More EPB woes

[iRS]

I've been taking a look at my handbrake. The left side caliper has been dragging for a while now, so time to try and fix it. I swapped out the EPB motor a little over a year ago and it was one of the worst jobs I've done on the car. Mainly because of the limited access space within the sub frame. My car has the separate parking brake calipers.

The problem may have started in February. I had problems back them with the EPB setting and not releasing and an associated error code. I put it down to a dodgy battery so swapped that out and hoped that was it. But maybe something wrong in the mechanism was causing that problem? I also replaced the parking brake caliper pads and recalibrated the EPB.

So, I've taken a good look at things. I sat under the car with my son operating the handbrake on and off from the driver's seat. From what I can see it goes on no problem, with both sides tensioning. When releasing, the driver's side released OK, but on the left side it only partially releases. I can then give the cable a yank (in the middle from under the car) or use a wrench on the cam on the caliper and it will fully release. The only thing I can see that may explain it is that when setting, the cable 'outer' from the motor move slightly towards the middle of the car. When releasing it doesn't relax back all the way without intervention as mentioned above. So, is this bit supposed to move back and forwards?

The bit that is blue in the photo is fixed to the subframe and the cable outer is moving within this.

Thinking through this, I assume for the brakes to work, the motor initially tensions the cable and that sets the caliper on the driver's side. When that doesn't move anymore, the movement is transferred to the cable outer that then transfers the force to the metal part in the photo that then tensions the left side. So, although I guess you can’t see it, the right side sets first and then the left. Does this sound correct?

If so, then may be my problem is that the black outer is not moving through the blue fixing bit freely? or any other suggestions?

[J44EAG]

As I understand it, Roger, there is one cable out of the drive motor which tensions an "across car" second cable (via a yoke) and pulls equally to set both calliper arms at the same time. I recall this from a Dave Marks lecture when he said if you have a jammed hand brake system you should only cut the across cable NOT the drive motor cable. At that point the park brake calipers should release. Obviously it is easier and cheaper to replace the across car cable that have to fit a complete new EPB motor assembly!

Having service my own hand brake calipers a few years ago, I recall both calipers are identical and that the lever arms have a propensity to seize.

I forget precise details of the cable mechanism but certainly any part of it should be releasing equally and with the same action.

Sorry I can`t be more helpful.

ATB

Mike

[iRS]

I think (hope) I've fixed this now. I am certain that the problem was the cable from the motor not 'relaxing' back into place. I groped around underneath for a bit attempting to move the cable into a better position and spraying WD40. I managed to manipulate it a little further into the back corner and attempted to get the blue bit out of the fixing point. I couldn't really get this out, but it did reseat with a resounding click/thump. On further testing the EPB was working again. I fitted new discs and pads for good measure and calibrated the EPB. So far, so good.

Mike - you've got a better memory than me! However, if anyone is reading this subsequently, I would encourage them to think through cutting any cables. From my experience they are all very difficult to remove. If you were to try and replace one of the middle-to-caliper ones, I simply can't see how you could get to the plastic latches to remove it from its fixing........

[J44EAG]

David Marks recommended NOT cutting any cables if at all possible.

Any replacement can be a nightmare job. If the car has jammed brakes, then separation of the across car cable from one of the caliper points is the best way to go. Perhaps easiest to unbolt one of the brake calipers, and try to lift it off the brake disc. Sorting out the issue should then be reasonably feasible.

Mike

[jeff1954]

Not just a Jag problem this, but why oh why have car manufacturers gone down this route. What was wrong with the old system of a hand brake lever and cables after all it's worked fine for the last eighty years or so.

Jeff