MC (25.4/19.05 and 26.99/20.64)
Thanks for any info here.
Mumzer, I could still use some help there. The guys at the part shop and at MB want more details, as there are at least three different part numbers for the same diameter MC (25.4/19.05 and 26.99/20.64)
Thanks for any info here.
08-18-2002, 07:46 PM
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[quote]Originally posted by GeorgeK:
<strong>Bump,
Mumzer, I could still use some help there. The guys at the part shop and at MB want more details, as there are at least three different part numbers for the same diameter MC (25.4/19.05 and 26.99/20.64)
Thanks for any info here.</strong><hr></blockquote>
Hi....i cant see the pN now that the thing is installed...im sorry...but i thing 25.4 is pretty big...and that you will wind up with une heeltoeable brake pedal height with that piece...
<strong>Bump,
Mumzer, I could still use some help there. The guys at the part shop and at MB want more details, as there are at least three different part numbers for the same diameter MC (25.4/19.05 and 26.99/20.64)
Thanks for any info here.</strong><hr></blockquote>
Hi....i cant see the pN now that the thing is installed...im sorry...but i thing 25.4 is pretty big...and that you will wind up with une heeltoeable brake pedal height with that piece...
