i have done lots of searching and reading...but i wanted to ask about the specifics of my problem...basically when i brake the steering wheel shakes...not always, just when i am slowing down from about 50+...any ideas what this is...i am assuming it is a no brainer? the rotors? any chance it could be the ABS, as i replaced my module a few weeks ago and wanted to make sure it wasn't that...could it be anything other than the rotors...?

 

which can be caused by various modes of wear and aging. I don't know if Jags have vented discs (which look like two discs slightly separated, but connected by fins), but vented discs sometimes have some of the fins rust away. Then the two sides are compressed by the pads when the rusty part gets to a specific place, thereby causing steering wheel shaking.

 

You don't provide your mileage but you describe a classic warped rotor symptom. My '02 XK8 needed new front rotors at 55k miles. Warped too much to turn. New rotors and pads and as new.

My other Ford car had exactly the same problem at 130k miles the same week.

 

Pdog,

Don't jump to the conclusion that your front brake rotors are shot just yet. Usually, but not always, the rotor symptom is accompanied by a pulsating brake pedel too.

My first vote is tires. You can get this exact symptom with tires worn in a particular way. Get the tires ballanced and rotated before starting in on the brakes. Mind you, a visual inspection of the pads and rotors is in order.

 

The above discribed phenomenon is a common problem on the older BMW 7-Series.
(I used to drive both E32 and E38 since 1992.)
On the Beamers it's a sign of worn out front suspension bushings.
(Dunno if this is the same thing with Jags as I'm fairly new to them.)


David

 

I just went through this issue. Mine would shake like crazy when up to speed and I hit the brakes. My pedal did not shake. I Replaced rotors and pads and the shaking is totally gone.
Also keep in mind that the warped rotors would cause the front tires to wear in a certain uneven pattern due to the pulsation of the brakes.

 

thanks all...I really appreciate it...I have 110000 miles on it...i did pop off both tires today...everything looks tight and the bushes look fine...when I went to turn the left rotor it wouldn't turn freely all the way round and would touch the brake pad ever so slightly so I am guessing it is the rotor...when I did the same test to the right front rotor it turned freely...I also looked at the tires and they look a-ok...I did slams on be brakes a few times afte I changed the anti lock brake control unit to test things out so I am wondering if that could have warped the rotor??? what do you think...

 

hey - fyi - i got the wheels balanced today and no dice...she still shakes while braking...they also told me i need an alignment and new front lower control arm bushings...they quoted me about $900 for the work...and $2800 for the brakes...i have the R1 package (brembos) so wasn't surprised on the brake quote...but what do you all think about the bushing quote...also i attached a pic of my lower front control arm bushing...does it look like it needs to be replaced?

 

I believe that If the problems was the wheels out of balance the car would shake at all times when at a certain speed, not just when braking.

What about the rotors? I still belive that's was causing the shaking.
My car needs alignment,balancing,and the front tires are unevenly worn,and probably some front suspension bushings too, yet the car dosen't shake when braking after I replaced the warped rotors.

 

Referencing your comments on hard braking testing; I barely avoided a head on collision by locking down anti lock brakes from 65 to 0. Ended up about a foot from a car in my lane.

Result was to replace both front rotors and pads.

Just imagine the energy focused on the rotors stopping a 4000 pound car in a seconds or two. It should be equal to the force required to accelerate from 0 to 65 in the same time.

 

Test point thanks for the info on the hard braking...I had a feeling that might pull out some car gremblems

 

Rotors n pads, lube the calipers and flush the brake system...unless you've done it in the last 30k miles or so

 

Could simply be pad residue on the rotor surface. 'Rotor warpage' is pretty much a myth.

 

Agree with you Mikey - Warped rotors are extremely rare. I've proven it time and again with customers that swear the rotors are warped. I've used dial indicators on front rotors and proven they are true.

The far more common problem is resin leaching from the pads as you've stated. This resin is always distributed on the rotors unevenly and causes the pulsating as the pad slips intermittently on the slick surfaces.

I've found a correlation with this phenomenon and cheaper pads along with milder/softer braking practices. Even with the cheaper pads I can usually take a customer for a ride and do a couple of aggressive brake stops and clear the pulsating temporarily. But, then I recommend a better (or different) grade pad and cures the problem.

 

I agree as well. A few aggressive, high-speed braking exercises should clear that up. Worked for me in the past.
Oh, and if you know how to use tools, you can do your own brake job for about a tenth of what the dealer is asking.