Which gears are best

[Fred69Runner]

Hi, I'm replacing the 741 carrier that came with my 69, with a 489 sure grip. I have a RM23 with the 335HP- 383 with the Hurst Package 4 speed. Question: will the 3.23 gear set up give the best balance between performance and mileage. Or is a 3.55 or 3.90 a better way to go. What set up are some of you running?

 

[69hemibeep]

If you expect to do 75 mph on the interstate and not get passed by a jeep full of girls 3.23 for sure, if its back roads 3.55

 

[Plybeep68]

What size rear tires are you using ? The taller 275/60 will affect the gear some

 

[69hemibeep]

Try this http://www.csgnetwork.com/multirpmcalc.html

 

[Fred69Runner]

What size rear tires are you using ? The taller 275/60 will affect the gear some

Tbank you. Have 14 inch Cragar mags with 270/60.

 

[Fred69Runner]

Try this http://www.csgnetwork.com/multirpmcalc.html

Thank you, that's a very useful tool!

 

[Ranger]

I'm running a 3.23. (4 spd), 15" Cragars 245/60/15
Mostly highway with some interstate.
I get 16 MPG on the interstate.

200 RPM increase for every 5 MPH
2000 RPM @ 50 MPH
2200 RPM @ 55 MPH
2400 RPM @ 60 MPH
2600 RPM @ 65 MPH
2800 RPM @ 70 MPH

I guess "performance" is subjective, but she's a cruiser, not a racer and fast enough for me. I prefer the lower RPM and better fuel mileage.

 

[Fred69Runner]

I'm running a 3.23. (4 spd), 15" Cragars 245/60/15
Mostly highway with some interstate.
I get 16 MPG on the interstate.

200 RPM increase for every 5 MPH
2000 RPM @ 50 MPH
2200 RPM @ 55 MPH
2400 RPM @ 60 MPH
2600 RPM @ 65 MPH
2600 RPM @ 70 MPH

I guess "performance" is subjective, but she's a cruiser, not a racer and fast enough for me. I prefer the lower RPM and better fuel mileage.

Thank you, that's very helpful information. I'm thinking the 3.23 might be the way I go....
Enjoy the Ride!

 

[jww69rrpost]

I'm running a 509 stroker; 275/60/15 rear and 235/60/15 front. Gears are 3:23 with a Detroit Truetrac and Gear Vendor Under/Overdrive unit. Overall it works out just fine. It launches solid and quick and cruises at 75 mph at 2600 rpm's, so you can have your cake and eat it too!!

 

[Fred69Runner]

I'm running a 509 stroker; 275/60/15 rear and 235/60/15 front. Gears are 3:23 with a Detroit Truetrac and Gear Vendor Under/Overdrive unit. Overall it works out just fine. It launches solid and quick and cruises at 75 mph at 2600 rpm's, so you can have your cake and eat it too!!

Wow, great info, will need to research that overdrive unit.. Thanks for the reply and input, much appreciated!

 

[Russ69Runner]

They aren't cheap. Every one is saying that is the way to go.

 

[RKNRLR]

Mine is sitting ready on the bench, al buttoned up, with no place to go

 

[Russ69Runner]

That is a hand full. How much weight dose that add to the assemble. Would love to have one but that will have to wait for when the car has been on the road for a while. When you get it in want a low down on every thing. Like you rpm's and what it dose for the road on MPH. Look's good.

 

[Russ69Runner]

Thank you, that's very helpful information. I'm thinking the 3.23 might be the way I go....
Enjoy the Ride!

I have the 3.55 gearing in a 741 rear end A 833 transmission with a 383. When it get's on the road will let you know how it dose. Fred69Runner. But you will probably have yours on the road before me then we can talk shop on how you like your set up. Russ.

 

[Roadtrip]

I'm running a 509 stroker; 275/60/15 rear and 235/60/15 front. Gears are 3:23 with a Detroit Truetrac and Gear Vendor Under/Overdrive unit. Overall it works out just fine. It launches solid and quick and cruises at 75 mph at 2600 rpm's, so you can have your cake and eat it too!!

Your tach might be out? Should be closer to 2300 (2260) rpm with that combo and speed?

 

[Russ69Runner]

Think it could be out of calibration. I like those number's Roadtrip.

 

[Fred69Runner]

I have the 3.55 gearing in a 741 rear end A 833 transmission with a 383. When it get's on the road will let you know how it dose. Fred69Runner. But you will probably have yours on the road before me then we can talk shop on how you like your set up. Russ.

Yes, I will sure let you know how it goes. I really like the sound of that overdrive unit, but at $3k might have to wait a little while on that.

 

[Fred69Runner]

Mine is sitting ready View attachment 31401 on the bench, al buttoned up, with no place to go

That is one nice looking set up. Wish I was putting that in my bird!! Good luck and have fun with that project...

 

[Russ69Runner]

 

[Fred69Runner]

Yup, that's the boat I'm in...