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-   -   Keep the 275/ 315 tire setup or trade off for less weight? (https://www.rx7club.com/race-car-tech-103/keep-275-315-tire-setup-trade-off-less-weight-944362/)

PandazRx-7 03-29-11 11:45 AM

Good info... I think I'm gonna go 285's up front, stiffer springs 700/550lb, and get it corner balanced and aligned. After I run that set-up then I'll fine tune with my wing.

I know the pyrometers is key when it comes to alignment specs, but any suggestions on initial alignment specs?

j9fd3s 04-03-11 07:29 PM


Originally Posted by PandazRx-7 (Post 10542165)
Good info... I think I'm gonna go 285's up front, stiffer springs 700/550lb, and get it corner balanced and aligned. After I run that set-up then I'll fine tune with my wing.

I know the pyrometers is key when it comes to alignment specs, but any suggestions on initial alignment specs?

generally...

starting in the rear. toe in in the rear adds stability. on our low HP we run zero, you have a LOT of power, you may want to run some toe in. i'm not sure what the stock spec is, but maybe half of stock is a good place to start?

you want to make sure that the THRUST ANGLE is 0 or square with the car. IE the rear wheels are pointing straight.

toe in the front kind of acts the same, toe in is stable, toe out should turn in harder. start with zero toe.

camber front and rear is what the pyrometer is for. tire construction, width, and the suspension all contribute so its hard to just toss numbers out. generally the R888 doesn't want as much camber as an Ra1, for instance. i think i'd start around -2 in the front, and maybe -1 or -1.5 in the rear, and be prepared to go to -3F or more

as an example we went from the R888 setup on the honda @ -2F and we're like -4 or something to make the hankook happy, so we've adjusted it at the track a couple times to make it happy.

castor, on the FD its linked to camber, so i think you get what you get


so id start with zero toe in the front, -2 camber, whatever caster that is, and in the rear -1.5 camber and maybe 1/8" toe in, realizing it'll change

j9fd3s 04-03-11 07:32 PM

time update!

the hoosiers are WAY fatter than the hankooks, so we think they will be faster.

they are all 225/45/15's, so even though all the tires are the same size the hoosiers are bigger

PandazRx-7 08-26-11 12:05 PM

Alright guys, ran her once more with the same 255/295 "understeer" set-up and surprisingly shaved off over 4 seconds... fastest in my group. Only thing different was I cranked the Koni rebound all the way and hotter track. Still had 200lb passenger and front end sliding out kept limiting my cornering. Tire temps finally up to about 180 but front end would get greasy after 2 laps.

September I'll report back with square 285/30's with new R888's... I should be much faster with a planted front end but I might go back to a stock rear sway bar.

Also, I think spring rates a real problem...If you look at the pics my suspension is compressing a good amount with the 550/400lb I run now... I'll be upping the rates but I'd like to do one change at a time... I also have revalved Koni yellows in the horizon.

Track pics ---> http://vanhap.com/imgs/2011/July/07-...0pm/index.html (Some nice cars on the track)

Brent Dalton 08-26-11 01:28 PM

I have a good bit of seat time in several different configurations in several different FD's on several different tires/tire sizes on several different tracks... no where near as many as Fritz has though. :D Listen to his advice, he is a gold mine... he has more seat time in FD's than anyone, period. There are alot of other guys in this thread that have waaaaaay more experience than I do and have put out all kinds of good advice.

My current set up is Hoosier A6 315 front and 335 rear. I have Penske 8665 coilovers with 900F/750R. My car is an LS1 FD with 330rwhp with added ballast and driver weighing in at 3000lbs to keep it TTS/ST2 legal. Despite what others think, I believe dampers have just as much if not more to do with your suspension as the spring rates. I'll leave it at that though. Current is my favorite set up to date.

I believe I have the same pyrometer as you as well Panda. http://www.longacreracing.com/catalo...id=188&catid=7

I'm with Fritz and the others, I do not like the R888's. I'd run the NT01's over the R888.

Different tracks will create different handling characteristics within your car. For example, one set up caused a good push at VIR but was perfect for Road Atlanta.

Last year I ran a square 275 set up on all 4 corners and it worked well. The new set up works alot better though. I ran a 2:07 at VIR last October(times are typically 2-3 seconds faster a lap compared to the summer months). This July, I ran a 2:05... that's 2 seconds faster in the heat of the summer. i would guess the car would run a 2:03 in October now. Same with Road Atlanta. I ran a 1:35 in December on my old set up. I ran a 1:33 in the August heat this year. If I were going to be around for the December event, I would be shooting for a 1:30.

Also, I know plenty of people that are (sprint)racing on A6's and have been for several years. That being said, I've known several people that, due to their driving style, can't make the A6's work for them.

BTW Logan, good luck racing Danny Popp. That's why I added weight to my car to keep it where it's at. I have my hands full with the other Vette guys James and Wally.

TrentO 08-26-11 06:36 PM

My thoughts on tires comes down to getting the smallest and stickiest tire you can afford to optimum temperature.
If you can put a lighter tire on the car, it should accelerate faster, brake better and handle better. If your tires are not getting to temperature you either have too hard of a tire or too large of a tire or both.
If your tires are overheating, you are too soft, too small or both.
We have a running discussion here and feel for a 400-500 rwhp FD the s (soft) or ss (super soft) Yokohama 280/650/18 tires are the best choice. They are short in height, allowing you to keep the car low, they are light and they are able to put down the hp and stay in the optimal temperature range. We've a few competitors who go wider, but I don't really see a handling advantage.
If you can fit a bigger tire in a softer compound, you may be able to generate more grip, but the extra weight will act against you and the extra drag from pushing out the body to fit the tires will also act against you on the straights. On the 4kruzn FD we've been able to fit the 280's with some fender rolling on Enkei RPF-1 18x10.5 rims.

My $0.02
-Trent


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