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View Full Version : rear end gears advice


nt4n
03-06-2010, 10:16 PM
Any advice on gears here guys:
I plan on running 31X18.5 tires. ( 4.10 gears w/AOD trani)
Since the T's are lite, do you need your gears low to get less tire spin?
In a high hp set-up when you guys drop back a gear does the T get loose down the HWY?
What problems have you guys ran into.
Ty 4 your time. "NT4N"

ellis8500
03-08-2010, 01:28 PM
It doesn't take much torque in your engine to spin the tires on a 2,000 lb car. With the 31" tires and 4.10 gears and an AOD, your initial drive ratio is 9.84:1. This is in the high acceleration, tire-spinning range. You'll be running about 2300 rpm at 75 mph. With a 300 ft-lb torque engine, you'll have about 540 excess lbs of thrust at the wheels in 1st gear. It only takes a few extra pounds to spin the tires.

italianrich
01-25-2011, 12:03 AM
i run 373's, seem to be great all around ratio. t's are light, tires break away easily!!

27T
01-27-2011, 03:49 AM
I also run 373 gears in my 27T and it does just fine. Great for hiway driving and still plenty of off the line go power. 383 Stroker attached to a Turbo 350, Happy Motoring

dangileri
02-07-2011, 08:36 PM
When I was younger I remeber figuring out gear ratio's by putting both wheels up in the air (jackstands of course), spinning the pinion and counting how many turns it took to get the tires to go around 1 time. The other day I did that and mentioned it to someone - they told me to double the number and that is my gear ratio ( i counted 2 + times, something like 2:10 gears) - I was told they are more like 4:23's.

What's up with that - did anyone ever hear about doubling the number and can anyone explain why ?

italianrich
02-07-2011, 10:54 PM
no need to double the number, they are trying to possibly compensate for the open rear differential? if you lift the rear up, turn the input and count how many times it takes to make the tires turn 1 revolution. thats your ratio. if you turn the input 3 1/2 times to make the tire rotate once, you have about a 3.50:1 ratio.... of course to be absolutely positive, take the diff cover off, count the ring gear teeth, divide it by the pinion teeth, and thats the ratio.