Five speed vs three speed

[Pichuki]

Thanks everyone for your inputs, I'm trying to find the tranny that has the longest gears, because I do alot of highway driving.if I'm not mistaking it's an (FS5R90A )now if the car is slower on city driving, I just won't shift into 5th.

[Z train]

As somebody else mentioned,it is not just a matter of tossing in the box with the biggest OD drop.Everything here is an equation.If your cruising RPMs drop below the rpm where your advance is fully in,that will hurt MPGs as much as without the OD.

[Pichuki]

Yes , that's very true. I guess I will find out when I put in the 5speed tranny. Maybe someone could suggest me a differant rear end?

[Racer_Z_]

Yes , that's very true. I guess I will find out when I put in the 5speed tranny. Maybe someone could suggest me a differant rear end?

Change the tranny and drive around a while before you decide to change the diffy.

If your overall gearing is too high, you will be out of your power band. Then you'll blow-up your gas mileage and performance will suck. I've been in more than one car that got the same MPG in fourth as it did overdrive. Why? Bad gear choices from the factory.

I would go with a OD (over drive) that has a small step, not a big step. All you need/want to do is drop the RPM down a little. To big a step is worse than leaving it in fourth.

[tlorber]

I agree with putting the tranny in and seeing how you like it, and then going from there. If you want to convert to an R200, a 3.9 will be easy to find but will involve swapping other components, or you can try to find a 3.9 R180. I used a 3.7 R180 that I got from Bill (Blackface Benny). It is about 5% taller than the 3.9 and I really like the combo with the '82 five speed.