w00tw00t

Calling seasoned Z06 track nuts -- I have two braking questions!


Since buying my Z06, yesterday was my first full-on proper track event where I pushed the car hard.


Here's how the car is currently configured:

- Tires - Michelin Pilot Super Sport
- Pads - Raybestos ST43
- BBK - Stoptech with SS Lines and Motul RBF600, Quantum Cooling Ducts
- Coilovers+Sways - LG GT2 + Hotchkis Sways (Middle Setting)
- No TPMS Sensors
- Running with F55 Sims + Steering Sensor Pulled
- I run with TC OFF
- Track Aligned with -3*F, -1.7*R, 1/16" Toe in Rear
- With this setup, I get errors for service ride control and active handling however since I run with TC OFF, I get no interference from the car.


The car performed like a champ and I even though I was on street tires was able to easily run laptimes that beat my best time with my M3 (which I ran on r-comps). I was amazed, blown away at how predictable my Z06 was. I was initially slightly worried about everything others had told me about it biting me in the *** with TC off etc etc. The car was very communicative, let me know when it was slipping and the power was always there but never felt out of control. Towards the end of the day I had fully settled into the car and it never did anything that caught me by surprise even though by the end of the day my street tires were greasy and sliding all over the place.



Temps:
Oil T - Remained <= 235*F
Coolant T - Remained <= 200*F
Ambient temp yesterday was around 50*F

I have two questions on braking
- When I pulled the steering sensor, did I also disable ABS? I noticed a slightly strange behavior on hard braking, the tires would actually lock up but the pedal would also vibrate (like ABS was intervening) - Can ABS be running and the tires still lock? The feeling again was, I initiate hard braking, the pedal vibrates at the threshold and then the car slides for a few feet with four tires locked -- I feel this is normal as I think I recall my M3 doing something similar.


- Even though I am running Stoptechs and have just freshly bled my brakes, after a few laps I started to lose brake feel - now don't get me wrong - the brakes were solid and performed amazing lap after lap - however the pedal felt like I didn't have much feel .. but still braked hard.. Is that me just adjusting to a different car and me not being used to the ST43 pads? I used to run Pagid RS29 pads on my m3 which IMO had better feel... any comments?


Cheers!
Vivek

Bill Dearborn

What year is your car? Pulling the steering sensor doesn't deactivate the ABS. As for your ABS feel I would suggest the brakes (ST43 pads are pretty grippy) are capable of overpowering the tires especially with the high static negative camber. Works fine in corners but does reduce footprint on straights. ABS works by sensing imminent lock up and releasing the brakes. It is calibrated to work with stock brakes and stock tires so any changes will affect the calibration. It is possible you will get pulsing lock up as it senses the wheel stop turning, releases the brake and then reapplies it with the amount of force stock brakes would apply. That would cause a quicker wheel stoppage than it anticipates so you go from lockup to free to lockup. Still ABS but not as smooth as with stock brakes. Sticky tires could rebalance the system to some extent but can swing it the other way where it can't compensate for the extra tire grip.

By the way I find the car runs just like you described Vs all of the people who say it is unpredictable. The only issue I have is with bumpy corner exits where I can't roll onto the power as much as I want until the rear wheels are off the bumps. Even then all I get is some sideways skitter if I use too much throttle as long as I don't tromp on it.

Bill

w00tw00t

Its a 2013. I think what you're suggest is exactly what's happening. The brakes are indeed super strong and are overpowering the street tires I was on -- it happened more often during the later part of the day when the tires were very greasy and overheated.


I decided to run street tires intentionally so I can learn how the car behaves when sliding around. If I ran R-comps from the get go I would have had a hard time finding the limit. I have now found the limit of the Z06 (on street tires) so I know how I hard I can push. I plan to run a few more trackdays on these MPSS and then I'll switch to R888. I'll then run R888 for rest of the season and then next year I will switch to Hoosiers. I feel this step-by-step approach will help me explore the upper limits of this monster car in a safe manner.


If I went straight to hoosiers on my first day, I think I would have maybe gone a bit faster but would not have known where the limit was.


Agreed on corner exit - For me, I have to really feather the throttle on apex track out as even a bit aggressiveness causes me to go sideways (which was fun though .. I felt I could play with the throttle to balance the car and it did everything predictably. I think the combination of coilovers, sways and a good alignment is all this car needed to balance it perfectly.




BTW I knew I could count on you to respond - you're an asset to the forum - Thanks Bill!!

Bill Dearborn

One thing that can might make the rear more stable powering out of a corner is to increase the rear toe in. I have done that every now and then while at the track. Make small but equal turns on the rear tie rods so you don't affect the thrust angle and just add a little toe in at a time then take the car out and see if the handling improves or gets worse. Some toe plates, two tape measures, a 2ft long laser level and a helper to take readings/hold things and you can make some quick but fairly accurate changes.

Bill

w00tw00t

good tip -- I'm going to leave mine alone for a few trackdays so I can keep learning the car. I'm running rear 1/8" toe in on each side right now.


