I have a super heated rear disc, just the one, and I cannot find the problem.

After just a short journey, without touched the foot brake for the last few hundred meters, disc is 100 degrees plus. Other side is only 30 or 40 degrees.

First I stripped off the calliper, cleaned, greased the pad sliders / gaitered slide pins - all back together, still heating up.

Today, striped down the EPB, lubricated and still heating up. Strange this is, that the inside of the drum (EPB lining) didn't look too shiny suggesting that the binding wasn't from here. Furthermore, there was plenty of effective surface left on the shoes.

When I put it back together and backed off the 'clicker' the disc freely rotated as you would expect. I purposely didn't teat the EPB before taking a road test. Temperature just shot right up which feels like it could not be the EPB.

I did take a look at the cylinder (as far out as I dared to) and it looked as clean as anything. Surely there isn't that much to fail on a calliper, is there?

Completely baffled now - anyone fancy a punt?

Is there any other component that could cause friction heat builf around the disc?

PS, no noise, scraping or anything. EPB works fine and releases on drive off.....

Is there an air lock in the brake system somewhere? Have you had the brake fluid changed recently? Or it maybe a faulty brake bias valve sticking, when its jacked up it may well work fine but as soon as you put any weight on the vehicle ie back on the ground it causing the brake to come on, well thats my theory anyway

This is a new one Ady 555. Never considered a fluid problem.

Did have an engine replacement by main stealer a couple of months back, surely they couldn't make such a mistake as an airlock, could they??!!

As to the brake bias valve, I have no idea. Any easy way to test / isolate? Would this just affect a single brake? not a diagonal pair?

I'm now at the limits of my DIY knowledge - I welcome you thoughts.

I don't think there is a way to test the rear brakes only on a 4wd vehicle but i would try and bleed the system first with assistance of course, then see how you get on, and yes anything is possible with a dealer, some are worse than others

If there's nothing else I can try first, around the hardware, then I will have to get it in for LR to sort out.

Problem is here (Sweden) the waiting time for main dealer is crazy (about 7 weeks at the moment). Unfortunately there are no really good private mechs either, unlike in blighty.

If thats the case i would book it in every week in advance for 52 weeks just incase you need an appointment then cancel it at last minute if you don't

Last edited by Ady 555 on Tue Jul 26 2011 8:56pm. Edited 1 time in total

Traction control issue ??? The brain may be slowing that wheel

Just a thought 08 2.7 RRS "S"
Td5 110......very modified
RS 5
Kawasaki ZX12R me, it's quick !

Is there a slight judder when you apply brakes?
Disc run-out can also contribute to overheating. Malaysia Boleh!
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No judder at all and braking appears to be as pin sharp and straight as ever.

Is it possible that the piston on the caliper IS sticking or a little bit tight / lazy, despite appearing clean and shiny?

It is more than possible that a piston is sticking in the caliper, it is possible with great care to clean as much as possible with the brake system live i.e remove any rubber gaitors and pump the pistons out almost to the seals and clean the piston walls, push the pistons back in squarely and repeat. It is known for condensation to form under the gaitors causing a bit of corrosion. 08 2.7 RRS "S"
Td5 110......very modified
RS 5
Kawasaki ZX12R me, it's quick !

One other reason is bad driving style whereby brakes are used hard with not enough cooling time between applications for the disc to cool.

Also a common cause for severe overheating is sticking (unlubricated or rusted) guidebolts or pins on calipers. It is highly recommended that caliper guide bolts and pins are lubricated when changing brake pads. Apparently sticking guide bolts will cause your brake pads to drag constantly on the disc, even when you are off the brakes. Even a light dragging action WILL overheat and destroy a brake disc.

I found the above in some old literature - you may want to check on this.  Malaysia Boleh!
4.2SC Chawton White, Stormers
Tasmod's Sills, Wind Deflectors, LR Sills
Clear Side Repeaters, Towbar
Larini Sports Exhaust, K&N Air Filter
______________________________
WINNER - 2008 'Tech-Head Of The Year' Award
WINNER - 2009 Outstanding Contribution
WINNER - 2009 'Tech-Head Of The Year' Award

I've just had this issue, it's worth you jacking it up and checking the wheel bearing for play (hand top & bottom, wiggle the wheel). Initially I was convinced it was a sticking caliper, so replaced the caliper. At the same time, we noted that the wheel bearing had some play in it. A week later the superheated disc re-appeared (along with the loud thumping noise under the car at 70mph).

It's warped the disc slightly, but the culprit turned out to be the wheel bearing, it was worn enough to allow the wheel to cant over enough to bring the disc into contact with the pads and overheat them all. The bearing was changed 2 weeks ago and since then the problem hasn't re-occurred. Ex-G4 Challenge RRS HSE, BV55 YZE. Subtle shade of orange ! Now registered YZE481 G4RRS in Melbourne.

A number of possible causes.

1. Jack up the offending wheel and see if it rotates relatively freely. With wheel still jack and car chocked Start engine in neutral obviously! - press hard on the brakes, switch engine off. See if the wheel still rotates or drags. Leave the car to sit for say an hour and try spinning the same wheel again. If the wheel rotates more freely than it did just after you'd applied the brakes its probably an air lock or bias valve issue.

2. How many miles has the car covered? it is possible for a ridge to wear in the caliper (or pad) causing the pad or the caliber to stick rather than sliding and not free off instantly, tyr copper brake grease; it only takes slight contact with the disc toraise the temperature.

3. If your usual route home involves a number of roundabouts and/or right or left ahnders and you corner the same turns reasonably quickly it could easily be that the DSC has activated that wheel's brake more often/harder than the opposite side.

We often used to find in our garage that low mileage cars and, strangely enough people who drove economically and did not thrash their brakes often experienecd more brake system issues. This was because the brakes were only used lightly - cyclinder/pistons etc never moved often or fully and also the pad surfaces could glazed and never got enough for long enough that the glaze 'burnt'. Cure was often to drive a few miles and use the brakes fairly harshly (be careful of other drivers). BMW used to recommend applying their handbrake occassionally while driving to 'clean' the handbrake's pads and improve the effectiveness.

Coming back today from Nantwich to the Wirral, outside temp @23 deg C, I came down the M53 at 90mph, then onto A roads for 5 miles at 30/40mph. Got home, decided to wash the car with a hose+brush, and the front offside wheel produced steam as the water hit it. Nearside less so, but that was 5 mins later. Do these Brembo brakes produce such heat? There is no drag on the brakes as knocking it into neutral the car will roll easily!

peanutbob wrote:

Coming back today from Nantwich to the Wirral, outside temp @23 deg C, I came down the M53 at 90mph, then onto A roads for 5 miles at 30/40mph. Got home, decided to wash the car with a hose+brush, and the front offside wheel produced steam as the water hit it. Nearside less so, but that was 5 mins later. Do these Brembo brakes produce such heat? There is no drag on the brakes as knocking it into neutral the car will roll easily!

Yes they do, especially stopping from 90 mph