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Smoking Brakes!

MrShoeBoy

NAXJA Forum User
Location
Cincinnati, OH
Today I was making a quick trip to the post office about 5 miles away and on the way home, the Jeep started to pull to the left. I was maybe a few mile from home and was going to look at it then since it wasnt pulling very hard. By the time I got home it was a constant battle to keep the Jeep stright and after parking and getting out smoke started to pour out from the disk and backing plate area in addition to the sound of grease poping/burning. For a second I thought I was about to watch my axle catch fire and burn the Jeep to the ground but nothing more happened and the smoke started to disapate. The backing plate and the rim where too hot to touch. The brake caliper wasnt burning hot but it was slightly warm.

I go back a few hours later and start to pull the driver side appart. I grabed the wheel and tried to rock it to check if the bearings where bad but nothing moved. Then with the wheel off I checked to see if the caliper was stuck but it moved freely on the pins. The disk had no heat marks on it and looked like any other brake rotor that has been used for a while. I pulled off the caliper and the pads looked like they where glazed over slightly but still in usable condition. I was also able to move the piston in the caliper back maybe an 1/8 of an inch with a slight bit of effort. It didnt seem like it was stuck but rather stiff. The grease that I heard burning was from the TRE on the backing plate. I grabed the hub and tried to see if there was any movement but again there was nothing out of the ordinary.

Any ideas on what happened to my front end? I am going to pull the hub off this week and put a spare on just in case its the wheel bearings so I can drive my piece home and get to installing my HP Dana 44. I dont want to put any money into the d30 with my 44 so close to being done.

Specs: 1991 Jeep Cherokee 4.6L stroker, AX-15, NP 231, F8.8 rear w/disks, Dana 30 front with stock brake rotors and calipers, preformance friction pads. Wheel bearings have 180k on them. Brakes have maybe 20k on them. Tires are bald 32x11.50s A/Ts

Thanks,

AARON
 
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I'm not sure of the cause, but at the very least flush the brake lines and refill it. You don't want boiled brake fluid in there....it may as well be water.

I saw this happen to a toyota once, but it got so hot it boiled over the master cylinder....the balancing weights melted and formed pools of lead on the ground.

Good luck.
 
Funny thing about the heat...The master cylinder has clear fluid in it. I flushed the brakes less than a year ago with new fluid and it hasnt changed color yet. I can still see the bottom of the master. And the disk had no signs of extreme heat, no discoloration.

Thanks for the reply.

AARON
 
i had this happen to me while I was still adjusting my new brake system (I was adapting a Caddy booster to my 91 XJ) Turns out The brake pedal did not pull back to the resting position and thus the brake fluid did not completely release. The difference is that I could see a little "bluing" to my rotor, indicating overheating...but not much. Its was hard to diagnose because the fluid pressure would leak down after a few minutes and release the brake.
 
i'm going with stuck caliper piston.
 
this happened to me and it toasted the caliper completely. I replaced the caliper, disc, and pads and it happened again to me two days later. I replaced the caliper and pads again (it had toasted it again). Some one mentioned to me that the brake lines can deteriorate on the inside and not let fluid back out once the caliper gets compressed. I replaced the rubber brake lines (on both sides) and the problem has not occured again in over two years.

In my case I believe the problem was in fact the rubber brake line.

hth

Matthew
 
Thanks for the input guys. The brake lines are stainless steel braided lines I got from Rustys offroad about 5 years ago when I put the first 3" lift on my XJ. Could the stainless lines have gone bad in 5 years?

AARON
 
Had the same exact thing about 3 months ago.... replaced the caliper and rotor.. went with new pads and replaced the caliper on the other side for unfiormity... no clue why the wheel locked up... plenty of lube everything was good... alota xjers report this problem though
 
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