I am working on changing my 85 Mustang T5 to the forward shift S10 tail housing and after reading all the threads it has left me a little confused. The s10 housing I have is the electric speedo model and I have read that the angle of the hole for the speedo drive is wrong to mate with the Ford tail shaft. Apparently the 700r4 drive gear and driven adapter will fit the S10 tailshaft and housing, which would allow me to go with a speedo cable, I would just have to go from the Ford speedo cable to one that has the 7/8 thread on GM style. If someone would let me know if I'm on the right track before I go searching for the 700r4 stuff, I would appreciate it. Here's my understanding so far: Remove Mustang tailshaft housing and output shaft. Take S10 output shaft, remove reluctor wheel, install 700r4 drive gear, install in Mustang trans. Install s10 tailshaft housing with 700r4 driven assembly on Mustang trans, use GM style speedo cable with 7/8 thread on trans end, and S10 driveshaft yoke. Will this work or will I have problems with interchanging the s10 output shaft to the Mustang trans. S10 trans is around a 91. The confusion I have had reading some threads is it seems some replies tend to use the word tailshaft to include both the housing and the output shaft, so its a little unclear whether some guys just put the s10 housing over the Ford output shaft, or if you need to swap both the s10 housing AND the output shaft to the Ford trans.
First you will need to determine if your mustang t5 is a world class, or the earlier non world class type transmission. You will need to install the appropriate s10 main shaft (world class or standard) in order for the speedo gear mount position to line up with your tail housing. If you have the electric style tail housing it will not work with a conventional gear speedo. You will have to locate the earlier tail housing from a 1983-85 s10. They are getting hard to find unfortunately.
As stated, there is no way to use the electric tail housing to connect a mechanical speedometer (short of a major conversion that relocates the hole). You will have to use an optional method to drive a speedometer such as GPS or a sensor pickup that mounts on the driveshaft. We are all in the same boat using the S10 electric tail housing! Sad but true.
We installed a mechanical speedo S10 tailshaft on a 88-93 Ford T5Z 5-speed. We measured how and where the S10 speedo gear resided on the Mustang tailshaft, used a shim and slipped over the S10 gear and glued it in place. Lined up perfectly once the s10 tailshaft was installed and the speedo gears meshed perfectly. Can't seem to find the pics at the moment - the shim used was one of the sleeves used in crimping your own AC cconnections as per one of the articles in Flaternie's T5 library of articles. PM me if you'd like to see some of the pics I took while doing the swap .... Also Kato King here on the HAMB will convert your electronic speedo tailshaft to mechanical.
This will only work with the mechanical speedometer S10 tail housing, not the electronic speedometer tail housing. The Kato King conversion was the one I was referring to as a major modification. Did he every get past the pro-type stage and if so any idea of the price?
Ok thanks guys. I had read that the electronic parts could be swapped for mech, but that was a Camaro T5 where they installed the s10 electronic tail housing. I guess the conversion box for 360 bucks may be the only solution at this point. Just to clarify, are guys putting the s10 mechanical speedo tail housing over the Ford mainshaft, or do you have to install the S10 mainshaft?
Putting the speedometer issue aside, and to answer your specific question, the S10 tailshaft must be used which means you also have to get a 27 spline GM driveshaft yoke to mate with your existing universal joint. As for the speedometer, a lot of guys are getting GPS speedometers instead of going through all the trouble of converting an electronic to mechanical.
I can convert your s10 electric speedo tail housing to mechanical. PM me for details. You don't have to switch out the output shaft. I also make some split bushings so that you can install the drive gear. Again PM me if interested.
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