SPEEDO/GEAR QUESTION

[dkins419]

I have a 88 GT. It has the 85 speedometer and i swapped out a T-5 from a 90 GT. Now I know the 90 GT has the 140 speedo. My speedometer is off a little bit . Is it because I swapped the trans from a 90 which uses the 140 speedo? I will be getting a 140 speedometer and i am just wondering if i have to get a dfferent gear for it since I have the gear that went with my 88 or will it work fine again?

 

[squeeeg]

The drive gear is the problem that you are having. You changed from a 7 tooth to an 8 tooth drive gear by swaping the tranny. You are going to have to get a new speedo gear no matter what speedometer you have(85 or 140). Here is what you are going to need:

2.73 Yellow 18 tooth gear
3.08 Black 20 tooth
3.27 Red 21 tooth
3.55 White 23 tooth
3.73 White 23 tooth
4.10 White 23 tooth(Jeep part)

 

[Roland69]

I will have a spare stock gear from a 88 tranny soon as I put my black gear in

 

[dkins419]

Alright so what gear will I need if I switch the speedo to the 140 with the 90 trans(or it doesnt matter which speedo just the gear)? Do i still need the 18 tooth gear? I still have a 2.73.

 

[dkins419]

please anyone?

 

[Roland69]

do a search on "speedo gear" there is tonnes of threads with lots of info and links.

Hopefully nothing about men in speedo's comes up lol.

 

[Roland69]

alright I was felling nice




Manual Transmissions with 6 Tooth Drive Gear



Not found in OEM applications



Item Number
Description
N/A
3.08 Gear Ratio / Not possible

C0DZ-17271-A
3.27 Gear Ratio / Maroon 16 Speedo Gear

C3DZ-17271-C
3.55 Gear Ratio / White 17 Speedo Gear

C0DD-17271-B
3.73 Gear Ratio / Yellow 18 Speedo Gear

C0DZ-17271-B
3.90 Gear Ratio / Pink 19 Speedo Gear

C1DZ-17271-A
4.10 Gear Ratio / Black 20 Speedo Gear

C4OZ-17271-A
4.30 Gear Ratio / Red 21 Speedo Gear



Manual Transmissions with 7 Tooth Drive Gear



1983-1989 T-5 OEM
Pre 1993 T-5 Aftermarket
1996-1998 Cobra T-45 OEM
All Tremec Transmissions



Item Number
Description
C0DZ-17271-A
2.73 Gear Ratio / Maroon 16 Speedo Gear

C0DD-17271-B
3.08 Gear Ratio / Yellow 18 Speedo Gear

C0DZ-17271-B
3.27 Gear Ratio / Pink 19 Speedo Gear

C1DZ-17271-A
3.55 Gear Ratio / Black 20 Speedo Gear

C4OZ-17271-A
3.73 Gear Ratio / Red 21 Speedo Gear

Jeep Part #j3167393
4.10 Gear Ratio / White 23 Speedo Gear



Manual Transmissions with 8 Tooth Drive Gear



1990-1995 T-5 OEM
1996-1998 T-45 OEM Except Cobra



Item Number
Description
C0DD-17271-B
2.73 Gear Ratio / Yellow 18 Speedo Gear

C1DZ-17271-A
3.08 Gear Ratio / Black 20 Speedo Gear

C4OZ-17271-A
3.27 Gear Ratio / Red 21 Speedo Gear

Jeep Part #j3167393
3.55 Gear Ratio / White 23 Speedo Gear

Jeep Part #j3167393
3.73 Gear Ratio / White 23 Speedo Gear (Not 100% accurate. This combination will offer the best accuracy without changing the drive gear. Change drive gear to a 6 tooth for complete accuracy. See 6 tooth table.)

Jeep Part #j3167393
4.10 Gear Ratio / White 23 Speedo Gear (Not 100% accurate. This combination will offer the best accuracy without changing the drive gear. Change drive gear to a 6 tooth for complete accuracy. See 6 tooth table.)



Automatic Transmissions with 7 Tooth Drive Gear



1983-1989 Automatic Transmissions



Item Number
Description
D0AZ-17271-A
2.73 Gear Ratio / Blue 16 Speedo Gear

C7AZ-17271-B
3.08 Gear Ratio / Gray 18 Speedo Gear

C7VY-17271-A
3.27 Gear Ratio / Tan 19 Speedo Gear

C8SZ-17271-B
3.55 Gear Ratio / Orange 20 Speedo Gear

D0OZ-17271-B
3.73 Gear Ratio / Purple 21 Speedo Gear

Jeep Part #j3167393
4.10 Gear Ratio / White 23 Speedo Gear



Automatic Transmissions with 8 Tooth Drive Gear



1990-1998 Automatic Transmissions



Item Number
Description
C7AZ-17271-B
2.73 Gear Ratio / Gray 18 Speedo Gear

C8SZ-17271-B
3.08 Gear Ratio / Orange 20 Speedo Gear

D0OZ-17271-B
3.27 Gear Ratio / Purple 21 Speedo Gear

Jeep Part #j3167393
3.55 Gear Ratio / White 23 Speedo Gear

Jeep Part #j3167393
3.73 Gear Ratio / White 23 Speedo Gear (Not 100% accurate.)

Jeep Part #j3167393
4.10 Gear Ratio / White 23 Speedo Gear (Not 100% accurate.)



Now if you really want to change the internal drive gear of your manual tranny you can match it according to the table below. Be aware that the 6 tooth will offer the most combos for numerically higher gear ratios and offer the greatest degree of accuracy. The 6 tooth gear selection table for a manual tranny is the first in the page.


Item Number
Description
E3ZZ-17285-B
6 Tooth Internal Drive Gear / Black

E3ZZ-17285-A
7 Tooth Internal Drive Gear / Yellow

F0ZZ-17285-A
8 Tooth Internal Drive Gear / Green

 

[Roland69]

from that above you have an 8 tooth drive gear and you will have to change the speedo gear to a Yellow 18 Speedo Gear

 

[Roland69]

I think that's right you situation has me confused lol (tired)

 

[dkins419]

lol thank you for the help, but i got 1 last question. Does it matter if you have a 85 or 140 spedometer?

 

[Roland69]

shouldn't

 

[blue302stang]

The Gauge cluster should be calibrated to the 85mph so it should work fine with the tranny

 

[_jb_]

lol thank you for the help, but i got 1 last question. Does it matter if you have a 85 or 140 spedometer?

Nope, I switched mine and it worked perfect.

 

[trbkrb]

As long as a speedometer is stock and has not been altered or recalibrated for some reason, it does not matter what one you use, they will read the same speed. They all calculate the speed by the number of turns of the cable, and 85 or 140 speedos count the same number of turns at every given speed.