07 Expedition. At 1,800 miles the truck started pulling to the left
while braking at freeway speeds. New front pads, nothing. New rear
pads, nothing. Rode with engineer who said while braking/pulling the
driver side rear tires is spinning 3-5mph slower than the rest,
causing the pull. They then replaced both rear calipers, pads, rotors,
and lines. Still pulls the same. Any ideas?
Ditto that. If the computer told the engineer that the RIGHT side is
going slower, but it pulls LEFT then it could be a bogus reading
causing the ABS modulator to ease up on the right side. Your wheel
speed sensor is probably good since it reports okay while not
brakiing, which means the bad data are appearing higher up the chain.
On Oct 2, 11:56 am, email@example.com wrote:
Yeah, but how do you know that? Because the computer says so? Maybe
the computer is wrong. Unless you put your own counter on the wheel
you have to take the computer's word for how fast each wheel is
On Oct 2, 1:23 pm, firstname.lastname@example.org wrote:
The right wheel having less braking power would also make it pull
left. The ABS can't increase braking power beyond what you input, but
it can reduce it.
I'm not trying to argue with you, which I hope you see. I'm just
trying to think out loud about other options.
A dead simple way to see if it's ABS. Discommect the darn thing.
However,I'm betting it's NOT ABS. I'd be checking tires first (switch
left to right and see what happens)
I'd also do an ACCURATE 4 wheel alignment to rule out alignment
issues, and check the suspension integrety to be sure the rear axle is
not shifting under braking.
I'd also be checking the brake hoses. Particularly on the front.
Rear brake inbalance rarely causes a "simple" pull.
Premature locking of a right rear wheel is just as liable to cause a
drift to the right as a pull to the right.
Posted via a free Usenet account from http://www.teranews.com
I really think it is a caliper or valve failing when it heats up. All
four tires have been ruled out as they have been rotated in every
position. Suspension has been checked.
The pulling doesn't happen on the first hard brake. It is the braking
after that that it gets progressively worse up to a point, which leads
me to believe its heat related. Alignment is dead on.
On Mon, 01 Oct 2007 15:19:58 -0700,
I have a '93 F150 that had a similar if not identical
problem. Ford spent something over $7K under warranty
attempting to correct the problem. They finally offered to
buy it back under the lemon law. We worked out an extended
warranty agreement since the buyback on a vehicle with high
mileage at the time was prohibitive. Soon afterward, I did
a front brake job and replaced the front calipers with recon
units partly because one was weeping a trace and partly
because this was the only components that were not replaced
by Ford in their attempts to correct the brakes. The
problem was immediately corrected with the recon calipers
and has not returned in more than 150K miles since. I still
have the original calipers ans we were never able to detect
any abnormal conditions. The curious thing is that the
first stop leaving home never had the problem but, if it had
been cruising at highway speed for a few minutes, you had
better have a good grip on the wheel or it was headed for
the wall in a hurry. IT also had an almost imperceptible
pull with no brake application. It was wearing my ass out
to drive a full day and I had not realized I was constantly
correcting and steering against it. It did require a wheel
alignment afterward to take out the adjustment the front end
man had dialed in to counter the normal steering pull.
Also, someone mentioned a rear wheel turning slower than the
other. For that to actually happen with the vehicle
traveling straight ahead, one tire has to be larger than the
other by a significant and measureable amount. The slow
wheel would be the larger in that case and would provide
less braking effect than the smaller one. IOW, it should
pull toward the faster wheel if that is the problem.
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