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hot brake rotors ?

mojojojo

mojojojo

NAXJA Forum User
Location
Gresham, Oregon
maybe a stupid question but searching turned up zip. anyway, i just completed the crown vic disk swap on my 44. everything seems to be working great. except the rotors feel really hot after driving even short distances. i checked the front and they feel the same. they are hot like i can touch them but i deffinately wouldn't leave my finger on for very long. the wheels feel warm but not hot. maybe they have always been this way ? is this normal ? i am getting different answers from everyone i ask.

EDIT: the rotors are junk yard. the calipers are new/ rebuilt. i did jack up the vehicle and rotate the wheels and there does not seem to be any resistance (like major rubbing)
 
Last edited:
just be sure your pads are free to move as well as the calip/sliders
 
Just a thought... But if your running through the factory proportioning valve, do they happen to have a residual pressere valve for the drums built in ?
 
Brake rotors get hot when you use them. I've burnt my hand pretty bad by barely clipping a Mountain Bike disc brake after 30ft down a steep hill (yes, a pedal bike).

I wouldn't stress it. Just make sure your disc arn't dragging too much (too much compression). But IIRC, the factory prop valve has some back pressure in it over the disc prop valves. I'd make the swap to the ZJ disc prop valve if I were you, it's simple and might help. I'm running the WJ booster, ZJ Prop valve, and 8.8 disc and am happy after driving it for two weeks and breaking it all in.

~Scott
 
mojojojo said:
is the zj prop valve the same ? as in bolt on ? same threads etc... ?
Click to expand...

Not sure, it's pretty similar, but you can also pull the internals and put them in your XJ prop valve...it would make it work the same. (the bolt with the rubber cap, just undo the bolt and swap the internals...beware of the high pressure spring that's a biatch to get back though)

Sorry I can't help more, when I did the WJ booster swap, I had to do all new brake lines anyways to make it work with the XJ prop valve since the WJ one if way weird threads.

~Scott

P.S. I'd highly recommend looking into a WJ booster swap in your rig if you have a single diaphram booster.
 
the prop valve is direct bolt-in. Just be sure to apply alot of pressure on the valve when installing. The spring will fight you and you could mess up the threads in the prop valve like I almost did. Just be sure to bleed the valve after you install it. It's pretty easy since all you have to do after installing it is back the valve out just a few turns until you see brake fluid coming out the nipple after applying brake pressure. Once no more bubbles come out your prop vlv is bleed and you are god to go!
 
cool. i did a booster swap before when i dumped the ABS system. just wanna make sure i dont need to bend more breaklines. i suck at the cut n flare stuff.

so is the heat with the rotors normal though ? cause man the breaks work awesome ! i really don't wanna change anything if i dont have to.
 
When I did the brake swap to rear discs I also touched the brake rotors. *tear* My finger will never be the same. lol It should be perfectly normal. You already tested for excess drag and that tested great.
Once you get your parking brakes adjusted you should try some parking lot drifting.
 
so i picked up a ZJ prop valve this weekend. looking at the difference between the two and the custom lines i made when i swapped in the dual booster. . . . i'm thinking that it is going to much easier to swap out the guts than to change out the whole prop valve.

before i do this a question came to mind after reading up a lil. . . .

if i understand correctly the XJ prop valve leaves some pressure in the system for the rear drums. after doing a disk swap, this causes the rear calipers to drag a lil . . . correct ?

if this is true then why are my front rotors also getting warm the same as the rear ?

just checking before i go tearing into it . . . . AGAIN !

thanks again for any info folks
 
the prop valve itself is exactly the same with XJ & ZJ I believe. The difference is in the spring itself. ZJ being shorter but stiffer. and you are right just changing out the guts is real easy. just unbolt the 1 nut on the front of the prop vlv making sure to maintain a good amount of pressure on it as it's under a good amount of spring pressure. Then just slap the ZJ one in, bleed, and test drive.
 
mojojojo said:
if i understand correctly the XJ prop valve leaves some pressure in the system for the rear drums. after doing a disk swap, this causes the rear calipers to drag a lil . . . correct ?
Click to expand...

Talyn said:
The Xj doesn't have any type of residual pressure valve for the drum brakes. If you want better bias replace teh prop valve with a ZJ one, or even easier just swap springs.
Click to expand...


There is in the system that should cause the rear brakes to drag.
 
insert :"after driving and stopping a few times your brakes will always be hot" where appropriate in any above post.

run your hand back and forth on the carpet 10 times, gets hot right? That friction force is nothing compared to the forces exerted by your brake rotors.
 
just thought i'd up date everyone since i'm sure this will pop up in someone elses search in the future.

I swapped out the "guts" on the prop valve (XJ / ZJ). the pedal actually feels a tad softer but breaks fine in normal driving. All 4 lock up together on gravel. there is still some slight drag on the rear disks though. The wheel will not do a full revolution when turned by hand. although this may be due to the fact that they are locked together (Aussie locker) ? still i can hear the disks dragging just a tiny bit.

gonna go drive the piss out of it now and see what happens . . . .
 
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