What gearing do I have?

[IL84JIMMY]

I drive an 84 Jimmy, stock with a rebuilt 350. I dont really konw what the owner before me did to it. How can i know what gearing i have. The truck is a manual with granny gear and then the three speed. When i am running on the highway at 60, my rpm's are at like 2200. Thanks

 

[55Willy]

how tall are the tires?

 

[mudhog]

jack up the rear of the truck and turn the tire one full revolution and count how many times the drive-line makes a full revolution. drive-line turns 3 and 3/4 turns 3:73's 4 and 1/4 turns 4:10's

 

[TXsizeK5]

wouldn't you have to turn the tire two revolutions if it is an open diff?

 

[IL84JIMMY]

tires are just 29 inch AT's for daily driving

 

[55Willy]

3.08's

 

[heavy4x4]

Using the calculators at www.4lo.com I come up with you having 3.08 gears (assuming the numbers you gave us are accurate).

 

[55Willy]

thats where i went. I love thier alcohol level calc. too,LMAO

 

[R72K5]

well 350 wouldnt be in the truck from factory,

if your SPID label says GQ1 standard axle then youre gonna have to pull diff cover and look on the very edge of the ring gear it will have teeth count(of pinion and ring both- divide these to get the axle ratio) stamped into it along with date and ring gear part number or find stamping code on RH axle tube and call chevy parts counter with the code and year make model of the truck,

in 84(10 bolt 8.5") it can be 2.73, 3.08, 3.42, 3.73



good luck