When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
If the flexible brake lines haven't been replaced, I would HIGHLY recommend that you do so before spending money on the calipers you replaced 16 years ago.
Also, before you remove the calipers, take out the brake pads, and substitute a paint stir stick between each caliper piston and the disc. Step on the brakes, and that will force the pistons out further. If you still cannot retract the pistons, try loosening the bleed nipple and try retracting them again with the nipple still open. If they retract easily then, your flexible brake line has collapsed inside, and is acting as a one way valve. Replace the hoses. If you caliper doesn't leak brake fluid, and the pistons retract and move out ok with the paint sticks in place, just flush the old fluid out. If your pistons still won't retract after trying to exercise them as above, replace/rebuild them.
Also, before you remove the calipers, take out the brake pads, and substitute a paint stir stick between each caliper piston and the disc. Step on the brakes, and that will force the pistons out further. If you still cannot retract the pistons, try loosening the bleed nipple and try retracting them again with the nipple still open. If they retract easily then, your flexible brake line has collapsed inside, and is acting as a one way valve. Replace the hoses. If you caliper doesn't leak brake fluid, and the pistons retract and move out ok with the paint sticks in place, just flush the old fluid out. If your pistons still won't retract after trying to exercise them as above, replace/rebuild them.
Once the pistons are pushed out further, carefully peel back the boots and see if thh sides of the pistons are corroded / rusty. If they are then just rebuild the calipers with new pistons or buy new calipers.
We don't need to tell you not to try and retract those pistons with the nipple closed!
Once the pistons are pushed out further, carefully peel back the boots and see if thh sides of the pistons are corroded / rusty. If they are then just rebuild the calipers with new pistons or buy new calipers.
We don't need to tell you not to try and retract those pistons with the nipple closed!
Also, use proper brake caliper grease (it's red).
Good luck
Paul
Hi Paul
I'm ordering a Repair Kit, which should be with me by Tuesday but tomorrow I'll check the Pistons and see what they are like.
You shouldn't use any grease on the outside of the pistons themselves. The brake fluid lubricates them. Any foreign substance can attack the rubber piston seals.
If you rebuild the calipers, there is a special lubricant that is sometimes used inside the caliper.
You shouldn't use any grease on the outside of the pistons themselves. The brake fluid lubricates them. Any foreign substance can attack the rubber piston seals.
If you rebuild the calipers, there is a special lubricant that is sometimes used inside the caliper.
There is a guy in Sydney that used to supply rebuilt Jaguar brake calipers, he told me to use copper grease during re-assembly. My brakes were done 4 years ago and are still leak and rust free.
BTW I put the grease around the outside of the piston bore, not inside the bore
You shouldn't use any grease on the outside of the pistons themselves. The brake fluid lubricates them. Any foreign substance can attack the rubber piston seals.
If you rebuild the calipers, there is a special lubricant that is sometimes used inside the caliper.
There is a guy in Sydney that used to supply rebuilt Jaguar brake calipers, he told me to use copper grease during re-assembly. My brakes were done 4 years ago and are still leak and rust free.
BTW I put the grease around the outside of the piston bore, not inside the bore
Hi Warrjon
I got some of that Special Grease like Paul Recommended.
I've got the Brakes all sorted now and found out the cause of the problem.
Owing to a slight variance in After Market Brake Pad Manufacture.
The Metal Part of the Brake Pads was touching the Brake Caliper Top and Bottom and was such a tight fit that I had to drift them out of there with a round Chisel and a FBH.
Which took an hour each side.
So using a Sander I shaved a few thou off each end and now they slide in easy and the Brakes work Perfect with no Binding.
Such a Tight fit that it took an hour to drift out and the same on the other side of the Car.
After shaving a few thou of each end the Pads slip in nice and easy and the Brakes work Perfect and don't bind anymore.
I got some of that Special Grease like Paul Recommended.
I've got the Brakes all sorted now and found out the cause of the problem.
Owing to a slight variance in After Market Brake Pad Manufacture.
The Metal Part of the Brake Pads was touching the Brake Caliper Top and Bottom and was such a tight fit that I had to drift them out of there with a round Chisel and a FBH.
Which took an hour each side.
So using a Sander I shaved a few thou off each end and now they slide in easy and the Brakes work Perfect with no Binding.
Such a Tight fit that it took an hour to drift out and the same on the other side of the Car.
After shaving a few thou of each end the Pads slip in nice and easy and the Brakes work Perfect and don't bind anymore.
If that was all the problem was it raises another question OB, did you use the same FBH to put them in originally?
my front XJS brakes, Wilwood aluminum calipers, EBS GOLD rotors, what ever they use rotors dont collect dust, 2 years nice gold color!
new SS flex lines all around, aluminum master cyl. also!
just saving weight!
Wilwood calipers would be nice, but here in Australia the car would need to engineered. It took my brother 2 years to get his Mustang Shelby GT500 engineered and registered, mirror RHD conversion, Willwood brakes, coilovers, rack & pinion and T56.
They made him dyno it and then with 620RWHP made him de-tune it, brake testes consisted of track time and emergency stops from 160km/h, bearing in mind the max legal speed limit in most states is 110km/h.
The tight fit of the pads in the calipers is something that I have also experienced on the front of an XJS. It seems that the caliper housing is quite prone to corrosion accumulating on the bottom edge where the pads seat. With limited use, you end up with one or more pads getting jammed and you can also then end up with caliper pistons getting stuck and potentially a warped disc. As you say, it's a real pain when the pads get jammed!!
I would suggest that if a car gets used infrequently, its worth pulling the pads each year, cleaning the bottom ledge of the caliper where the pads sit, and also exercising the pistons to keep everything free. An easier and more enjoyable alternative is to drive the car a lot!
The tight fit of the pads in the calipers is something that I have also experienced on the front of an XJS. It seems that the caliper housing is quite prone to corrosion accumulating on the bottom edge where the pads seat. With limited use, you end up with one or more pads getting jammed and you can also then end up with caliper pistons getting stuck and potentially a warped disc. As you say, it's a real pain when the pads get jammed!!
I would suggest that if a car gets used infrequently, its worth pulling the pads each year, cleaning the bottom ledge of the caliper where the pads sit, and also exercising the pistons to keep everything free. An easier and more enjoyable alternative is to drive the car a lot!
Paul
Hi Paul
Cheers! You are so right.
What I have been experiencing is all the symptoms of NOT using your Car.
Stuck Injectors, Sticking Calipers, New Fuel Filter, New Fuel Pump, New Fuel Pressure Regulator, New Radiator, New Hoses, New Tyres, New Battery, New Cooling Fans, Soft Top Not Working, Immobiliser Not Working...........The list goes on.
Needless to say I won't let that happen again!
Last edited by orangeblossom; 09-27-2016 at 09:24 AM.
Absolutely, use it or lose it (your wallet!).
They do not like being ignored.
Hoping to drag mine out tomorrow after 6 weeks of non use and change the FPR; probably won't start at all.
09-24-2016, 07:31 AM
