SaabCentral Forums banner

1 - 11 of 11 Posts

·
Registered
Joined
·
172 Posts
Discussion Starter #1
I just noticed over the past few days that when I brake I am getting a slight vibration in the steering wheel. It's not too violent but noticeable. The pads and rotors don't look too bad and before I change them out I wanted to check and see if anyone had other suggestions. The brakes are working fine and aren't showing any stopping problems.
 

·
Registered
Joined
·
365 Posts
mpetruzz said:
I just noticed over the past few days that when I brake I am getting a slight vibration in the steering wheel. It's not too violent but noticeable. The pads and rotors don't look too bad and before I change them out I wanted to check and see if anyone had other suggestions. The brakes are working fine and aren't showing any stopping problems.
Sounds like a warped rotor........When was the last time the rotors were changed?
 

·
Registered
Joined
·
172 Posts
Discussion Starter #3
i bought the car off lease and assumed that they were changed then. but after closer inspection they don't look like they were. the brake pads looks worn to, but i never thought of it because i've had no problems stopping etc.
 

·
Registered
Joined
·
21,583 Posts
Usually, warped rotors can be felt thru the brake pedal.

A true wheel out of balance is sensed thru the steering wheel.
 

·
Registered
Joined
·
917 Posts
I have the same problem...my mech says it's either unbalanced wheels like earthworm said, or most likely just warped rotors. As for me, the slight shake isn't worth the $80 or so to machine my rotors.
 

·
Registered
Joined
·
365 Posts
earthworm said:
Usually, warped rotors can be felt thru the brake pedal.

A true wheel out of balance is sensed thru the steering wheel.
Right, but wouldn't a wheel out of balance have a shake in the steering wheel at speed, and not just when braking?



 

·
Registered
Joined
·
10,382 Posts
That's how mine have been. When a front wheel has been out of balance, I've felt it through the steering wheel at freeway speeds. Also, when my rotors were warped, the steering wheel shimmied when I was braking from freeway speeds. I never felt anything through the brake pedal.
 

·
Premium Member
Joined
·
11,181 Posts
I have had this symptom twice. The first time it was control arm bushings, rectifed by the VRK. (I took this an opportunity to upgrade). Recently it returned with steering wheel shake and pedal pulsing. Replacement of the brake rotors cured that one.
 

·
Registered
1999 9-3 4dr/hardtop 275K
Joined
·
468 Posts
Spinning Rotors

My 9-3 experienced a brake pedal pulsing and vibration upon braking. The rotors and pads were only a year old so I just couldn't see them being the problem. Regardless, I called around and got prices for turning the rotors. The prices were anywhere from $25 to $ 50 each. Thats a lot $ considering the price of a new set of brembos. I realized that everywhere I called was farming the work out. So then I hunted down a small auto machine shop (not listed in the yellow pages) that turned them for me right there on the spot. Only $12 a rotor and when I put them back on the shake was gone.
Now, there are cautionary statements about turning Saab rotors. The minimum thickness for the rotors is not too far off from the thickness that they come with when new. So my newly turned rotors could easily warp again before the year is out. But for me it was a cheap diagnosis of a problem.
By the way, the one rotor that was warped (causing the pulsing) also had a wheel that was badly out of balance and the CV joint that failed. This same wheel is the one that was overtightened during a winter tire change over (also put 45 lbs in the tire). The service guy pounded the daylight out of the wheel to get it off. All these things occurred within 10 days of one another(tire changeover/cv joint/imbalanced wheel/warped rotor/over-inflated tire) . Made me wonder if they were all related, then again it could all just be dumb luck. (I do change over my own tires now :))
 

·
Registered
Joined
·
2,170 Posts
'Warped rotors' when tested generaly turn out to be perfectly true. The main cause of this problem is often uneven friction characteristics on ther surface of the disk caused by hot rotors being in contact with the pads when stationary. They can be cured by a series of high speed hard applications of the brakes.
 

·
Registered
Joined
·
556 Posts
I have experienced this with my Saab. These cars seem to be very sensitive to things such as wheel balance and uneven braking. After getting the shakes via the steering wheel when braking, I checked runout of the front rotors and it was less than 0.002" which should be ok. However the surface of the rotors had different colors around them, with imprints of the pads, probably caused by stopping after getting them hot and then keeping the brakes on. If you search on this forum there are references to running the brakes in so that the braking material transfers evenly to the rotor at the beginning of their life. There is a definite technique to doing this without getting uneven pad contact. If this is done unevely, such as the way my rotors were, I don't think any amount of harsh use will change that. I ended up putting the rotors on a lathe and grinding the surfaces until the discoloration was removed. The shakes were considerably reduced after refitting them even though the runout was the same. However, I ended up putting new rotors on the front to try to eliminate the shaking during braking, but it never went away completely.

A few months after replacing the front rotors, the shakes were starting to get on my nerves and I was very surprised to find it was due to the REAR brakes which had bad rusting/flaking of the inside rotor surfaces (which couldn't be easily seen without removing them. Turns out the caliper inner pistons had seized. Replacing the rear rotors and calipers eliminated the steering wheel shakes completely. I can only surmise that the pressure pulsations created in the rear wheel cylinders due to uneven braking were fed through to the front circuit which in turn affected the front brakes and hence the steering!
 
1 - 11 of 11 Posts
Top