[digicon]

Guys, can anyone tell me what kind of rpm's I could expect at 65-70mph running a TH350 and 3.73 gears on around 28" tires?

I am having a hard time making a descision on my trans/rear combo and thought I would ask for a little help.

Thanks, Mike

 

[acardon]

About 3138 RPM at 70 MPH. ....http://www.angelfire.com/fl/procrastination/rear.html

 

[mickym521]

I think you should also factor in your motor. I have a 383 stroker and with a 350 tranny and 373 rear end I was turning 3K at 60mph. I now run a 700r in order to bring the rpms down at highway speeds.

 

[digicon]

All good points guys. That's what I was afraid of.

That Rear Axle Calculator is handy. That's really what I needed.

Thanks again,
Mike

 

[55mike]

Some sort of an OD is really the only way to go imo... either AT or manual the OD makes for a much happier cruise. It's been my experience 30% OD with 3.50 rear gears is a very good combo.

 

[belairdave]

Some sort of an OD is really the only way to go in my imo... either AT or manual the OD makes for a much happier cruise. It's been my experience 30% OD with 3.50 rear gears is a very good combo.

:dito:Mike has it right:five:Later, Dave

 

[pistoncan]

It really doesn;t matter what transmission you use if it has a 1:1 final gear . Its going to still turn 3100 or whatever at highway speeds with that rear end, so you really only have two options OD trans or taller gears if you wish to get the RPMs down.
Gary

 

[r66ss]

Guys, can anyone tell me what kind of rpm's I could expect at 65-70mph running a TH350 and 3.73 gears on around 28" tires?

I am having a hard time making a descision on my trans/rear combo and thought I would ask for a little help.

Thanks, Mike

good luck Mike and keep us posted,

 

[USA1]

All automatic trans are going to have a certian amount of slip, the higher stall converters are less efficient than stock. A manual will turm less rpm at a given speed as a result.

 

[MikeB]

Tell us about your engine. For example, a mild 350 works very well with 3.08 gears. In fact, when I got my 55 sedan it had a 350 with TH350 and a 7.5" 10-bolt 2.73 axle. However, it worked great for cruising and had decent 1st gear performance, especially after I replaced the sluggish 750 carb with a 600, and loosened up the spark advance curve.

However, when I converted to a Muncie, first gear was way too tall without the torque converter, so I went to a 3.42. The 3.42 is a bit too much for the highway (~2900 RPM at 70 mph), but as it turns out I'm replacing the rear axle with an 8.2" 10-bolt with 3.08 gears. That will lower my highway revs by 10%, with the trade-off being a little more clutch slipping to get rolling in 1st gear. Again, not an issue with a torque converter.