Handbrake adjusters - Inboard brakes

[Jag190902]

Hi, I have an issue with auto adjusters (I think) on the inboard brakes. I've set them up as per the manual and when in the air, the handbrakes locks the rear wheels solid at 6 to 7 clicks of the handbrake. All was fine until I lowered the car and apply the handbrake with the car on the ground and simulated the MOT test, slow roll (<1mph) and apply the handbrake. The handbrake initially grabbed then a loud thump followed by alomost total loss of braking. The only way to get the braking back is to slacken the h'brake cable remove the split pin from the adjuster scew on each caliper and turn 1/2 clockwise, re-insert the split pin, then re-adjust the cable - all then is fine until the above test is repeated. The calipers were re-built last year when I had the subframe out and the pads were replaced at the same time - no issues with last years MOT. Can anyone shed light on this please as this (as I'm sure you know) is a pig of a job when lying on your back

[bokapita]

I am not saying this will do it, but it would be worth checking the following:

1) That the two return springs from the levers to the cage are attached peoperly and are stilll pulling

2) That each end of the cable (outer one lever, inner the other lever) is properly engaged in the indent in the lever, and

3) Adjust the cable a bit tighter at the lever end so it only takes about 3 clicks to start braking. The adjusting nuts are on the outer and are accessible by moving the driver's set fully forward and then pulling up the carpet from the inner sill just behind the B pillar. It adjusts just like a bike brake does, two 9/16ths spanners from memory

[PaulGover]

...
The handbrake initially grabbed then a loud thump followed by alomost total loss of braking.
...

One possibility is one of the pads pulled off its backing - happens quite easily in my experience, possibly due to the use of cheap pads. If that is what's happened, beware of using the adjusters to get the brakes back - you end up with the disk wearing directly on the affected pad backing/calliper.

[oldtimer]

Hi,
Just sitting with the parts manual on my knee gazing at the exploded view of the park brake assembly thinking, what on earth would make a thumping noise.

Bolt part No 8845 (the adjusting bolt that is secured with a split pin) That bolt passes all the way through the brake assembly and screws into adjusting nut 8980. When the two operating levers are pulled together by the brake cable that load is multiplied by the length of the levers and exerted upon bolt 8845 and nut 8980. From memory that adjusting nut is brass and I reckon that under full handbrake pressure the brake suddenly releases with a thump because the brass threads are worn out.

What do you think?

When the park brake assembly was last overhauled I wonder if that nut and bolt was replaced.

You have my sympathy doing that "crap" job

Oldtimer

PS If you do go that far be sure to change 8836 adjusting pawl assembly

[Jag190902]

That's great advice from you all - thank you. I've just checked all the springs are present/taught and re-adjusted the cable but still the problem occurs. I also found a small piece of pad lining on the floor tonight which suggests that one of the pads may have pulled/partly pulled off its backing. I think the next step will be to remove the calipers completely and strip/check all the parts and check the loading on the adjuster bolts. These were replaced last year along with the adjuster nuts, however being a hoarder of parts I still have the originals which although pretty filthy appeared OK when removed. Will let you know how I get on over the weekend - weather permitting!!

[almcl]

My handbrake pad experience is that although it sounds like a lot more work, dropping the cage is actually quicker in the long run.

I've lost count of the number of brass spreaders I've come across that weren't properly engaged in the calipers and as you already know, reaching up from underneath trying to get everything properly assembled is no fun at all.

Doing it from above with the cage on the floor takes a little longer (splitting the exhaust can be time consuming the first time) but the brakes are much easier to do from above.

[PaulGover]

My handbrake pad experience is that although it sounds like a lot more work, dropping the cage is actually quicker in the long run.
...

Strongly seconded. After doing this on my old XJ6, the handbrake was superb. On my XJS, where I couldn't be bothered to drop the rear cage, it took about 4 goes fiddling in the dark over 3 years before it was properly set up - I hope.

[oldtimer]

Hi Jag190902.
I'm inclined to agree with the two previous entries that it is probably easier to drop the sub-frame complete. The only consolation is that you had the assembly out couple of years back which should make it fairly strait forward--- except maybe the exhaust

I have two bits of five ply glued together and cut to fit just inside the central tie plate which I use as a jacking pad.

Good luck

Oldtimer

[PaulGover]

A comment about testing the handbrake. While it's obviously necessary for safety and the MOT for the handbrake to stop the car when moving, it's nonetheless intended for main use only when stationary.

Using the handbrake on the move will generate a lot of heat in a small confined space. I suspect there are two ways to tear the pads off their backing - testing the handbrake or trying to bed the pads in by repeatedly using the handbrake to stop the car in a short space of time, and that oh-so-easy mistake of driving a couple of miles with the handbrake on. I wonder if the heat affects the glue, perhaps more-so on el-cheapo aftermarket pads.

[Jag190902]

Evening all. Managed to remove the handbrake calipers today and look what I found! The loud 'thump' was the material detaching itself bit by bit from the back plate whilst releasing its grip from the disc. These pads have only covered 400 miles since they were fitted so I'm not at all impressed with the quality. That said, the next job is to strip and check each caliper and will check the self adjusters are working on the bench before refitting to the car. Managed to get away with not removing the subframe as I have only done above miles since the whole lot was rebuilt last year so although access was tight-ish, it all came apart fairly easily. I'll be ringing the (well known) supplier tomorrow to see if anything can be done, but failing that I shall replace with a set of genuine pads from Jaguar - 3 times what I paid for these, but the last set managed 63K miles before the material detached itself from the pad.

Thanks again and will keep posting on the progress

[oldtimer]

Well Done but what a bummer, all that work for crap material.

When I worked for XXXXX we used to pay consequential cost, to the trade ie labour. Mind you we made every effort not to sell rubbish. Give it a try 4hrs at £25 an hour.

Oldtimer

[NATONEIL]

This thread was started years ago but it is worth reading again just as I have. Frequently the handbrake pads fail if they have been dragging for a long time owing to poor adjustment.

[Bill99]

I am trying to replace the rear brake pads and rotors on my Jaguar XJS - V12. Unfortunately, the brake cable is really stretched to the max and I can't dislodge it from the hand brake arm. I loosened the handbrake adjuster nuts and then tried to use a ratchet tie down to compress the two hand brake arms, as well as removing the spring attached to the right side arm, but no success in getting any slack in the cable. Also the hand brake lever in the car freely moves up and down with no clicks at all. I do not want to drop the whole cage and would need to remove the hand brake anyway, What can I do?

My thoughts are to try to remove the handbrake arms and see if that is possible. Any suggestions?

[PaulGover]

Something's wrong, possibly the cable inner is seized in its outer; it shouldn't be that hard to release the cable.

AFAIR, if you slacken off the cable at the adjuster by the handbrake lever, you can disconnect it there, as if you were removing the cable. Then you ought to have oodles of slack. What might be happening is the cable end is reluctant to come out of the handbrake lever, and so the cable's disappearing back into the hole from whence it came, so it looks like it's still taut, but actually is loose.

[poprivet]

Bill, I can understand the reluctance to drop the rear cage but it really is the only way to do the job properly, especially as you want to change the discs.

Apart from access, it allows you to inspect the radius arms and bushes and generally clean everything up. The cage comes out easily although it is heavy and unbalanced. I've done it by myself a couple of times even without a proper car lift.