UKC

About 18 months ago I changed the front disc brakes and pads on my wifes toyota yaris as they were juddering violently under normal braking. That solved the problem for a year, then it returned. I changed the discs last October for a different brand thinking that the others were crap.
3 months later the problem has started again!
Its quite a light car and she doesnt drive or brake hard, Ive replaced various parts of the suspension recently so I know they are good, the wheel alignment is correct, the rear drums have been cleaned and adjusted.

What on earth is going on with the brakes?

In reply to ow arm: did you change the pads in October?

In reply to Mountain Llama:
no not the second time, I didnt see the point a they were hardly worn, looked clean and no reason to be contaminated with oil etc.

In reply to ow arm: sounds like the discs may be warping. Check your warranty on the discs, you may be able to claim.

I would always match new discs with new pads as its not worth the risk considering how little they cost.

Have you tried posting on one of the car forums?

In reply to Mountain Llama:
yeah its on astraownersnetwork as we speak
Ive read up about warped discs and as far as most people are concerned, they cant warp, but you can get pad deposits on the surface causing the juddering.

I know pads arent expensive but changing the disc and pad only lasted 12 months the first time so I guessed that the discs were poor?

In reply to ow arm:
Getting the discs and pads hot then allowing the car to stop with the brakes applied will lead to pad deposit on the discs, like you mention. This can be invisible. The good news is you can get rid of it with some repeated hard braking, obv. being careful to avoid resting the brakes on the pads. There's a good tutorial on 'bedding in' pads on the Performance Friction website (crappy internet at the mo so can't link), I'd imagine that a careful application of that process would sort your problem out.

Edit: should have said obviously be careful and don't attempt if the car pulls to one side. Also, what you said about your wife's driving style means pad deposits are quite likely, as she is not braking sufficiently hard to scrub the stuff off. My missus is the same!

In reply to ow arm:

I've had a similar problem which was down to a sticking caliper. It would disappear after a pad change, presumably because the piston was in a different position within the caliper, only to reappear later.

In reply to ow arm:

This can be a misleading symptom another fault altogether:
1. anti roll bar bushes/drop links or other suspension bushes. <Very common on the old serria & Rover 2/4 series, exactly the symptoms you describe, magnifies warped discs x10>
2. ABS fault <operating even when not needed>
3. Buckled wheel.
First off confirm the disc are at fault - take wheel off and use an axle stand with a pencil taped to the top. Align the stand so the tip of the pencil is just touching the disc the slowly trun the wheel while carefully watching the pencil tip. You should see a gap open up as you are turning then close again if the discs are warped. If they are shot perhaps look at the wifes driving, holding the car on the foot brake after braking to stop anyway can cause this, motorway driving usually, heavy braking for the exit jn then sitting on the brakes at the jn traffic lights for example. A yaris don't sound like this sort of car though!

In reply to ow arm: either the wife or the car has to go. You decide

In reply to imkevinmc:
well, by the looks of them, both will need replacing in a year or so!

Whilst your helpful replies were being posted I was thinking along the same lines as Turdus and went out to regrease the pistons and caliper sliders.
That seems to have done the job for now.
If thats all it takes I dont mind doing that once or twice a year

In reply to ow arm:
Sticking caliper is a good start, had this on my land rover