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Severe Brake Judder on Heavy Braking

mikes48

Distinguished Member
Car - Jaguar S-Type 2.7D Sport Auto, 2005/55 reg, 64,000 miles, mostly daily commute on M61, 35 miles each way, generally driven quite briskly.

Nov 09, new tyres all round (Pirelli P Zeros, which it's had on from new, 245/40 18), rear discs and pads renewed, front pads renewed, had been developing a bit of judder on braking but the garage said front discs were OK, didn't need changing, just the pads.

Two months on, the judder/vibration on braking, especially from motorway speeds, has got a lot worse, the front of the car shaking and vibrating badly on heavy braking. At lower speeds, brake pedal pulsing on braking gently.

Yesterday, pedal going right down on braking, needing a couple of pumps to work.

Had already booked it in for new front discs and pads, and dropped it off this morning. Garage rings - pads and discs all OK, can't fing any faults in suspension/steering, no fluid leaks, says he's checked for run-out and it's OK, it's an MoT garage and they are stumped. Can only suggest I take it to a main dealer to investigate master cylinder and servo.

To me, all the signs are warped discs - pushing the pads into the calipers, hence need to pump them back into contact with the discs, and undulations from the warped discs transferring to the rest of the car.

So the car is stuck in a garage that can't fix it, 35 miles away. Wife's had to stay at home so I could get to work in her car, and I'm mighty perplexed.

I'm tempted to ask them to replace the discs and pads regardless, if only to eliminate them. Quote is £224, which isn't bad for a Jaguar.

Any ideas, guys?
 

Solomon Grundy

Distinguished Member
Have they checked the calipers? It's a long shot but you never know I guess.
 

bazonix

Prominent Member
the discs and pads fine usually, have a good read and be prepared to explain why u are still experiencing it to fitter :)
 

mikes48

Distinguished Member
I would ask that the disc and pads be replaced from the garage you you got them fitted

The front discs are the original ones (unless they were replaced before I bought the car at about 9,000 miles).

The garage had the new discs and pads in this morning, ready to go on, so it's hard to believe they are not being genuine, as it is losing them a sale. They were throwing in the new pads free, btw, on the basis that maybe they should have replaced the discs back in November when they put new pads on all round.

All very confusing...
 

Aerojon

Established Member
Juddering when braking is normally a sign of warped discs...

should always put new pads with new discs..
 

Nismotronic

Established Member
I agree with the Disk change. Sounds like you know your stuff anyway. Not a lot of folk would realise about a warp in the disk pushing the pads back in the caliper and the need to pump the pedal.

I'd maybe suggest you maybe take the opportunity to upgrade the pads. You say you drive "quite briskly" so maybe opt for something between standard and race pads such as green stuff. It's a big heavy car with loads of power so good excuse to upgrade the brakes.

Just make sure they give the calipers a real good clean as a potential seizure could have maybe overheated them and warped them in the first place. Plenty copper grease on the sliders n that.
 

muckybucket

Established Member
Does it have ABS? Have heard that grit can get into the braking system and fool the ABS into thinking the wheels are slipping when braking... And with all the tonnes of grit that have been applied to the roads! Is it a new problem?
 

paul1967

Established Member
I've had this under heavy braking caused by the abs kicking in, was it on wet or damp roads ,try it on a dry road thats if you can find 1.
 

accyuklad

Banned
usaly the discs can cause the problem if they warped which you cant really tell that much only way is getting new ones replaced and see how it goes from there but if you was to get new disc then get new pads aswell
 

stainless-steel

Established Member
Just a thought but autos can be prone to warped discs, particulary if you're braking from high speeds or drive enthusiastically.

Do you often find yourself braking from speed and then sitting at the lights with your foot on the brake pedal? You may end up with hot spots as the pads clamp the roasting hot discs - giving rise to warped discs.
With the limited contribution of engine breaking from autos the brakes end up working that bit harder.

If I find myself braking hard to a stop I usually either pop it into neutral and put the hand brake on, or creep foward bit by bit every few seconds so that the pads aren't clamping the disc in the same place for any significant period.
 

Nismotronic

Established Member
Yeah lack of engine braking on auto's can use more brakes than a manual.

creep foward bit by bit every few seconds so that the pads aren't clamping the disc in the same place for any significant period.

lol I thought I was the only strange person that thinks of such things! I'm very aware of that too. Tend to pop the handbrake up most of the time to give the fronts a chance to cool down evenly.

Also we have a very very long downhill section of road near me with a junction at the bottom so try to release the brake a couple of times to aid cooling rather than continuous pressure.

I've thought of another weird thing I do. If I'm in traffic a really long time I sometimes wind the passenger window down n put the heating on to cool the engine. :rolleyes:
 

Epicurus

Prominent Member
Just to add, S-Types are notorious for poorly cooled brakes which is what can lead to advanced disc warping. They just don't like fast driving and braking!
 

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