OK, at the end of long straights, I have learned to give the brake pedal a little "Luv Tap" to confirm that I have a good brake pedal for the next corner.
(Pad knock-back and/or brake fade)

The problem is is I do this at WOT, and tap the brake pedal, the engine dies! WTF. Does anybody else have this problem

Is there anyway to stop this from happening?

BTW : I have a stock engine & drive-train 2006 Grand Touring

 

Do you turn off your VDC?

 

Huh? End of the long straight the brakes are cooling because your not on them. A tap is not going to determine if they are going to work properly when you hit them hard in the braking zone, especially, if you brake let in the zone and trail brake the corner.

And, if they were gone that actually happened after the last turn.

If your going to lose them (Brake Fade) it would be under hard braking especially later in the session.

Are you bouncing off the rev limiter?

Experience brake fade anytime on the track?

 

Tapping the brakes before a braking zone to seat the pad against the rotor is very common in road racing, especially in cars that have weak wheel bearings. The 350Z is notorious for having weak wheelbearings which causes excess flex and increases the problem of knockback. By the wheelbearing flexing (which can move well over 5mm with 275 R-compound tires) the pads are knocked-back and a gap forms. When applying the brake pedal, the pedal sinks to the floor to take up this gap before becoming stiff and creating pressure on the pad against the rotor. Tapping the brakes help seat the pad and prevent this.

I forgot what it is, but their is a brake pedal sensor that cuts the throttle when you apply the brakes. I think their are a few 350Z models that dosn't have this feature, but I think its more of the throttle-by-wire equipped cars that experince this. You can't "power-brake" or do a standing burnout or drift that well with this feature enabled.


0.02

 

Sorry, never heard of that. I know a handful of drivers that race in SCCA National T2 and they have never mentioned that before.

 

Your problem is most likely what stuntman said, the throttle is cut when you step on the brake. Pretty sure the only way to stop it is by pulling the brake light fuse.

 

VDC is completely disabled via removal of the yaw sensor

 

Well said!

BTW: I don't recall this happening at part-throttle, on WOT!

 

Obviously, I can't pull the brake fuse, but that does give me an idea on "work-around" thnx

 

Great answer. and brake tapping is very Common in Competition driving

 

FWIW, I have heard this referred to as "ice" mode. I watched Andy Hohl driving Chris Hammond's 03 Z come to a complete stop because the engine quit in the middle of a National Tour Solo run because he was left foot braking. I was told that the ECU does not understand why anyone would do both.

 

I heard that this "feature" was designed into most modern cars after multiple law suites in the USA .related to "unintended acceleration" over the years...

 

Ice mode is where you lift a wheel off the ground when braking (just enough to cause that wheel to lock) and the ABS thinks you’re on ice so it reduces the braking force to about 1/10 of full brakes. Just unplug the sensor under the console to resolve this.

When you hit the brakes and gas it cuts the throttle to just about nothing (closes the actual throttle body-reduces fuel-etc). The drag racers pull the brake lamp fuse to bypass the issue, maybe Sharif can chime in a better solution. Try doing a burn out and you'll feel the same thing...

But we have the same problem with our Z with pad knock back and just give the brake pedal a quick stab (right foot) before laying on the brakes going into the braking zone. Takes a little getting use to-but as Marty said it's very common-especially when the rotor diameter starts to increase in size to place even more pressure on the wheel hub & bearing.


mpowers

 

Software issue. The driver-by-wire throttle gets cut if the brake and throttle are applied at the same time. There's usually a .5 second delay after the brakes are released. In every other race car I've driven I sometimes trail brake with my left foot while picking up the throttle mid-corner (smooths the weight transfer back). Can't do it in the 350Z.

Move your braking point back a heartbeat and give it a quick double pump before hard braking.

 

You can also run a inline switch to the power wire in the yaw control unit behind the ebrake. On 03-04's its the purple one in the loom. You'll trip all your dash lights but you'll have complete control.

 

I have already performed a "Yawrectomy" on my car by unplugging the main harness from Yaw sensor...so VDC is completely disabled and all the lights on the dash are on.

Sounds like I need to re-train myself just do the double-pump instead of the left-foot Luv tap.

BTW: I had the pad-knock-back deal at Barber entering the carousel in my 1st TT event. The pedal went to the floor, on the second pump the brakes worked...however I missed the corner and $%^!@#$%^&*() in my pants as I drove sliding past the corner worker in the grass.

So I started dong the luv-tap. My last event at Road Atlanta has 2 big ugly places that you REALY want the brakes to work, T1 & T10A...the engine dying was very obvious in both of these situations (WOT)

So I have proactively changed by front wheel bearings out...I will do this every season or when ever I hear the "growling" noise...

Thnx for the input!

JE

 

Yea, a few Mustangs I drove had a similar knock-back problem at Barber. Apex curbing or rumble-strips definatley increase the problem.

Once a season isn't as bad as once every other weekend

 

My 2005 Track model cuts throttle to 50% if I LFB, but it doesn't throw ABS codes.

I have to fully release the brake pedal to restore the throttle.

That being said, I've got accelerometer data showing a 1/10th second acceleration "flutter" by using LFB to actually modulate the throttle coming out of a turn when traction was less-than-ideal. The computer can move the throttle between 50% and 100% faster than I can physically do that with my right foot, but all I have to do is move my left foot less than 1/4 of an inch to accomplish the same thing by using (abusing?) the computer. I honestly didn't realize that I was doing that until I started looking very closely at the data.

 

Maybe mine is only going to 50% throttle, not Zero. It is hard to tell at >100 MPH. So I will experiment in a parking lot somewhere and see if mine will just go to 50%, not ZERO

 

Has anyone done this, so your just adding a switch. Sounds like my answer.