Brake screech after new discs and pads.

[DarrenH]

Hi all.

I've successfully (or so I thought) changed the front brake discs and pads. I replaced this due to the steering wheel vibrating when braking, these news discs / pads have solved that issue on my first drive to the supermarket since the change.

However, I have an intermittent and rather loud screech from the front near-side wheel. At first it was just a little screech, but it got worse and quite loud on later occasions.

The noise got worse when not using the brakes, and it was pulling to the left, so I thought the piston and or pad was getting stuck on. I pulled over a couple times, as I didn't want to drive if it wasn't retracting. As I drove off after a minute (after engaging the brakes to stop), the noise was gone, and the car didn't pull to the left as much. It's always pulled a little to the left on the old pads / discs.

Any thoughts, or things I can check / look for to solve the issue? Or bad brake caliper? There wasn't any heat difference between the two front wheels that I could notice, but then it was only a 2 -3 mile drive each way. By the way, this is the first time I have changed the pads / discs following some YouTube videos and the German pdf gude on this site.

Cheers, Darren.

 

[Dave M]

Just a thought Darren. Before you put the new disc on did you clean the hub with a wire brush/ brake cleaner. I had a similar problem once with a Lupo - i hadn,t cleaned off the crud and the disc wasn,t "sat" properly ?. The other simpler answer is that a small stone or dust had got between the pad and disc and after you,d stopped it may have dislodged itself.
Ta
Dave

 

[Birchall]

Please inspect it again in detail. Those symptoms are a bit scary.

It does sound a bit like the Pistons could be sticking. Applying the brakes might then move them a tiny bit and so it stops screeching fir a bit until they stick again.

But brakes that pull to the left are worrying. BUT almost all cars will pull to the left on a road with some camber. So are you sure it is not just that.

On a straight flat road you should be fine but on a road that tilts towards the kerb you will find that your car will pull to the left a little anyway.

The screech could even just be the dust plate touching the disc, but a quick inspection should show that up.

is that wheel getting very hot when this happens?
If the brakes are binding it would be very hot.

But please do jack the car up and check everything again. For safety's sake

Steve B

 

[spartacus 68]

Sounds very much like the dust shield is touching the disc itself. Whip the wheels off and check again. When the piston was compressed to refit the new pads - was it easy enough to do, or was there a degree of resistance? I take it you wire brushed the caliper to remove any surface corrosion so that the new pads sit properly?

In addition, did you grease the backs of the pads slightly with copper-ease and clean the slider bolts? These should be spotless and then regreased. I use Lockheed red grease.

 

[DarrenH]

Thanks for all the advice, everyone.

I haven't jacked it up to inspect it again yet, I'm going to do that shortly now that I've got some feedback. If I can't see anything obvious, I'll get a garage to check it over.

To answer your questions:

- I did use a wire brush on the hub, although I didn't use any brake cleaner on that, I only sprayed the discs with it.
- The car has always pulled to the left, on my first discs and pads, the previous ones that caused the vibrating steering wheel, and the ones that I fitted yesterday. But it did feel like it was pulling more when screeching, which is why I was thinking along the lines of the piston / pad getting stuck.
- When I finished the journey, I did try and check to feel for any heat, and I couldn't notice a difference between the two, if it was hotter. But then it was a short journey.
- I used a wind-back tool to push the pistons back, but I'm struggling to remember how easy they were to push back. I have a feeling the the troublesome near-side may have been a bit harder to wind back. But I can't be certain.
- I didn't use a wire brush on the brake capiler.
- I did use copper grease on the back of the pads, and the edges to help them slide.
- The sliding pins might be where my mistake lies, I didn't really clean or grease them. I just used the existing that was already on the pins.

 

[6stings]

Check the disc surface for deep scratches, maybe something got stuck between the pads and the disc?

Happened to me once, the screw holding the disc snapped and got stuck there...

 

[DarrenH]

Thanks all, for your advice.

I took another look today and spotted a small stone lodged in the disc. When I tried to remove it, it dropped down between the disc and hub. When rotating the wheel after it dropped down, I could hear the horrible screeching again. I guess this is why it was intermittent, getting lodged in one of the gaps of the disc, and possibly why I thought the car pulled more to the left with the friction of the stone rubbing.

I had to take the caliper and disc off to free it. I took it for a quick test drive of maybe a mile, and it's been fine. I went on a longer drive later, maybe 20 miles or so and it's still good. I don't think there was any damage to the disc, I couldn't see any deep scratches.

And finally, the culprit lodged in the disc:


Cheers, Darren.