(G) rear passenger bake squeeking!

right, my passenger side rear brake is squeeking. the pads are only 12,000 miles old and therefore wonchanging. is there anything i can greece? the pistons? any ideas as its annoying lol

Dunc

the turbo's have disks all round dont they?? does it only squeek if you are breaking or is it all the time?

If it is only when braking, the disk is probably glazed. try doing some hard braking to shift it. if not a very light sand with emery cloth to remove the glaze might help.

edit: not 100% on the emery cloth route - i cant remember how i got rid of the sqeeks on my mums vitara

yeah discs all round. hmmm, i'll have a go at hard braking heheh

Dunc

lol, just dont push so hard that they lock otherwise its a wasted exercise. you want to put lots of force down tho, enough for it to take the glaze off but still move round so you get it all off round the disk.

What is glaze?



Morten, the non-English.

i think its when the dust coming of the pads, and any passing crap from the road, is heated up by the brakes doing theie work, if i remember right it's like hundreds of degress in there on full load, and it bakes a layer of all that crap onto to disc. sort of like the shiny stuff on the top of a donut.......arggggghhhhhhhhhhhhhhhh DONUTS!!!!!

anyway, er, sorry, back to the point....

if you stick on cross-drilled and grooved brakes, it minimizes the abilty for glaze to form/build up, as the hot air and road/dust crap have an escape route to free air...

at least thats the theory i heard...

now where's the nearset krispy kreme.....?!

And yea, drilled & grooved brakes should reduce the problem of that happening

And a wierd analygy

Glazing is when the metal surface of the disc is sort of 'polished' by a combination of prolonged light contact with the brake pads and heat. Both the pads and the discs can get glazed like this.

Both the surface of the disc and pads need to have a degree of courseness to create friction when they are applied to each other. If they are glazed, then the surfaces are too smooth and actually slip rather than grip on each other. This can also cause squealing.

Two options are available to try and sort it out. One is as Luke suggested is to apply the brakes hard a few times and hope that will break the glazing. The other is to dismantel the brakes and rub the surfaces of both the discs and pads to roughen them with course emery paper.

Rear disc brakes glazing/ seizing is a common problem on small cars equipped with rear discs. This is because something like 75% of the braking of most cars is done by the front brakes, so the rears get very little use. Even on the small engined rear drum braked Uno's there is a rear brake load proportioning valve to stop the rears locking up. This is because the standard drums can be at times too powerful for the car!

A lot of cars have rear discs fitted more for cosmetic reasons. Discs look more sexy than drums, but a lot of cars do not actually NEED rear discs under normal driving. This is why a lot of modern cars with rear discs have problems with them seizing.

Dunc, I suggest that the best option for your rear brakes is to take the car to a track day. Then you can use all the power of the Turbo and actually get the rear brakes working hard - and have a lot of fun in the process!

Oh, and cross drilled/ grooved discs aren't as efficient as vented discs. Drilled discs don't actually help at all, and the reason race cars used to fit them is because of weight saving over solid discs. It was purely a way of reducing weight, not increasing braking efficiency though at the time it was thought they helped disperse heat as well. If anything, the holes can weakned the disc, and under hard use cross drilled discs have been known to shatter.

Grooved discs can help to disperse dust and heat better than a solid disc, but they still aren't as efficient for heat dispersion as vented discs. Unless of course they are grooved AND vented. Also, grooved discs can cause brake 'chatter' (noise, plus vibration through the brake pedal) and wear out pads much quicker.

To improve braking, the solution is to fit more efficient brake calipers (bigger piston, twin piston or more etc.) with a greater pad 'swept' area. Another option is to fit larger diameter discs with matching calipers.

With the exception of the turbo cars which under hard use might need a brake upgrade, most people with standard Unos would find that a change of brake fluid, a clean up, service and a good brake bleeding session will improve the braking no end.

i like the donut analogy better....or do i just like donuts.....?

Policeman + liking donuts = fate

thanks for you replys people

my rear brake has been slightly catching for a while now and i think its eventually become glazed. will take it to bits this weekend (another bloody job to the never ending list) and get sanding hehe!

oh yeah, and 1986uno45s, i will indeed be going to a couple of track days this year at donnington park :P bring it on baby!!

Dunc