Larger Master Cylinder
01-18-2019, 11:08 AM
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Larger Master Cylinder
Several master cylinder questions: -
1. Has anyone changed out a 993 master cylinder (23.8mm) for a Cayman master cylinder (25.8mm)?
2. Does anyone know the diameter of the 993 master cylinder and or the Cayman master cylinder portion that fits into the booster canister?
3. Does anyone know the length of the operational rod/shaft (static position) on either master cylinder that also slides into the booster canister ?
I am looking for a larger MC that I can adapt to the 993 booster canister with little modification. Someone has recommended the larger Cayman MC.
Thanks
1. Has anyone changed out a 993 master cylinder (23.8mm) for a Cayman master cylinder (25.8mm)?
2. Does anyone know the diameter of the 993 master cylinder and or the Cayman master cylinder portion that fits into the booster canister?
3. Does anyone know the length of the operational rod/shaft (static position) on either master cylinder that also slides into the booster canister ?
I am looking for a larger MC that I can adapt to the 993 booster canister with little modification. Someone has recommended the larger Cayman MC.
Thanks
01-18-2019, 11:19 AM
#2
Several master cylinder questions: -
1. Has anyone changed out a 993 master cylinder (23.8mm) for a Cayman master cylinder (25.8mm)?
2. Does anyone know the diameter of the 993 master cylinder and or the Cayman master cylinder portion that fits into the booster canister?
3. Does anyone know the length of the operational rod/shaft (static position) on either master cylinder that also slides into the booster canister ?
I am looking for a larger MC that I can adapt to the 993 booster canister with little modification. Someone has recommended the larger Cayman MC.
Thanks
1. Has anyone changed out a 993 master cylinder (23.8mm) for a Cayman master cylinder (25.8mm)?
2. Does anyone know the diameter of the 993 master cylinder and or the Cayman master cylinder portion that fits into the booster canister?
3. Does anyone know the length of the operational rod/shaft (static position) on either master cylinder that also slides into the booster canister ?
I am looking for a larger MC that I can adapt to the 993 booster canister with little modification. Someone has recommended the larger Cayman MC.
Thanks
01-18-2019, 01:12 PM
#3
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01-18-2019, 05:48 PM
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01-18-2019, 05:49 PM
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01-18-2019, 06:43 PM
#8
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Ok, my understanding is preserving brake balance is a goal when switching out calipers. I understand preserving brake balance has to do with the surface area of the combined caliper pistons. I was working under the theory that for Porsche bigger calipers mean more pistons giving better modulation at the extremes of performance but the total piston area remains the same and is just spread across more smaller pistons to preserve this balance. The only other factor I can think of influencing fluid volume range at actuation would be the retraction volume change of each piston which is governed by the roll-over geometry of the special flat sided o-rings use with each piston cup. I don't know if this travel varies much on bigger calipers.
So I guess I need a little education as to what changes in racing applications that need greater dynamic fluid modulation by the master cylinder.
Andy
So I guess I need a little education as to what changes in racing applications that need greater dynamic fluid modulation by the master cylinder.
Andy
01-18-2019, 06:51 PM
#9
Ok, my understanding is preserving brake balance is a goal when switching out calipers. I understand preserving brake balance has to do with the surface area of the combined caliper pistons. I was working under the theory that for Porsche bigger calipers mean more pistons giving better modulation at the extremes of performance but the total piston area remains the same and is just spread across more smaller pistons to preserve this balance. The only other factor I can think of influencing fluid volume range at actuation would be the retraction volume change of each piston which is governed by the roll-over geometry of the special flat sided o-rings use with each piston cup. I don't know if this travel varies much on bigger calipers.
So I guess I need a little education as to what changes in racing applications that need greater dynamic fluid modulation by the master cylinder.
Andy
So I guess I need a little education as to what changes in racing applications that need greater dynamic fluid modulation by the master cylinder.
Andy
01-18-2019, 07:01 PM
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Andy,
lets go back to basics - if you increase the number of pistons and increase the size of the pistons the volume of fluid needed to obtain equal travel for fewer pistons and smaller pistons is going to increase. If you do this on all four corners the brake pedal travel has to increase because more fluid needs to be pushed to the larger and greater number of pistons. So if you want your brake pedal to start working at the top you have to get a larger MC that allows more fluid to be pushed to the pistons for equal travel.
Another option would be to add a second MC, dual MC with one for front and one for rear.
Right now I am trying to gather information which will allow me to decide if I can adapt a larger MC or modify my pedal box for a dual MC setup.
does that help?
lets go back to basics - if you increase the number of pistons and increase the size of the pistons the volume of fluid needed to obtain equal travel for fewer pistons and smaller pistons is going to increase. If you do this on all four corners the brake pedal travel has to increase because more fluid needs to be pushed to the larger and greater number of pistons. So if you want your brake pedal to start working at the top you have to get a larger MC that allows more fluid to be pushed to the pistons for equal travel.
Another option would be to add a second MC, dual MC with one for front and one for rear.
Right now I am trying to gather information which will allow me to decide if I can adapt a larger MC or modify my pedal box for a dual MC setup.
does that help?
01-18-2019, 08:53 PM
#12
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Now I seem to understand, a setup for racing may include calipers with greater piston total area than the stock street pistons and so the volume of fluid needed from the master cylinder can be greater in such cases and exceed the capacity of the stock master cylinder.
Thanks for the education.
Andy
Thanks for the education.
Andy