I'm probably going to be running this combo in the summer...is there any way that I can correct the speedometer? Will a speedcal work on the M5R2? Or will I need to buy an aftermarket adjustable speedo?
The M5R2 has the below gearing and as you can see a 3.75 first gear. 4.10s in the rear will make fist gear completely useless. Even the 3.55 rear gearing is about max even for the track. I am planning this setup... M5R2 3.08 rear and 26" tires and shifting at 5800 RPMs. With a 5.0 and this combo is right for my setup. The M5R2 has a very steep 1st gear and I want to be able to take advantage of it.
Some of the F-150 trucks with the M5R2 were equipped with a 7 tooth speedo drive gear, Ford p.n. E7TZ 17285 A. Starting with that, you can then gt pretty close with an off the shelf driven gear. Using the calculator over on SCCoA, you would need a 21.8 tooth driven gear with a stock height tire. Ford sells the driven gears up to 21 teeth.
I know that the M5R2 won't bolt up to the 4.6, but I'm not staying with that engine. I'm going to be getting a 90 SC 5-speed parts car soon, so I guess I'll just use the 3.08 trac lok off of that in my car, and sell the 4.10 pumpkin on here to someone with the 4R70W .