Should my rear brakes get hot?

[Andy Lynch]

I have just renewed my brake discs and pads, the rears are standard solid discs with ferodo pads, however after a 30 mile journey, normal driving, the disks get hot to the touch, too hot to touch for more than a second or two, The alloys also warm up, I did a second 10 mile journey today and they seemed to get to a similar heat. By comparison the front disks are cooler and the alloys dont warm up. Is this normal?

When I brake the braking is smooth with no juddering.

When I push the car on the flat it moves easily and I can't feel or hear the brakes binding.

[GreenV8S]

No that isn't normal. The rear brakes are dragging. Did you clean the part of the calliper that the pads slides in, and clean and grease the sliders?

[phillpot]

Did you wind the adjusters/pistons back in ?

[ketvrin]

could your handbrake cable be too tight ? just enough to have the pads touching the discs perhaps? (I dont know what the adjustment is if any at the caliper as I have drums...)

K

[Bagpus]

Have you replaced the master cylinder? I had a problem where the adjustment between the master and the servo was set incorrectly adjusted which mean't the front and rear got hot, but as we progressively backed it off, the rear calipers still dragged even though the front became cold- we backed off only slightly further and the problem disappeared. Forgot to say when the car was cold it was possible to push it without any signs of binding

[Andy Lynch]

Thanks for the info,

I think I put copper slick on all the relevant bits, and cleaned and greased the slide studs, and took a fine file to the bits that the pads sit on in the calliper, so I thought I had got it all covered, on the handbrake front I disconnected it tonight and gave the car a spin and still got hot brakes and warm wheels, so the handbrake is probably not the problem.

On the Servo front I have recently replaced it and the master cylinder, so next I will try and back the adjuster off a bit

I will let you know if backing the servo adjuster off a bit helps.

Again Thanks,

[phillpot]

Still think you need one of these or can be done with a pair of circlip pliers or similar

[Andy Lynch]

Thanks Phill, I managed to turn the piston using a pair of long nose pliers, when replacing the calliper over the new pads there was loads of clearance.

Cheers

Andy

[Andy Lynch]

Sorry Mike, Just looked at your profile, and I assumed you were a Phill

Andy

[Barkychoc]

Grinder disc tightening tool fit calipers perfectly to turn the cylinder in

[Andy Lynch]

Adjusted the servo adjusting screw, test drive again, brakes hot, alloys warm, blast, wheels off again, will strip down again, screw in pistons, reapply copper slick, and try again. if that doesnt work I will have to pay someone.

[GreenV8S]

If you go out for a drive, come back and park without using the handbrake, are the brakes dragging at all? You should be able to get some idea by rocking the car backwards and forwards on level ground. Also consider jacking up that hub (with the car securely chocked, but still no handbrake used) and see whether the pads are being held against the disks. There are a couple of master cylinder faults that can cause them to hold residual pressure which could produce symptoms similar to this - or you might have handbrake cables flapping around and tweaking the brakes on slightly when they bounce, or there could be a sticky slider.

[Andy Lynch]

Thanks for the reply re master cylinder issues, please can you give some more info,
I have had the rear of the car up on axle stands, front wheels chocked, re-checked the brakes, made sure the slides and guides are clean and regreased. With the wheels off and discs secured, I ran the car, both the brakes are dragging ever so slightly, causing the discs to warm, I disconnected the handbrake and no difference. So the only thing I can think can be causing both brakes to drag is pressure in the system, either the master cylinder, or possibly the pressure regulating valve.
any one any other ideas?

[GreenV8S]

What do you call 'slightly'? The pads will naturally stay in contact with the rotor unless heavy cornering knocks them back, but the hub should turn easily under light finger pressure even though the pads will rub. If you get the brakes hot and then crack a union downstream of the bias valve, is the system under any pressure?

[Andy Lynch]

Thanks

`Slightly' is difficult to explain in any clear context, with the wheels on, I can turn the wheel `easily' with one hand, with the wheels off I can still turn the hub, although more force is required, I will crack a bleed nipple on the caliper next time I run the car.

I thought of bypassing the bias valve and running the car, to discount that holding any pressure, any ideas?

Thanks

Andy

[GreenV8S]

Andy Lynch said:

Thanks

`Slightly' is difficult to explain in any clear context, with the wheels on, I can turn the wheel `easily' with one hand, with the wheels off I can still turn the hub, although more force is required, I will crack a bleed nipple on the caliper next time I run the car.

I thought of bypassing the bias valve and running the car, to discount that holding any pressure, any ideas?

Thanks

Andy

Quite a lot of work to replumb the brakes, potentially dangerous since the brake balance will be wrong. Much safer and easier just to see if the system is holding pressure by cracking a bleed nipple or union once the brakes are hot.

[Andy Lynch]

Thanks for all your help, I have driven the car over the weekend, and taken it to work a couple of times, which is a journey of 30 miles each way, the wheels get warm, and the disks are hot, but can be touched, I think I will monitor the situation over the next few weeks, and see how it goes.

Again thanks, I hope to see some of you at Chatsworth.

Andy