[af62cobra]

Is their any way to get what the rear end gear ratio is without removing the cover. just got a 93 coupe that was a 4cly but now has 5.0 and 8.8 so body tags and vin are no help.

[atbrown]

go to the articles setion of the website and you will see a section on decoders and calculaters that should help

[stlwagon]

Put the back on jackstands. Mark the driveshaft and one wheel. Rotate the wheel one complete rotation and count the driveshaft rotations. If the d/s turns 3 3/4 turns, you have 3.73s. If it turns just over 4, you have 4.10s, and so on....

[93gtvertgt]

if the axle tag is still attached to 1 of the differential cover bolts, it will reveal the ratio. if the number is followed by an "L", then it is a traction-lok

[5.0Stanger]

The tag doesn't always tell the truth. My first Fox-body Stang had the tag on the rear cover, it said 2.73. It turned out to have 3.73s in the housing. Best to jack it up and count the revolutions. It's not super-accurate, but it'll get you close.

[Jelinski]

On jacking, turning the wheels, & counting d/s turns....
Don't forget the action of the differential (sun & planet) gears.
Do as stlwagon describes, but you have to turn BOTH wheels the same amount & count the driveshaft turns.
Watch out that as you turn one wheel forward, that the other one is NOT turning backwards!

A variation on this is to mark one wheel & the driveshaft, lock the other wheel (or jack up only one rear wheel & leave the other on the ground), then turn the raised wheel precisely 1/2 turn & count the driveshaft turns.

all the best!

[Jelinski]

on second thought, if you block one wheel, you turn the other wheel 2 turns & count d/s turns.
... getting stupid in my old age!

[5.0Stanger]

Jelinski,

Did you know that there are no planetary gears inside either an open or limited-slip differential? I ask, because I think you may have confused how a differential works with how a planetary gearset works.

Inside a rear axle differential, there are at least six (6) gears. The first two are common to either the open or limited-slip. They are the ring and pinion. I don't think I need to go over how the power is transmitted to the axles via these two gears. But, where I think you may be confused is in the last four (4) gears. These are the differential gears. They allow a vehicle to go around a corner without having the inside tire (in a turn) fighting the outside tire (in a turn). If the axles were just locked, as in a spool housing, the inside tire would be trying to turn the same speed as the outside tire.

For my example, I'll stick with the open differential. In a turn, the inside tire must turn slower than the outside tire. The differential gears are arranged in a manner that lets this wheel speed change occur, in a turn. Two gears are splined to each axle and mesh with two others that are floating on a stationary pin. When driving in a straight line, these gears do very little. But, when making a turn, the differential gear that is splined to the inside wheel's axle, will have the floating differential gears walk around it to allow the outside wheel's differential gear to move at a faster rate. It is this 'walking' that the differential gears do that allows the inside wheel to go slower than the outside wheel, and (what I think) makes you think this is a planetary gearset.

Planetary gears transfer power in many ways, depending on what portion of the gearset you hold (sun gear, planet carrier, or ring gear). From what I remember, you must have a sun, to allow the planet carrier mesh the planet gears, and a ring gear to mesh with the planet gears.

Now, I'm not trying to disrespect you or anyone else here, by explaining these operations. I just want to know that everyone's correctly informed. And, you do have to hold one wheel, to get an accurate count on rotations. With a spool axle, you do not have to hold the opposite wheel stationary. But, I'd like to see you try and turn the other one, while doing so.