86 K10 with <2.0 gear ratio?

[Max1775]

Picked this truck up a month about a month ago and was going to do a brake job. While I had the truck in the air I figured I'd check gear ratios because they seemed really high for the 35s on it and I'm planning on putting in 4.56.. I checked front and rear by spinning the tire one full revolution and counting revolutions of the driveshaft. Unless I'm smoking crack or have completely lost my mind, the truck has gears taller than 2.00. I've never experienced that tall of gears. Truck has a 454 mated to a 700r4 tranny. Anyone ever seen this before?

[Max1775]

Damn I feel silly. Open differential. I haven't had one in years. Have to multiply the driveshaft rotations by 2 to get the approximate ratio or spin the tire around twice.

[mongocanfly]

Huh? If its a open diff simply jack one wheel up and rotate it one revolution and count the revolutions of the yoke and that will give you a close idea of what you have. I had a 85 that had 2.73s but I'm not aware of anything higher. Glad I had a sm465 in it.

[slotard]

With an open diff you need to leave one wheel on the ground, otherwise you'll likely get no driveshaft rotation.

If it was just a hair under 2 you probably have 3.73s

[mongocanfly]

One revolution of the wheel will result in approximately 3 3/4 revolutions of the pinion to equal 3.73....just under 4 not 2

[mongocanfly]

One revolution of the wheel will result in approximately 3 3/4 revolutions of the pinion to equal 3.73

[Max1775]

Originally Posted by slotard

With an open diff you need to leave one wheel on the ground, otherwise you'll likely get no driveshaft rotation.

If it was just a hair under 2 you probably have 3.73s

Yes, you are correct!