Replacing speedo drive gear?

[RMB]

My car has been on the road for about 7 years now, but because of the drive gear in the T5, I have never been able to get the speedometer correct. I have tried all the different speedometer gears on the cable, and if I recall, the white was closest to accurate, but it was still off quite a bit and got eaten up pretty quick. I'm wanting to swap out the drive gear in the trans and get the correct speedo gear to match. I never installed the carpet in my car, so I'm guessing if I just remove the aluminum on top of the trans tunnel, then I can do this with no issues?

Also, I'm not sure what drive gear is in there now, but what do you recommend for the drive gear? 6, 7, or 8? And which speedo gear?

I'm running 3:55's, 17x10.5 wheels, with 275/40/17's.

Thanks,
Rob

[RMB]

Over two hours and still not response...I'm shocked! Where is everybody?

Rob

[South Dakobra]

One of these links may help.

http://www.fordracingparts.com/download/charts/142.pdf

http://www.ddperformance.com/PDF/SpeedoChart.pdf

http://www.corral.net/tech/gearcalc.html

[RobBaker]

To change that gear is a nightmare.
Drop the trans and seperate the t5 case to get at the gear not a fun job but I did it.
I'd say get a driven gear thats close and live with it.

[snakeboost]

If the white gear is not large enough@ 21 teeth the gear on the trans needs to be changed to a 6 tooth [most t5s are 7] You may also want to call us at the store we may have a few alternatives to fix this

Steve

[Mr Goodwrench]

Changing it out to a Speedhut GPS Speedo would be a lot easier!!! I did it because there is NO drive gear in my transmission,and on a MK II you have to pull the engine to get the tranny out.

DEnnisT

[J Persons]

If your T5 came from a 1990 through 1995 Mustang, it came stock with an 8 tooth drive gear. This needs to be changed to a 7 tooth drive gear, and use a black 20 tooth driven gear. This will get you about as close as you can get when using a 3.55 rear ratio. The only Mustang T5's that came stock with a 7 tooth gear were the 83 through 89 and the 96/98 Cobra with the T45, and the T5Z aftermarket transmission. As others have said, the tailshaft housing needs to come off, and it's best done with the trans out of the car. The correct 7 tooth drive gear is yellow in color. The 8 tooth is a pale green in color.

[dv/dt]

What gauges do you have? May be easier to swap to an electronic gauge than to remove, rip the trans apart and reinstall. What gears you have won't matter then since you calibrate the gauge over a fixed distance.

Cheers, Rod

[AC Bill]

I agree with Rod..In the long run an electric speedo that you can calibrate, will save you other potential issues as well, IE broken speedo cable..

When I set up my Classic Instruments electric speedo, I just used a handheld GPS to get my land speed, then simply adjusted the speedo to match it. It offers quite a large range of variance, so you likely will not have to pull the tranny gears.