brake upgrade (MC and booster)
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Senior Member

Joined: Feb 2012
Posts: 627
Likes: 3
From: newjersey
Year: 2000
Model: Cherokee
Engine: I6
Hi guys. So this summer I upgraded my rear end to discs from a grand cherokee. way better braking now, but I do have a problem. My pedal is very spongey even after flushing and bleeding it like 4 times. I think my MC is starting to go out. Some days the pedal is nice and i have good stoppage, other days it feels really soft with a lot of travel, and i have to really lay into the pedal to stop. I did some reading and it looks like there are some upgrade options out there from dodges or the WJ. I have a 2000 so I think my booster is the best one possible (???) I just need some guidance on what MC and booster to get. Thanks
CF Veteran

Joined: Apr 2016
Posts: 1,820
Likes: 60
From: Pasquotank, NC
Year: 1990
Model: Cherokee
Engine: 4.0
I'm sure Cruiser will chime in soon, but until then I'll quote what he told me when I did mine. I have a 90, so the WJ booster with ZJ prop valve guts was an awesome upgrade. My understanding is the 2000 is already a good setup. You might swap the prop valve internals to see a better balance in brake biasing.
Probably just time to replace the master cylinder with a stock replacement.
Probably just time to replace the master cylinder with a stock replacement.
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Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
I'm sure Cruiser will chime in soon, but until then I'll quote what he told me when I did mine. I have a 90, so the WJ booster with ZJ prop valve guts was an awesome upgrade. My understanding is the 2000 is already a good setup. You might swap the prop valve internals to see a better balance in brake biasing.
Probably just time to replace the master cylinder with a stock replacement.
Probably just time to replace the master cylinder with a stock replacement.
Senior Member
Joined: Apr 2013
Posts: 781
Likes: 2
From: Dawson Springs, KY
Year: 1985
Model: Cherokee
Engine: 2.5L
I'm sure Cruiser will chime in soon, but until then I'll quote what he told me when I did mine. I have a 90, so the WJ booster with ZJ prop valve guts was an awesome upgrade. My understanding is the 2000 is already a good setup. You might swap the prop valve internals to see a better balance in brake biasing.
Probably just time to replace the master cylinder with a stock replacement.
Probably just time to replace the master cylinder with a stock replacement.
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CF Veteran

Joined: Apr 2016
Posts: 1,820
Likes: 60
From: Pasquotank, NC
Year: 1990
Model: Cherokee
Engine: 4.0
On the 85 you should be able to just swap in the WJ booster and master. You only need to mess with the prop valve if you add disc brakes. Cruiser is the subject matter expert, so I would verify with him.


