mk4 brake shudder

[Stiggy_21]

my sister's mk4 2.slow has some front brake shudder.
don't know much about mk4's as I only deal with mk1/2's, so I thought I'd ask you guys.

I'll start from the beginning.
About a year ago the car was in perth, the RH front was shuddering. So Joe from elite euro in Perth had a look, and one of the calliper sliders on the hub had broken. So got another one of them, tie rod, new pads and disks and no problem.
but now the car is back in Melbourne, and a similar issue has cropped up.
so my initial thought was the hub, had a look at both sides and everything seems normal.
Disks don't look warped, caliper isn't moving.

Now when driving it, pressure feels good, just intermittent at any speed, and it doesn't feel like air in the lines.

so my question is, can anyone think of anything that I'm not looking at?
And could it possibly be something to do with the ABS?

Cheers,
Dave

[Sirocco20348]

When does it shudder... all the time?

Braking in a straight line?

Full turning lock at slow speeds into a carpark?

[Stiggy_21]

This might be a bit confusing.....

when doing slow speeds it doesn't seem to be as prominent as doing higher speeds (eg highway driving) then coming to a stop.
yes it does it all the time, corners or no corners.

I'll do a few more thorough driving tests tomorrow, and see if I can narrow it down

[Stan]

disks might not looked warped, but would be my first guess for shudder

[Stiggy_21]

I know it could be a 'bad batch' of disks, but they're nearly brand new ATE disks, only had about 1000km on them....

anyone know when ABS kicks in? Is it only under heavy braking?

[dylan8]

car got driven through a puddle while disks were hot? I know I had that issue after driving through some flood water once

[Stan]

ABS should only operate with very firm braking. In just normal around town driving, they should not be coming on

Does it do it when not braking, just driving along? - if so look at wheel balance

[Stiggy_21]

According to my sister, she hasn't driven through any puddles.
she doesn't drive it very often, only once or twice a week if that accounts for anything.

And it is only under braking, heavy or light

[Flea]

I've got the same problem with my wife's mk4. The rotors are warped.

[Martin]

Any time the rotors are overheated you can get minor warping
If the caliper is not able to float this can also be a contributing factor
(could cause heat and provide lateral pressure too warp the disk)
You've had caliper slider problems in the past, may have fixed the symptom but not the root cause

[JustCruisn]

Could be a bit of brake compound on the disk (glazing), or the pads may not have bedded in.

[Stiggy_21]

Cheers guys..
I stomped on the pedal a few times and it made it a little better, so I'd say justcrusin is right, the pads or disks are glazed. Ill give it a few more goes and see how she is after that.

It seems likely, the car hasn't been driven much lately and my sister has a very soft left foot.

[JustCruisn]

You could pull the pads and rough them up, and maybe sand off the disks.