how can i tell if my rear end is geared - Northern California Ford Owners

This is topic how can i tell if my rear end is geared in forum Tech Talk at Northern California Ford Owners .

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Posted by 87fox302 (Member # 7655) on :

so i slaped a new rearend on my stang and got ride of my old on...i belive that the gears i have on now are 273 when mine came with 308s im not sure it by lowering the gears it messes with the speed tak?

Posted by F8LSN8K (Member # 7080) on :

quote:
Originally posted by 87fox302:
im not sure it by lowering the gears it messes with the speed tak?

yezzzur

Posted by opie (Member # 7693) on :

You can mark the driveline and wheel, then rotate how many time the driveline spins to 1 full turn of the wheel. Its not perfect but it will give you an idea.

Posted by Curt (Member # 6254) on :

2.73 are actually higher gears

I know that tach isn't really all that accurate but you can use this formula to determine your gear ratio; (RPM x Tire Diameter)/ (MPH x 336) = Gear ratio

Say you were turning 2000 RPM @ 70MPH on 26in tires it would be (2000 x 26)/(70 x 336)------> (52000)/(21840)= 2.38

Oh yeah, that formula is for a 1 to 1 transmission ratio, so you will have to get RPM and speed while in 4th gear

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