Brake pulsing...time for some new discs?
 

My brakes have been pulsating a little for a while now but recently it's got a lot more noticeable. I'm assuming warped discs (well, probably excessive deposit buildup rather than warping) but the result is the same, probably need new discs.

They weren't done that long ago by a previous owner but I have a feeling they were done on the cheap without proper break-in procedures.

Anyways, my guess is I need to do the discs and pads. What brand discs and pads should I buy? Pagid? Bosch? Brembo? I can't really afford OEM ideally.

Hope someone can help, all the best

why not check them first and see where the problem lies before ordering parts that you might not need

Fair enough, how would I check them, run out gauge?

Other options
 

Could also be bushes in the suspenders or a stuck caliper so that the disc is forced to flex, or even a wheel bearing. Or wheel balance. It is a problem that is close to my heart! The one of mine that stops best has Chinabay drilled and grooved discs front and rear and standard pads. I put a full Black Diamond set on another (discs and pads) at VAST expense, religiously broke them in, and a couple of months later judder was back - and I am no longer QUITE the animal that I was in my teens (I'll be 70 in September). What sets all of my 5 off is braking really hard from over 110 - judder starts, and then eve easing off the brake pressure and the judder stays.

To check jack each corner up and spin the wheels - listen if there is a consistant rub at a certain spot on the rotation cycle (bit of tape on a spoke/tyre helps keep track of your spinning).

If you do have a certain spot that rubs before ordering some new discs try a few very hard stops in quick succession ideally downhill while keeping on the power to get them REALLY hot - may burn the grot off. (High spots can be build up of brake pad material if after a hard stop you stay on the brakes and the hot disc/pad is in constant contact on one point for a while.) May fix it but if the discs are warped no difference but it's not like you can bugger them up even more if they need replacing anyway.

Found this tip on the jag forum i used to frequent and it saved me a fair few quid when i thought i needed new discs (not cheap on an xjr).

As above though i would also check bushes - when they get sloppy there is a load of movement under breaking. If you can get a friend to film you stopping hard while driving next to you - obviously not on the public road - and see if you have wheel shimmy.

I have also heard good things about fitting an under chassis brace (wentworth or ipd style) as a test as this helps aleviate worn bushes to some extent and would rule out the discs.

or (and I know this is heresy but, really...) take it to someone who knows what they are doing.

Its literally half an hour of labour to lift the car, remove the wheels and check the run-out on the discs while inspecting other potential causes.

Less than the cost of half a tank of gas.

Come on... that's cheating!!! :tounge_smile:

(But seriously, it is a good point. If you aren't confident/have the tools to try any of the above brakes are the one thing you really don't want to mess around with... It's not only your life on the line if they fail)

Stuck slider pins
 

Check the slider pins are free to move, common to seize and cause progressively worse wobble.

Thanks for all the advice, with regards to taking it to someone professional, I have nothing against that and would love to but as I'm a student I don't have the funds for half a gas tank! I also would classify myself as a fairly competent mechanic, I've done quite a lot of work on this car including the headgasket amongst other things and have accumulated a fair selection of tools. I am more than happy working on cars etc but I won't claim my diagnostic skills are particularly outstanding (still need more experience for that!).

A year ago when this car got MOTd, it was flagged up as having brake fluctuations on the back left and front right wheels. I now have an MOT in two weeks time (with very little time to work on the car due to university exams) so I guess I'm wondering if it's likely to be a failure. It's not terrible and only really noticeable above 40mph. I'll give power braking a try to see if it removes some of the build up and will check the slider pins.

And yes, I am also replacing the spaceship bushes on this car as it does also pull left whilst braking. (Always has, even before the brake pulsing started), I think there's quite a bit of cheap rubber used in the bushes unfortunately - replaced by a previous owner. So I'll stick some quality polybushes in the spaceships whether that's a cause of any of my braking problems or not I have no idea!

Is it more obvious on light or hard braking or the same? Also do you have ABS on this car? If so, does the ABS warning light behave as it should?

I'm thinking a dirty ABS sensor if you have ABS, especially with the previous advisory about "fluctuation" or it could simply be old fluid and you need to change it.

Picking up on what Roger said above, brake discs these days are generally much of a muchness. Pagid, EBD and Eicher are all the same, just different prices!

You could also remove the wheels, clean behind them where they mate with the hub, also (if you're feeling enthusiastic) remove the discs and clean where they mate with the hubs just to make sure there isn't any grit giving a slight imbalance by pushing the wheel or disc out of line.

Also has it been parked up for any length of time? Sometimes the pads can cause a "rust patch" on the disc either from masking the disc from the damp atmosphere or by holding moisture between the pads and discs.
Easiest way to clean this is to drive for a while with the brakes lightly applied.

A few ideas to try there, if you get really stuck i'm not far from Cambridge so could probably have a look and/or give you some ideas. ;) :D