[blueracecar]

i have an 85 gt with a sbf 306. it is a 1/8 bracket car right now. i run out of go at about 1000' mark. so it crosses finish line in the area of 13.10@60mph right now my 60' is 1.68-1.70. 1/8 is 7.72@90. is there some formula to figure ring and pinion ratio. how much will it affect my 60'?

[EagleAutosports]

I don't have a formula to figure the ring and pinion ratio but I can tell that a change to a 4:30 would be about right, considering it's a bracket car. What size tire do you run, 26 tall, 28, 30? Another way is to get some taller tires as that will effectively decrease the ratio too. But if you're running out at the 1000' mark, a 4:30 would be what I'd go with. I don't know if it'd affect your 60' time considering that's probably determined by your traction.

[blueracecar]

right now i am running 28" tire. i have had the car two weeks. i am still learning how to drive it. 1.68 is the best 60' but it is usually right on 1.72 the car is gutted and leaving off the foot brake so i am not to terribly worried about traction. thanks for all the info

[830hp]

if your car ran 7.72@90mph.you should be able to ran12.03@113mph in the 1/4 mile. 28 tall tire if you shift 6000rpm you need a 4.42 gear.5900 shift 4.34. 5800 4.27. 5700 4.20. 5600 4.12. 5500 4.05.if you are going to spray the car cut the gear down.not sure about 60 foot times.if you are going to use nos use smaller gear so you dont have to change gear twice.

[county2]

Try this and see if it will help.
www.users.erols.com/index.html
it has a lot of calulators on it.
Good Luck,

[county2]

you could go to a taller tire that would help.

[county2]

tire diameter X rpm example 25.66 X 5500 =4.279183
340 mph 340 97

hope this helps

[county2]

let me try again. tire diameter divided by 340 times rpm divided by mph equal gear ratio for 1/4 mile

example 25.66 divided by340 X 5500 divided by 97 = 4.279183