Overheating Rotors.

G'day Dave

I had the same problem with mine (89 GQ) & found the problem was non genuine inner bearing dust seals which I replaced along with new bearings. The aftermarket ones seemed to rub on the stub axle. Also check you didn"t over tighten the bearings.

Capstan.

Thanks Well 55.

i did do that prior to re positioning the caliper over the rotor. i then bled the brakes and found that the pads were binding on the rotor, to the extent that the wheel would not turn without undue force.
When i replaced the rotors i did not dismantle the calipers at all, i just unbolted the whole brake assembly and replaced after the rotors were installed, nothing should have changed, but i have red hot rotors. wheel bearings are not to tight, but pistons in caliper do seem very tight.

Dave

Hi Dave,

Just an idea, when you cleaned the pistons did you check inside the cylinder for any rust spots. I had the same problem on my hilux and upon further inspection I found rust spots inside the cylinders, when the pistons were pushed back the rust was grabbing them and not letting them to slide properly thus jamming on. No probs now.

The obvious: are the callipers within the tollerances of the car's manual? Are they too wide? Just wondering if they are meant to be skimmed (to cut them down a millimeter or so) before installation.
Also, did you put on brand new pads at the same time?

On a previous vehicle, I put through a piston kit (new rubbers and pistons) and attacked the inside of the callipers with a strong pipecleaner. This got me back movement in all the siezed pots- Im not sure if it is common, but I only found rust on the pistons, no trace on the bore of the calliper itself.

The patrol has only one brake hose to the front diff doesn't it?
You may have a partially collapsed flexible hose which is preventing the brake fluid returning to the master cylinder when the pedal is released.
I've had this happen twice over the years to different cars, the hose will let the fluid through when the pressure is behind it but traps the fluid when the pedal is released.

Evening Jendav

I have a Datsun Bluebird S/wagon (81) which I have had since new.

Approx 2 months ago, for no apparent reason the front brakes (discs) started to stay on when used and slowly increment up the pressure with each touch of the pedal.

When vehicle had stopped (engine off etc. etc) they would release.

The morning I took it to the Brake shop, man! I had smoke billowing out of the front wheels on Warrigul Road, Melbourne, much to the consernation of myself and fellow drivers.

I thought, if it seizes, then I am walking off and leaving it.

Made it to the brake shop and after three days it was tracked to the master cylinder.

Something had s h i t itself inside. Brake techo reckons he has never come across such a fault before and just added it to his 'experience bin'

Regards

Ken Robinson

I've had that problem with the master cylinder too, meant to add that to the previous post.

Jendav

I forgot to mention that I never pursued what the actual fault in the master cylinder was other thanthe Brake man mentioned that all it needed was to be serviced properly.

So I took it that it must have been a worn, perished, dud seal, cup, broken spring etc., etc, after all those years.

What I'm getting at is that yours might need more than a flush with metho, though that is a starting point.

Whatever, I hope it is the fix you are looking for as it is a real disturbing experience slowly having your break pads turned into charcol blocks.

Fair dinkum, that morning I took it to the Brake shop, it looked like I had come into the pits at the Bathurst 1000. The smell was horrific and you could feel the heat just billowing out of them.

Another thing of interest was the Brake techo basically refused to service the caliper other than put on new pads. In his considerable opinion ( I've been using him since 1986 on this car) the rubber seals in the calipers are made to take such heat and if there was a problem later due to the heat, he would fix it for nothing.

Oh! also required a brake line flush and fluid replacement.

Amazing. works like a charm now and no distrortion in the rotors at all.

Ken Robinson

Just a thought, but have you checked the caliper slide pins? The calipers need to centralise themselves to the discs and does this with the slide pins. On my 92 gq Ti the same as yours the slide pins were jamming and I had endless problems. One was so tight it bent on removal and had to replaced and there some different problems started. Nissan spare parts delivered the top slide pin as asked and it was wrong, so they supplied the top slide pin of a single piston caliper and that was wrong too. Eventually someone in spare parts remembered a similar problem previously and remembered that the caliper shown on the computer was actually upside down and they were sending the smaller bottom slide pin instead of the larger upper one. It's just one thing to keep in mind if you need to order one.
Regards Andrew.

Jendav

Sounds like one or some of the suggestions offered may be helping.

It will be interesting to see what the cause is/was, if and when you nail it down.

Just keep at it and you will beat the 'mother'.

Ken Robinson

C'mon

Waiting to hear it all went.

Dave.

Excellent news mate. I only knew of the master cylinder thing because I to always used to do the brakes on that old Blue Bird.

One day when picking up new pads, rear shoes and cylinders, the ABS techo giving me the gear said

"you want to get a spare master cylinder and have it done up as a spare, because they just S H I T themselves for no reason at no given time and cause bizarre problems"

Taking that advise, I picked up one from the wreckers, had him service it and put it away for a rainy day.

Well about 15 or so years later that rainy day came to be. (about two months ago)

As I said earlier the brake guy who had done my front brakes ( and now all brakes) for many years on that Bluebird wouldn't believe it was the master cylinder at fault for two days and then caved in an swapped the master cylinder (recon one) that I had given him and all was well.

He had no idea what was wrong with the original other than on a quick inspection afterwards, it needed a good service.

As usual, a tad of experience goes a long way.

Glad I good help

Regards

Ken Robinson