Ranger Split -Gear Overdrive Unit f250/Buick
 

Ok, this may sound strange but I'm building a 87 ford 6.9 with chopped frame on which I will mount a 1930 Buick body. Since this 4 speed is going to be a daily fun driver I'm wondering about the advantage/disadvantage of adding a Ranger overdrive unit to increase my topend. I also want to add a limited slip to my 3:55 differential. Comments, questions and advise is solicited since I've got the time now to play with this creation. Oh, yea..its also gonna have a WVO tank..

How big a tire are you running? 3.55 is a fairly high gear, depending on your tire size.

I haven't picked the tire size yet. Since it is primarily going to be a daily driver I'm thinking 17-20 inch tires mounted on alloy wheels. Not overly wide, probably narrow to replicate what a 30 Buick tire would resemble. I am open, however, to suggestions since this is an agressive first time project for me.

Make sure you have a way to heat your WVO. Also I hope you're using two tanks, one for diesel when you start and then a way to switch to your WVO when the engine is fully warmed up and then switch back to diesel when shutting down. Starting up cold on cold WVO is a good way to coke up your engine and put an end to your hobby.
I've been running a Mercedes with two tanks and a heater for almost seven years now. I love giving the oil companies the finger every time I drive my car.:D

Yep, two tanks in the plans.,,with preheater for the wwvo.

:-X22 Sounds like you've done your homework about running WVO.
Good luck and have fun!

sounds like a great project! send pics (a lot) when you are done. If you feel like documenting your project with pics and comments through the process I'm sure other would be interested. Good luck!

A gear splitter of any kind is awesome in a truck that regularly pulls heavy loads, however in the project like yours it may not really be needed at all. If a good top speed is what you're after then you may wanna consider regearing the rear axle to something like 3.08 ratio, keep in mind however this will slow down your acceleration some but then again you may not really notice this all that much (especially if you put a turbo on that 6.9 diesel). Another option would be to use a 5-spd ZF5 transmission in place of the 4-spd you have now, then you'll get an overdrive gear and you can keep the 3.55s in the rear axle. Or you can do both, which may not be a bad idea if you're gonna be using some smaller tires (factory tires for the truck you're working with are like 32" in outer diameter, most car tires are 27" or less in OD). Don't take me wrong, the Ranger is a real nice thing to have, but it also ain't cheap, so depending on your budget and amount of work needed for the entire project you may find a better use for the funds that you'd otherwise sink in it.

I'd definitely hold off on doing anything with the final drive ratio until you pick your tire size. That will give you more accurate info on what your RPM's will be at a given speed.

Gear Ratio Calculator

Pretty neat calculator that will let you try out different combinations before you decide.

Sounds like a cool project!