Very Hot Rear Brakes

[airbox]

I have a problem with my rear brakes which is baffling me. Brand new discs and pads, brake pistons go back easily by hand ( just), caliper pins all greased and slide easily, brakes bled. I came home from work today, 5 miles, braked maybe half a dozen times, when I got out I could smell the heat and the discs were literally glowing red!!!! I must be driving with the rear brakes on all the time, they are not letting off. It is definately not the handbrake cos I haven't used it since putting on the discs and it is adjusted to not rub. Heat was also the reason the last discs cracked so it is not new but I want to sort it before I f**k these discs. I am tempted to buy replacement ( the same ) calipers but I am not convinced it is them cos it is on both sides.

There is one brake line which runs to the rear and then it splits to each wheel, not sure how the ABS works out which wheel is which, but I am thinking could it be this splitter unit or maybe the one in the bonnet, ( think the ABS unit) that seperates the fluid to the front and rear and has electrical doobries on it.

The front brakes are fine.

Any help anyone please!!

[KiwiRS4T]

No idea what's causing it but doing the easy things first I would

1. (if you haven't already) replace all the fluid with something like Motul RBF600 - worth doing anyway and it may push out some foreign material in the system.

2. Go talk to a brake specialist and see if they come up with a likely cause.

3. Swap out the mastercylinder

4. Swap out the abs unit ( I have a spare unit but maybe someone closer has one).

Good luck!

[QWK32]

first thing i'd be checking is the handbrake shoe adjustment, i'd say they are up a little too tight and are rubbing on the rotor as you drive causing the heat buildup on the rear rotors only. it could be either the shoe adjustment behind the rotor or it could be the handbrake lever itself. i've seen it before on one of my old cars, never got hot enough that the rotors were glowing, just changed them to a nice blue colour. you said you've checked it but maybe remove the shoes from the handbrake assembly just to eliminate them as the problem.

Edited December 28, 2009 by QWK32

[airbox]

no it is definately not the handbrake. As I said I have adjusted the handbrake so that the shoes are not making contact with the drum at all and I haven't touched the handbrake since I put the new discs on. i just feel it isn't the calipers as they are both hot.

[KiwiRS4T]

Probably still a good idea to remove the brake shoes or at least back them right off. At least it is a simple task and the park brake is the most logical suspect. Also I noticed when I used to have that kind of brake that it was possible if your left foot was in the wrong place for the parking brake to fail to release completely when you pull the lever.

[QWK32]

as Bob has said, still a good idea to remove them just to help rule it out as a problem. i remember stuffing around a few times trying to set up the shoes so they didn't bind on, even though they felt good with plenty of clearance when sliding the rotor on, they still locked up once i started driving.

you said you changed the rotors for new ones, are you sure the rotor offset was exactly the same as the original nissan ones, if its out it could cause the rotor to rub heavily on one side of the callipers brake pads. i haven't had to go through changing the rear rotors yet but from what i've read its hard trying to find a perfect matching rotor???

[airbox]

As I said before, that is exactly what I have done with the handbrake. It is backed right off and the shoes are clear of the drum and I haven't used it since. It is NOT the handbrake, the calipers are binding on. I'll give it another free-up this morning but I know that the calipers slide ok and the pistons go back fairly easily. It is happening on both sides which is the odd bit, it's almost like the pressure to the rear brakes is not being relieved when I take my foot off the brakes but the front brakes are fine. that is why I was thinking of maybe the ABS unit being duff or something. I suppose I'll have to try replacement calipers first just to make sure it isn't them. It's a pain in the arse cos it's my only transport.

[airbox]

rotors wre the same and the caliper carrier is clear and the caliper itself slides so I can't see that as the problem. It may just be the pistons are too stiff, I'll try recleaning and greasing them today but it seems odd that they are both doing it.

[GTR-32U]

How are the brakes if you need to pull up quick ? Are the fronts working fine?.....Odd problem that could be very dangerous.....I wonder if its worth cleaning out the whole system and having master cylinder checked

[airbox]

had another look today, passenger side rear wheel turned easily with only slight scraping of the pads. driver's side ( the red hot one last night ) I could just about turn it. I regreased the pins and around the contact points etc and pumped the piston out and it pushed back in nice and easy, not quite by hand but nearly on the passenger side. On the driver's side I did the same but pumped the piston out, took the rubber boot off. the piston was very dry and had rusty score marks on it. I wet and dried what I could, using brake fluid as a lubricant, then cleaned it off, put brake fluid on the piston and pushed it back in ( not by hand ). I then pumed it back out and repeated the process. Now I could push the piston all the way back in by hand, pumped it out and pushed it back in again by hand. I then kept the piston in and bled that caliper. Then pumped it back out and pushed it back in again by hand. Put the boot back on, clip is fiddly, then reassembled everything. Put the wheels back on and pumped the brakes a few times. Both wheels now turn with minimal scraping of the pads. Hopefully that is it sorted for now.

I think I should really replace the calipers with some newer better condition ones before it happens again!!!

[KiwiRS4T]

Hopefully you have solved it. I had a similar problem with the fronts on a Toyota Corona and after cleaning them up with sandpaper to get rid of all the score marks but without success i figured that there was so much clearance that the pistons were able to tilt and jam. Another set of calipers from the wreckers fixed it.

You should be able to test the brakes by seeing if the car will roll away on a very slight incline or be held by sticking brakes.

[airbox]

yes that is what was happening, even on steepish ( sort of ) inclines and the wheels were hot. I will keep checking it after every drive cos I am paranoid about it now!!!! I'll look out for a replacement set of calipers. I would like to upgrade but money says I'll have to stick with stock items, just hope the ones I buy are better than mine, always a risk.

[KiwiRS4T]

Look out for a set of 2 pot rears (e.g. GTT) - you don't have to do front and rear all at once.

[airbox]

I have managed to get a pair of ecr33 r33gtst rear calipers at a good price off ebay. They haven't turned up yet but I have a few questions.

They are the 2 pot ones.

Are these calipers made from aluminium?

To do a seal change on them, do you need to split the calipers?

I understand ( correct me if this is wrong please) that stagea rear discs are 280mm and the r33gtst ones are 296mm?

The stagea rear discs are vented, are the gtst ones or are they just one solid disc?

I shall try and keep my standard ones going until I have refurbed and painted the gtst ones and saved up for more discs and pads!!

[pipster11]

rear 33 brakes are 297 (1mm bigger than the 33 fronts) they aren't as thick as the fronts but they are vented (99% sure they are, my 32 rears were)

make sure you put 33 rear rotors in there cos the 33 ones are prob different offsets