Brake judder

[nchamberlain140]

I have an 03 super V8 which is equipped with XJR Brembo brakes, due to brake judder I recently replaced front discs and pads and all was well for a month or so but the judder has now returned, but it only happens at very high speeds. Was wondering if upgrading the discs will rectify? Anyone have any experience of this.
Cheers
Nick

[3.8etypephil]

The later Teves brakes are better and less troublesome, but it's unlikely that the components have failed after such a short period. Check the condition of all the suspension and steering components, especially the rubber bushes; excessive movement can manifest itself as judder under braking.

[PaulGover]

Probably telling granny how to suck eggs, but the usual causes of brake judder are disk runout (check with a dial gauge), bad wheel balance, and commonly these days, disk corrosion. I guess in just one month the last is unlikely! I presume you cleaned the new disks before fitting - all the guidance says that new disks are coated that must be removed; perhaps that could lead to contamination. (I've never bothered, but my new disks seem to be clean when I fit them. IMHO the rotation and heat generated by braking will scrape off most contaminants.)

New Jurid pads for my XJS used to come with instructions (and probably still do, not bought any recently) saying they needed "running in" much like a new engine - light use and low speeds for the first few miles, gradually increasing with more miles.

As it's only at high speed (a) drive slower (b) I'd go for bad wheel balance (or possibly out-of-circular tyres).

AFAIK the braking system itself should not cause judder other than that generated intentionally to warn you that ABS has kicked in.

[ptjs1]

+1 for getting wheels balanced. I found on my X350 with the ligt weight of the car, as the tyres started wearing I got more imbalance occurring at speed.

The other thing you might want to check is that one of the pads isn't slightly sticking either due to slight caliper corrosion or else the pistons sticking.

Good luck

Paul

[nchamberlain140]

Thank you for all your replies, lots of useful things for me to consider.

Kind Regards
Nick