Gear Ratio - 741 & 489 Rear Ends on a 8.75 Axle ???

[DaWeezzz!!!]

Question....????

What gear ratio would you pick if these were the only gear ratio's available?

3.23
3.91
2.76 or 2.93

I know i've been told to get a 3.55 gear ratio, but that's not available on these used rear ends?
Also not building a HOT ROD. Just a 1974 Duster car with a 340 Engine & 904 Transmission to drive around and sometimes a little fast on the freeway. Thanks for the help....

Alec

 

[gzig5]

Depending on how much 65+mph you plan on doing on the highway, either 3.23 or 3.91. I have 3.55 and I know I wouldn’t enjoy too much 3.91 for long periods on the highway. 3.23 will work fine and give better pep than the 2.xx gears but the 3.91 wins out for general around town stoplight to stoplight cruising in my opinion.

 

[Alaskan_TA]

Not enough information.

Tire size and diameter?

And..... what does that riveted on tag say on the one in front? I have not spotted one before, thanks.

 

[273]

depends what you care about more highway or performance me 3.91 you?

 

[Dana67Dart]

741 has fewest options currently.

 

[George Jets]

741 & 2.94 ratio

= 20 miles per gallon, and still gets out and hauls the mail.

 

[RustyRatRod]

3.91 and never look back.

 

[Dartsun]

I like 3:23 gears with a 26ish inch tire. Dustin

 

[Jeffrey67dart]

No hot rod. Then i would say 3.23. Good for some fun around town and highway driving.

 

[my5thmopar]

Any of them suregrip, pitted teeth? I cant tell from the pix. I tried all 3 in my D100 project, 3.91 nasty fast and tire burner. 2.94 not impressed. 3.23 good around town and highway. Should have mentioned its a 440 and really doesn't care what gear in a light truck. I went with the 3.23 in my 318 Dart.

 

[toolmanmike]

3.23 would be my choice.

 

[Jadaharabi]

Put some 3.55s in a 489 housing with a crush sleeve eliminator.

 

[AJ/FormS]

Also not building a HOT ROD. Just a 1974 Duster car with a 340 Engine & 904 Transmission to drive around and sometimes a little fast on the freeway. Thanks for the help....

It kindof depends on;
your cam/cylinder pressure/and stall,
and how much off-the-line punch you are willing to give up, to be able to drive fast in reasonable comfort.

If your 340 is already sucked out when taking off with whatever you got, then going to a smaller gear will only make it worse. but
If your 340 is a tire-burner off the line, then you might be able to give some gear up.

Then take it out on the hiway and decide if you are willing to put up with more rpm than you currently have..... or not. Drive a lil faster, say 20% and drive a lil slower say 10%, and see what you think.

If you choose a smaller gear, you will lose low-rpm performance. Some of it you can get back with a higher stall rpm, but this pretty much only helps off the line.

The bigger the rear number is, the more quickly the Duster will scream thru the trans gears.
3.91s make an excellent city gear, especially with a low-compression engine.
2.76s make an excellent cruising experience. But in a 340, they may not get you any better fuel economy than 3.23s. Again it depends on the cam and the cylinder pressure.

Everything is connected to everything else. When it comes to gear selection, IMO this is too much of a wild card to leave to someone else's opinion. IMO,lol, only you can decide, based on careful analysis of the current gear and stall, and how it performs in the current combo..