T45 Speedo

[ACLR8R]

I have a mechanical speedo, but a electronic T45.

I have read that you cant make it work and that you can, anyone made the conversion to mechanical? If so can you tell me what cable and gear I need?

Thanks!

[Gordon Levy]

If you are running a 4.6 EFI you need the electronic signals running through the computer if the car will not run correctly. It would be easier to change the speedo to electronic. Another thing to think about is what year your gearbox is. 96-98 used a VSS signal and the 99-04 uses a VCC signal. Running a VCC signal through a VSS compatible computer will drive it nuts and visa versa.

[ACLR8R]

Originally Posted by Gordon Levy

If you are running a 4.6 EFI you need the electronic signals running through the computer if the car will not run correctly. It would be easier to change the speedo to electronic. Another thing to think about is what year your gearbox is. 96-98 used a VSS signal and the 99-04 uses a VCC signal. Running a VCC signal through a VSS compatible computer will drive it nuts and visa versa.

Its a 98. So would a GPS speedo be the best option?

[Gordon Levy]

It would probably be the easiest.

[pcolapacker]

I have the same transmission and had the same issue. You can buy a gizmo that takes the signal from the T-45 to spin a motor that is connected to the speedo cable. It wasn't cheap. It made more sense to sell my gauge set and buy a set with an electric speedo.


Sent from my Autoguide iPad app

[SPeace-ATL]

Originally Posted by pcolapacker

I have the same transmission and had the same issue. You can buy a gizmo that takes the signal from the T-45 to spin a motor that is connected to the speedo cable. It wasn't cheap. It made more sense to sell my gauge set and buy a set with an electric speedo.

Yes, if you need a speedometer cable from a 99-01 T-45 you will need the converter box called Cable-X.

If you have a 96-98 T-45 you just need the right VSS sender from a Fox Mustang.

[ACLR8R]

Originally Posted by SPeace-ATL

Yes, if you need a speedometer cable from a 99-01 T-45 you will need the converter box called Cable-X.

If you have a 96-98 T-45 you just need the right VSS sender from a Fox Mustang.

Even a 98? I thought they wouldnt work?

[SPeace-ATL]

Originally Posted by ACLR8R

Even a 98? I thought they wouldnt work?

The all digital OSS sending unit was introduced in the Mustang with the 99 model. The 96-98 T-45 uses a VSS like the Fox Mustangs used, but the opening for the speedometer cable has a white plastic plug in it. That plug can be picked out and a Fox type speedometer cable will click right in!

[mn12]

Be careful there though some of the trans cases had the hole with a plug in it not all have the old tailshaft with a gear to drive it. There are some early ones that do but not all. Make sure you pull the plug and check before you make any plans

[SPeace-ATL]

There are just three versions of the T-45.

They are tagged as follows:

1381-001 1996-1998 Mustang 5.0 GT - 8-tooth internal speedo gear & VSS
1381-002 1996-1998 Mustang 5.0 COBRA - 7-tooth internal speedo gear & VSS
1381-011 1999-2001 Mustang 5.0 GT & COBRA - digital Electronic OSS Speedo

Those with the VSS sending unit will drive a FOX Mustang cable speedometer if the white plastic plug is removed from the VSS.


When choosing a T-45, the 1999-2001 units seem to be more reliable.

They have:

• Carbon-fiber synchros for gears 3, 4, 5, & Reverse
• A solid tube for the throwout bearing sleeve that won't snap off
• The Factory Service Bulletin for the 5-R Forks is already installed
• The 3-4 forks in these units seldom shatter like the 96-98 models

Remember that the 96-98 COBRA T-45 has the cross member located further back than the other Mustang transmissions.

When rebuilding a T-45 specify the 1-2 rings from a 2003/2004 COBRA T-56 so that all of your rings will be Carbon-Fiber.


Happy Hunting!

[ACLR8R]

Originally Posted by SPeace-ATL

The all digital OSS sending unit was introduced in the Mustang with the 99 model. The 96-98 T-45 uses a VSS like the Fox Mustangs used, but the opening for the speedometer cable has a white plastic plug in it. That plug can be picked out and a Fox type speedometer cable will click right in!

So I just need to pull the white plug out and put a cable in?

It already has the speedo gear in the tranny?

That would be great and save me a couple hundred bucks!

[SPeace-ATL]

Originally Posted by ACLR8R

So I just need to pull the white plug out and put a cable in?

It already has the speedo gear in the tranny?

That would be great and save me a couple hundred bucks!

Yes, if it is a 96-98 T-45 it has a gear-driven VSS.
Remove the white plug and a speedometer cable will clip into the hole.

A 96-98 T-45 will be tagged 1381-001 for a GT or 1381-002 for a COBRA.

If somehow you have a 99-01 it will be tagged 1381-011 and will not have a gear drive.

The gear on the tip of the VSS can be changed to calibrate the speedometer.
A -001 T-45 will have an 8-tooth internal gear and a -002 T-45 will have a 7-tooth internal speedometer gear.

You can pull the VSS unit straight out and see the gears.
The 8-t internal gear is green and the 7-t gear is red if you can see inside the hole...

[SPeace-ATL]

Originally Posted by Gordon Levy

If you are running a 4.6 EFI you need the electronic signals running through the computer if the car will not run correctly. It would be easier to change the speedo to electronic. Another thing to think about is what year your gearbox is. 96-98 used a VSS signal and the 99-04 uses a VCC signal. Running a VCC signal through a VSS compatible computer will drive it nuts and visa versa.

Gordon makes a good point. We've all been focusing on making a cable-driven speedometer spin, but Gordon is saying that a 4.6 ECM won't manage the engine properly with the VSS signal being applied to it rather than the OSS signal.

I don't know how the ECM will react with NO signal at all from the OSS...
In other words, don't connect the VSS to the ECM.

That might be preferred over the incorrect signal. I think applying the VSS signal will cause the ECM to engage "Speed Limiting" somewhere in the 30-40 mph range since too many pulses are sent by the VSS and the ECM thinks the car is going way, way fast.