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rear disk brake swap now very weak rear brakes

kippo1

NAXJA Forum User
Location
Alabama
I just got finished swapping over to rear disk. I got the disk set up off a 96 grand with dana 35. So after bleeding 4qts of fluid through the brakes the rear brakes will not stop the wheels turning while idling on jack stands.

No I have not swapped the prop valve. Could that be my problem?

I have to get her back on the road tonight. I am about to pull the master cylinder off and bench bleed it then bleed everything else again.

Has anyone done the rear disk swap had this problem and fixed it?
 
I couldn't tell you what's wrong, but it shouldn't be any different than changing out a caliper!

I did the swap on my 8.25 with junkyard parts from a ZJ and didn't bother swapping the prop valve. No issues
 
proportioning valve is not the problem-- it is designed to direct fluid pressure to the rear (drum) brakes first to overcome the spring pressures. If everything is bled correctly, and the master cylinder has sufficient volume, the rear brakes should be stronger than necessary on initial braking.
 
Forgot about the calipers being switched around! That could be it.....

Happens to the best of us! I've done it
 
Ok sorry for late reply. I went through and bled the master and then all the calipers. I had bled the calipers all the way around 5 times. A lot better drivable but still think I have air in the system. Going to go by a buddy's shop tomorrow and pressure bleed the whole system and see if that works.

Here is a heads up. If you read were someone used e brake cables off a 03 liberty don't buy them. They are way to long. I read 2 or 3 post were someone said they worked perfect. I ordered them and they have a no return policy so 50 bucks down the drain.

I just looped the xjs cables and they work great. I may try to find some correct length cables latter.

Now it is entirely possible I was sent the wrong cables or 2 of the passenger cables since they were exactly the same. Who knows.

Now to get on my bumper builds hopefully start that Monday.
 
When I did my disc brake conversion on my '98; I replaced the shorter length XJ emergency brake cable with one from a '98 TJ.
Just needed to cut off the return spring off the cable.
 
Ok sorry for late reply. I went through and bled the master and then all the calipers. I had bled the calipers all the way around 5 times. A lot better drivable but still think I have air in the system. Going to go by a buddy's shop tomorrow and pressure bleed the whole system and see if that works.

Here is a heads up. If you read were someone used e brake cables off a 03 liberty don't buy them. They are way to long. I read 2 or 3 post were someone said they worked perfect. I ordered them and they have a no return policy so 50 bucks down the drain.

I just looped the xjs cables and they work great. I may try to find some correct length cables latter.

Now it is entirely possible I was sent the wrong cables or 2 of the passenger cables since they were exactly the same. Who knows.

Now to get on my bumper builds hopefully start that Monday.


Still never answered the others question, is the bleeder valve on top and the right way for the calipers? Are these used or new calipers also
 
New calipers and calipers are on the correct sides.

OK.

What about the disk pads? New or used? Rotors,...new, used or resurfaced?

Disks on the rear of an XJ do not automatically make the rear breaking better than the drum brakes. The only improvement I see is the reduction in maintenance. With both rear wheels of the ground, engine idling in drive, the rear wheels tend to push through the breaks wit a normal pedal pressure applied. However, on slippery road and a panic stop, the rear have a tendency to lockup before the front.
If you are sure everything is good, drive it around a little and see how it goes.
 
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