Having got my car back from having rear calipers done , bads, and handbrake....by mechanic A.
I have developed a loud noise when I apply the brakes hard...its very low pitched like a cello...but is not music to my ears. I took the car to another jag mechanic "B" because I can no longer get a response out of the origonal mechanic "A"...and there was a nasty clunking form the rear and as well...they said the handbrake caliper was loose, they've fixed that and the clunking has gone away but this has not fixed the deep cello sound .

Any idea what this sound might be....something loose...pads...?

 

Could be pad composition? I've had trouble with premium compounds on other vehicles, namely my '02 gmc truck, in which going back to organic pads solved the issue and everything is happy. Just a thought, maybe the cheapest and easiest route to troubleshoot if nothing is loose back there. Also check exhaust pipes for contacting other parts when the cage rotates under hard braking. Those upper exhaust mounts are very often neglected. If pads are the problem the rotors may show signs of overheating or unusual scoring.
Bill

 

Thanks Bill good ideas. The exhaust is very close to the cage. Could it be subframe bushes soft as well, allowing for rotation?

 

More likely would be radius arm bushes.

 

They were new when I put them on, mind you someone else has had a go at em since

 

Checked everything out today....usual scoring from brake pedal application. Rear control arms seem fine...exhaust close to body at some point. Ive got some EBC pads on the way now.

 

Be sure to check those upper exhaust mounts, they sag and cause mis-alignment of the pipes in the cage and at the mufflers, not really too bad to get to with a long extension, flex and 7/16 socket.

 

Well I got some new pads...EBC. Fun putting them in...quite tight at each end had to tap them into place not sure why. Should move side to side I would have thought.Old ones came out easy enough. Rock auto calipers..new. Do you put a bit of brake grease at the top and bottom of the brake pad base?

Anyway off for a run ...half hour traffic and windy road up the hills. Stopped, started again and a moderate to firm pressure on the break pedal and the noise starts to come back. Bugger. Anyway down hill all the way back just feathered the brakes ....nothing heavy and noise didnt return. Running in process ?

 

I'd say yes, probably running in. Iirc, ebc pads have a temporary sandpaper type coating to aid in surfacing the rotors while breaking in pads. Was this the case with your pads?
If you didn't release the bleeders and press the pistons back they would have been tight. Sometimes you can push the pistons back very slowly and carefully without loosening the bleeders. Large pry tool etc...
Oh, you're saying they were tight at top and bottom? Against the caliper body? Idk but a quick buzz on a belt sander would alleviate that, or a hand file. They should be free to move.

 

Yes one of the old pads had abrasion marks top of the pad base wear it is obviously grinding on the caliper. Might have to grind a bit off...see if that does anything

 

Been running around in them got two noises now the deep vibration and a constant squuquing. Interestingly the pads did not include shims on the back. Yet I've recieved front ebc pads in the mail today which have a stick on pad which is used as a shim. The rear ones did not come with these.

 

Well well. The ebc pads out again, gave them a buzz on the grinder where they were rubbing on the caliper...applied ceramasil to top and bottom edges pad, plus the facing where the piston contacts. Feels and sounds bit better...drumming coming back but not as bad as before....and I decided to take it for a repeated firm stop test. Each one car stopped well...no drumming 15 stops. Comes back under light braking...riding the brake to slow down. Hmmmmmmm

 

Well, at least you know it's a brake problem and more specifically maybe just a pad problem, as it is changing with altering the pads. Like I mentioned before, I've had a situation where I had to go back to cheap organic pads on my gmc truck to eliminate very similar problems.

 

Well shes playing up and even more now, but I must admit its after a bit of driving I get the big booming vibration on light application of the brake, followed by incessant squeeking. Firm application and I can avoid it. I very quick call to the local mechanic/guru and he says they do get problems if discs are installed that have not been heat treated. This could align with the fact it is present/worse after Ive been driving for a while.

 

That's why I was saying earlier to use cheap organic pads. If it were me, I would get the car in the air again and pull the pads, and using a pry bar make certain there's not a lot of lateral movement in the brake disk, both sides. If nothing seems amiss, loose or misaligned I would get a fresh pair of cheap organic pads, grind those top and bottom edges if needed to make sure they move freely and try again. I know it's natural to want to go more expensive/better quality pads but in this case I've had to learn that some rotors you get aren't happy with premium pads. My front rotors on my gmc truck are a prime example, new brake job with rotors and best quality ceramic pads, quickly started having same symptoms you describe. I had to keep driving (my DD) and by the time I got to address it the new rotors were quickly destroyed by heat. Next set I went with a mid grade pad and still had problems, changed to cheap organic pads and it's been perfect ever since. I think it has everything to do with the quality of the rotors that are available these days. When you pull your pads again do check for run out by spinning a tire and watching the rotor carefully, check for end play with a pry bar and check for loose caliper bolts.

 

What brand would be cheap and organic?

 

Well turning wheel by hand dont see any warping in disc. Discs have a mirror finish which is interesting. no sideways movement of disc, tested with pry bar... and calipers seem to be on tight. Will try some soft pads, cheers!!!

 

The mirror finish may be troubling. It's been glazed and possibly overheated but maybe not. Look very carefully at the rotor surfaces for hairline cracking, spider cracking. If none, I would make an effort to sand the glaze off the surface with sandpaper somehow to allow the new pads to bed in. Rock Auto, amazon etc... for pads or maybe a new old stock set of repco? Or local auto parts store should be able to order regular organic pads. And the regular jaguar suppliers but just don't get the "better" premium metallic or ceramic pads.

I think it's going to be pretty imperative that you cut that glaze off the surface of the rotors before putting the new pads on. Otherwise it may overheat and glaze the surface of the new pads causing the same problem all over again but from a different reason.

 

Hey @mickvic , any updates on the brake problem?

 

Hi, mate up the road is a mechanic he gave the pads a grind on the face, and chamfered the edges slightly. Quick run and 90% better so far but he pointed out my steering rack is leaking oil so Im getting that reconditioned right now.
Never a dull moment!