Bad ABS sensor - or something else?

[00Psst]

For the last couple of rotor and pad changes, I've had a problem with a nasty shake when braking - not even especially hard but more exaggerated when I do.  I feel the shake in both the steering wheel and the seats but not in the pedal.  This had me conclude that I had warped rotors and probably did it when bedding in the pads.  But now I'm wondering since I just did brakes again and its back and this time I didn't bed the pads to see if I was right, and the shake is still there if it could be a bad abs sensor causing the ABS to kick in too soon.  

Or is it something else that I haven't thought of possibly?  Any suggestions?

[elitedübs]

so you changed rotors and pads a few times and the shake doesn't go away? have you been running the same set of wheels and tires?

[00Psst]

so you changed rotors and pads a few times and the shake doesn't go away? have you been running the same set of wheels and tires?

Yup, pads and rotors changed twice and I've had the same problem now with three sets of wheels and tires - my old summers, my winters and now my new summers.

The shake is only when I brake and is most noticable when I am braking harder as on an off-ramp but is noticable almost all of the time during braking.  There is no shake any other time.  And I feel it in the steering wheel and seats but not in the brake pedal.

[elitedübs]

rear rotors and pads as well?

maybes its suspension or caliper bushings?

[00Psst]

I've done one brake change on the rears with the same problem showing up.  Hadn't though about the caliper bushings...hmmm...

The suspension is fairly new and the problem existed before that swap as well.  I'm going to have to look at the bushings.

[elitedübs]

yeah check it out, i really don't know whatelse it could be...

[Irish]

For the "Don't do this at home" tester's...it is possible to have a faulty ABS module, that is going off every time you break...to test...big parking lot...some speed, and double foot braking.  If you can go from 30+ to 0, while extreme braking, and you do not trip the abs...then most likely it is either not working at all, or possibly already activated thus causing your shake.

[00Psst]

For the "Don't do this at home" tester's...it is possible to have a faulty ABS module, that is going off every time you break...to test...big parking lot...some speed, and double foot braking.  If you can go from 30+ to 0, while extreme braking, and you do not trip the abs...then most likely it is either not working at all, or possibly already activated thus causing your shake.

You know - so simple yet brilliant.  Thanks, I'll give it a shot.

[00Psst]

For the "Don't do this at home" tester's...it is possible to have a faulty ABS module, that is going off every time you break...to test...big parking lot...some speed, and double foot braking.  If you can go from 30+ to 0, while extreme braking, and you do not trip the abs...then most likely it is either not working at all, or possibly already activated thus causing your shake.

Okay so did this test over the weekend and sure as shit - I got on the brakes hard after running up to about 40mph in an empty parking and didn't feel the ABS kick in - one wheel even locked.  

I'm thinking its got to be a sensor now for sure.

[enginerd]

You can datalog the individual wheel speeds with a vag com. Open up the ABS control module, measuring blocks, and scroll through the different blocks. I think it's 2 or 4. but you will see there are 4 readings that show km/hr. you can watch them to see what one is reading funky. Prob woudl see codes in the abs controller as well.