Front Disc Brakes HEAT-UP like a MOFO! ‘89 XJ!

Front Disc Brakes HEAT-UP like a MOFO! ‘89 XJ!

My front brakes were all fine and dandy last month. But after I installed new hubs and universal joints my front brakes heat up incredible hot!

How hot? After a 30 minute drive averaging about 30 mph with a little stop and go traffic thrown in....the spokes on my stock rims were too hot to touch. I can feel the heat radiating off the wheel from about a foot and half away.

I waited about 15 minutes and the right side cooled down where I could touch the disc but still hot...then I assumed the driver’s side was cooled the same and touched the disc and burnt my finger and a got a blister! Said a couple of bad words too!

Also I noticed after driving with the brakes hot the jeep would pull to the right...my guess is the right brake is not as hot as the left and is fading less.

The strange thing it doesn’t feel like the brakes are dragging. The Jeep is as spry as ever. I don’t hear any dragging of the brakes.

I removed each caliper and inspected the discs and pads and they look fine. They have about 5000 miles on them. I wired brushed the “rails” that the pads ride on and re-installed but still the brakes heat up.

A couple of the stainless steel rods that the caliper rides on are pitted...could that be a problem even though they’ve been that way for years...I grease them.

When I replaced my hubs I used a c-clamp on each caliper to hold them in...could that have damaged them or the proportioning valve?

What would be next on the agenda to look at?

Many Thanks,

John V.

First impluse is the calipers, they normally ride inside their bores smoothly but as the brake fluid absorbs moisture they start pitting and the don't ride so smooth anymore, whats worse is the don't relax when you let off the pedal, I say relax because they don't retract like rear brake shoes do. The pads are always touching the roto. I've had them do this on 5 year old factory calipers and in extreme cases they can lock the wheel. Another cause is if you have alot of moisture in the brake fluid it will expand as it gets hot and make the situation even worse and break fluid does get hot under normal use.
First thing I would do is suck all the old fluid out and replace it with new then see what happens

My xj started doing that shortly after I swapped in my waggy axle, the calipers were sticking and causing them to get very hot.

Thanks guys. I'll give draining and bleeding a try.

I'm worried that the extreme heat damaged my new hubs! Is it possible?

Thanks,

John

You'll find out if they warped or not, as for the hubs, not usually, theres alot of steel around there to bleed off heat, even extreme heat.
You are going to have to bleed the WHOLE system, starting from the passenger side rear to the driver side rear to the passenger side front to the driver side front in that order. Get two big bottles of brake fluid and two small bottles, been a while since I've done mine but I seem to remember that I did put both big bottles thru till it got all cleaned out and ran clear and one small bottle topped it off. Some people I know buy their fluid in colors, say red and gold or blue and gold but they change it every few months with one of the pressure bleeders, makes it real easy to see the changed fluid but with older fluid going from black to clear is usually enough

My driver side caliper used to heat up to the point of smoking, changed the caliper, no more probs.