Hello enthusiasts,
I just hate it when qualified/unqualified mechanics just mention a thing of two or three as source of a problem and none of them is it!!!!!
As I drive my 2001 S40, for speeds above 60km/h and as I hit the brake pedal there appears to be some rather heavy vibration on the steering wheel and front train if I may say, that makes one worry; this only when you hit the brake pedal either for slowing down or for a complete stop. I could also feel a pulsation on my foot incoming from the brake pedal as if it was going back and forth up/down (I am alittle bit dramatizing, but this is the feel). when the car speed is below50-60, this problem is not encountered.
OF course, the first thing to check are the brake pads and then the brake disc, and I was almost sure it were the pads or the disc that must have been damaged after some condultation with a mechanic on the possible reasons behind. ARmed with my tools, over this weekend, I got down to it and removed the calipers on both front wheels,only to discover that both 4-pads and the 2 discs ofthe front wheel were NEW and smooth. I was frustrated. I was wondering what could be the source of the vibration...
Thanks for any feedbacks....

 

I have similar issue. Bottom bushing on front LHS wheel is worn. Has play. RHD 05 S40 Car

 

Heavy vibration in the steering wheel when braking is usually warped rotors. They may look perfectly new and still be warped. Not many shops turn warped rotors these days, depending on where you are located. It's possible to setup the rotor and measure to make sure. Mine had deep grooves from the soft factory steel rotors and over time became so thin they easily overheated and warped.

The 2001 also has anti-skid brakes. You feel this activate through the brake pedal. Although I'm not sure why you would feel this only above 50-60. I'm thinking the vibration is the problem and the pulsing brake pedal is a symptom of the warped rotors.

Have you tried the wheel bearing test? You jack a front wheel and try to move it by grabbing it at 9 o'clock and 3 o'clock and wiggling. The tire should not move at all but most cars will have small movement. (very small)

There is also the ball joint test where you jack the front wheel and grab the tire at 12 o'clock and 6 o'clock and wiggle. Again, no movement should be there but most cars have a tiny bit.

 

Concur. Do the wiggle tests first because they are the quickest, easiest, and cheapest things to do. If you have more than the tiniest bit of play, you have components in the front suspension that need replacing.

If all is well there, check for warped rotors. I use a dial indicator on a magnetic base. Mine were pretty pricey years ago BHF (Before Harbor Freight), but these days tools of this sort are inexpensive enough to warrant purchasing. Even if your ride fails the wiggle test, you can use the dial indicator to localize and quantify the wear.

Hope this helps,

Lynn B.

 

Thanks for yourvalued replies.
I cannot explain the fact, but with the suggested reason of Hudini and Lyn_B: Warped disc rotors; I would have to remove them and do the suggested test. But meanwhile I wonder the cause of warping; we are in Canada, cold climate, and there are seldom downhill, so to say there ain't any... I know warping can occur as a result of heavy excessive usage that leads to overheating the rotor disc and metal twisting; but the swedes in general are known for their heavy metal components and its toughness and reliability... So it is diffcult to believe that wraping occured on a volvo rotor disc, some Korean most likely...this finding, if true would change my latter belief.
About the wiggle or giggle test, YES I already did the 12 and 6 oclock one, because a mechanic 1-year ago told me I needed to change the left ball joint; frankly I could not see any play, I tried and tried to move it to feel any play, but I didnot succeed and thus was relieved; plus another mechanic reassured me it doen't look like a ball joint. The bearing test I have not done, but wonder it would be hard to notice movement since the steering wheel would turn in that 3 and 6 oclock position...
Will post you on new developments....

 

You won't be able to turn the steering wheel if the steering wheel is locked. Besides, it's a wiggle test. You are only looking for excessive play. If you get a tiny bit of movement it's usually the tie rod end. You can look behind the wheel to see this. Excessive movement needs closer inspection.

I've had a few cars warp rotors on me. My old 1986 Volvo 240 did it once for no good reason. Came to a stop, drove it some more, and the next stop shook the steering wheel. My 1985 S10 Blazer I drove for 175k miles when it decided to warp the rotors. I had them turned and they have been fine ever since.

I'd suggest looking for a shop that turns them. They can tell you pretty quick if they are warped. My local high school shop class turns them for learning. This is tricky though because you don't know if the instructor is watching them closely. They can be turned too thin.