Brakes binding?

[Howard-]

Evening all,

Had my MOT today and aced it, apart from the guy mentioned that the front offside brakes are binding/grabbing only very very slightly. Gonna have a look at the weekend. What should I look at?


Cheers


This pre-cat emissions test is great isn't it

[S7Paul]

I've just had a similar problem, having just put new discs & pads on a 2002 1.8 Sport before the MoT. The tester said that both were binding (though one noticeably more than the other). Things to check:-

Are the pads free to move in & out (i.e. not sticking in their guides)?

Are the sliding pins seized (i.e. with the caliper off, do the caliper mountings move freely in the mounting bracket)?

Is the piston seized in the caliper? With the caliper off but the brake pipe still connected you can pump the piston out a bit then push it back in with a large G-clamp. Also, when the piston is sticking out, you can grip the edge (taking care not damage the dust seal) and gently rotate it. Either way, all you're doing is ensuring it's not binding in the caliper.

Having done all this the brakes were still dragging a bit. At the moment I'm suspecting that it's because I had to push the pistons fully in to get the caliper to fit over the new disc & pads, and I'm hoping that once the pads have worn slightly the situation may improve.

Warning: Don't forget that when you push the pistons in, the fluid level in the reservoir will rise. Keep checking to ensure that you don't get brake fluid spilling out.

[Howard-]

Thanks Paul,

I noticed today that the front nearside wheel and brake disc are getting rather hot So I think something needs to be done..

However, having never fiddled with brakes before I'm a little cautious over what to do! Can I check most of the above without having to remove the caliper and re-bleed the system?


Cheers

[nfo]

If it's the slider pins that are sticking, that's very easy to deal with - one bolt on the front brakes. If it's the piston that's sticking, I'm not sure what you can do without reconditioning or replacing the caliper.

[Howard-]

How do the "slider pins" work? Is there a diagram anywhere or anything? I like to know what I'm looking for before doing it

[Howard-]

Well sod it, I just thought I'd dive in - jacked the car up, wheel off, caliper lifed up and held up with string, pad out, clips out, springs out, gave it all a good clean to get rid of crud blobs built up on grease, put it together, the springs do their job now and I can turn the brake rotor by hand

For now..

The piston wasn't actually stuck out by more than a MM or two, so that must mean the caliper isn't totally siezed

Edited by Howard- on Sunday 16th August 14:51

[covmutley]

Just changed rear discs and pads - had to push piston back with g clamp to get caliper to swing over. Bled brakes, took it out for a sping and had smoke pouring from the brakes- not good. A rest and then a few more miles and it has subsided.

Anyway, when i was bleeding the front brakes i put a wire brush to the rust that had formed around the rim of the disk where the pads dont contact. This seemed to allow the hub to rotate more freely. Perhaps the rust was interfering slightly and causing slight drag, this may be the same in your case??

[BonzoGuinness]

covmutley said:

Just changed rear discs and pads - had to push piston back with g clamp to get caliper to swing over. Bled brakes, took it out for a sping and had smoke pouring from the brakes- not good. A rest and then a few more miles and it has subsided.

Did you try using the adjuster screw to pull the rear piston back first? They don't just push in like the fronts - there's a small adjuster screw to rewind the piston. For me, the G-cramp was a last resort - but only because the piston was corroded and the adjuster spindle couldn't pull it in. Even after cleaning everything up, a recon caliper was needed to stop the piston rusting up again and the binding reoccuring.

If you didn't do anything after the first test drive and plumes of smoke (like I had), then surely you've just worn the pads down enough that they're not binding any more - but they'll be glazed over and the disc will have endured some crazy heat!

[covmutley]

yeah i wound them in but they weren't retracting well. Just used the clamp for the last few mm and it went back easy enough.