Gear Ratio
 

Is there an easy way to tell what gears are in my 89 AZ DPS car?
Thanks
Gary

The gear ratio tag is bolted to one of the bolts on the rear end cover.If the metal tag is not there then someone removed it. The way to tell from the outside of the car is to look at the tag and you will see a code like 3L.55 so that would mean 3.55 Ratio with a limited slip differential. If It is a non limited slip it will just list the ratio # without the L. If you have any other questions on rear axles West Coast Differential in Rancho Cordova Ca has a Great site that has just about everything you would ever need about differentials on there site. Rich

Considering the age of these cars, your gears could have been swapped out along the way and the tag lost. You could safely jack up both rear tires, and with it outa gear count the driveshaft revolutions for one complete rotation of the rear tire. With a t-lok, you'd find:

* just shy of 3 turns would be around 2.73:1 gears (depending on year)
* close to 3 turns would be 3.08:1
* 3-1/4 turns = 3.27:1 (or 3.31:1, depending on year)
* 3-1/2 turns = 3.55:1
* 3-3/4 turns = 3.73:1
* just shy of 4 turns = 3.90:1
* just over 4 turns = 4.10:1
* just over 4-1/4 turns = 4.30:1

For some reason, open rear-ends don't work with that method (they are half that). I need to read up on why that happens.

Thanks for the quick response guys. I'll look into it today.:thumbsup:

Gary

If the rear end is original to the car and the tag on the driver door is readable, the axle code is listed on there. M is 2:73, Z is 3:08, and E is 3:27. Any of your guys' cars have the optional 3:08? I found my brother a '92 Feature car last summer and his car has them. That was the first one I had ever come across.

Some years ('82-'84) 3.08 was standard with the manual transmission and there either was no option ('82-'83) or 3.27 was an option ('84).

Some years ('84-'86) 3.27 was standard with the auto transmission and there was no option.

One year ('87) 3.08 was optional with the auto transmission, instead of 3.27 ('88-'93).

Tons of 5-speed cars got the 3.08s. Check out the '93 FHP car:

http://www.specialservicemustang.net...s/Doordata.jpg

Several other manual cars with Z codes on the page as well.

http://www.specialservicemustang.net/Doortags.html

My old WSP car had 3.08 gears and my current FHP car has 3.08 gears...both are 5 speeds.

Door tag says Z so 3:08s it is. It didn't feel like 2:73s so this confirms it.
Thanks!!
Gary

Good for you, the 3.08's make a nice little difference.