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Author Topic:   Final Drive for fast 3/8 track
20bmw
Dirt Full Roller

Total posts: 74
posted September 25, 2003 09:45 PM  
I`m running a powerglide and a 9"

If i run high gear(2nd)would the rear gear ratio be my final drive??

What final should i be shooting for on a fast 3/8 track and keep the rpm`s at 6000??

Thanx, 20bmw

racer17j
Dirt Forum Champ
Total posts: 5390
posted September 25, 2003 10:03 PM  
6.00 to a 6.20 gear,that's what i've always ran at a fast 3/8 mile that was closer to a 1/2 mile around the top.

flanndad#17
Dirt Full Roller

Total posts: 59
posted September 27, 2003 11:36 AM  
I'm running a 6.12 and turning 5,800 rpm's on our 3/8's track.

pit_boss
Dirt Forum Racer

Total posts: 80
posted September 27, 2003 09:33 PM  
We ran a big 3/8's and ran 6.50's and turned 6100

gonfast
Dirt Full Roller

Total posts: 67
posted September 29, 2003 09:23 PM  
We have a Ford with 6.00 and turning the engine 7000, on a 3/8 mile oval . we are running 27X10X15 tires

20bmw
Dirt Full Roller

Total posts: 74
posted September 29, 2003 10:09 PM  
quote:
Originally posted by racer17j:
yes with a 1;1 ratio your final wouild be your rear gear ratio if you ran in low it would be the ratio either 1.76 or 1.82 x the rear end gear as for what gear what is the roll out of your tires that a big part of desiding a gear

racer17j i`m building my first car for 2004 season and have no help.
this will be my first time in a car and have no idea on gears,roll out,springs,or back space on the rims or where to put them.

i don`t know the weights on the car or nothing.
the car is a 86 cutlass and i will be running a 406 sbc. and a powerglide..

the help i`m looking for is a starting point
and i thank all who helps because you racers are the only help i have...

thanks, 20bmw

[This message has been edited by 20bmw (edited September 29, 2003).]

[This message has been edited by 20bmw (edited September 29, 2003).]

Raz_900
Dirt Forum Champ
Total posts: 635
posted September 30, 2003 08:34 AM  
Take a string or thin tape measure and measure the circumference of your rear tires. That is the 'roll out' of the tire. Most will be somewhere between 84" to 93" depending on what your track requires.

If you're running 93" tires, you'll want something up around a 6.20. If you're running 84" tires, you'll want something down around 5.67 or so.

gould
Dirt Forum Champ
Total posts: 730
posted October 06, 2003 09:53 PM  
6.83's in boone

racer17j
Dirt Forum Champ
Total posts: 5390
posted October 07, 2003 06:19 PM  
Running a 6.33 at our 3/8 track and also have a 6.50 to back that up if need be. Ran a 6.27 final on the 3/8 asphalt. Eddie

dreamcatcher
Dirt Maniac

Total posts: 160
posted October 12, 2003 08:19 AM  
i run a 6.98 final and 6900 rpm with 275/60/15 tires , i dont know the runout of the tires. this is with a big 76 monte carlo with out hoosiers and weight jacks against cameroes and metric cars that run weight jacks and hoosiers on a 3/8 high bank track. won 11 features and the championship.


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