Master Cylinder Upgrade
12-06-2014, 08:27 PM
#1
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Year: 1999
Model: Cherokee
Engine: 4.0l
Master Cylinder Upgrade
Parts:
•1999 Dodge Durango brake master cylinder (V8)-with reservoir-
•1999 Jeep Cherokee XJ dual diaphram booster
No pics but it's straight forward:
Remove old parts and replace with new. There is a huge increase in braking power. Bleed brakes from passenger rear, driver rear, passenger front, then driver front. In that order.
Perfect for stopping more weight and larger tires!
•1999 Dodge Durango brake master cylinder (V8)-with reservoir-
•1999 Jeep Cherokee XJ dual diaphram booster
No pics but it's straight forward:
Remove old parts and replace with new. There is a huge increase in braking power. Bleed brakes from passenger rear, driver rear, passenger front, then driver front. In that order.
Perfect for stopping more weight and larger tires!
12-07-2014, 10:28 AM
#3
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
12-07-2014, 04:50 PM
#4
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Year: 1999
Model: Cherokee
Engine: 4.0l
I have a 1999 and it's a direct swap. No lines were bent, no modifications. The Durango BMC had a larger piston and increases braking power. If you're doing this on a rig with a single diaphram booster, grab a dual diaphram from a new 4.0L. When you do the swap, drain all of you old fluid out of the system and replace it with brand new fluids. It is well worth the 2 hours of work. And more questions let me know.
12-08-2014, 05:21 AM
#5
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Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
Thought...Wont bigger lines be required . Only gonna push so much fluid thru factory line dia .
12-08-2014, 06:33 AM
#6
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Year: 1990
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12-08-2014, 11:41 AM
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Year: 93 2 door
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Engine: 4.0
direct swap? you've got my attention. anyone have any estimates on how this would fair with say 1/2 ton dual piston brakes?
what about this one for $60? CENTRIC Part # 13167025
https://www.rockauto.com/catalog/x,c...,parttype,1836
damn. boosters are expensive. I might just pick up one of these at the local parts store and take advantage of the core charge
https://www.rockauto.com/catalog/x,c...,parttype,1884
did you have to do anything about a prop valve?
what about this one for $60? CENTRIC Part # 13167025
https://www.rockauto.com/catalog/x,c...,parttype,1836
damn. boosters are expensive. I might just pick up one of these at the local parts store and take advantage of the core charge
https://www.rockauto.com/catalog/x,c...,parttype,1884
did you have to do anything about a prop valve?
Last edited by Atmos; 12-08-2014 at 11:47 AM.
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12-08-2014, 05:46 PM
#8
Doesn't increasing your master cylinder bore size (Decrease) your braking power?
You get less hydraulic leverage...............
Yes, you wouldn't have to press the pedal down as far to get the same movement of the slave pistons, but you would have to press the pedal a bit harder to get the same braking force..........................
You get less hydraulic leverage...............
Yes, you wouldn't have to press the pedal down as far to get the same movement of the slave pistons, but you would have to press the pedal a bit harder to get the same braking force..........................
12-09-2014, 07:31 AM
#10
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Year: 1990
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12-09-2014, 08:09 AM
#11
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Did you have to change the length of the rod?
I have the CENTRIC Part # 13067025 Premium MC sitting here waiting to be installed. I have had better luck with Centric Premium parts.
I have the CENTRIC Part # 13067025 Premium MC sitting here waiting to be installed. I have had better luck with Centric Premium parts.
Last edited by CobraMarty; 12-09-2014 at 08:12 AM.
12-09-2014, 12:50 PM
#12
The size of the brake line has little to do with it, as I would bet the Durango has the same size brake lines......
The problem with putting a larger master cylinder in, without changing anything else, is you are changing the hydraulic ratio of the braking system.
This goes against most of what I know about hydraulics, and is going to have the opposite affect of what you are trying to achieve........
By doing this, you are going to decrease your braking power at the wheels.........As well as make the pedal harder to push.
If you want to increase stopping power, you have to either (Decrease) the size of the master cylinder, or (Increase) the size of the caliper pistons......
The problem with putting a larger master cylinder in, without changing anything else, is you are changing the hydraulic ratio of the braking system.
This goes against most of what I know about hydraulics, and is going to have the opposite affect of what you are trying to achieve........
By doing this, you are going to decrease your braking power at the wheels.........As well as make the pedal harder to push.
If you want to increase stopping power, you have to either (Decrease) the size of the master cylinder, or (Increase) the size of the caliper pistons......
12-09-2014, 01:15 PM
#13
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Year: 1999
Model: Cherokee
Engine: 4.0l
I just got a new master with the reservoir, put it on and bled my brakes. No bigger lines are needed. Nothing was altered.
12-09-2014, 01:17 PM
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Year: 1999
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The size of the brake line has little to do with it, as I would bet the Durango has the same size brake lines...... The problem with putting a larger master cylinder in, without changing anything else, is you are changing the hydraulic ratio of the braking system. This goes against most of what I know about hydraulics, and is going to have the opposite affect of what you are trying to achieve........ By doing this, you are going to decrease your braking power at the wheels.........As well as make the pedal harder to push. If you want to increase stopping power, you have to either (Decrease) the size of the master cylinder, or (Increase) the size of the caliper pistons......
12-09-2014, 01:19 PM
#15
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Year: 1999
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The piston is 1/4" bigger than the XJ I believe so it's not a negative affect. If you've done the Durango steering box upgrade you know it's just heavier duty but still direct bolt in. Size of the lines doesn't matter as the fluid in the lines just creates pressure. I do plan on doing the WJ knuckle swap with brake assembly so I just started with the BMC