speed gear gurus

the number of rotations the driveshaft turns will not change unless you change the rearend gears....3 and 3/4 turns would equal 373 gears in the rear end and 4 plus a little will equal 4.10 gears check it again and mark lines to ensure number of rotations, but the white 23 tooth would be correct for both sets of gears but it will not fully correct speedometer but its as close as you can get without opening the tranny tailshaft and replacing the drive gear or using a Speed Calibrator.

bobbyd said:

thanks. i marked it and did 4 times in a row and each of those 4 times i got 4 and little over so i guess is 4.10 gears.

you think that this will be just as good as the white one? http://www.latemodelrestoration.com/iwwida.pvx?;item?item_no=LRS-17271J-K 1&comp=LRS

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that one will be fine but you will still be a few mph off to achieve exact mph you might want to spend the $100 and get a Speed Calibrator heres one in link http://www.americanmuscle.com/speed-calibrator-94-04.html its your call..

Mark the driveshaft and a rear tire. Have a helper rotate the tire exactly 10 times, while you count the number of time the driveshaft turns. Then divide that number by 10. 35 times = 3.55s, 37 times = 3.73s, 41 times = 4.10s, etc.

As you have seen, it can be hard to tell 3 3/4 rotations from 4 rotations. Turning the rear wheel 10 times will be sure to give you a more accurate result.

also depends on what year the tranny is from.

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

bobbyd said:

my car is a 93 lx came with 2.73s stock thats what it says on the door

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That's just the rear end gear ratio. It would be an 8 tooth drive gear on the tailshaft, unless the transmission has been swapped at some point, could be 7 tooth or 8 than. The speedo gear is white from 50Resto (they use the same picture for all the gear teeth). You could also call your local Chrysler dealership and see if they have one in stock, it's a Jeep part.

Edit: If the tranny in the car has an 8 tooth drive gear, the 23 tooth speedo gear won't be terribly accurate, but certainly better than the 19 toother on there.

Great info Roland69... I will have to right some of that down... am considering 4.10 gears in my 88 gtc. How do you like those gears BobbyD? Good for city??? How is it on the highway??

AnthonyR23 said:

Great info Roland69... I will have to right some of that down... am considering 4.10 gears in my 88 gtc. How do you like those gears BobbyD? Good for city??? How is it on the highway??

Click to expand...

Personally, if I was going to do a fresh gear swap I'd pick 3.73s. Simply, because I'm not into the drag scene, and I need to do city driving with the car. With 4.10s there is almost no first gear, so in traffic it's kinda sucky. On the highway, I rarely push it past 110KM/H as my gas goes down very quickly after this.

3.73s get my vote for a streetable Fox.

4.10's are overkill for a 5-speed, unless you're strictly running a track-only car with slicks ... and even then, it's a little much. I'm running a stock H/C/I motor and I'm almost completely out of gear (almost 6000 RPM) in 4th by the time I hit the traps. But boy, they sure are fun ... even in town.

Mileage, according to my inaccurate speedo, tells me I get 24 MPG highway ... but if I had a straight-reading speedo, it'd probably be more like 19-20 MPG.