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Does the Brake pad touch the disc when u jack the car up?

I jack my car up just now to check the amount of pad left on it and found out that the front pad is actually touching and slightly rubbing on the disc.(Nobody step on the brake.) There are about 80% of pad left.

Is it suppose to be like that or something is wrong?

I usually figure out what I'm doing as I go along when changing pads, because every car/motorcycle seems to be different (at least the ones I've owned). But they're all fundamentally the same, you have a calliper held onto the hub with some bolts, and a disc inside the calliper which comes off when you take the calliper off (or on motorcycles, it comes off with the wheel).

The primary safety thing you should be aware of are getting air in the lines, which won't happen if the callipers aren't faulty and you don't remove the hose. Also, once you've put the pads in place, pump the brake pedal a few times to push the pads up against the disc. Once the pads feel firm again your brakes are ready to go. Definitely don't forget this step or you will be driving into a tree before you know it!

Originally posted by red17

The four potters on the front are dead easy, unbolt the caliper and pull the 2 retaining pins that go across the back of the caliper out... pads, shims the lot will just fall out.  

Red17

Unbolt the caliper ??? Why ??

Just pull the pins , push the pistons back and drop the pads in.

But I have to ask if someone who doesn't know if the pads are supposed to be touching the disc is really qualified to work on a fairly important safety item as this ?

Cheers

Ken

Ken,

Sorry ive only done it on 3 sets of calipers which werent on cars at the time, hence me thinking they had to be unbolted, should have thought more before opening my mouth.

Your right though, despite it being easy, perhaps its best to have at least someone knowledgeable to help you first time out. Just in case.

Red17

Guest Yoda

Disc brake pads always touch the disc. They work by clamping the disc when you put your foot on the brake, increasing the friction between the surfaces, slowing the car. (cut down version). the disc is smooth, so there is little friction when no pressure on brake. its not like a drum or pushbike brake that has a gap...

What's the easiest way to get then pistons back?

I tried openning up the bleed screw and pushing them, but they wouldn't budge. Since, I've had the pads changed by the pro's while I had it in for other work.

Thanks,

Michael

use a g-clamp mate, thats the easiest way. its a bugger otherwise. while youre there you might as well bleed them. pump the peddle 3 times, on the 3rd go get someone to undo the nut and the brake line and push the peddle to the floor. the fluid will leak out, once the peddle is on the floor tighten the nut back up. make sure u have extra fluid to top it up

Be extra careful if you are going to push the piston back into the caliper (which you will have to do if you are putting new pads in). If you pinch the rubbr boot around the piston dust will get into the seals and within a few months you'll have a leaking piston.

It sounds like a straight forward job, and it is, if you know what you are doing. If not, get your mechanic to show you how. Don't mess around with your brakes if you don't know how to do it properly.

I may be the poor bugger crossing the road infront of you one day. :D

Originally posted by GaryD

also make sure u get the discs machined at a brake shop!!

Depends on what pads are going in and what you're using the car for...

I'm setting mine up for track work and have recently put RB74's in and I was told by a brake specialist to bed the pads in on old rotors, and not to machine the rotors before the pads go on...

I tried a screwdriver on the metal part of the piston when I was trying to push them back so I think I'll double check that I haven't damaged the seal in the proces...

Michael

mmm yeh yur right actually! i just checked bendix's site and they recommend only doing it if the disc isnt the same thickness all the way around. apologies, ill delete that post. the dodgy brake shop musta been telling me porky pies :D

you'd know if you cracked the brakelines, your fluid would be low and your wheels would be covered in shit. theyre made to be pretty robust really, cuz its wat keeps u alive :D

All disc brakes have the calipers touching the disc at all times. they do this because they are auto-adjusting. unlike Drum brakes which are un-adjusting. the point of auto adjusting is so that when the pads wear down they are pushed into contact with the disc so that there is no travel for the pad to the disc. if they were un-adjusting like the Drum brakes the travel the brakes must do translates into travel in the brake pedal. so auto-adjusting means that movement in the pedal = contact.

i dunno..i done it a couple of times in my old cars.. u get a bit nervous but it all worked out fine..

You can do it yourself.. and you'll have that warm fuzzy feeling of doing something yourself :P

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