700r4 is in.

[BigSky71]

So based on what I read here a 30% overdrive with 3.08s is too much overdrive, but 3.73s would be better. So the doing the math it sounds like the a good "amount of overdrive" is about 13% over stock, does that sound right?

My reasoning; 3.08s are turning the engine 17% slower than 3.73s at the same road speed, then add in the 30% overdrive with the 3.73s and you have a total change of 13% [30-17].

[mocwon]

Originally Posted by Longhorn Man

I'll bet a punch in the gut that your MPG will not go up by much... if at all. Lower RPMs do NOT always mean better MPG. your freeway RPM there is simply too low and it is under the curve.
If lower is better was true, then all the new stuff would have 2.50 or so gears.... or a straight one to one and overdrive.
It simply wouldn't work.


Try the 3.42, that is probably your absolut best bet.



Onless you have a motor with gorlla low end torque like a 455, any caddy big block, or a diesel.

I've confirmed what Longhorn Man has indicated. I was kinda' from Missouri when he replied I shouldn't sell my 3.42 gears sooooooo, I went and talked to the tranny guy that built mine and hundreds like it along with a slew of racing, towing and other trannies as well. He said that 3.42's should be the minimum for stock height tires but that 3,73's would be likely be better, depending on the type of driving I do. As others have said, the tranny will hunt for gears and not go into overdrive unless way over the speed limit. I'm going to run the 3.07's (see Longhorn Man, even an old coot like me can change) awhile to prove it to myself (substitute hard-headed here) and will most certainly move to the 3.42's.

[Sonny]

My electrical system working fine. I have an underdrive pulley kit (March) and a chrome aftermarket one-wire alternator (rebuilt by a reputable alternator shop in town about 6 months ago). Everything was fine before the March pulley conversion. I'm not worried; I just have to make sure I give it a little humph when I get going when I bring the beast to life!

[Buckman]

Mocwom, what is your rpm to mph ratio? Like 60 and 70 mph.

[MrC1]

Hey guys, nobody mentioned anything about lock-up vs. non-lock-up 700R4s here. I'm running a non-locker with 3.54s and it feels about right. I'd prefer to add the lockup and some more gear, but...

Think I'll post a question about adding lockup.

[Longhorn Man]

That's becouse we are talking manual shift