khaurl

I'm driving an 88 firebird with a 350 TBI 700r4 and 4.11 gears. The suspension has all new bushings that reduce body roll when driving on the road. I just draged my car for the first time on street legal drag night. I have a race street legal tires. When I slammed the pedal to the floor all the tires do would spin. I was getting beat off the line every time. The car only has about 300-350 Hp so I don't think I should be over-powering the track. I didn't take any air out of the tires which I think I will do next time, but what else could I do to improve my traction. The tires are 245/50/r16.

five7kid

iTrader: (14)

Welcome aboard thirdgen.org.

What tires exactly are you running? What pressure were you running them at?

Has the car been lowered?

Typical modifications are lower control arm relocation brackets, boxed lower control arms, poly torque arm mount (at the very least, aftermarket torque arm also common). Tire pressure optimized for your car & track.

Track starting line prep is also notoriously poor on street nights.

AlkyIROC

The 700R4's low first gear of 3.06 through a deep gear ratio of 4.11 gives a very low effective ratio or starting line ratio of 12.57. Even a low HP can spin wheels with that much torque multiplication. Take the engine torque and multiply it by the starting line ratio so see how much difference it makes with different gear ratios.

My car only has a starting line ratio of 8.55 but I also produce at least twice as much power as you so I don't need to create as much torque to the wheels through gear ratios. A typical street car should have a starting line ratio in the 9-10 range. You're overpowering the tires simply because you're putting too much torque to the wheels because of the low first gear and 4.11 gears in the diff.

Options
Change the tranny to a TH400 or a TH350 to get a better first gear ratio, Change the diff gears to no more than 3.73. Install a taller tire. Slicks will always help but then they're not designed for street use or high mileage.

You've got a gear ratio that should be used in a 4x4 for rock climbing.

Trevor86TA

What tires are you running? At your power level even with stock suspension you should hook hard every time with good DOT slicks, even on an unprepped track.

WheelsUp84z

iTrader: (2)

i agree, that gear ratio is way too tall. with a 700r-4 and will overpower a drag radial, i can imagine what it's doing to street tires. My advice would be to get lower control arms and relocation brackets, and some sticky tires at minimum, if you can afford the gear swap go back down to 3.73's.

MrDude_1

unless you have a drag car, you cant floor it off the line.

you need to be smooth and roll the power on.

this SEEMS counterproductive.. if FEELS slower.. but if you look at the timeslips you'll see its a heck of alot faster then spinning the tires.



so once you have the idea that spinning is BAD, then you can work on making them harder to spin.


start with tires. get slicks or drag tires if you can.... if not, then still lower the air pressure some.


unbolt the front swaybar... if nothing else, undo atleast one endlink. leave the rear swaybar on and connected.

IHI

iTrader: (1)

Which track are your running at? CFR? if so lemme know, I have a nice set of my used stickies I just took off that will do wonder for you and at great price, will just need a set of 15" rims, but you will dead hook.

FWIW, dont ever expect much on a street night, track prep is minimal. Street nights are all about maximizing track profits-hence the big spectator entry fees and almost nill track prep...while it looks like they're spraying VHT, make no mistake the mix is ALOT more diluted than race day VHT and have you noticed they never clean the track with the broom of driers...think of all the crap and sand these radial tired street cars bring to the line...I used to go out and run for fun when they paid money since it was like shooting fish in a barrel, but it literally got too dangerious for a sane person to run any decent hp out there....night I blew the first motor I had 2 hyabusa's doing 150mph+ coming straight at me (i blew up just before the finish line)

Drop me a line and lemme know where your racing at.

5678TA

how do you guys get traction?? good question, cause i still dont.. i even have an almost full drag car suspension.. moroso sbc front springs, 90/10 struts, stock rear springs, stock replacement shocks, all the rear suspension bolt ons, LCA relo brackets and i still burned 275/50-15 drag radials off the line with a 3500 clutch dump.. 1.810 best 60ft..


now i got 4.30 gears and 26x8.5 mt slicks.. track is hopefully gonna be prepped alot better.. rubber was scraped last weekend so it should be ON.. lol

IHI

iTrader: (1)

what are you running for a tq arm, air bags in rear or anti sway bar? 2 area's that are kind of important for traction

I see a few things wrong in this equation...crazy low gear and a short and small rear tire....slicks are going to give you a better shot at traction than those DR's, but that's asking alot for such a small tire and big gear.

What kind of hp do you think your making? what ET do you think you should be running? what's your current mph? is this 1/8mi racing or 1/4mi racing?

WheelsUp84z

iTrader: (2)

wow thats alot of motor/gear and a LITTLE slick for a manual car! no wonder you cant hook, you need some 28's at least

5678TA

i have a spohn adjustable TA set at -2*, 4 coil spring spacers in the pass. spring as an "airbag", and a 1" sway with poly bushings..

i run 1/4 mile.. i'm guessing around 350-380rwhp.. i have no idea how much it weighs, but it should be pretty damn light considering its literally your basic drag car setup with powersteering, power brakes, factory glass and a steel hood.. i'm thinkin i'll be up with evilcartman(11.8) since i have run the same 1/8 (90) and 1/4 (114) mph as him but a half second slower.. 12.31@110 was my best 1/4 but with a 3.89 gear.. trapping at 5700, shifting at 6500..

i'll be going to the track today to see what the 4.30 and slicks do.. so we shall see what happens.. the exhaust is also coming off..

ok, one last question.. should i get a 27x11.50 or a 28x11.50 hoosier qtp?? on these 26's i should be trapping at 6300..

IHI

iTrader: (1)

With your current 4.30 gearing...28" all the way. Heck, I only run 4.11's and just put a new set of 29's on the back to help lower my finish line trap rpm and also help with traction.

Trevor86TA

I saw your sig in another post. It looks like you must have had someo big improvements!

khaurl

thanks,

I am running Goodyear HP's they are z rated. The car hasn't been lowered at all.

I race in Brainerd, mn at street night its usually every other wensday I make it there every night that I can.

Should I really need higher gear ratio even though I'm not at top speed by the end of the track??

5678TA

yup, i was surprised myself.. only a gear swap, tiny slicks and 2 jets up on the secondaries netted me an 11.899@115.. open exhaust went the 11.76 but i think i coulda hit 11.6's.. i'm gonna try go 11.4's by september(my last races before i go back to school and have no action for 8 months) should have better tires and an electric water pump.. *fingers crossed*