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Technical => Drivetrain Tech => Topic started by: quicksilver on December 13, 2006, 12:30:30 AM

Title: gears and posi help!
Post by: quicksilver on December 13, 2006, 12:30:30 AM
well, my father knows some stuff about cars. and he said if the gears in the trany and the gears in the rear end arent the same, the trany or the gears will break. is this true? or do i just need a speedometer thing to out in my trany so it will read the right mph.
oo by the way, where can i get a thing to out in my trany to tell how fast im going with 3.73 gears?
Title: gears and posi help!
Post by: jcassity on December 13, 2006, 01:02:23 AM
I wont come between dad and son things but this might help,,,,,



eves drop in on an old topic i have in my saved goodies,,,,,,,,,,


MISC SPEEDO GEAR INFO
---thunderjet302
For those of you who have installed 3.73 gears with your stock AOD you know how hard
it is to find a speedo driven gear to make your speedo close to accurate. In reality a
24 tooth gear would put it dead on but a 23 tooth gear makes it with in 1-3 mph of being
correct. The only problem was that there was no 23 tooth auto trans driven gear avaliable
from Ford. You either had to use a 21 tooth gear like I did and accept the 6-7 mph
difference between what the speedo said and your actual speed or use a 23 tooth gear
for a T-5 which would wear out fast. There is a solution though. I found a 23 tooth
AOD driven gear at Mustangs unlimited. I ordered it and it looks just like my 21 tooth
gear with 2 more teeth. I installed it and vola my speedo is almost right on. Here's
the link if anyone is interested.  ---thunderjet302

--turbocoupe50
Cool... But I have the later super coupe AOD with a 7 tooth output.
A 21 works fine for me.--turbocoupe50
Title: gears and posi help!
Post by: 88sportcoupe on December 13, 2006, 01:50:33 PM
Ok dont mean to hijack but: How can you tell what drive gear you have without taking the tailshft housing off? Is there a way to tell? I know the trans in my car has been swapped and i think the trans in it came from a Mustang but im not sure. Thanks
Title: gears and posi help!
Post by: quicksilver on December 14, 2006, 10:23:55 PM
so the tranny and the rear end gears dont have to match?
Title: gears and posi help!
Post by: tbirdscott on December 14, 2006, 11:03:12 PM
Nope, just the rear gears and the speedo gear.


Scott
Title: gears and posi help!
Post by: quicksilver on December 15, 2006, 12:07:28 AM
ok thank you!
Title: gears and posi help!
Post by: 84 Fila on December 15, 2006, 12:38:29 AM
Alittle off topic, how hard is it to put in the speedo wire itself. My speedo doesn't work after we had to drop the trans for the flexplate. I *think* it may be the wire but maybe just a new speedo gear?
Title: gears and posi help!
Post by: Tbird232ci on December 15, 2006, 03:30:31 PM
Quote from: 84 Fila;118434
Alittle off topic, how hard is it to put in the speedo wire itself. My speedo doesn't work after we had to drop the trans for the flexplate. I *think* it may be the wire but maybe just a new speedo gear?

The wire is like any other wire, find it, splice, solder, done.
Title: gears and posi help!
Post by: 84 Fila on December 15, 2006, 04:16:05 PM
On, the paice that the speedo gear goes on. Say speedo cable insted? If not would a pic help?
Title: gears and posi help!
Post by: quicksilver on December 16, 2006, 03:58:04 PM
SPEEDOMETER "DRIVEN" GEAR BLACK 23-TEETH W/ AT
Speedometer "Driven" Gear, 23-Teeth Black, for Ford Automatic Transmission.

Nylon 23-teeth black speedometer "driven" gear. Commonly used with 7-tooth speedometer "drive" gear and 4.10:1 rear axle ratio.

This is the gear located on the speedometer cable.

Related Parts:
-Speedometer Gear Clip, #F1151
Title: gears and posi help!
Post by: quicksilver on December 16, 2006, 03:58:33 PM
is that the only thing i need to go along with my gears?
Title: gears and posi help!
Post by: jcassity on December 16, 2006, 07:25:47 PM
if i owned your car,,, i would pop out the speed sensor and swap in a new / different plastic gear.

so your right on track man,, just do that easy task and see what happens.  tom or thunderchicken may know right off the bat the exact ford PN,,
anyone know the pn he needs?


84FILA
im not sure what you are getting at but if you are saying you have a cable type speedo then look underneath an early 90s bronco or pickup and you'll see how that speedo transitions a cable drive type speedo into an electric sensor as well.  that will be the part you need , it will accept a cable and create an electrical output for your dash.  Dont ask me if it will work cause id be like you,,,experimenting.  now stop hijacking this thread,,,,LOL
Title: gears and posi help!
Post by: jcassity on December 17, 2006, 02:43:05 AM
oh yeah,,
its TRAC LOCK (ford)
not chevy posi:grinno: :beatyoass:
Title: gears and posi help!
Post by: 1BadBird on December 17, 2006, 03:50:55 AM
My 86' Bird has the speedo wire and the electrical sensor for the computer as well.
Title: gears and posi help!
Post by: quicksilver on December 17, 2006, 12:58:04 PM
so i need the speedo wire and electrical sensors too?
Title: gears and posi help!
Post by: quicksilver on December 17, 2006, 01:07:56 PM
i found a speed sensor. do i need this too?

VEHICLE SPEED SENSOR 83/86 2.3, 84 3.8, 83/93 5.0L
Motorcraft Vehicle Speed Sensor for 1983-1986 2.3 L4, 1984 3.8 V6 & 1983-1993 5.0L V8

Mechanically operated and electrically activated to transmit the vehicle's speed to the speedometer. Attached to the transmission. Fits manual or automatic transmissions.
Title: gears and posi help!
Post by: 1BadBird on December 20, 2006, 09:47:16 AM
I'm correcting myself....... my car doesn't have a speedo wire, but a speedometer cable and speedsensor wire.

No, you only need the driven gear to correct for the taller gears.