Pat Goss or Volvo Dealership.. who to believe.

Pat Goss is a auto guru local to the DC area, but also a syndicated
columnist, radio talk show host, and contributor to PBS' Motorweek.

I called the guy on his weekend car talk radio show to discuss chronic
brake warping on my '92 740T wagon. Pat mentioned a possible source of
the warping might be due to improper tire mounting. He suggested
turning the rotors "on the car". The Volvo shop manual (for brakes)
backs him up on this.

I called the Volvo dealership and they never heard of such a thing. I
mentioned the shop manual and cited the page even and the mechanic
denied the existance of such a device. I mentioned the advice of the
vaunted Pat Goss; the dude said Volvo has "issues" with Pat.

I ended up buying new plates from IPD. But still...
Whats the deal? It appears from the shop manual that a device exists
that turns rotors while mounted to the car. So Goss is correct. Yet
the dealership claims otherwise. What gives?

 

Take advice from neither. It's much better to listen to free advice you
get from anonymous strangers on the internet!

While I do watch Motorweek on PBS, I find what Goss says to be almost
useless most of the time, although he is right in this case. And of
course your Volvo dealer, well that's just typical for a Volvo dealer,
certainly the ones I've dealt with.

Turning the rotors while mounted on the car is only necessary in the
most extreme of cases. If the wheels nuts are improperly tightened the
rotors can warp. If the rotors are true and all else is good, the
vibration will go away. First make sure that the surfaces where the
rotors and hubs touch are clean and rust free. There are 5 ways to
mount the rotor, pick the one that minimizes the runout. Make sure that
the rubber bushings in your front suspension are all in good shape,
especially the cone shaped ones at the front end of the diagonal link.
(You can't really see these until you remove the link from the control
arm.) These bushings absorb the minute vibrations caused by minor
variations in the rotors, and if they're worn out they vibrations are
transmitted to the car.

 

There are indeed devices that will do just that. Only problem is that it is not
recommended for use with Volvos. I would certainly agree with this and ensure
that the wheel nuts are tightened to no more a torque figure than 63 lbsft (85
Nm). Anything more than this will cause the rotors (brake discs) to warp. When I
have my tyres and wheels cleaned/changed I always tighten my wheel nuts with my
torque wrench to ensure that they are never overtightened. My local tyre chappy
is perfectly happy with me doing it as it saves him a job. This problem, has
been very well documented in the States/Canada for a number of years. One of my
local garages has just obtained one of these machines which do admirable jobs
for most cars but it is after all only a short cut and does not last as long as
new ones and in fact will increase the possibility of warping.

Cheers, Peter.

: Pat Goss is a auto guru local to the DC area, but also a syndicated
: columnist, radio talk show host, and contributor to PBS' Motorweek.
:
: I called the guy on his weekend car talk radio show to discuss chronic
: brake warping on my '92 740T wagon. Pat mentioned a possible source of
: the warping might be due to improper tire mounting. He suggested
: turning the rotors "on the car". The Volvo shop manual (for brakes)
: backs him up on this.
:
: I called the Volvo dealership and they never heard of such a thing. I
: mentioned the shop manual and cited the page even and the mechanic
: denied the existance of such a device. I mentioned the advice of the
: vaunted Pat Goss; the dude said Volvo has "issues" with Pat.
:
: I ended up buying new plates from IPD. But still...
: Whats the deal? It appears from the shop manual that a device exists
: that turns rotors while mounted to the car. So Goss is correct. Yet
: the dealership claims otherwise. What gives?

 

Honda recommends this too. I have had several Hondas before and I know
they do it that way. I have a Volvo..I am not sure if my dealer does this
I will find out next time.

fb