Vibration when brakes are applied

[Javier Sanchez]

Hello Everyone;

My wife is having problems with her recently "fixed" brakes.
Here is the information:
The car is a '89 Mercury Cougar and about 5 months ago she had the brakes
done. At first the brakes were to low so we took it back to the shop and
he supposedly fixed them. I recently drove the car and found out that
the steering wheel/front end vibrates when using the brakes, there is
no vibration when the brakes are not applied at any speed (what I mean by
vibration is like the shaking of an unbalance wheel.)

has anybody had this problem before? What are the possible causes for this
problem?

Thanks in advance
Javier

jsan...@corp.hp.com

[Shazad Barlas]

In article <336...@hpcc01.corp.hp.com> jsan...@hpcc01.corp.hp.com (Javier Sanchez) writes:
>Hello Everyone;
>
>My wife is having problems with her recently "fixed" brakes.
>Here is the information:
>

>has anybody had this problem before? What are the possible causes for this
>problem?
>

>jsan...@corp.hp.com

Yeah - I was doing 140 a few years back and I aplied the brakes.... and next thing I know >>>> SHUDDERING - like MEGA SHUDDERING!! The problem was warped front
discs!
...Shaz...

[Rob Reilly]

In article <336...@hpcc01.corp.hp.com>, jsan...@hpcc01.corp.hp.com

(Javier Sanchez) wrote:
> The car is a '89 Mercury Cougar and about 5 months ago she had the brakes
> done. At first the brakes were to low so we took it back to the shop and
> he supposedly fixed them. I recently drove the car and found out that
> the steering wheel/front end vibrates when using the brakes, there is
> no vibration when the brakes are not applied at any speed (what I mean by
> vibration is like the shaking of an unbalance wheel.)
>
> has anybody had this problem before? What are the possible causes for this
> problem?

You have front brake rotors that are either warped, badly worn, or have
been cut (machined) crooked by a shop. This happened to my Volvo, the local
shop cut my rotors crooked and then would not admit that they had made any
mistake. I had to buy new rotors.

[James Bruder]

Hi Javier, (how are things at Corp, my old stomping ground was c-level?)
Vibration when applying the brakes can be caused, on disc brakes at least,
by warped rotors. When the brakes are applied, there results uneven pressure
on the rotor. Turning the rotors by a brake shop will remedy this problem
as long as there is enough rotor width left for turning (i.e. within spec).
There could be some possible front end suspension problem but a brake shop
should be able to confirm warped rotors by a visual inspection which is free.

[Peter Sorich]

>Message-ID: <reilly-26...@rreilly.fnal.gov>
>Date: 26 Apr 93 18:19:27 GMT
>References: <336...@hpcc01.corp.hp.com>
>Followup-To: rec.autos
>Distribution: world
>Organization: Fermilab
>Lines: 15
>NNTP-Posting-Host: rreilly.fnal.gov

Also keep in mind that the shop that worked on your
car might have had some machanic that wasn't too
bright tighten your front wheels with a air powered
torque wrench.

For a car with disc brakes, the wheels should be secured
and torqued with a manual torque wrench. Using the proper
sequence to the pattern of lug nuts to be tightened will
insure the proper torque is applied evenly on the rotor.
If they used a air torque wrench to take off AND PUT ON
the wheels, then they more than likely didn't take care
doing it and torqued the hell out of it. The rotors
probably have been unevenly torqued down as a result.
This will cause big problems in a very short period of
time during normal stop and go driving. This is probably
what you are experiencing now. Just my $.02 observation.

Mon-Fri mild mannered Support Technician for Informix Software
Peter Sorich Internet: pet...@informix.com
Informix Software, Inc. UUCP: uunet!infmx!peters
4100 Bohannon Dr
Menlo Park, CA 94025 The opinions stated are mine,
(415) 926-6846 not Informix'.
Sat-Sun volunteer Corner Worker for Sports Car Club of America

[ronald.j.deblock..jr]

Is it safe to drive a car with warped rotors for a week or so? I just bought
a used car that exhibits the classic warped rotor symptoms (vibration,
pulsing in the pedal). Yes, I got the seller to lower the price because
of it. But I won't have time to fix it till next weekend. Pads are nearly
gone, but still safe.

Thanks!
--
Ron DeBlock rd...@homxb.att.com (that's a number 1 in rdb1, not letter l)
AT&T Bell Labs Somerset, NJ USA

[Douglas N. Good]

In article <336...@hpcc01.corp.hp.com>, jsan...@hpcc01.corp.hp.com
(Javier Sanchez) wrote:
> The car is a '89 Mercury Cougar and about 5 months ago she had the brakes
> done. At first the brakes were to low so we took it back to the shop and
> he supposedly fixed them. I recently drove the car and found out that
> the steering wheel/front end vibrates when using the brakes, there is
> no vibration when the brakes are not applied at any speed (what I mean by
> vibration is like the shaking of an unbalance wheel.)
>
> has anybody had this problem before? What are the possible causes for this
> problem?

This is a known problem with the '89 and '90 T-Bird and Cougar --
you've got warped front rotors. Ford has a recall out on this
problem, I'd imagine that Mercury does, too.

I'd take the car to my local Mercury dealer and ask them to
fix it under the recall program. (Phone ahead to make sure
that they have the recall and it's good on your particular car.)

--Doug
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Douglas Good
Amdahl Corporation, Advanced Systems
do...@key.amdahl.com || ...!{pacbell,sgi,amdahl}!key!doug