Gear ratio question (1 Viewer)

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Dec 19, 2009
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I have a 90 model 4x4 and it is supposed to have 4.56's G252 code and I jacked the rear up and spun the tire 5 times and pinion only spun 11.4 times, is that right for 4.56's
 
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I meant G252, I changed it and posted a pic, I wouldnt thing tire diameter would have anything to do with that test.
 
G252 is 4:56 ...


Sorry I don't know the spin technique.


:D




:flipoff2: < Newb welcome sign BTW....
 
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If it is locked then you can count the tire rotation.
 
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I wouldnt thing tire diameter would have anything to do with that test.

Do you have stock tires?

Another way you can tell is RPM's. Get at a speed of say 55 or 70. And find out the OD ratio of your transmission.

Punch that in a gear calculator

Gear Calculator


and, voila!
 
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Wow is there some bad info in this thread...

Yes, the spin test works with an open diff. And tire size has nothing to do with it.

And that gear caculator is worthless, certainly not accurate enough to tell the difference between 4.11's and 4.56's.

Lift ONE tire, put the tranny in neutral. Now, the driveshaft will spin at TWICE the gear ratio. So, spin the lifted tire one complete revolution, count the driveshaft rotations. Should be about 9 or so (4.56 x 2).
 
KLF is close, you jack up one tire, and spin that tire 2 full revolutions, and the drive shaft (or pinion if the shaft is out of the truck) will spin the gear ratio.

Tire size has nothing to do with it. It's based on axle shaft rotation, not tire diameter.
 
Nice try, but you've got it backwards, the driveshaft will spin at half the speed with one tire jacked up.
Look at the original post, he spun the tire 5 times, the driveshaft rotated 11.4 times. Divide 11.4 by 5 = 2.28 x 2 = 4.56.
Yes you have 4.56 gears!



Wow is there some bad info in this thread...

Yes, the spin test works with an open diff. And tire size has nothing to do with it.

And that gear caculator is worthless, certainly not accurate enough to tell the difference between 4.11's and 4.56's.

Lift ONE tire, put the tranny in neutral. Now, the driveshaft will spin at TWICE the gear ratio. So, spin the lifted tire one complete revolution, count the driveshaft rotations. Should be about 9 or so (4.56 x 2).
 
Ok, this is what got it all started, when I bought the truck and ran the codes it said 4.56 gears, the truck is gutless as hell. It was supposed to come out with 225/75/15's and now it has 30x9.50x15's. When the speedometer is showing 55mph I am really only going 50mph, and with the larger tires shouldnt my actual speed be higher than lower.
 
Oh, and I had both tires jacked up, I will do it again tomorrow with only 1 tire jacked up.
 
You have 4.56's.
The jack one side only up, rotate the tire 2 times, count total driveshaft revoloutions = gear ratio is the correct way.
I just had to buy a front IFS for my truck.

I'm guessing you have a 4cyl auto. They came with 4.88's when you have 31" tires.
 
Ok, this is what got it all started, when I bought the truck and ran the codes it said 4.56 gears, the truck is gutless as hell. It was supposed to come out with 225/75/15's and now it has 30x9.50x15's. When the speedometer is showing 55mph I am really only going 50mph, and with the larger tires shouldnt my actual speed be higher than lower.

your truck should not be that slow. i would start looking at things besides gear ratio i have a 85 4runner with 35's that is auto and i run 488 gears and it is by no means a race car but i can 75 mph on the highway with out even trying. your truck most defently has 4:56 gears in it. if you wan to go to large tires try to find a auto 4runner with a 4 cyl. engine as they have 4:38 or 4:88 gear how ever you wan to call it.
 
BTW, O/P..IMHO, don't go posting your vin info publicly. Next time erase out the private info, including the bar code and just leave the last 6, k? You'll thank me for this tip one day.
 

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