I'd venture to say more people have it than know they have it... some people may be confusing air in the lines with knockback. Also, there are some of us that do the little left foot tap anyway, just as a confidence builder before a really hard braking zone after a long straight (turn 1 VIR South and Full come directly to mind... turn 1 at CMP as well).

 

I can't get myself to left foot tap...it is so un-natural.

I practiced on the streets for some time, and mostly made my car jerk about. These brakes are so sensitive when heated up! I've been getting off the throttle early to right foot tap, and that sure doesn't help my lap times. I'll have to watch some of you experts in a ride-along because the whole left side of my body is completely uncoordinated (even the left side of the brain).

 

Train it ! (Your left foot I mean).

Your right foot wasn't born with a gaz/brake pedal combo under it. Do it on the street where there is little traffic. It doesn't take that long to adapt and minimise the car's "jerkines"

 

STi's have exactly the same problem. Heat from the brakes, calipers at 12:00, larger diameter rotors and high cornering loads in a heavy car with mass produced parts not really made for that. I'd check for a loss in bearing preload after track sessions and maybe repack the bearings - it probabyl wouldn't fix it but it may reduce/slow it some.

 

subscribing........

 

You know the Thread Tools menu allows you to subscribe without posting?

 

Its harder than people think. I'm taking a data aquisition class from a guy who coaches Nextel drivers and he said its difficult for even some top drivers to get it all right. He gave us a coordination test. Grab a notebook and a pen, and sit down. While seated, rotate your right foot, from the knee, in a clockwise rotation. While you are still rotating your foot, put the pad of paper on your lap and write the number 6. Keep an eye on what happens to your foot!!

For the guys who say its probably happening and that the driver is just unaware of it or mistaken, It could just as easily be a problem with brake technique. How many of you with pad knockback ease off the brake slowly?? Have you videoed it or logged it? You'd be suprised how many Nextel cup drivers sideslip their foot off the brake and go back to the loud pedal. Just something else to consider.

 

Good remark.

A bit of gossip ? David Coultard and Rubens Barrichello are the only two F1 drivers who do not left foot brake...

 

A few months ago, we had some discussions about trail braking. While going through some of the exercises, I noticed my habit was to release the brake abruptly so that I can go quickly to maintenance throttle.

That habit has made the already complex exercise of trail braking even more difficult to perform. I acknowledge that this is a skill that will take me a very long time to master.

My family still wonders how I can get any joy out of driving a car around in "circles". Some folks will never understand...

 

Take them for a spin. They'll understand...

 

Just to let you know I also experience the knockback on my Rotaras when I am racing. I have just learned to expect it, and tap it just like the others have recommended.
Haven't ever had it when I am on the street - and I don't drive like a grandma on the street.

 

The best way to learn is to practice left foot braking in an Automatic ... normal street driving, learning to apply and release smoothly will translate into doing the same thing on track. I did this with my '90 NA Automatic, but I started the other way... left foot braking on track led to doing it on the street. (BTW, I still can't get it right in my '71 5-speed... feet are just too darn big.)

But we are talking about two different things... like the StopTech article says... if you're hitting the brakes after coming out of a hard bend (to negate the knockback effect), it should not be enough for you to even feel it.

Normal 'left foot braking' is a different beast alltogether and really can't be done without using a 'dog box' or seriously compromising your transmission by not using a clutch while shifting... if you're in a turn where you don't have to downshift, you're probably not threshold braking anyway.

 

We changed our GAC cars front hubs every three races and crack checked them after every race weekend. We never had one fail...but that is what you call prevenative maint on a race car......having one go and hour into the race is too late!
If you have one go......it wont be fun...or cheap.

 

Do you use OEM nissan parts? Are there any other (better) alternatives?

 

I've had this since day one in my 2003 Track model... I never fell it in other model Z's I drive... does anyone know if the track model has different size master cylinder than other models? I never expected Brembos to feel this way! I've gotten used to the left foot tap for the last 3 years now and still do it while driving other cars I get people asking why I do that all the time.

I did notice that having fresh pads (thick OEM/Hawk style ones) helps a bit and I double up the shim plates (OEM + the ones that come with the Hawks) this makes it tough to install the pads but helps a little. Probably time for new wheel bearings all around as well

 

I've experienced knockback since my second track day in the Z (that was on stock non-Brembos.) Since I got the 13" Stoptech's it's gotten worse (larger diameter rotor = more leverage), but once I figured out what it is, I learned to expect it and have been able to adapt, more or less.

I've worked on the left-foot-tap (I felt better after seeing the Best Motoring drivers having to do this in most cars they drive, including the GT-R,) but it's still not fun, as you just never know if you completely got all the slack taken up when you hit the braking zone. Like a previous poster said, it's much less noticeable with new brake pads, probably because there's less clearance in the caliper for the piston to be pushed away from. I've thought about making a set of shims to put it in there between the piston and the caliper so that I can always keep the clearance taken up (as the pads wear, I'll put in more shims), but I'm not sure what this will do to my overall braking performance or pedal feel.

Anyone know of any heavy duty hubs/bearings for the Z that might be able to help counter-act this?

 

Jason H told me that there was change in the part for the 04.5 models, slightly beefed up. Maybe you should get the new hubs and bearings and see if that fixes the problem. So far have not had this issue with my racecar

 

I think I have an 04.5. My build date is only 04/04, but I have the revised suspension. Do you think the new hubs are a direct replacement for the pre 04 cars?

 

As prpe on Jason H car.....we also crack check them. We talked to a manufacutre who produces nothing but real racing hubs........but they had no interest in producing them. Plus.......the market doesnt seem like it was there for them as the cost would be fairly expensive. This was another product we had on the drawing board for 350EVO.

 

Dave, I would just bite the bullet and get new hubs and bearings, you may just have a set that are slightly out of optimum tolerance.