You can "measure" it as accurately as you want. Lets say you rotate the tire
exactly 10 revolutions. If the pinion rotates exactly 41 revolutions you
have a 4.10:1 or 4.11:1 ratio (41/10). If the pinion rotates 35.5 times, you
have a 3.55:1 ratio (35.5/10). The more revs of the tire, the more accurate
the measurement. There is also the possibility that the pinion will give a
2X reading (some differentials do this). So if your math indicates an 8.20:1
ratio, obviously it is really 4.10:1! -Bill
>Date: Fri, 11 Dec 1998 09:35:45 -0600
>From: "Bernd D. Ratsch" <bernd@texas.net>
>Subject: DML: RE: RE: RE: Fast Daks
>
>Here's simple (non-mathematical) way to find out...it gets close but not
>accurate:
>
>(1) Jack up the rear end and make sure the brakes are off and it's in
>Neutral
>(2) Put a mark on your driveshaft and then a mark on your tire.
>(3) Turn the tire one full revolution and count how many time the mark on
>the driveshaft turned (that's where you'll need a buddy to help)
>(4) You ratio will be: How many times the driveshaft turned (ex: 3.5 times)
>in relation to the single revolution of your tire (obviously 1). (ex:
3.5:1)
>
>It's a really old-fashioned way and isn't that accurate but if you already
>know what gear options were offered with your truck, it's easy to figure
>out. (If you driveshaft turned almost, but not quite, 4 times to the 1
time
>with the tire...this means it's probably in the 3.92 ratio. (It could be
>also a 3.73:1 but this is where your buddy needs to watch closely.
>Sometimes...it's best to do it twice for accuracy.)
>
>
>Regards,
>
>Bernd D. Ratsch
>Pflugerville, TX
>bernd@texas.net
>"Gonna buy me a Dodge Truck and blow those Fords off the road....."
>
> -----Original Message-----
> From: owner-dakota-truck@buffnet4.buffnet.net
> [mailto:owner-dakota-truck@buffnet4.buffnet.net]On Behalf Of Tim S
> Sent: Friday, December 11, 1998 12:48 AM
> To: Dakota-Truck-digest@buffnet.net
> Subject: DML: RE: RE: Fast Daks
>
>
> So how do I find out what Gear ratio I have With out pulling the diff
> cover off and counting the teeth. I do have limited slip.
>
> >What axle ratio do you have? I've got a 3.90 and switched from the
> >stock 235-75's to 31x10.50's. I went from blowing the doors off of
> >5.0's to having problems running with a pathfinder. It was nice
> (sorta)
> >to trade that for 24-25+ mpg highway, plus it'll jump from 70-100mph
> >with quickness.Jon
>
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