Hello everyone ! Please Help . I have a Jag XJS Convertible 4.0 from 1994. The back brakes are locked . I left the cat unusued for about 18 months .Before that i have changed the back brake rubber pipes. I have just tried to go on the road with it after i put the batery on but i realised the back brakes pads would not release. I did check the caliper pistons and works nice. I have a brake pump simillar with the one from the picture attached . If you sugest any valves can please tell me where is that placed and how to change , or what else shoul i do ? Thank you very much for your help guys ! Kind regards to everyone !

 

Teves III system. I can't help you as I have the Teves IV. You might find some information searching for Teves III? Other cars, including Buicks used it, so I would think the information is out there.

One thing I'll ask on my way out.... do you have any dashboard lights on? Brake light, check engine light, abs light?

 

Thank you very much for your help. I don't have any lights comming on the dash . I have checked both of the back rubber pipes and calipers and both are working well . Here is the pictures with brake system .

 

I am assuming you have the outboard rear brake discs, which were changed from the inboard system that my 1993 has, sometime in 1993. If so your car should have handbrake shoes mounted inside the disc/hub assembly. If the handbrake is left on for a long time the actuating mechanism may have seized if the main disc pads are clearly free. Otherwise, you could have stuck calliper pistons, but in this case the pistons will not retract. It looks like you have the same Teves system as my car, in which case I don't think there is any way it will hold pressure to hold the brakes on while the car is sitting. If you switch the ignition to position 2, the brake warning light will come on and you will hear a buzzing sound which is the pump filling the accumulator. This should stop after 20 or 30 seconds and the antilock warning light will go out. If you hear the pump running when you switch on the ignition after the car has not been run for a day, then I think the system is depressurizing normally when the car is off and the problem is in the physical brakes or hand brake.

Hope this helps you to move forward,

Tim

 

Hello Tim and thank you very much for your answer! Yes i have the outboard rear brake disks . The Shoe brakes are not blocked at all and works fine . The calipers and pistons are working fine . The brake rubber tubes back connections are working fine to . So here i'm finding myself stuck and dizzy by this situation . If you think you have other idea about how t get out of this mess please let me know !
Thanks a lot again and best regards !
Constantin . In case any other easy contact my whatsapp here oo4o 72 667 99 oo

 

Constantin, I assume that when you stored the car the brakes were working OK? Usually, the most likely thing to happen over extended storage, especially if the brake fluid is old, is that the pistons seize up in the calipers.This can be from general dirt and corrosion in the brake caliper cylinder bores and the rubber seals the cylinder bores to stick to the pistons and prevent them from moving. In this case the rear brakes would probably be stuck in a position where the pads would be rubbing on the disks but would not prevent you from moving the car when you engage gear and try to drive away. The way to check this would be to try to retract the pads so that there is clear daylight visible between the pads and the disc on both sides. If you can do this fairly easily then the pistons are not seized. In this case, if you are sure that the handbrake is also releasing properly, It seems the problem is in the drivetrain and not the brakes. The way to check this would be to raise the rear of the car (make sure to chock the front wheels first, so it cannot roll forward) and put the car in neutral. At this point the wheels should be able to easily rotate by hand, if the handbrake is released. If you still cannot rotate the wheels, then as a first step I would remove the calipers from the rear disks ( no need to disconnect the brake pipes) which is fairly simple and see now if the axles rotate easily. This will pinpoint if the problem is really with the brakes.

I would also suggest you track down a copy of the Jaguar XJS service manual for XJ-S 3.6 XJ-SC3.6 and XJ-S 4.0. This was published in about 1998 as a book, which I find easier to read than using a computer screen. The Jaguar official description is AKM 9063 and Supplement AKM 9063BB. It looks like this is still available on Amazon. You should be able to find this in Europe either new or used and will prove invaluable if you plan to keep the car.

Tim

 

Hi Moise

Your Problem has got nothing to do the the Brake Pump

So what you have to do is remove the Calipers and then once having done so Pull the Rotors OFF and then Clean all the 'Crud off' everything you can see, although be sure to Soak everything with Water, so that you are not breathing in any Brake Dust

Then Remove the Pins and Sliders and then Lubricate them with 'Copper Grease' and then re-assemble it all

With a bit of luck you may not have to adjust the 'Hand Brake' Shoes on the inside of the Rotors, as the Hand Brake doesn't always get used very much, where many of us just give the Hand Brake just a couple of 'Clicks; to get the Soft Top up or down on a Convertible

You can always adjust the Hand Brake Pads later if you need to without pulling the whole lot apart by inserting a Screw Driver and using it to Flick the Ratchet over inside the Rotor through an access hole, though don't do that yet as if you do, then you may have a problem, putting the Rotor back on

So leave the Hand Brake Pad Adjustment alone for the time being in order to keep it simple and not over complicate things

You will also need some Allen Keys as opposed to Spanners to remove the Calipers where the Caliper Bolts are down Tube blocked off with a Rubber Plug

At first Glance this looks like the 'Job From Hell' although it is anything but, as you will hopefully realize that this Job is dead easy and may in fact be easier than conventional Calipers

 

Moise,

Please be very careful with how you deal with the back brakes on your Teves II system.

I'm not quite sure by what you mean when the say teh rear brakes are "locked". Do you mean that when you press teh pedal and release it, you then can't turn the disc by hand? However, a few points to mention:

1. Do not ever push back the pads / caliper pistons without first undoing the caliper bleed nipple and attaching a tube to allow the fluid to escape as you push back the pads or piston. Ypu must not push back the pads / piston the conventional way and push fluid back up the brake lines!

2. You have sliding calipers on the rear. Check that the application of the brake pedal pushes out the caliper piston AND allows the caliper to sliding on it's mount to pull in the pad from the opposite side to the piston. As OB has said, checking movement of the pad on one side of the disc and the sliding of caliper on the other side is important.

3. Make sure you understand how the system works in normal operation and how to properly bleed the rear brakes. The system is not conventional! The movement of the pedal is not "pushing" fluid to the rear brakes. Rear brake fluid movement is only from the pressure built in the Accumulator being allowed to flow through the back of the Actuation Unit. So, to check the rear brake operation, you need to know that pressure has built up via the ignition circuit being on.

Good luck

Paul