T-5 w/3.73's Speedo Gear

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T-5 w/3.73's Speedo Gear

May 08, 2011, 09:44:06 AM

I have a '93 Mustang T-5 transmission coming to swap into my 'Bird. Ever since I put the 3.73 rearend end in my car, my speedo has never been 100% correct with the AOD. I did swap to (I believe) a 23 tooth speedo gear but it was still off about 7-10 mph.

Places I have read say you must use a 23-tooth speedo gear with a '93 T-5...some say otherwise. By using the formula on this site: http://www.fordracingparts.com/download/charts/142.pdf , it says I need a 24 tooth speedo gear (which is not even made) with my 245/45/17 tires.

Anyone know what the correct speedo gear would be and a good place to buy? Will a 23 tooth gear even be accurate?

T-5 w/3.73's Speedo Gear

Reply #1 – May 08, 2011, 10:06:31 AM

What driven gear do you have on the T5? A 6 7 or 8? That might change up the gear to something you can find

T-5 w/3.73's Speedo Gear

Reply #2 – May 08, 2011, 10:10:15 AM

Supposedly, per the guy I'm buying it from, it is a 93 T-5, so it should have the 8 tooth drive gear.

I think to get this thing accurate, I am going to have to go with a 7 tooth drive gear and a 21 tooth speedo gear. I just didn't know if anyone had experiemented with using a 23 tooth speedo gear in a T-5 with an 8 tooth drive gear with any success.

Hopefully taking the tailshaft off and changing the drive gears is not that big of a deal. To me, if I'm gonna do it I better do it now before I install the tranny.

T-5 w/3.73's Speedo Gear

Reply #3 – May 08, 2011, 12:58:34 PM

If you change the drive gear on the output shaft on the T-5 go with the black 6 tooth. This will allow you to get the driven gear number down low so that it will last longer. I have a 6 tooth black gear on my T-5 in the Coupe with 3.73's and 245/40/17's and with a 17 tooth driven gear the speedo is only off about 1-2 mph, verified with my Garmin GPS.

http://www.angelfire.com/mb/mustangsrule/speedogear.html

Darren

T-5 w/3.73's Speedo Gear

Reply #4 – May 08, 2011, 05:53:08 PM

Cool man thanks for the input. Its not that big of a deal to change the drive gear, right?

T-5 w/3.73's Speedo Gear

Reply #5 – May 09, 2011, 09:19:56 AM

That all depends on what you consider a big deal. The tail housing has to come off so if the tranny is out of the car then its an hour or so job. Go here to download the manual on it and that should help you get it apart and back together correctly:

http://www.ttcautomotive.com/English/products/T-5.asp

Just below the picture on the right side you will see a logo with an open end wrench on a nut. Click on this to get the service manual and you should be able to download the .pdf file. Just remember to very careful when reinstalling the tail housing so that you line up the reverse roller pin assembly correctly in the tail housing. There is a little tab on the assembly that needs to go into a slot in the housing, kind of hard to explain without showing a person. It has to do with the WC units having syncros for reverse and fifth or so I have been told. I broke mine not knowing this and had to get one from my buddy off a (hold your breath) trashed T-5 with the main shaft broke and third gear completed exploded (gasp, not a T-5). Anyhow, hope this helps.

Come to think of it I am almost sure this is covered on U-Tube so try a search there. I cannot look here at work so post up if you find a good video showing how to swap the driven gear on the output shaft.

Darren

T-5 w/3.73's Speedo Gear

Reply #6 – May 09, 2011, 11:04:30 AM

Quote from: Aerocoupe;359559

http://www.angelfire.com/mb/mustangs...peedogear.html
Darren

>>giggle.<<

T-5 w/3.73's Speedo Gear

Reply #7 – May 09, 2011, 11:54:08 AM

I printed out that entire T-5 tech manual...should come in handy! I never thought about trying youtube for a "how to" no the speedo drive gear change. I'll try that.

Thanks!

EDIT: Found a how to vid http://youtu.be/C5CCzgTRnc4

T-5 w/3.73's Speedo Gear

Reply #8 – May 09, 2011, 12:11:53 PM

Once you see it done its pretty easy but trying to describe it here without the visual aids is painful. Hopefully this will be easy.

On another note, I typically use two quarts of Mobil 1 synthetic AFT and one quart Mobil 1 gear oil. Now I can hear the gasps and murmurs of a lynching from the cheap seats but it works. I have talked to several guys running T-5's up on the limit of the torque the casing can handle and they are doing the same thing with good results. My Coupe is putting down 318 rwhp / 328 rwtq and before that it was 268 rwhp / 297 rwtq on the same WC T-5 for 5 years since the rebuild (bearings and synchros) and I beat on it like I stole it. Granted I have never ran any kind of slick or drag radial on the car so that has contributed to the life of the T-5. A high quality shifter with positive stop locks is a must. I have a Pro 5.0 with the stock shifter handle but have been thinking of getting an MGW shifter.

http://www.mgwltd.com/mustang_shifter.shtml

Just use a high quality AFT and you should be fine. The T-5's are sensative SOB's but they are a great transmission as long as you don't put the drag radials on the car and expect them to live. They were never designed for that kind of abuse.

Darren

T-5 w/3.73's Speedo Gear

Reply #9 – May 09, 2011, 04:59:21 PM

With the HP my car makes (on a good day), I'm sure the T-5 should live just fine. My 5.0 is basically what would have been stock equipment in front of these trannies.

Yeah I watched that youtube video and it doesn't seem all that bad to take apart and change out. I have a new drive gear ordered but will make sure and check the color of the one in there now to make sure its not already been changed out before going to the trouble.

T-5 w/3.73's Speedo Gear

Reply #10 – May 09, 2011, 05:53:51 PM

Shine a flash light into the hole the vehicle speed sensor (http://www.partstrain.com/store/details/Ford/Mustang/Standard/Speed_Sensor/1993/LX/8_Cyl_5-dot-0L/SISC37.html) goes in and you can see the drive gear. Yellow is a 7 tooth and a funky green yellow is an 8 tooth. The six tooth gear is black but I believe it only came on the 4 cylinder cars as they had the 3.73 gears from the factory. Good luck with the swap!

Darren

T-5 w/3.73's Speedo Gear

Reply #11 – May 10, 2011, 08:46:07 PM

Trans didn't show up yesterday, should be here by the weekend. I'm hoping its equipped with the yellow 7 tooth drive gear to avoid any extra work.

Right now I am in the middle of pedal swap hell, lol. I've got the column and front seat out and started on the pedal removal tonight. Boy all those t-5 swap threads were not lying. Getting the pedal out is a major PITA and I imagine getting the new in will be even worse. Oh well, just gotta keep telling myself its going to be worth it in the end.