hi was wondering if i can leave stock master cylinder and portion valve and booster with rear disc brakes on 97 tj thanks
Can I use the stock master cylinder and everything with a disc brake conversion?
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From all the comments and other threads I have read about it the answer is YES but I can't say 100% that is correct. I have a Vanco hydro boost so my system isn't even close to stock any longer.
Absolutely yes. The factory uses the exact same proportioning valve part number whether the rear brakes are drum or disk.
Only convert to rear disks for easier brake maintenance. Converting from rear drums to disk will not improve braking performance.
Chentally Mallenged
New Member
I just did mine a month ago for easier maintenance and because the caliper will help keep the axle in somewhat incase I ever break an axle. But when I did mine it didn't feel right when braking so I removed the rubber grommet from the end of the proportioning valve and now it stops perfectly.
The rumors of being able to drive on a broken axle shaft due to the caliper keeping the axle in place are greatly exaggerated. That's not a good reason for installing rear disks, You're going to have two axle shaft halves that only mate properly every 360 degrees and they're going to be pushing each other apart every 180 degrees.
Removing the rubber grommet used to be a popular modification after converting to disk but no longer is. Jeep uses the same proportioning valve for rear disk and drum brakes, it was designed to allow normal rear brake pressure for normal braking but decrease the pressure to the rear brakes for hard stops so the rear brakes won't lock and cause a skid or slide. You definitely don't want increased pressure to the rear brakes. Really.
Chentally Mallenged
New Member
Is why I said somewhat on the axles. If the rear axle snaps it decreases the likelihood of me chasing a tire down a mountainside and gives me time to stop or get off trail, hopefully without doing more damage because I was dragging one side of the rear end. And as far as the grommet I did it because I was having a problem with my front brakes locking up on wet pavement, removing it decreased the pressure going to the front and they no longer lock up on wet pavement, neither do the rear. <—— tested. It works and I will put a new one in when I upgrade/replace the master cylinder. I work on cars everyday.The rumors of being able to drive on a broken axle shaft due to the caliper keeping the axle in place are greatly exaggerated. That's not a good reason for installing rear disks, You're going to have two axle shaft halves that only mate properly every 360 degrees and they're going to be pushing each other apart every 180 degrees.
Removing the rubber grommet used to be a popular modification after converting to disk but no longer is. Jeep uses the same proportioning valve for rear disk and drum brakes, it was designed to allow normal rear brake pressure for normal braking but decrease the pressure to the rear brakes for hard stops so the rear brakes won't lock and cause a skid or slide. You definitely don't want increased pressure to the rear brakes. Really.
