Front brakes locked up @ autox (no abs), driver or hardware failure?

**NLZN** · 06-20-2017, 10:25 AM

This weekend was my first autocross on new rotors and pads.
Pads in the front are Hawk Street/Race and I added slotted rotors. Rears are running standard Axxis and blanks. Fresh ATE200. Front brakes are sparklers

Needless to say the brakes got quite a workout on their first session (maybe more-so than they should, I also have a codriver). Abs worked fine until the last session.

On the last run when I jammed on the brakes, both times I encountered complete wheel lock with no abs. abs never threw a light. Car drove fine on the way home, braking seemed decent, I had a full car load so I did not try to test them hard.

Am I just running too aggressive up front and needing to change the back brakes as well? The only thing I can say is beforehand I mentioned to my driver that the pedal seemed a bit soft.
Any thoughts?

**jayjaya29** · 06-20-2017, 10:27 AM

Had a similar problem last year, ended up being a faulty wheel speed sensor. Front passenger side if I remember correctly.

**NLZN** · 06-20-2017, 10:43 AM

Literally 3 weeks back I ran through the entire ABS diagnostic guide from bavauto. Everything checked out in range, including the values for the wheel speed sensors (as measured from the abs module in the dash).
Did your issue sensor throw a fault or anything?

**jayjaya29** · 06-20-2017, 01:14 PM

I don't recall exactly but I think the ABS light came on when my wheels locked up during autocross.

All my sensors checked out fine when doing the static resistance test but I tested them individually at each wheel and the signal wasn't being generated when the wheel was spun for the front right wheel.

**NLZN** · 06-20-2017, 01:55 PM

Thanks for the reply. Ill test the fronts at the plugs and see if they read ok. I guess I should clean them and the trigger wheels too to take it out of the equation.

**PrinceE30** · 06-25-2017, 04:19 PM

Did they lock for an entire run? Could you turn the car off and on and reset everything? Often time, when they come across an uneven path of asphalt, the sensor will freak out enough where it'll turn off (assuming theer's a mechanical issue).