[Woody31coupe]

I have a choice of a 3.73 or a 4.10 for my 31 coupe I'm building. I will drive this to work as often as I can and drive it to shows and such. So should I go with the 3.73 or what?

[70 runner]

Originally Posted by Woody31coupe

I have a choice of a 3.73 or a 4.10 for my 31 coupe I'm building. I will drive this to work as often as I can and drive it to shows and such. So should I go with the 3.73 or what?

Depends on how fast you want to get to work!! I would probably go with the 3.73 it will be a good gear to cruise around with and still have good low end power.


70 runner

[Deuce]

It depends..........

The taller the tire ( diameter ) ...the more gear you can use.....
A small inch motor likes RPMs better than a big inch motor.....

With the pretty much standard V8 and a street able engine......I would go with a 3.73.

If you have a Overdrive transmission......the 4.10 .....definitely.

If you know the tire diameter.....you can figure out the RPMS at speed.

With a 29 inch tall rear tire...... ( I have 29's ) .........a 3.73 gear will make the engine turn 3025 RPMS at 70 MPH.

Same setup but with a 4.10 is 3325 RPMs....no overdrive

[willys36@aol.com]

For street/strip use, 3.73 is at the top end unless you run an OD. My preference is 3.54 for all-round get-up and go and streetability.

[astroracer]

It sounds like you plan to drive this car. In any event I would go with an OD Trans and the 4.10's. The 3.73's, with an overdrive ratio of 0.67 (700R4), will work out to a 2.50 final drive ratio and the 4.10's will be around a 2.75. Not enough difference to be concerned with when combined with the O.D. trans but the 4.10's will give you a big kick off the light in 1st gear.
Mark

[Woody31coupe]

All, this is one of the reasons I love this site. I get so much feed back from people who know what they are taking about, thanks so much . Well I'm off the pick up the rear end this morning.

[astroracer]

Great! What did you decide on?

[Woody31coupe]

OK, this is a great site and great people thanks all...
I got a 3.73 today . the guy I got it from is building a 1930 three window coupe himself.

[techinspector1]

Originally Posted by willys36@aol.com

For street/strip use, 3.73 is at the top end unless you run an OD. My preference is 3.54 for all-round get-up and go and streetability.

Exactly. First gear final drive with a 700R4 and 3.54 gear is 10.83:1, still useable. First gear final drive with a 700R4 and 4.10 gear is 12.54, not exactly useable unless you're pullin' a lot of weight from a stop.

Here's a chart comparing a 700R4 and a TH350 first gear with different rear gears.....
http://www.enjoythedrive.com/content/?id=7088