Jeep Speedo Gear? Really?

['88Cobra]

So my car has 3.55 gears in the rearend, and my speedo is out. After doing a search I found that I need the 23 tooth white speedo gear that is apparently a jeep speedo gear in my tranny. But the info I didn't find is what jeep speedo gear do I need? Meaning what year of jeep? What model? And what tranny did it come out of? Any help please?

 

[jrichker]

See Speedometer Chart for the proper gear. A 23 tooth gear isn't correct for 3.55 rear axle.

 

[TRWXXA]

Jrichker is right (as usual).

You probably need a 19-tooth (pink) or 20-tooth (black) gear for the 3.55s. You're leaving out info. You need to know your tire size, the number of drive gear teeth (we're assuming it's a 7-tooth (yellow) gear in your '88 T-5), in addition to the rear end ratio.

 

['88Cobra]

Oh, sorry. I am totally leaving info out. The T5 is for a '90 GT, not an '88. So it should have an 8 tooth drive gear. And the rear gears are 3.55's, and the rear tires are about 26.5" tall. So a 23 tooth gear should be right, shouldn't it?

 

[TRWXXA]

Oh, sorry. I am totally leaving info out. The T5 is for a '90 GT, not an '88. So it should have an 8 tooth drive gear. And the rear gears are 3.55's, and the rear tires are about 26.5" tall. So a 23 tooth gear should be right, shouldn't it?

A 1990 tranny does change things.

# Driven Gear Teeth = 20.168114 / Tire Height (in.) * Axle Ratio * # Drive Gear Teeth

20.186114 / 26.5 * 3.55 * 8 = 21.6

A 21-tooth gear should get you to within a 3% speedometer error (discounting other factors), which is pretty good.

 

['88Cobra]

Okay, sounds good to me. Thanks for the help.

 

[Mustang5L5]

Visually confirm your drive gear though. Being a 1990 t-5, it's had 18 years of history and someone could have changed the gear. A lot of guys tend to swap to the 7-tooth gear

Take the speedo and look inside. If it's yellow, it's the 7-tooth

if it's green----8 tooth

If it's black....6 tooth