Im just wondering if anyone knows which gear to use in order to calibrate my rx7 speedometer to the ford t-5 tranny? im using the stock N/A rear end which i believe is 4:11 gears unless im mistaken.

 

I used a Ford AOD tranny, and I don't suppose there would be much difference in the gear setup, but possibly a different ratio. I don't believe you will get anywhere near the right ratio with stock parts. Grannyspeedshop offers an adapter, which is made by Tacoma Speedometer. Check Granny's web site for details.

Since I live in the area, I took my car to Tacoma Speedometer and they made a gearbox which they spliced into my cable. It is within one mph from 30 to 70 mph. The cost was about $150. Any old fashioned speedo shop could do this, but of course most of them have long since gone out of business.

I found that I could make a slight modification to the Ford cable end so that it plugs into the Mazda speedo.

 

i actually have the adapter from grannys, but it does not come with a gear on it, you have to put a gear on the end of it, all it really does is adapt the connection so that it slides into the ford transmission properly.