Well I had a bad day with the XJS. Last week I changed out the brake accumulator and since then brakes have been functioning perfectly. Today when pulling off the highway the calipers seemed to be sticking badly. I tried pumping the brakes to free them with no response. I made it about a 1/4 mile down the road before I had to pull over and see what's up. At that point I saw flames under the car. I called the fire department (less than 1/2 mile down the road) and they came and put it out.

I have the car home and jacked up now. The front brakes are working properly but the rears are completely seized. Luckily the fire was fairly small and I think it just burned a bit of leaking fluid around the differential. The pads are in good shape, the brake hoses look to be in good shape. The only difference I note is that the hand brake lever does not "feel" like it has the same amount of tension as normal.

Anyways, I need to get these brakes unlocked! What could be causing them to both seize the way they have? Collapsed brake hose? Could both calipers be stuck? Could my handbrake be stuck?

Any and all ideas are appreciated. I have no experience with the brakes on these jags. Also, does anyone know what differential was used on the 1993 I6 model?

Thanks

 

You may have left the handbrake on. You may have the warning light on the handbrake not burning. Try pulling the handle up as far as possible and pushing the button in and lowering the lever.
A lock in the calipers is not as liikely but possible I suppose. Some of the more Jag experienced members will chime in soon
.RagJag

 

The handbrake light is off and it was not left on unless it stuck after releasing the lever. From underneath the car it looks as if the pads are hard locked against the rotors. There does not appear to be any gap for the rotors to spin freely.

 

I know the main rear brake pads lightly drag the rotor, so there will be no gap. On my car, the parking brake pads also lightly drag. I'm not sure if that's normal or not, but it doesn't seem to cause me any problems.

 

Well I managed to get the rear brakes free by releasing the bleeder screw and manually pushing the piston's/pads all the way inwards.

The fluid that came out of the bleeder was black and disgusting followed by seriously bubbly fluid. I bled the rear brakes to the point that only good looking fluid flowed out.

They no longer seem to be sticking. Could poor fluid quality cause the calipers to hang up the way they did?

I am planning on possibly completely bleeding the system tomorrow. Does anyone know what brake system is on this 1993 XJS? My VIN number is below 188104.

 

I think you should change the rear flexible, this can collapse internally and stop the fluid from 'retracting' when the brakes are released. In any event, this would be a very wise precaution.

Greg

 

Have you changed the pads? It is a common problem after putting in new pads - the piston gets corroded as the old pads wear and you push the corroded part in when you change the pads so it binds.

 

That makes sense. I definitely will be changing that hose. Also, no I have not changed the rear pads but they look as if they have been done within the last few years, there is very little wear on them.

 

The piston sticking happens just after you've changed the pads so that's not the problem.

 

As a '93, I'm not sure if you have the inboard or outboard brakes. If they are inboard, you will probably have cooked the caliper piston seals, so even if you free of the pistons the seals will leak under pressure.

As with you, I had this happen to me in about 1998, and in the end I put in service exchange calipers, plus all-new hand-brake parts. In my case too, the diff seals were cooked so these were also replaced.