what's the best gear ratio for interstate driving

[69_500]

I now have 2.76 gears and 28" tall tires on the 500. Cruises great for long trips.

[odcics2]

I now have 2.76 gears and 28" tall tires on the 500. Cruises great for long trips.

At 6,500, you'll be a little bit over 200...   

[Daytona Guy]

Ok, after one year and two 727 tranys here is my 2 cents.

I love my 2.94 gears for driving. I get 14 MPG out of a 713hp 739trq engine. The issue I ran into using high HP, with a 2.94 gear is this...

1. tooooo much load on the tranny and trq converter.
2. The rear bushing could not handle it – ate into the case - Torrington bearings are required.
3. Your trq converter creates too much heat because of slippage.
4. Must start off in 1 low to hammer it. (Should no matter what, but more so with hwy gears)

A new converter is being made that allows for stall (2800 for my HEMI) but also, for reasons this layman can't articulate, at cruising speeds creates a 1 to 1 or even an overdrive effect, so that if using a 3.54, or  3.23 gears (Only 3.54 for Dana) will keep your RMPs down.

[Daytona Guy]

Can one install a lockup TC with a manual switch so that on a longer drive you can just lock it up and get 1 to 1? This would give 8-10% more gain.

Dane

[SBBob]

My car is a 3.54 dana with a 4 speed.  I found an 833 long shaft 3 speed with forth gear being a 26% over drive ratio.  Just had to change the 18 spline to a 23 spline clutch disc and flip the 3 - 4 shift lever upside down to make the pistol grip shifter work right.  Works out to be about a 2.56 final in over drive.  I run stock size tires and have got as high as 18 mpg on the freeway.  Not a race tranny, but is fun to drive on the highway with 60mph being just over 2,000 rpm.