poor man's overdrive?

Granny 4 speed is way too far between gears to actually work at optimum.

If you want a real poorman's OD, slide a gutted 3 speen turned around backward behind yout other transmission. I would loose the 1st/reverse cluster and use 3rd for 1:1 and second for OD.

 

One of my buddies has that setup in his mid 70's Chevy 4x4 that he has a 454 in. I'd have to ask what rear gears he runs though. His truck is a dualie conversion that hauls a camper and he claims a pretty decent mileage improvement with the two speed OD working. It is big and heavy though, I picked it up and moved it one day when I was doing something in his shop and wished I hadn't.

 

The one advantage of a setup using available a wide ratio 4-spd car trans, is that with the right final gear, you will be 1:1 thru the gear box, so minimal energy loss there. Slightly better mileage, if the other factors the posts bring up are well chosen.

 

I would think cheapest would be to just use a T5 from a 4 cyl fox body.

 

I have an OT diesel pick-up with a 5 speed (manual) Alison box...granny gear in first....overdrive in 5th...often wondered how it might work in a rod. The diesel operates at a much lower RPM (redline is 4000).

 

Borg Warner super T-10 out of late 70s trans am has a low 1st gear around 3.42:1 I believe.


Ago

 

I was having a gears talk just the other day so this is fresh.

I had an O/T Mustang that I swapped the pumpkin with a set of 2.86 gears. A dog off the line but I wasn't racing it. Straight 6 and a 3 speed. I got about 25 mpg.

Diesels are another game, but same principle. 5.9****mins as an example is very happy between 1800 and 2100. Consumption increases dramatically on either side.

Back on topic, A poor mans overdrive is probably not the right term but tall geared rears to get the rpm is what I am getting from this thread. I say yes and in normal circumstances, you will get improved mileage and better highway streetability. I know from the Mustang and a 3 speed, but same concept.