JRusty15

I'm finally at a point with my project Jeep ('99 XJ) where I can drive it on the road and it's fairly comfortable. The import bits here are that I did a rear disc conversion from a ZJ, which included new wheel bearings and ZJ wheel studs, and installing a 3" lift kit from trail masters.

Bottom line, after driving the Jeep for a while, you can smell something near the rear wheels that, to me, smells like some type of heat / burning caused by friction. I'm not sure how else to describe it. A quick visual inspection reveals nothing and I'm trying to find time to get it in the garage for a more thorough look. To help make good use of my time, I'd like to ask you guys what type of things I should look for. It's possible, I suppose, that it's the new pads / rotors? Maybe the shoes from the brake are rubbing the rotor on the inside? Maybe I mucked up installing the wheel bearings? Maybe the wheel studs aren't pulled through all the way? Maybe I installed the gears in the rear end wrong? I have no idea since is the first time I've done ANY of this on a Jeep. So just looking to see what things I can inspect and how to inspect them.

Thanks Jeep friends!

Dumajones

When was all this work done on the brakes?.. When I did mine It took a good week before all the grease and paint stopped stinking from the brake heat.

JRusty15

Well, technically, the brakes were done like 8-9 months ago. But I haven't really driven then Jeep, because the suspension was unsafe and wanted to wait until I installed the new suspension parts with the lift kit, got tires that weren't dry rotted, alignment, etc. So the brakes have maybe 100 miles on them?

Dumajones

Try and give it some time.. My garage would stink up big time for a week after i did the disk conversion .. But if you think its excessive after or no change over time,,(like smell not slowly going away) Then I would start to look into it.

Maybe someone on here has another Idea to look at.. for me its give a little more miles and time.

SexyDexy

A trick that I used was I went and drove the vehicle for about 10 minutes and then tested the rotor, caliper, etc with an infrared thermometer (comparing the left side to the right side.) (In my case, I found that I had a crushed brakeline that was not allowing the brake fluid to release the caliper.) The thermometer is a good tool to determine what exactly is getting hotter than it is supposed to be,

https://www.harborfreight.com/non-co...ing-61894.html

JRusty15

Thanks! I think I actually have an IR thermometer somewhere. I just need to find it.

However, I ended up replacing all the brake lines in the rear, so I would doubt it. But still worth a check.

fb97xj1

Could be a sticking or misadjusted parking brake. If its dragging even just a little bit it will get hot. You will definitely smell it. Used to work with a guy that cooked his rear brakes because he didnt adjust the parking brake properly after replacing the cables. He drove it for 3 miles down the highway like that before he turned around. You could tell it the drums as he limped it into the driveway. It was a hot metallic smell, some smoke. He cooked them good.

Check your parking brake cables. That may be it. Check the axle seals while youre at it.

TRCM

Make sure the lift isn't putting tension on the parking brake.

I had an issue once where the parking brake came loose and was riding against the inside edge of the tire, and it would catch on the wheel weights every now & then.

JRusty15

Over the weekend I loosed up the parking brake shoes via the access port in the back of the dust plate. Keep in mind this is a ZJ disc brake conversion. I also noticed the dust shield was pretty close to the rotor, so I bent it back a bit in a few places. Then on Sunday I drove it over to the in-laws about 10 miles each way and didn't smell anything. (hooray!). So I decided to take it to work for the first time. My commute is about 20 miles, about half of which is highway. When I got to work in the morning, no smell. When I got home from work, I smelled it again. Visibly, there is nothing noticeable. I have no idea what is going on.

SexyDexy

What did the IR Thermometer say? Did you test the calipers and rotors with it like I suggested?

JRusty15

Duh, I totally forgot about this. Let me look for the IR thermometer and test this out later in the week. Thanks!

JRusty15

I was supposed to work from home today, but was called in to the office last minute and had to drive the Jeep since my truck was at the dealer for service. I brought the IR thermometer with me, but didn't have time to check when I got to work so I'll check when I get home. However, I did notice something new. There has been a high pitched screeching / squeeking sound coming from the rear. I thought it was my loose roof rack scratching the roof. But when I was driving to work I noticed it was in the rhythm of the wheels and when I apply the brakes, the noise goes away, even if the road is smooth or bumpy. So I'm guessing that noise is indicating something rubbing, creating friction. I'll get some thermometer readings when I get home too.

JRusty15

Ok so I have a few updates:

1) As I mentioned above, I noticed that this screeching sound I've been hearing goes along with the speed of the wheels turning. I usually hear it somewhere between 45 and 60mph and seems to start after the car warms up a bit.
2) Applying the brakes while I hear this noise makes the noise stop. After accelerating again, the noise will start up.
3) Turning the wheel to the right will make this noise go away
4) Turning the wheel to the left will NOT make this noise go away.

I then took my IR thermometer to the back of the car when I got home. Unfortunately it was dark and I did this in my garage, so trying to take pictures while doing this did not go well. However, I can summarize my findings.

Driver's side:
The wheel (rim) itself was around 120F
The temp on the rotor on the outside, towards the front part of the car was over 300F. Like closer to 330F. <-- not a typo
The temp on the rotor on the outside, towards the rear part of the car was around 170-180. The caliper was similar temp.
The back side of the rotor (from the weird angle I could get) was around 120F

Rear Diff: 92F

Passenger Side:
The wheel (rim) itself was around 91F
The temp on the rotor on the outside, towards the front part of the car was around 161F
The temp on the rotor on the outside, towards the rear part of the car was around 92F
The back side of the rotor was around 102F

So it sounds like whatever is rubbing and making noise is happening on the passenger side. I'll have to get it up in the air and take a look, but in the meantime I wanted to post my findings.

TRCM

I know you said when driving, applying the brakes made the noise go away.....did you try applying the parking brake ?

That would isolate it even further.......or let you know where you don't need to look .

JRusty15

Unfortunately I can only hear this noise at like 45mph and over. I'm not comfortable pulling the ebrake at that speed