[xj-s] pulling under light braking

my 91 abs xjs convertible pulls, quite violently, to the right when
braking lightly after a period of not braking

it appears to be worse after a series of bumps

it only does it the first time in any series of brakings

i can’t detect any runout on the front left disc (i was working on
the theory that it was knocking the pads back on that side, and
therefore initially only braking on the right)

suspension, tyres, etc, all good

any clever ideas?–
michael hewittt
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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In reply to a message from mhewitt@bigpond.net.au sent Mon 10 Feb 2003:

HiI had exactly the very same problem as you, in fact the car
nearly killed me.

There I was cruising along minding my own business, when I touched
the brakes to slow her down and nearly spun the car (which is the
same year as yours)

After that the brakes were fine for a little while and then wham!
it just happened again right out of the blue, again exactly the
very same symptoms as you.

Without going into the technical stuff, apparently this fault is
not uncommon with ABS cars.

The primary cause appears to be when for instance the brake pads
have been changed and the wheel cylinders pushed back into the
callipers forcing the brake fluid to flow in the other direction.

Other possible cause: Not changing your brake fluid at regular
intervals.

What apparently happens is that a microscopic partical of
grit/water/crud or whatever blocks up a valve in the ABS so that it
dosent brake evenly.

I have heard tell that in some cases you may have to replace the
whole valve unit (which could be expensive) but not compared to
your life!

The other way is to totally flush out your system with new brake
fluid and do it at least once a year to be on the safe side.

Following a thread on here I do it every six months!

So far the problem has not reoccured but I am now very nervous when
driving this car.

It could happen with out warning anytime any place and to be really
honest the experience really scared me!

You don’t expect it from a car that can cruise all day at high
speed.

I have now developed ‘Super Tanker’ syndrome! If I see a braking
situation coming up, I test and apply the brakes well in advance!

It spoiles the enjoyment of driving but is better than winding up
dead!

If you decide to flush out your system, please be warned! this is
not a job for the backyard with another guy pumping your brakes
while you are underneath it with a spanner.

You will probably lose all pressure and the pedal will go dead, the
reason is with ABS you need to power flush the system.

Ok sometimes you can get away with the pedal pumping method as used
for conventional brakes but if the pedal goes dead then you are up
the creek!

Two options here: Buy a DIY power brake flushing system Which I did
and wasn’t expensive or get a garage to do it for you While you
WATCH! all 4 wheels should be bled right through.

I prefer the DIY method, as like I say I wan’t to do this on a
regular basis.

Apparently when changing pads or wheel cylinders you are supposed
to clamp the brake hose to prevent dirty fluid going back up the
system and blocking this valve but I very much doubt if many
garages do this.

One final point: Flush plenty of fluid through with hard hits on
the pedal (waste about 5 litres)

Hope this helps, let me know how you get on.–
The original message included these comments:

my 91 abs xjs convertible pulls, quite violently, to the right when


willpower
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–

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Michael,

In my case these symptoms remained after replacing front calipers and
pads. Turned out to be
the hoses connecting the calipers to the hydrauilc system. As surprising
as that seemed to me,
I learned that it is a well known problem.

Ed Sowell
76 XJ-S

mhewitt@bigpond.net.au wrote:

my 91 abs xjs convertible pulls, quite violently, to the right when
braking lightly after a period of not braking

it appears to be worse after a series of bumps

it only does it the first time in any series of brakings

i can’t detect any runout on the front left disc (i was working on
the theory that it was knocking the pads back on that side, and
therefore initially only braking on the right)

suspension, tyres, etc, all good

// please trim quoted text to context only

I had the same problem several years ago on a '93. Mine turned out to be
worn rack bushings. It seems that which ever wheel bit first, that’s the
way the steering wheel would go! I too made the discovery under a pressure
situation but found & corrected the problem at once!

Earl Kiker-----Original Message-----
From: Edward F. Sowell [mailto:JagerEd@myRealBox.com]
Sent: Monday, February 10, 2003 10:16 AM
To: Jag-Lovers
Subject: Re: [xj-s] pulling under light braking

Michael,

In my case these symptoms remained after replacing front calipers and
pads. Turned out to be
the hoses connecting the calipers to the hydrauilc system. As surprising
as that seemed to me,
I learned that it is a well known problem.

Ed Sowell
76 XJ-S

mhewitt@bigpond.net.au wrote:

my 91 abs xjs convertible pulls, quite violently, to the right when
braking lightly after a period of not braking

it appears to be worse after a series of bumps

it only does it the first time in any series of brakings

i can’t detect any runout on the front left disc (i was working on
the theory that it was knocking the pads back on that side, and
therefore initially only braking on the right)

suspension, tyres, etc, all good

// please trim quoted text to context only

// please trim quoted text to context only