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I'm getting ready to do my rear brakes. I've done a lot of reading and research on this. Some do nothing and say it's fine ? Some switch out the internals and swap out ? Some say that they removed the O-ring in the back ? Which is the CORRECT way ?
Flip a coin CR. lol
Either run the oem XJ valve as is or swap out the guts of it for the ones from a ZJ. DON'T mix the parts. I ran the oem one for a bit then just for the heck of it I swapped them out. Both work fine FOR ME.
I've read that there really isn't much difference. FWIW, I swapped the guts when I did mine. Couldn't tell ya how useful it was. I have no basis of comparison for the effect of just changing the prop-valve by itself.
Test it yourself, install the brakes then bed-in the pads using the stock prop valve. Mine would lock the rears up before the fronts (because drum cylinders take more force to actuate than the caliper pistons).
With the ZJ prop valve this is greatly diminished, but in my rig the rear still wants to lock up just before the front. I can only feel it on a dirt road really, but I think I need bigger calipers in the front to compensate
Probably doesn't mean a thing but with both p/v innards I had to come down hard on the brakes once with each. Both times on tarred and chipped roads. Hard to describe but with the ZJ innards the brakes just "felt" better. No lock ups with either but came to a quick stop with full control. Maybe just me but I like the ZJ guts better.
One more thing,,, I read somewhere that the main difference between the two guts, was the length of the spring ??? In the same post one person even said that the ZJ spring was 1/2" shorter, and that they just cut the XJ spring to match ?
One more thing,,, I read somewhere that the main difference between the two guts, was the length of the spring ??? In the same post one person even said that the ZJ spring was 1/2" shorter, and that they just cut the XJ spring to match ?
Bumping an old thread since I still need the answer to the above question and hopefully Cruiser will chime in and clarify for me. In my case, the ZJ spring is shorter than my XJ spring.....
I am in the middle of swapping Disk brakes in on my 8.8 and I found another thread were cruiser had mentioned he did the same to his 88 but cant find that thread now.. Not to sure how different the prop valve is from 90 up (which is were the majority of these threads come from) but I was at the JY today and pulled a 96 ZJ prop valve guts since I fiqured I needed them. When comparing the springs they are quite different in length but a big difference in strength of the springs! Question is, has any on done the ZJ guts swap on an 88, or 89-90 for that matter with these parts and does the spring length have any affect?
Pic below shows the spring difference. (zip tied spring is original 88 spring) valves and caps appear to be the same. top is ZJ Bottom is 88 XJ
My initial concern was that the shorter spring would not allow the valve to "seat" correctly. after installing the valve i found that it does indeed seat correctly with the short spring and is actually a bit difficult to get the cap on. Long and short, it will work just fine. Thanks Cruiser for the quick reply.
My initial concern was that the shorter spring would not allow the valve to "seat" correctly. after installing the valve i found that it does indeed seat correctly with the short spring and is actually a bit difficult to get the cap on. Long and short, it will work just fine. Thanks Cruiser for the quick reply.
Originally Posted by cruiser54
You should be fine. Note how it goes together. should be some resistance when pushing the cap into the threads.
Posted at the same time...again..thanks Cruiser your best as always.
06-18-2018, 10:59 AM
Proportioning Valve with ZJ Disc Brake Swap
