can i tell my gear ratio with this info

[Confederate9]

hey guys, i need to know what gear ratio i have because i think my rear is goin out, and im searching for a new one just in case. but to my knowledge the rear axle is fully stock and on a 85, the specs said:
8.5-in. 1.28 Axle Dia. 28 Spline

am i able to know what gears i have?
if not what other ways are there, i know the code thing, but i cant figure out what it says plus i don tknow the codes... are there any others ways, thanks guys

 

[milspecjimmy]

look in the glove box or on the door jam near the latch of the drivers door. youll see a list of of numbers and letters. 3 digits apiece. the gear ratio codes usually start with a G, and are some what like GU4, GU5, GU6 ect...im not positive of what each one is but some one on here may. and the dealer will definately know


~~~jeff

 

[84K5cedric]

The best way to find out is to pop the cover and count the teeth. Divide the number of teeth on the ring gear by the number of teeth on the pinion gear.

ex. 41/11=3.7272727272 (rounded 3.73)

 

[tRustyK5]

Why count teeth when the ratio is stamped on the edge of the ring gear???/forums/images/icons/confused.gif

Rene

 

[84K5cedric]

really? haha, didn't know... I just count /forums/images/icons/blush.gif

 

[tRustyK5]

The last 3 or 4 digits are the build date, the 4 digits in front of the build date is the ratio. For example my old 14 bolt reads "11 41 74 9" Built in Sept 74, 11 pinion teeth and 41 ring gear teeth...3.73's

12 41 =3.42:1
11 41 =3.73:1
10 41 =4.10:1
9 41 =4.56:1

Rene

 

[POWERMAD]

Or chock the wheels and put it in nuetral, then raise one side and mark the pinion.
then spin the tire 2 times and count the turns of the yoke.

just over 3 times is a 3:08
about 3 and 3/4 turns is a 3:73
just over 4 times is a 4:10

 

[m j]

my favorite is the string taped to the driveshaft and roll the truck forward one tire revolution and count how many wraps the string now has on the shaft

 

[84K5cedric]

of course for a truly accurate check, a live chicken and a vat of virgin's blood is required. /forums/images/icons/tongue.gif

 

[m j]

LOL
of course

 

[POWERMAD]

Let's not forget about if it is a locked diff, it only requires one tire rotation then.