how to replace the speedometer gear (not in the instrument cluster)

rz5.0 · Nov 26, 2012

when you change gears your speedometer will be off. This is the cheapest way to fix it. replacing the gear.

now depending on year model and trans type the gear need might be diffrent
list of transmissions with gear drives..
Manual Transmissions with 7 Tooth Drive Gear
1983 - 1989 T-5 OEMAftermarket T-5
1996 - 1998 Cobra T-45 OEMTremec
3.73 Gear Ratio / Red 21 tooth
4.10 Gear Ratio / White 23 tooth
Manual Transmissions with 8 Tooth Drive Gear
1990 - 1995 T-5 OEM1996 - 1998 T-45 OEM
3.73 Gear Ratio / White 23 tooth
4.10 Gear Ratio / White 23 tooth
Automatic Transmission with 7 Tooth Drive Gear
1983 - 2000
3.55 Gear Ratio / Orange 20 tooth
3.73 Gear Ratio / Purple 21 tooth
4.10 Gear Ratio / Black 23 tooth
Automatic Transmission with 8 tooth Drive Gear
1990 - 2002
3.08 Gear Ratio / Orange 20 tooth
3.27 Gear Ratio / Purple 21 tooth
3.73 Gear Ratio / Black 23 tooth
4.10 Gear Ratio / Black 23 tooth ..

i just replace mine on my cobra. Since my cobra t45 came with the 7 tooth drive gear and has 3.73. i have to put in a red 21 tooth speedometer gear..
1st get your car high enough for you to get under it securly.. how ever you like to do it..
2nd get under it find the tail shaft area of your trans driver side. look for for this sensor

rz5.0 · Nov 26, 2012

remove the bolt i used a 7/8 but i think its actually metric.. then it just pulls out..

thats the 19 tooth for 3.27..
pull the clip metal clip with some pliers then the gear should slide off.. put in your new gear install clip

the slide it back in put the bolt back on. your all set you speedometer is accurate again.. for only $15 dollars.. some aplications require the change of the spedometer drive gear. which i might do on my t5 eventually..

MustangChris · Nov 26, 2012

i had no idea it was that easy. lol. thanks for the write-up!

rz5.0 · Nov 26, 2012

figure id do something.. instead of arguing.. its not the best but you get the idea.. i search before i wrote it didnt find one.. so there it is.
excuse my puctuation and spelling tho.. hate proof reading..

MustangChris · Nov 26, 2012

lol. we get the point.

BruhBrahBrad · Nov 26, 2012

I had no idea it was that easy either...im gonna do it asap.

rz5.0 · Nov 26, 2012

Hardest part is figuring out the right tooth count..

Mustanger · Nov 26, 2012

Thanks I needed that!

mike97gt · Jan 15, 2013

Reading this, the chart does not have a white 23 tooth gear. But your writing above does. It also shows that the white 23 is used for 3.73's and 4.10's.
Is this correct or should i be getting a speed-cal?
Car is a 97 GT with a T45 and will be getting 3.73's put in by the time the snow melts

rz5.0 · Jan 16, 2013

That's because like some one said its not a Ford oem. If your not scared to deep the tranny i would change to a seven tooth drive gear and a red 21 which is what i have.. It be spot on and still cheaper than the speed cal. That's for 3.73. The 23 could be a lil off.

mike97gt · Jan 16, 2013

Would i need to blow the tranny apart just to change the drive gear? If its that labour intensive it'll be easier to just pay for the speed cal.

Echo · Jan 17, 2013

Anyone want to do the calculations for me on what gear I need?

Don't know how to figure out my RPM, or anything. 1995 V6, everything stock but I'm sporting some 20" rims.

Apreciate it if anyone decided to do me a solid. If not, suppose I'll deal with the inaccuracy.
Wouldn't mind a calculation for 4.10 differential as well as I'm wishfuly thinking of switching to it if I ever get the car where I like it and start doing some real upgrades.

rz5.0 · Jan 17, 2013

mike97gt said:
Would i need to blow the tranny apart just to change the drive gear? If its that labour intensive it'll be easier to just pay for the speed cal.

Its not hard hardest part is dropping the Trans.. All you basically have to do its remove roll pin and remove the tail shaft section then remove the gear put new gear back in and go about 30 min..

rz5.0 · Jan 17, 2013

mike97gt said:
Would i need to blow the tranny apart just to change the drive gear? If its that labour intensive it'll be easier to just pay for the speed cal.

Its not hard hardest part is dropping the Trans.. All you basically have to do its remove roll pin and remove the tail shaft section then remove the gear put new gear back in and go about 30 min..

rz5.0 · Jan 17, 2013

Echo said:
Anyone want to do the calculations for me on what gear I need? Don't know how to figure out my RPM, or anything. 1995 V6, everything stock but I'm sporting some 20" rims.

Apreciate it if anyone decided to do me a solid. If not, suppose I'll deal with the inaccuracy.
Wouldn't mind a calculation for 4.10 differential as well as I'm wishfuly thinking of switching to it if I ever get the car where I like it and start doing some real upgrades.

You can find calculators you just need to know how tall your tire is in inches and insert all your other info..

Echo · Jan 17, 2013

rz5.0 said:
You can find calculators you just need to know how tall your tire is in inches and insert all your other info..

How to I get the RMP and # of drive teeth?

rz5.0 · Jan 17, 2013

You prob have the 8 tooth rpm is prob the rpm you shift at.. Prob need a diff calculator

Slykin · Jan 17, 2013

Here's a table I found that's a bit simpler to read. Nice job on the write up too.. I did this a week or so ago with the trans out(had to replace the internal speedo gear) and it's really easy. My speedometer works perfect now.