Brake question for a Newbie

[smelvis]

Hey all, first off, I am so happy to have found this forum..SO MUCH INFO!!!! :) Anyhow I recently bought a '02 TT..50000 miles and I love it!!! However when driving it, the brakes do this weird thing. If I am getting off on an off ramp or sometimes just taking "the twisty" at a decent pace, my brake pedal will kick back HARD...hard enough to push my foot off. It just does it for a second and then its fine but its enough to surprise the HECK outta me. My brakes also SQUEAL like a banshee...not sure if thats related. ANyhow I brought my car to the dealer and they tell me the brake kick is normal, and that its part of the ABS system sensing I am cornering to fast. I just cant believe that though...sometimes it doesnt feel like I am anywhere near loosing traction and it just does it. My brakes have about 85% life to them too according to the dealer, so the squeal seems kinda odd as well. Please can someone put my mind at ease or tell me what to tell the dealer to look at?? Thanks agoan from your newest Turbo lover!! :drive:

[mpaton]

Hey all, first off, I am so happy to have found this forum..SO MUCH INFO!!!! :) Anyhow I recently bought a '02 TT..50000 miles and I love it!!! However when driving it, the brakes do this weird thing. If I am getting off on an off ramp or sometimes just taking "the twisty" at a decent pace, my brake pedal will kick back HARD...hard enough to push my foot off. It just does it for a second and then its fine but its enough to surprise the HECK outta me. My brakes also SQUEAL like a banshee...not sure if thats related. ANyhow I brought my car to the dealer and they tell me the brake kick is normal, and that its part of the ABS system sensing I am cornering to fast. I just cant believe that though...sometimes it doesnt feel like I am anywhere near loosing traction and it just does it. My brakes have about 85% life to them too according to the dealer, so the squeal seems kinda odd as well. Please can someone put my mind at ease or tell me what to tell the dealer to look at?? Thanks agoan from your newest Turbo lover!! :drive:

In this case, they are quite correct. One of the PSM components that provides Yaw Stability under Braking (which does not disable when you turn off PSM) will push back quite hard on the brake pedal. It does this because it does not approve of people braking while turning.

The only reasonable way for this to be an error is that PSM does depend on steering wheel angle, so if your steering wheel is not straight when the car is going straight, I would have the dealer fix that.

If the wheel is straight, then I'll tell you that you are indeed driving too fast to be braking around a turn. You'll probably find that your local PCA region holds High Speed Driver Education events several times a year at a local track. As a PCA National Instructor for these events, I can tell you that not only do you probably have something to learn from these events, but you'd find it a whole lot of fun at the same time.

Regards,

Michael

[SpawnyWhippet]

I'd agree with Michael here. Heavy braking should always be carried out and finished before the corner turn-in point. You can apply light braking (known as trail braking) into the first 3rd of the corner to shift some weight to the front of the car and allow greater front grip. You should never be braking through the whole corner as this seriously upsets the balance and grip of the car. If I wanted to try the best way to crash at high speed, heavy braking in a corner is how I'd do it.

Having said that, trail braking is a racing technique and best learnt (and left) on the track. If you find you have getting ABS moments in fast corners, you are travelling way too fast and in a lesser car you would have already made a visit to the scenery. I would also advise some lessons from a race instructor, we can really teach a lot about performance car driving in a single day.

[ez996]

I have seen something simular on Land Rovers (Range Rover) Bosch ABS system. On fast sweepers, getting on the ramp etc. ABS would kick in without even touching brake pedal- factory had a TSB for that issue. Fix was replacement of the ABS module with updated part.

[wvicary]

I had a VW passat that used to do this and it turned out to be a wheel brng. The brng made no noise but was loose and it caused the ABS system think that the one wheel was turning at a different speed,it would only happen while turning and braking like when pulling into my drive way. Replaced the brng and it never did it again.

[jackchung]

I had the same problem. Check to see that the front tire's size is close to the rear. If one is off, the car thinks it is losing traction and the PSM kicks in. I was running 245/35/19 in front on 11 inch wide whees, and 315/25/19 on 13 inch wide rears. At on ramps at faster than normal speeds but no where near at speeds to lose grip, my brakes would come on and the PSM light will flash. Scary feeling! With the PSM off, it will not happen as often but it still kicked in at higher speeds around a corner while braking. I am now running 235/35/19 and 315/25/19 on the same wheels and it seem to do it much less. I think the ideal size for me is 225/35/19 and 315/25/19 but the front will not support 225 on 11 inch wheels. The dealer checked my ABS sensors and it seemed fine. Also, two different makes of tires in front and rear with different amount of traction can also affect it. Hope this helps!