This is what I am dealing with.  The '55 Thunderbird adapter vs the T-5.  I am going to try to find a newer Ford speedometer cable and check the ends to see if they are compatible with the speedometer housing, and the T-5.  I have plenty of plastic gears for the transmission end of the cable.  Joe-JDC

JDC

Both the speedometer cable design and gear at the transmission changed in 1957 and stayed that way for at least three decades.  As mentioned by Ford Dearborn, the gears are available with the helix being either left or right.  When I upgraded the T85 in my ’55 Customline, I simply purchased a speedometer cable for a ’57 Ford with overdrive and it bolted right in my ’55.  I did have to also use a ’57 & up speedo gear and pick the one with the right tooth count that matched my tire size and gear ratio to get the speedometer to read close to correct.

Lorena, Texas (South of Waco)

I think there was a cable design change at some point in the '50s.

I didn't take a picture for reference, but what FORD DEARBORN shows looks like I remember.  '61 to ?? cables and gears seem to fit the T5 without any adapter needed.



Lawrenceville, GA

I have built and raced, Fox Mustangs since 1986, with WC T-5Z transmissions, I have a '86 GT with 383W stroker/5 speed, and just sold my 91 LX a couple of months ago, and gave my youngest son my '89 GT with 23K miles on it.  I have lots of experience with the T-5 transmissions, and lots of plastic gears for the speedometer cable.  The LX had 4.10 gears, my '86 has 3.73 gears, and my '89 GT now has 3.73 gears and WC-Z.  This T-5 came out of the '89 GT.   All those transmissions had a speedometer cable adapter for the cable end that goes into the transmission.  It has different cable ends from your pictures.  I can get pictures tomorrow.  If a regular speedometer cable for a truck will work, then I will try to find one locally.  Joe-JDC

JDC

I'll try to post a pic of what the cable end with gear looks like for the T5 I installed in my 64 F100. If this is what you have, those gears, as Charlie stated, are available for numerous ratios. They can be right hand or left hand determined by wether the gear is above or below the output shaft.  NPD used to have a very good assortment of those gears. I believe this style ran from 57 on. Not sure about 55. If your Tbird has the "mushroom" style gear then simply buy a cable for a 57 and that will fit the T5 and your speedometer. The speedometer head connection is the same through the 50's and 60's as far as I can remember. 

64F100 57FAIRLANE500

The gear and cable for my 3 speed (1961) worked and I have since bought a gear assortment to adjust for different rear gear ratios so a cable and gear that will mesh with the T5 should be pretty easy to find.  The gears are very common.

But I guess that the rotation is opposite for yours?



Lawrenceville, GA

Next question for those who have done the swap:  What did you use to adapt the speedometer cable to the T-5 transmission?  The Thunderbird cable adapter has the gears that are cut in opposite direction from the T-5, and will not intermesh.  I have this about ready to start up, and the speedometer cable is no way going to work with the T-5 as is.  Joe-JDC

JDC

If the T85 is not larger than the Fordomatic, which was used for all three years of the 55-57 Tbird, why did Ford enlarge the transmission tunnel for 56-57? Was the larger diameter driveshaft required for the additional power of the 312?

I'm not sure what Ian's post has to do with transmissions.

The bent gasket reminds me of when I order lots of parts from a Tbird supplier. One of the parts I ordered was a fuel line. They bent it 180 degrees so that it would fit in with the rest of the parts. There was no time to replace it as I had to pack it all and get it to the warehouse for shipping back to Australia before I flew out myself. They did refund me the cost of the fuel line though.