Lime Rock 3/27/10 Video
 

My last session at Lime Rock Park on 3/27/10:

http://www.youtube.com/watch?v=c5GPdnnvn9k

Nice!

thanks for the ride. it was fun to see Lime Rock again. my compliments to you for always maintaining a steady steering wheel. not alot of wasted motion.

what's w the front tire squeel? unhappy front tires. i could see they were your speed limiting factor.

what tire pressure? what suspension settings? any suspension mods? tire/wheel size?

thanks again,

howard

Thanks for the compliment Howard, means a lot coming from someone of your experience and driving talent. The tires were 31psi front and 29psi rear cold but I can't recall the hot pressures, I should have written them down. Last year my intention was to dial in some understeer so I had a good car to learn on that wouldn't snap around on my if I push it too hard which I had accomplished. I've made some good progress in my driving skill so it may be time to start to shift some more slip toward the rear.

Suspension setting:
Toe= 0 all around
Front Camber=-2.5 degrees
Rear Camber=-2 degrees

Mods:
Stance Coilovers 12kg front 10kg rear
30.4mm front bar
stock rear bar

I forgot to mention tires: Nitto NT05 F255/R275

2nd session- On the last lap I missed the first apex and over corrected to hit the second apex:
http://www.youtube.com/watch?v=XQQeS9g9SSo

Part of the 3rd session- Damn ACR Viper

http://www.youtube.com/watch?v=hjKcmIGRllg

Great videos. You may see me around Lime Rock very soon so say hi if you see a blue FEED kitted FD.

Also I'm curious how much power are you running because you're just smokin people in the straights. What turbo?

Thats great, have you registered for an event yet? It would be nice to see another FD at the track. I'll be at Lime Rock on Apr 30th and June 14th. I'm running about 320hp (never been on a dyno so I'm estimating) with 99spec twins.

that was an interesting line thru one near the end of your second session.

as mentioned you are basically driving your front wheels. there is too much roll couple in the front. (you probably know this).

if you were to check tire temps you would find LF real hot and RR cold. if all your settings are correct you need to either lighten the front bar or add more rear bar. your car doesn't appear (it is hard to see from the incar) to have much roll. if you add more rear bar you may make it too hard to drive... too stiff.

a pyrometer would answer all the questions. there's alot of time in your car. that's what tomorrow is for. i would also lower your tire pressures a couple of pounds.

keep us updated in your progress this year.

howard

My amateur opinion: seems the car is too stiff for the tires. Would probably work well with some slicks, but those NT05 probably need a little more give in the suspension. What do you have the dampers set to on the Stance?

I haven't run NT05's, but I've found other Nittos like colder starting temps than other tires on my M3.

Wow. A March Lime Rock event and its dry? ;)

Nice vids

I have some pictures that show the car doing exactly what you're talking about regarding the roll couple, I'll get them posted up. I'm planning on getting a pyrometer and doing some research on it. Any suggestions on a good one? My cold pressure are usually F29/R28 but it was quite a cold day (ice around the track in the morning session) so I raised them a bit. What pressures do you recommend?

I'll keep the updates coming with 3 track days in April.

I think there's some grip left to be found in the NT05s, I believe I need to shift the grip back to the rear and will get some better results. I agree that the rates may be slightly high and I actually planned to drop them to 10kg/8kg but decided to leave it. I'm going to be adding some aero to the car later this year and need the stiffer rates. The dampers were set in the middle of the range with the front slightly higher. I'm trying to stay on street tires as long as possible and getting as fast and comfortable on them before moving up on the tire ladder.

Thanks, I was glad to have a sunny day even if it was freezing out. Last years first event was in a downpour.

Howard, I believe this shows what you are talking (I know I've got a better picture of it somewhere):

https://www.rx7club.com/attachment.p...1&d=1257799819

I'm a suspension novice ;) , so I just looked up Roll Coupling and I believe that's basically what I was suggesting with the stiffness. You can see in the video that as soon as the car begins to turn in, you hear your tires squealing. It seems if you soften up the front, you can get more bite with the tires by allowing more weight transfer and improve your turn in.

I'm like Cole Trickle, I just drive. Most of the other stuff just confuses me. :D

I'm the same way, I'd love to have someone at the track making my adjustments and just drive since I have very little knowledge (read none) on setup. In regards to the issue, I'm going to working on doing just that, I'll be swapping out the front bar for stock before the next track day.

Love your rx7. Amazing seeing it run lap after lap without issue. My day was a total bust. Brand new Mazda fuel tank was leaking and primary turbo was smoking.

a picture is worth alot of words!

holy rear downforce batman! the wing!

guess what happens when you add a ton of downforce on the rear?

you lose downforce in the front.

i actually run the same wing but i modded it so i can flat it out and then add just a little DF if i need it. you have a ton of rear DF.

the first thing i would do is flat out the wing, go out at 29 27 and see what happens. leave the front bar for later.

BTW, beautiful pic of a beautiful car and it has a lot of time in it...

howard

Nice driving! I enjoyed your video's. When is your next event?

Thanks, were you in the black FD? I was wondering where you went, that's a bummer. Fix the issues yet?

Man oh man, that should have been the first thing I looked at. I have no clue why that didn't come to me sooner especially after all the aerodynamic research I have done recently. Thanks for pointing it out, that will be adjusted asap.
Thanks, I appreciate it. I'm going to be at NJMP Lightning on April 17th and 18th.

Nice vids :icon_tup:

I'd leave things the way they are with some push to keep you pointed straight but work on balancing the car with proper threshold braking technique, entry speeds and power application.

From what I can tell you're braking the hardest at the end of the brake zone and should be gently releasing the brakes to balance the car instead of safety checking (hard brake sqeeze at the end of the brake zone). The bulk of the braking should happen as early as possible without upsetting the rear end leaving the end of the brake zone to balance the car for proper entry. Doing this should shorten your brake zone and increase entry and exit speeds in other words it's really important or the most important thing we do in road racing and something I still haven't mastered in over 10 years.

Don't sweat the wing it's not big enough to make a difference.

Yes, that's true and something I need to work on. Essentially what you are talking about is trailbraking to help rotate the car through the corner? Or do I have it wrong?

It's tuff to pick up much from a vid but from what I can tell the front is getting loaded up under braking just before turn in, it's diving when it should be rising. Once again I might be reading way too much into it so if what I'm saying isn't making sense than I certainly understand. Bottom line at the level of most of us hackers car setup really shouldn't be taken all that seriously and driving technique goes a long way in how a car will handle.

Trail braking is braking later and carrying the braking into the corner to shorten the brake zone and certainly with a quick release of the brake over steer can be initiated. but again the nose should dive very hard upon initial braking (doing this smoothly is where the skill comes in) and then start rising as the corner approaches and with trail braking the rise accurs as you are turning in balancing the car into the turn rather than before the turn.

I see what you are saying now, I'll take note of what I am doing next time I'm out on track. I thought I was hard on the brakes in the beginning of the brake zone but there may have been times where I felt I needed to bleed more speed off and squeezed them toward the end of the braking zone