Welcome to a great habbit (or is it a money pit?).

Seca has been on my hit list - yet is a little far for me.

 

It's the NASA season closer at thunderhill this weekend. Their website is www.nasaproracing.com

Yup they're actually on Archer St. Us west coasters are lucky enough to have nice tracks and shops that work ONLY on Z's! Life is good.

 

haha thanks for the vids! This is getting really expensive!

 

Congrats on your first track day. They are fun fun fun. My next is at Infineon on 11/24 and I can't wait.

I gotta ask though....How the hell did you get on that line over the corkscrew? Did you go too far and slide out the backend a bit? Just curious.

Marc Mc

 

No...I noticed when i was going down the corkscrew i wasn't turn to the right enough at turn 8b. So the next time around I got too excited and starting turning the car before i finished turn 8a. Pretty much didn't line up correctly. I'm kinda glad i did cause i knew where not to be afterthat..hehe

 

Corkscrew = my favorite turn. Even though you aren't travelling that fast, more of a roller coaster.

 

Are you getting stock hub assemblies put in, or some type of upgraded ones? You and I (and very few others) seem to be the unlucky few to experience knockback on the Z. I'm curious to hear if you've got a source for an upgraded hub.

 

Just getting stock hub assemblies. Upgraded hubs are big bucks. If that doesn't work, than I might consider some springs inside my stoptechs to keep the pistons in place.
I'm hopeful the new hubs will work. I'll know this weekend.

 

Can you or daveh describe "knockback" in more detail? Is this condition noticable at any speeds or only under braking from high speeds? Thx.

 

I think most have answered but I will add a few things.

The Stock OEM and HPS brakes do tend to glaze with extended heat applied (IE Riding the brakes, or insufficient cooling). They also transfer a lot of heat to the caliper, thus the fluid as well. Either will cause decreased braking in a session. If it is a fluid issue then the brakes will return after a cooling down or a bleed if needed. If the brakes still feel weaker, but still have a strong petal feel, it could be a glazed pad and only new pads will fix it. Stack gave a good description to tell the difference. The OEM and standard street pads seem to wear badly on the rear, more than the front in hard use so make sure you check all the wheels.

Brakes actually like short hard burst vs. long softer applications. As you are learning the line and track, choose a braking point that is conservative and will get you speed down to what you want with a hard brake. As you get faster move the brake point back a bit each time but still apply a hard but not necessarily full, maybe 90%. Long braking points with say 60% will keep the pads and calipers on the hot rotor transferring more heat and wearing the pad more.

 

Thanks for the explanation. I will try that at the next track event. It's hard to break daily driving habits

 

I would like to know more about "knockback" also.

 

Knockback - http://www.stoptech.com/tech_info/wp_knockback.shtml

I've experienced this too many times with my oem Brembos. I too will be replacing my front hubs. Hope that helps.

 

Definitely something I don't want to experience. Good to know what watch out for. Thanks for the info.

 

+1 Thanks for the knockback link!

Now I understand why a race car driver will tap the brake with their left foot on the straight away before entering a heavy braking zone. I always thought that it was them checking to make sure they still had brakes (that the pedal didn't go to the floor). I'm sure it is both, but doing so corrects their knockback situation.

I love watching Rolex Grand Am series, World Speed GT or ALMS on Speed when they have foot-cams setup. It is just awesome to watch their footwork.

 

If you really wanna see footwork...go checkout some best motoring videos. They're corny as hell but they are fun to watch.

 

How does replacing your front hubs fix this? Wont you still get knockback even with the new front hubs? I would expect knockback to be more prevalent when running R-Compound tires, but Falken 615's too!??? Everyone I have talked to said 615's are great for the first handful of laps but get greasey half way or two-thirds into a 20 minute stint out on the track.

 

Since the hub is what's allowing the plane of the rotor to flex in relation to the rest of the wheel assembly (namely, the mounting brackets that hold the caliper), the theory is that replacing the hubs more frequently than what might otherwise be necessary can help stop or reduce this deflection of the rotor.

As for tires, I agree that r-comps would likely increase the effect, but I've had knockback even on the street after some particularly spirited transitions (traffic circles, etc).

 

Good luck - let us know if that works. I've also thought about the anti-knockback springs for my Stoptechs, but wasn't sure if I wanted to live with those in there all the time.

Keep us posted!

 

As I haven't replaced the hubs yet I'm not sure how much it will help with the knockback. The theory is that the bearing/hub assy is flexing under lateral load. The front caliper location applifies the knockback (since they are significately above horizontal). The front hubs were revised in '04 but I haven't heard the final word if they reduce the knockback or not but I'm willing to try anything.

As far as the Falken RT-615s go, I don't drive that fast But in all seriousness, I believe most people overinflate these. When they first came out, on Falken's website, they had an application chart showing their recommended camber and inflation values. I've followed those recommendations with good results. FTR, 275/35/18 front 1.5 neg deg @32 psi, rear 2.0 neg deg @30psi.