How hot should brakes be getting?

dgeist · **Posted:** Wed Mar 06, 2013 11:27 am

In troubleshooting a noise I'm hearing in my driveline, I've been using an IR thermometer on the brake discs after doing a typical daily drives (5 miles of mixed stop/go and highway; enough to get the engine and brakes up to a normal operating range). I found that while the rear discs were within a few degrees of each other, the fronts greatly favored the driver's side temperature wise. On one trip, the range was L:210F R:176F and on another trip, it was L:175F R:130F.

The delta between the two appears consistent. Would normal variations in brake load explain this much difference in disc temp or and I'm pretty much guaranteed something is rubbing or dragging on the left side? Unfortunately, with the full-time diff on the front axle, it's difficult to spin the wheels by hand to tell if there's drag in the bearing or breaks.

Dan

papaindigo · **Posted:** Wed Mar 06, 2013 3:59 pm

The front brake pads are known for binding which would explain a temp difference if one side is binding a bit and the other is not. I've not dug into the front brakes but chat over on the KJ CRD forum indicates that there is some sort of rubber boot that swells and as a result the pads don't fully retract when the brake pedal is released. IIRC ditching the boot and greasing (high temp grease) what the pads slid on will solve the problem.

Another possible cause I've seen discussed is a bad brake fluid flex line (the rubber one from the hard line to the caliper.

If you cannot check for drag by hand (I would have thought you could even if the front wheels won't spin freely) then try getting on a very slight incline (enough to make the vehicle roll downhill when in neutral with the engine off) and see if you can hear brake drag.

Luke09 · **Posted:** Wed Mar 06, 2013 4:06 pm

I can attest to the rubber swelling on the leading pin/bolt. I removed mine as they were almost seized and the problem was resolved. The only issue I can see arising is that it may lead to uneven pad wear as I believe the rubber was there to stop the leading edge of the pad from making contact before the rest of the pad. So far I have not noticed any wear problems.

Jeepjeepster · **Posted:** Fri Mar 15, 2013 11:56 am

As mentioned above...

http://www.jeepkj.com/forum/f196/someth ... kes-53303/

dgeist · **Posted:** Fri Mar 15, 2013 2:57 pm

Jeepjeepster wrote:

As mentioned above...

http://www.jeepkj.com/forum/f196/someth ... kes-53303/

So, here's a "Duralast" replacement pin set for the front:

Are the two pins actually that different? Having never taken off the pins for inspection, it seems bizarre that one side would have the sleeve an the other not.

Dan

Jeepjeepster · **Posted:** Fri Mar 15, 2013 7:48 pm

Yup, wild huh? Ive got two sets of pins so i may reuse my old pins so ill have all four solid pins. Right now ive just removed the rubber sleeve.

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How hot should brakes be getting?

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