I love this car BTW, I'm glad I moved up from a m3. I almost hugged my car yesterday, it performed like a champ!!

JerryTX

Congrats on a great track day and a fantastic setup. Only thing I would add is LG mono ball suspension, otherwise that thing is perfect. I started tracking with an E46M3 and loved it in terms of how balanced and predictable it is. I now race a C6 and to me it is an M3 with more power, perfectly balanced and predictable, just a lot more power on tap and therefore burns through brakes quicker! I gotta stop using that middle peddle!!

w00tw00t

Thank you!! agreed. I think the notoriety of the "tail happy, unstable corvette" within the general crowd has to do with the fact that there are a bunch of novice street drivers who don't know anything about throttle management and get in trouble with their 'vettes on the street... I found it amazing and super stable on the track.. and oh the POWWEERR!!


I'm assuming you mean the LG monoball control arm kit correct? Its on my list but I'll get it next season.

skxf430

Vivek,

Your car is looking great!!!

What rear spoiler are you running on your Z?

w00tw00t

thanks!!! Its what came with the car, I think its the ZR1 full width spoiler...

FASTFATBOY

Try leaving the trans one gear up from where you are now in any particular corner.

As soon as the car is done rotating crack the gas open and start feeding it in.

I started doing this and it made me carry more entry speed and settled the car down on exit....this helped everything for me on my solid axle barge Camaro. No more roasting rears on exit and my times dropped.

Won't hurt to just try it for a session.

EDIT, your car looks killer.

taken19

Bill is on point here... I've run a Z51 C6 and spent over a year playing with alignment to see what happens. I found that if the rear gets loose on track out, simply toe in the rear. 1/16" toe in is a good start. I found that 3/16"-1/4" worked well on my 407 rwhp C6 on Hoosier R6's. When I wanted more, I would dial in 5/16' or even 3/8" toe in and I found that I could almost go WOT before I hit track out on the right tires (newer R6's and R80's). The toe in adjustments got my full weight street car competitive with F430 challenge cars (even got around a few of them).

Tires, brakes and suspension makes much more difference then Hp for sure

w00tw00t

Actually, that's exactly what I did - I'm coming from a M3 with a DCT (Dual clutch paddle shifter) - plus being my first day in the Z06 on a proper trackday with TC off, I decided that I will keep the car in 3 and 4 - and knew that the car had enough torque to pull out of low speed corners easily. I've been practicing heel-toe on the street for all my gear changes, but realized heel-toeing when slowing from 145mph+ to 70 is quite another thing haha! .. but with practice I will get better.


Staying in 3 and 4 and never downshifting to 2 really helped a lot like you note above. Next time around, I will add fifth.. which means coming down the straightaway, I will go up to 5 - then down to 4 - stay in 4 and then down to 3 ... You're absolutely right about more entry speed. A lot of people brake too hard and lose all their entry speed and momentum and because they pause before they go on throttle in the turn, their car understeers. For me, braking a bit softer and carrying more speed into a turn has helped my laptimes and feels gentler on the car..



I'm certainly tempted to increase rear toe in a bit more... perhaps I will try it after a few track days.


Also, completely agree on hp.. I think this car has more than enough hp for the track - I have left the engine completely stock - not even a air intake. My next few mods are almost all handling related. I have the parts in my garage just need to install them


- Pfadt Engine and Tranny Mounts
- DRM Aluminum Steering Rack Bushing
- R888 + CCW C10 or C14 (Bought the tires, shopping for wheels)


Not sure I want to add a 160 Thermostat yet. I have one sitting at home but will wait and see what my temps are like in the summer before I decide. I already have the larger Z07 radiator.

FASTFATBOY

Next mod I would do is a GOOD seat and belts. I should have done this first with no doubt.

This will make you more comfortable in the car, less fatigue in turn making you faster.

I was amazed at what a Kirkey seat did for me.

EDIT, I would leave TC on for the first day on track at least.

w00tw00t

On TC - I'm just new to the Z06, I have several years of experience on a M3 and am a fairly seasoned track driver. I had no problems with TC off on my Z. when it started to move under me, it felt very communicative and I was able to modulate slides using throttle and steering inputs.


Also, agreed on the seats - I already have OMP ARS seats and Schroth Enduro harnesses with the vetteworks harness bar and necksgen neck restraint.




Here's my full list of mods


Hotchkis Swaybars
HB Camber Kit
949Racing Lugs
LG GT2 Coilovers
Akra SS Slip On
Clear Side Markers
Katech Belt Tensioner
Z07 Radiator
Rear Tow Hook
MGW Shifter
Schroth Enduro Harnesses
OMP ARS Seats
Vetteworks Harness Bar
Elite Catch Can
CCA Billet Pedals
WeatherTech Floor Mats
Stoptech ST60/40 BBK
Quantum Brake Kit
Grey Ultralegerra 19/20 Wheels with MPS
AiM MXL Dash + ECU Bridge
Sparco R383 Wheel + NRG 2.8 Quick Release