dan ok

iTrader: (1)

Ive recently fitted some performance friction discs with Z rated pads and they seemed fine,did the recommended bedding in process and again seemed fine but now im getting a judder under braking when im lightly touching the pedal if i press very hard it doesnt seem to be as bad.

Any ideas? thanks.

stockcar

were they checked for "run-out" when fitted???

alyn

dan ok

iTrader: (1)

Run out?

tanyatriangles

iTrader: (2)

You spin the disc while holding a probe in a fixed position against the outer face. You can then see if it's touching all the way round.
If it's done properly, it's done with a gauge that actually measures the deflection of the disc as it spins

dan ok

iTrader: (1)

oh ok,who does that service then?
thanks.

s70rjw

iTrader: (2)

Are they under warranty?

tanyatriangles

iTrader: (2)

Try a local engineering place, they will have the dial gauge to do it for you. The smaller the enginners the more likely they will be interested.

Mark1983

iTrader: (2)

You're not going to be able warp the discs under road use or even trackdays. I can almost guarentee you it is a build up of brake deposits on the discs. I had this when changing from Z to the harder 01 compound pads. Some hard braking should soon clear the deposits. It took several laps on track on for the juddering to stop.

I've done hundred of laps on the Nordschleife and Spa plus UK trackdays and never once warped PF discs.

Aztec Performance Ltd

iTrader: (234)

Glad your still enjoying them Mark

Dan: A brake/tyre/exhaust chain will be able to check disc run-out for you. Usually FOC.

stockcar

im not aware of that many "chain" type places that will own or know how to use a dial gauge correctly in my experience, it has toi be done on the car as if its a fault with a hub, etc. it won't show up on an engineers bench................

alyn

Jay m A

iTrader: (2)

Best thing to do is really hammer the brakes, go to a deserted m-way and do a couple of big stops. If its deposits it will get better, if warped it'll get worse!

tanyatriangles

iTrader: (2)

A deserted motorway? What, he's got to go all the way to France?

Aztec Performance Ltd

iTrader: (234)

Alyn: I must have got lucky with the local chain brake/exhaust centre as they have one and measure the disc runout with the discs in-situ.

Always worth a ring around beforehand.

JohnD

iTrader: (5)

Hey! you're from the south east - when did you ever see a deserted motorway?
JohnD

JohnD

iTrader: (5)

Is it a wobble through the steering or the brake pedal? If it's the steering, when did you last have your wheels balanced? Lateral inbalance can feel ok but show up under braking.

JohnD

Jay m A

iTrader: (2)

Late at night!

Mark1983

iTrader: (2)

I found the juddering quite violent in hard stops so started by left foot braking whilst driving then some 120mph-20mph braking did the trick for me but then again I was working at a race circuit so had that to play with.

I couldn't fault the PF discs with 01 pads in track, simply awesome. My mate running PF discs and Z pads even noticed the difference.

dan ok

iTrader: (1)

Thanks for all your help guys,ill try getting the wheels balanced first then ill find that closed private road to give the brakes a good work out.

daddyscoob

Hi I bought an 03 STI with these discs and pads fitted and it was suffering the same judder. Tried all the hard braking stuff but did not help.
I noticed one dics had a dull patch on it and over a short period this then became pitted.
Took them off and put the original discs - supplied with the car - back on and problem solved, perfect brakes.

I still have the PF discs and could dig them out and get a picture if needed.