Re: Brake bias & caliper BORE size. Problem found?
[Re: Kern Dog]
#1233128
01/27/14 09:13 PM
01/27/14 09:13 PM
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Joined: Jan 2003
Posts: 28,067 Irving, TX
feets
Senior Management
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Senior Management
Joined: Jan 2003
Posts: 28,067
Irving, TX
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I don't understand why you had a problem with manual brakes.
I've got large diameter multi-piston manual brakes and the pedal feel is equivalent to that of the modern performance cars I deal with at work.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind. - Stu Harmon
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Re: Brake bias and caliper BORE size.
[Re: feets]
#3058760
07/13/22 03:02 AM
07/13/22 03:02 AM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
OP
Striving for excellence
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OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
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Or, in my case, you could run all the numbers, calculate that you need a 7/8" bore master cylinder for that perfect pedal effort on a manual setup, only to have the "expert" at the brake store tell you that you're wrong, and that every manual disc combo really needs a minimum of a 1" bore for fluid volume.
I had a pedal that was too stiff, and I never could lock up the fronts, although I was able to make it stop very hard, so I wasn't too concerned about it.
just annoyed that I allowed myself to be talked out of what I wanted because the guy posed himself as an expert who deals with this all the time
It's kinda funny. As your master cylinder size goes up your pedal effort goes up but the brake pressure goes down. [/quote] Here I am, ten years later and I'm revisiting this same issue. I have the engine, trans, K member and suspension out of the car. I pulled the power brake booster and MC and swapped in another 15/16" MC from Dr Diff but I have a drum-drum distribution block. A video online featuring a crash involving a 64 Mercury Comet really shed light on the importance of upgraded brakes for high performance cars. I'm also looking into the Dr Diff 13" front brake kit.
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Re: Brake bias and caliper BORE size.
[Re: Kern Dog]
#3059279
07/14/22 07:04 PM
07/14/22 07:04 PM
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Joined: May 2019
Posts: 6,240 nowhere
Sniper
master
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master
Joined: May 2019
Posts: 6,240
nowhere
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I am starting to understand it a little better but it still seems strange that a smaller surface area in terms of piston caliper sizing can provide more clamping force. It doesn't, in the caliper. Andy said in the Master cylinder though.
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Re: Brake bias and caliper BORE size.
[Re: Sniper]
#3059290
07/14/22 08:48 PM
07/14/22 08:48 PM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
OP
Striving for excellence
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OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
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I am starting to understand it a little better but it still seems strange that a smaller surface area in terms of piston caliper sizing can provide more clamping force. It doesn't, in the caliper. Andy said in the Master cylinder though. Here is where I am hung up.. My car currently has the Cordoba 11.75 rotors and 2,75" single piston front calipers. Going to a larger rotor makes sense regarding leverage. I am trying to understand how a caliper with less surface area could provide equal to or greater clamping force IF the master cylinder size is the same for both.
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Re: Brake bias and caliper BORE size.
[Re: Kern Dog]
#3059366
07/15/22 09:58 AM
07/15/22 09:58 AM
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Joined: May 2019
Posts: 6,240 nowhere
Sniper
master
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master
Joined: May 2019
Posts: 6,240
nowhere
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I am starting to understand it a little better but it still seems strange that a smaller surface area in terms of piston caliper sizing can provide more clamping force. It doesn't, in the caliper. Andy said in the Master cylinder though. Here is where I am hung up.. My car currently has the Cordoba 11.75 rotors and 2,75" single piston front calipers. Going to a larger rotor makes sense regarding leverage. I am trying to understand how a caliper with less surface area could provide equal to or greater clamping force IF the master cylinder size is the same for both. Not sure where you got the idea a smaller bore caliper will have more clamping force.
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Re: Brake bias and caliper BORE size.
[Re: Kern Dog]
#3059372
07/15/22 10:42 AM
07/15/22 10:42 AM
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Joined: Jan 2003
Posts: 31,022 Oregon
AndyF
I Win
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I Win
Joined: Jan 2003
Posts: 31,022
Oregon
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I am starting to understand it a little better but it still seems strange that a smaller surface area in terms of piston caliper sizing can provide more clamping force. It doesn't, in the caliper. Andy said in the Master cylinder though. Here is where I am hung up.. My car currently has the Cordoba 11.75 rotors and 2,75" single piston front calipers. Going to a larger rotor makes sense regarding leverage. I am trying to understand how a caliper with less surface area could provide equal to or greater clamping force IF the master cylinder size is the same for both. It won't. The smaller pistons will reduce clamping force. You need to reduce the MC bore size to rebalance the system and then you need to change the rear wheel cylinder size so it isn't isn't out of whack. Most people fail at either step one or step two of this process. You at least are thinking about it so you're a step ahead of most.
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Re: Brake bias and caliper BORE size.
[Re: Kern Dog]
#3059441
07/15/22 03:14 PM
07/15/22 03:14 PM
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Joined: Jan 2003
Posts: 31,022 Oregon
AndyF
I Win
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I Win
Joined: Jan 2003
Posts: 31,022
Oregon
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I am trying to understand how and why a switch from a 12 inch setup to the 13 inch setup would provide a gain. If the larger rotor provides more leverage but the smaller caliper size isn't as effective, why wouldn't they increase the caliper size ? Is there so much gain in the leverage that it greatly offsets the loss from a smaller caliper? You are mixing and matching parts so there is no logic to the question. If you look at a late model car with 13 inch rotors you'll see that the MC bore size and the piston caliper sizes are all on the small size. The engineers figured out a few years back that if everything was smaller then it could all be lighter but still provide the clamping forces required to stop the car. The old 2.75 caliper used by Mopar back in the 70's doesn't really exist anymore. Now everything uses multiple pistons and small bore sizes.
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