Chirping / squeaking noise in time with wheel rotation?

[JagAsh]

Hello chaps, long time reader, first time poster here. The time has come because I need to pick your collective brain! (I'll do the introduction & photos of my cars another time, I promise!)

I recently purchased an XJS (1992, 4.0, after 20 years of waiting and wanting, wanting and waiting!) and all was good. A few minor niggles but they're all cosmetic; I can live with that temporarily.

However, in the last couple of days, the brakes have started chirping. It still pulls up straight and in good time, so I'm not overly concerned from a safety perspective, however the chirping is really starting to drive me round the bend now.

It seems to change in pitch & volume depending on the pressure on the pedal, and is definitely in time with the wheel rotation. Sometimes it will continue after the brakes have been released, for no more than 8 to 10 wheel rotations. Annoyingly, my amateur XJS ears cannot pin down if the noise is front or rear. Is there a trick to finding out?

I'm not sure when the brakes were last worked on so shall be ploughing into the history to try and find out.

If any of you knowledgable folk could point me in the right direction I shall be eternally in your debt. And definitely owe you a pint. Ideally something that doesn't involve me having to get too far under the car due to a pitiful lack of axle-stands Jacks, however, I can do.

Thanks in advance!

[ptjs1]

Ash,

it could be a number of things and probably requires a bit of investigation. Some initial thoughts:

- Friction noise between the piston and the back of the pad. Can be relieved with a smear of copperease on the back of the pads.

- Ridge wear on the outer edge of the disc. Possible to carefully grind off a bit of the excess but may indicate it's time for new discs.

- Ridge wear on pads. Time for a change.

- Sticking caliper piston (although you'd often feel that in terms of straight-line braking). Fairly common on XJS. Remove pads and carefully check that all pistons are able to move out and retract.

- Something stuck between pads / disc / disc backing shield. Check for a small stone or similar


I would advise extreme caution on working with only a jack. You can't trust them, even good new ones! Invest in a decent pair of axle stands; it's possible to get good quality ones at good prices these days.

Let us all know how you get on.

Paul

[Brakebuster]

sometimes the brake dust guard on the front brakes ( and rears on facelift ) can end up touching the disc etc, , they are not the strongest, and can be moved while peeps pull on them when working in the area ,

get a good hand lamp , some axle stands and have a good look round,

BB

[dhdove]

Hi ash

Comprehensive reply from pjts1 (as ever Paul )
I think you may just have a stone or debris jammed in there.
Jack up, spin wheel and listen, remove wheel if necessary would be my initial advice.
BTW welcome to the BB and congrats on your ownership of a beautiful car

TonyS

[JagAsh]

That's some comprehensive advice! Knew joining up was a good plan

Got some axle stands coming tomorrow. On nights though so may not find the time til the weekend. I shall keep you all updated.

[JagAsh]

Right, after a bit of buggering about, I'm fairly certain the chirping is ... coming from the rear. *holds head in hands*

I have absolutely no desire whatsoever to disappear under the car and start poking around in that horrendous subframe. Going to have to call in an expert/specialist to sort this one I think. Anyone vaguely know how much it might cost me for new rear discs & pads, to be fitted by someone with more skill & patience than I possess?

In the meantime, I'm going back to sleep. Bloomin' nightshifts!

[Brakebuster]

rear ' chirping ' can be atributed to the UJ sheilds used on the drive shafts as they enter the rear hub , either out of center , or debris catching , and in some ways is simpler than the front end to inspect , witness marks on the UJ cover will tell you if its those scraping on something.

your has outboard brakes as well being a 92 car, so isnt that bad

same principles as doing the front

BB

[JagAsh]

Is that something that would manifest itself under braking? Really don't want to go fiddling around back there but will if I have to.

Definitely inboard brakes, BTW. Was about 94 or 95 they went outboard, I think?

[ptjs1]

Ash,

Outboard rears are from mid-1993.

All the comments that I made about the front brakes apply to the inboard rear, with the exception of the backing shield. However, being inboard rear, they are much more difficult to do without dropping the rear cage.

BB's point about the UJ shield is a good thought, I had this problem on my car, although it only happened from cold. You could check the outboard end of the halfshaft fairly easily with the car up, wheel off, and supported on your new stands.

Being based in Coventry, I'm sure there are a few independent Jaguar specialists there! Alternatively, you could drive over to David Marks who, I am sure, can solve your problems!

Good luck

Paul

[Brakebuster]

every day is a school day , lol

i dont know to much about these ' modern ' jags..........


BB

[Brakebuster]

noise from inboard rear brakes......


handbrake pads ?

loose or worse

needs looking at properly to be honest

BB

[dhdove]

Ash

I had a problem with inboard UJ shields squeaking, if you can get under the car it's easy to see and fix.
They were fouling on the exhaust I think, maybe because rear exhaust sections had been replaced but drive shafts were in a position where the potential fault didn't manifest itself.....the rear over the axle exhaust pipes can be a bit of a bugger to locate exactly and they are a tight fit with little room where they pas over the drive shafts.
In my case poorly located jubilee clip/shroud just loosened, moved a bit and re-tightened.

TonyS

[poprivet]

Well...
If the noise is coming from the rear..
and only under braking..

Maybe its the rear brakes.

[JagAsh]

Captain Obvious, here to save the day

Decided I'm too much of a wuss to attack the rear brakes myself, so have got her booked in to have the discs & pads changed at CFS Motors early next week. (What a nice bunch of guys, BTW!)

All the help is hugely appreciated though, and had it been the fronts I'd have had a go myself, so I reckon I probably owe Paul a pint should we ever cross paths!

[ng4xjs]

This happened to me a while back (front). Grease cap had popped off and rubbing everso slightly.

Happy days
Nick