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"BetterCall Paul" (ptjs) Where did you get your Front Brake Discs?
Hi Paul
Front Calipers are still Sticking on my (1995) XJS 4.0L
Pulled everything apart for the 3rd Time Today, so unless you have any better ideas I think I am going to have to take the Front Calipers off and then Rebuild them which may also include New Front Brake Discs, though having said that they do look quite ok
What sort did you get? were they Solid Disc or the OEM Ventilated? and where can I get them from if I should need them
I've done the Calipers on my V12 as you probably know but I've never done them on an XJS 4.0L
Is everything the same on these or is there anything special to look out for, as there doesn't seem to be quite as much room as there is on the V12 or maybe there is, I don't know
Must be ventilated discs on the front Alex. EBC USR discs are fantastic on the XJS, and they do not warp; I had endless trouble with front discs warping as soon as they started to have to do some work. Bit pricey, but once you have them you will never want any others!
The front calipers are the same thoughout the XJS models.
First of all, can you just clarify what you mean by the front calipers "sticking"? In my limited experience, XJS calipers only tend to stick when the pads are really worn down, the pistons are extended, they are not used much and then the pistons get stuck in their extended position. Are your pads very worn and the pistons extended?
What perhaps may be more likely is that the pads get slightly jammed on the bottoms of their edges on the calipers. I had that on some EBC pads on my 4 litre.
So you really need to establish what is happening on the front. If the pads are jamming, you could try and remove them and then relieve the bottom and top edges a bit, and refit them with some copperease on their edges. If the caliper pistons really are the problem, then what state are the pistons? Are they badly corroded? If so, I would just go for recon calipers.
If the discs have gone below their safe working thickness, or have a noticeable lip, I would change them and the pads.
As regards discs, all XJS have vented front discs. I've never felt that XJSs are underbraked, so I've always fitted standard-type discs rather than any grooved or drilled upgrades. Whcih type? I would fit Brembo or standard EBC, but it's obviously a personal choice. You can pick up EBC OE discs at either SNG or EBC Direct for about £135 a pair. That's a pretty good price. SNG also do Brembos for about the same but I don't think they have them in stock right now. I did find some front Brembo discs at £50 each at EUspares.co.uk tonight which is very cheap.
As regards front pads, I'd probably go EBC Greenstuff. But if I were fitting Brembo discs, I'd probably put in Brembo pads.
I've Skimmed the Sides of the Brake Pads, so they slide nice and easy The Discs look Good, The Pistons look Good and though I can freely Spin the Wheels, they both lock up after only a very Short drive round 'Orange Blossom Towers'
Hopefully Tomorrow I can have another look to see whats wrong but here's a quick Pic of the Pistons!
Have you ever replaced the rubber brake lines? When they get old, they can start acting as a one way valve, and not allow the pistons to retract. Having both go bad at the same time would be unusual, but not impossible.
Have you ever replaced the rubber brake lines? When they get old, they can start acting as a one way valve, and not allow the pistons to retract. Having both go bad at the same time would be unusual, but not impossible.
Very good point. Fit a set of Goodridge guarateed for life. And drive the car a bit more and a bit harder Alex!
Alex
JAL's point is that the reason why they are stuck may well be because the flexibles have deteriorated internally. If they are the originals, they should be changed in any event.
I had problems with one of my front calipers. I ended up replacing both fronts with rebuilt calipers from RockAuto. I tried rebuilding mine, but they sent me the wrong sized parts, so on the second attempt I just got the rebuilt calipers. I think I might have even SAVED money just buying their rebuilt calipers.
Now one of those rebuilt calipers from Rockauto ended up being bad, and they replaced it without hassle, but I thought I would mention it. I couldn't bleed the damn caliper!
Front Calipers are still Sticking on my (1995) XJS 4.0L
Is everything the same on these or is there anything special to look out for,
Maybe, just maybe, the calipers are not parallel with the discs? And perhaps causing the pistons to become cocked? And maybe require centering by using the alignment shims?
Personally I've never seen the caliper alignment shims in any oldie Jag I've owned or worked on. But they do exist, and the ROM does make mention of the process. Might be worth thinking about?
(Note that the caliper alignment shims are not the same as the shims behind the steering arm....which are sometimes incorrectly referred to as caliper shims. I've seen these on every oldie Jag.)
If I don't change the Calipers, I think I'm going to end up going round in Circles
So that's what I'm going to do and also thanks for your Help
Alex
Do your pistons retract easily if you open the bleeders? If so, it's not the calipers. Its either the brake hoses going bad, not allowing the fluid pressure to be relieved when you let off the brakes (very common issue), or something is up with the ABS and not allowing the pressure to be relieved.
Jon
The end of the Pistons that push on the back of the Brake Pads are all looking rusty and don't all exit or retract at the same time, so seeing that new Calipers are one of the very few things that seem to have gone down in price during this Cost of Living Crisis
A very interesting suggestion, so Thank you for that
Except I can't get the Caliper Bolts undone and I also cannot get the Pistons out either, as the Rotor prevents me from doing that
I had a similar thing happen on my other Car, where a well meaning mate, no longer on my Christmas Card list (lol) not only Snapped the Caliper Bolt that went through the Steering Arm but did all sorts of other Cackhanded Stuff as well
Which is why I much prefer to do all this stuff on my own, with advice from the Forum from those who have done it before, like for instance yourself
Removing the Calipers should have been quite easy but The Jaguar Gods were nowhere to be seen
I've been trying to unbolt the Calipers with the Mains Rattle Gun, except it wouldn't touch it!
I also heated the Steering Arm with my Plasma Cutter until it was Cherry Red but it still would not undo!
Just by chance I spoke to a Guy who had a fairly new MX5 (Miata) and he was telling me that he also had to have some new Calipers but even the Garage couldn't undo the Old ones and so he got charged £500! just for the labor in cutting them off with a Gas Axe
He reckons the manufacturers are doing this on purpose but who knows
"BetterCall Paul" (ptjs) Where did you get your Front Brake Discs?
