ZTwentyAteU

iTrader: (12)

Building a 98 Z, all out LSXrace car, and bout to get a 12 bolt(cant run a 9inch if I want to run Stock). My father is buddies with the guy who owns Currie Enterprises. Anyway we are trying to decide on gear ratio? We are running a race ready(as ready as you can get) 4l60e. This car will more than likely hardly ever see the street, but a very short gear (like 5.19) isnt going to be in the picture here. I was thinking of 4.56s, but i'm wondering what everyone is running in their dedicated race cars? I think 4.11 would be too tall, and not enough for the track.
any opinions would be great here.

thanks,
James

3.4camaro

iTrader: (1)

I think lots of people run 4.30s for the dedicated street cars.

mrdragster1970

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Combination decides the gear. Tire, Rpm, slip.
I run 4.10 or 3.90, but much different combination. Try to estimate final Mph & rpm and take a shot at it. Good luck.

.

8a8mfh

iTrader: (3)

First off ditch the overdrive on a full race car.
Take your peak rpm and this calculation, what ET you're shooting for, the typical trap speed for your approximate ET.
Rear gear x 355 x mph/ rear tire diameter. 355 is a fixed number for a non lock up converter, say you're looking to run 10.00 at 120mph and your max rpm is 7000, shoot for 6800. Rear tire is 28"tall. 4.56 puts you at 6900 rpm through the traps. (4.56x355x120/28=6937) If you want the numerically higher 3.06 of the 4L60E you'd be better off with a custom th400 with a 2.75 first gear.
Thats how I do it.

cnorton

iTrader: (1)

If Stock Eliminator is your goal, consider a TH200 metic transmission with a 2.75 low gear (contact Scott McClay Engineering in Tehachapi, CA) and either a 4.88 or 4.56 gear. McClay's tranmission has an adjustment on the throttle body that allows the 1-2 shift to be made automatically. Or, the LS1 stocker can legally run a Turbo-Action E-shift transmission that eliminates manually shifting the car at all. Either of these is worth consideration. When they're set up correctly, these cars usually shift before the front tires come down and it's hard to hit the 1-2 shift point consistently due to the relatively violent nature of the launch.

If the car can get light enough for A/FIA, it may want a 4.88 with the tallest radial 9"-wide slick you can find (Goodyear, Hoosier, M/T). To run B/FIA, you might want to go to a shorter tire. Attend an NHRA divisional or national event to pick up more information from people actually running this combination. Most of them are willing to share information with someone looking to build a stocker.

Good luck.

ZTwentyAteU

iTrader: (12)

yea i've heard about running a metric 200, but when I go to a different tranny I will run a th400. I will get more advise, I know a lot of stock/ super stock guys. I was just trying to get a general idea on what people are running. Thanks for the replys

RE AND CHERYL

iTrader: (31)

What other people are running has NOTHING to do with what you should run. Pick the wrong gear and you will be changing them again.

Re'

ShiznityZ28

iTrader: (11)

I run 3.55's LOL. You should not! Like the guy said above. figure out what rpm/mph you need to hit your goals and gear /tire/convertor the car for that.

bjamick

iTrader: (31)

If the car is like you said going to be just a pure race car, then definitely go with a high gear like 4.56's.. Us street car guys have to think about highways and stuff of that nature but you just need to figure out what rpm's you want to finish at.

Like said before with the 4.56's and a 28" tire you will be finishing at around 6900rpm's which would actually be perfect if your shifting at 7.

my advice is to get rid of the 4l60e bc it will break on you after a few hard passes, just an FYI.. I say go ahead and bite the bullet and put a big stalled TH400 with a tranny brake in and be done with it. The 60E just wont put you where you want to be and also will not be reliable for a track only car.

Im not for sure if you planning on spraying the car or not but you need to figure out how much your spraying and how much that will up the trap speed so you wont be on the rev limiter at the top of the track.

Best thing to do is just to do trial and error, like start out with a 26" tire then move to a 28" and see what happens to the ET's. Try different gear ratios to see if it helps the ET. Just try different tire and gear combos to see what the car likes.