axle code

[mhagie]

Have a axle ratio code GQ1 rear axle- standard for 82 4x4 1/2T auto.
Anyone have a clue as to ratio?
Merle

[waorth]

As far as I know, there's another RPO code determing exactly the gear ratio (never know why they invented the GQ1 code :confused: ).

Best way to tell the ratio, however, is to look at your rear axle. On the front of passenger side tube a 8 digit code is stamped. The first 3 digits (i.e. CZ3) contain vehicle and axle code.

Assuming you have a locking rear in your 4x4 K10, there are the following ratios:

CZ3 - 3.42
DA3 - 3.73
BH3 - 2.73
BJ3 - 3.08
BK3 - 3.42
BM3 - 3.73
BRB - 3.08
BSB - 3.08

This is from a 1985 parts catalog, the codes should not have changed since 82.
Don't know why there're duplicates, maybe different lockers/Limited Slip.

The RPOs in my glove box (85 K30) show the axle ratio, it's HC4 for 4.56 (also printed is the vague GQ1 code).

Walter

[DmaxMaverick]

The GQ1 RPO code indicates a "standard ratio". The "standard" would depend on an option package which includes engine code, tranny, emmissions, wheel/tire size, towing package, and geographic location the vehicle was delivered. There was a spec. tag on the axle at one time, but they rarely survive this long. Unless you are the original owner (or know the original owner), the axle or gears may not even be original. I have found the stamping on axle housings to be seldom reliable.

The best way to determine the ratio would be to remove the cover and count the teeth on the ring and pinion. This is not always practicle. You could also count rotations of the prop. shaft/wheel. With one wheel stationary, and the other elevated, rotate the prop. shaft. Allow the wheel to turn exactly 2 turns, and count the turns of the prop. shaft. (if it has limited slip, preventing one wheel to turn, jack up both wheels and allow one rotation, both wheels equal) Marking the tire on the inside with chalk or crayon makes it easy to see while underneath turning the shaft.

4.10 = just over 4 turns (probably not for a 1/2 ton)
3.73 = about 3-3/4 turns
3.42 = just less than 3-1/2 turns
3.08 = about 3 turns
Etc...

You could allow the wheel to only make one rotation, but then you would have to double the ratio number. This is because one wheel is stationary, and the turning wheel will turn at twice the rate. It does work, but is much less accurate.