1fas92

I am about to get a ford 9 inch. My question is what gears should i get?

383 motor
fast Comp. Management
afr 210 heads
tpis miniram
vortech v-1 s-trim
turbo 350 trans


This is a street/strip car as well as a daily driver if i want to drive it around town or to work.

I currently have 3.42 & i am leaning towards 3.89, 3.70 or 3.50.(correct me if iam off on the ford gears)

Thanks,
Robbie Sheffield
1fas92

blown3rdgen

Depends on rpm range of motor, tire size, etc

I have a 383 w/ 700r4 and 3.89 gears. I have to use a 6600rpm pill or will hit rev limiter in 1/4. I'm thinking of switching to 3.50 or at least taller tire for track. However my first gear is deeper than yours. Hope this helps.

Matt

1fas92

Thanks for your help. But I also will be changing the 1 gear out of the 350 trans. There is a trans shop in the Dallas area, that can take the 1st gear out of a 700r4 and make it work with a turbo 350 trans. I don't have alot of details on what they are doing but, a couple of people that i know have done it to there cars. And they love it. Also I think the 3.50 gears are the way to go.

Thanks again,
Robbie Sheffield
1fas92

will62085

figure out what you think the car will trap in mph in the 1/4, or at least your goal ...and then using your tire size, and gear in the tranny (1:1, third in a th350) and rear end gear you can figure out what ratio you will need to put your car at peak desired rpms through the traps...usually right below your rev limiter

for instance, i want to trap around 150mph, at top of 4th gear, with a 26 inch tire, i will need either a 3.5 or 3.55 gear to do that at around 6800 rpm

here...great site http://www.smokemup.com/auto_math/rear_end.php

1fas92

Thanks for your help.....

Later
Robbie

wingnut

go with 3.50 ish gear. I use 3:73's (just took out the 4.10's ) and i hit 145 ish in 1/4 @ 7200 rpm and High 9's. I wish I went to the 3:55.

Wingnut

LameRandomName

You know, the beauty of the 9" Ford is that you can have more than one gearset and swap them out with relative ease just by changing the drop-in center unit.

If you just want to have one gearset in there all the time, I see that Precision Gear sells a 3.5 and a 3.6 gearset. (10-tooth pinion and 35 or 36 teeth rings.)

rskrause

There isn't much like rocket science in picking a gear for the 1/4m. As has been stated, you just estimate trap speeds from weight and hp, factor in tire size and the rpm trange of your combo and calculate the needed gear. The problem is that it will be spinning very fast at highway speeds without an OD tranny. You need to decide what is more important. Something you don't mention, but comes up all the time, is what kind of differential to get. A spool, optimal for the track, is intolerable to most people on a street car. There is an inverse relationship between optimizing track and street performance. However, a good posi does not give up much at the track unless you are making huge hp and running big, fat tires. A locker is an intermediate choice.

Rich