JAG IRS brake shudder

[Tom Wells]

Olly,

Can't get my car on the lift for the next couple of days maybe so here's some Googling from Jag-lovers.org:

> I know the parking calipers are tightening and releasing,
> but evidently they are not always releasing fully.

It might not explain ALL of your symptoms, but one common problem
with the handbrakes on these cars is a misadjusted cable. By that I
mean, some nimnul has misadjusted the cable; they don't get
misadjusted on their own. The pads wear, the self-adjusters in the
caliper sieze up, and then when the lever can come all the way up
without engaging the brake, the solution is to readjust the cable.
Then when you FIX the worn pads and the siezed calipers, they still
don't work correctly because they're not being fully released when
the lever is lowered to the floor.

Full release of those handbrake calipers is imperative if you ever
want them to work correctly. The only way I know to be sure is to
get under the car and grab ONE lever and try to move it in the
release direction -- possibly pulling the other lever tighter if the
cable is in place. Each lever should be felt to be against a hard
stop. If it's not, you'll need to adjust the cable looser. The
adjustment is at the lever, where you've gotta fiddle with the
carpeting to get at it.

-- Kirbert

and

Aahhh. I think you've hit upon it. On the car with the dragging parking
brake, I discovered that the "plate" (the U-shaped thing with the points
that go in the holes on the top of the handbrake calipers) actually bends as
the pads wear. Whereas the original condition has the arms farther apart at
the points, the dragging pad side on mine had bent past perpendicular so
that it was parallel to the side that wasn't dragging.

Which came first, the bent arm or the dragging? I'm not sure, but it would
seem that as the pads wear, the arm would have to give. Also, it's made of
rather soft metal, and I could almost straighten it by hand. I used pliers
anyway because looking at the pictures and the ones I've removed, they are
supposed to be pretty much straight down the outside edge of each side.

If you can see what you are doing, align it with the holes in the handbrake
calipers. Then reinstall it and safety wire it. I'd add that if it isn't
wide enough, it will probably act as a spring pulling the pads together a
little, until they wear enough to remove the tension.

The bent arms may have been the cause of your problems all along, so you
might want to see if you can straighten the arms and reinstall the "plate"
before dropping the calipers. I don't know if you'll be able to safety wire
it in that position, but I don't know how necessary that is. Anyone?

To sum this all up, it appears that the "plate" acts like a spring, bending
in as the pads wear, but having just enough give to pull the pads away from
the rotor when the brake handle is released. Ingenious engineering.

Mark

P.S. Just so everyone knows I'm not a complete idiot, in the previous
e-mail, I said to disconnect the brake lines from the rotors. Of course, I
meant calipers. Thanks to everyone for not being cruel and pointing that out
(while laughing uproariously).

-----Original Message-----
From: owner-xj at jag-lovers.org [mailtowner-xj at jag-lovers.org]On Behalf Of Darrin hodges
Sent: Sunday, April 08, 2001 5:05 AM
To: XJ Lovers
Subject: Re: [xj] hand brake

Mark
thanks for that suggestion. my main problem was the brass
hook thingie, the original park brake pads were quite worn, im not
sure if the 'arms' on the brass thingie have been 'pushed' inwards, making
it difficult to get the hooks easily back into the holes in the calipers, so
i think ill give your idea a go and see what happens. after that i was going to
change the trans filter/fluid and reseal the exhaust joints, phew, getting worn out
just thinking about it, hopefully, ill even get to drive her before the holiday
is out!

cheers
darrin

Anyway, if you cruise over there and look, maybe one of those guys can point you in the right direction.

Tom