Now my Jag stops properly!! Had a seized slider unknown to me

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I always thought my brakes on my newishly acquired 3.0l 2004 were a bit poor. Thought it was just a heavy car or had poor pads on.

MOT time this month so I'd thought it was a good idea to replace the rear discs at least. 7pm Friday night I'll pop out have have the rear offside done in a couple of hours max.

oh boy was I wrong!!

Firstly I almost broke my back trying to remove the main 15mm caliper bolts!! OMG how much blue loctite did the previous garage put on (medium strength but had copious amounts on)??? Every 1/4 turn was a workout using a fairly long breaker bar, one I could just fit in.
Literally had to lie down after I finished each one.

Then after clenaing up the caliper I saw that one of the sliders looked a bit rusty. It was completely seized, caked in thick rust. Took me about 30 minutes of hammering just to break the rust seal.
no wonder the pads weren't clamping properly. The piston was just pushing against a seized slider!!

I managed to release it and clean it up nicely, new grease and slides perfectly now.

Under floodlight I finished about 10.15pm.

Saturday morning I tackled the nearside (with bad knees , cuts and bruises).
Again a good hour at least getting off the 2 15mm bolts. They certainly didn't want anyone to remove these!!

Well after a good bleed on both sides, new disks and pads braking was a brease coming to work this morning.

Fronts do need chaning but enough pads and disc material to get through the MOT this month.
Think I need a month to recover before hitting the fronts!!!

Looked like about 2 years of rust on the slider. How that accumulated since the last MOT puzzles me!!!

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Hi Chris,

Well done and I hope you're fully recovered now - thats the S Type for you though - money, sweat, blood and perhaps a few tears too, but nothing gets rid of the big grin.

On 6/4/2018 at 8:45 AM, piria33 said:

Looked like about 2 years of rust on the slider. How that accumulated since the last MOT puzzles me!!!

Had the car been standing unused outside for some time?

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Not as far as I know. Both brakes are working well now but still the nearside gets a bit hotter than the offside. Maybe I need to strip it again and make sure all the moving parts are super clean and free of rust. The contact surfaces for the brake pads on the caliper surfaces for example.

Once you have wound out the piston and replaced everything they are self adjusting aren't they? I mean if I have wound out 1 piston more than the other both will push back in until they have full contact?

I did recalibrate the electronic hand brake just in case.



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My memory is a bit uncertain but I seem to recall that Jaguar recommend replacing the slider bolts rather than re-using them. I did not follow that advice though as after cleaning and greasing mine worked well and did not appear to be stressed or damaged in any way.

Yes the pistons are self adjusting. First application of the brake pedal will advance the pistons and apply pressure to the pads and disk. On release of brake pressure they would typically back off by a small amount only to allow pressure release on the pads and disc.

Some ideas to consider, but not in this order (I'd try the last one first): -

  1. There may be some interference between the piston and the piston barrel caused by dirt contamination or perhaps even corrosion. I would also check the piston seal to make sure its in good condition and press/wind the piston back and check for improvements after re-assembly.
  2. If you can, check the disk itself to make sure it running/rotating true and within tolerance, you'll need a clock gauge for this though. Corrosion between the disk and the hub mounting plate or distortion of the disk itself could produce the symptoms you're seeing.
  3. The EPB cable is exposed and can be affected by corrosion. Its a good idea to make sure the cable, and the lever mechanism it connects to at the hub, are moving freely. If they are not then you may be able to get them moving properly with a little DW40 and some suitable grease.

Hope this helps, keep us posted.


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