Which gear ratio?

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GDL

GDL

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Ok, so here is what I currently have in the car (72 dart)

Original 727 with the stock convertor
Built 340 with bells and whistles
25 inch tall tires
2.5x rear gears in a 8.25 rear

I know that the rear end is killing me, but strength wise it is better than the 7.25 that was in there prior.


So, my wife wants to peel out in the car and have more acceleration, should we run 3.55, 3.73 or 3.91 gears?

That's next year's project so I need to start planning for it now.
 
With only a 25" tall tire, the 3.55 will be good. However, if you ever plan on going taller, the 3.73 or 3.91 would be better.
 
RustyRatRod said:
With only a 25" tall tire, the 3.55 will be good. However, if you ever plan on going taller, the 3.73 or 3.91 would be better.
Click to expand...

We are planning on going bigger but need to swap the front spindles due to the front still having the lame 5 on 4 bolt pattern.

That being said 3.73 gears might be a good compromise? Also, would this be a night & day difference coming from 2.5x gears?
 
with 25" tires you should be able to brake the tires loose easily with 3.23's...unless you have a fairly long duration cam.
 
Run as much gear as you want, unless you plan on doing some Hwy driving !
 
Yes there will be highway driving..... so stop at 3.73?

I'm a gm guy and that's usually where we stop gear wise.
 
+1 for "...wife wants to peel out and have more acceleration..."
 
Hey, Mike. I would honestly go with 3.73, and compromise the Hwy, until you get taller tires. OR you could follow my build and go 4.10 with a 42rh overdrive. :)
 
I agree with the converter too. Buy a nice (NOT off the shelf) converter like PTC or ATI and then do 3:55’s or 3:73’s depending on your highway usage. The converter will make all the difference off the line, even in the 2500-2800 stall range, and won’t drive horrible either.

Joe
 
I vote 3.23 if you'll be doing a decent amount of Hwy driving. My 340 dart with 255/60r15 has 3.55's, 383 coronet with 275/60r15 has 3.23's .... the coronet "cruises" much better, and still lights the tires up ....
 
Mike, as much fun as overdrive would be the wife would kill me for swapping out a trans we just redid 3,000 miles ago. LOL
 
If you have a built 340 with a stock converter, then you already have a problem, in my humble opinion. Before converting my 69 Cuda to a 4 speed, I built the 340, and kept the stock converter. It didn't like to idle, and it fell on its face from a stop until about 2000 RPM even with the 4.56 gears it came with. I picked a 2400 stall, and my car drove GREAT while it still had the automatic. I eventually switched to 3.55 gears. FIRST, I would think you'd need to get a higher stall converter. Then I would highly recommend 3.55 gears. That being said, you can not only "chirp" your tires with 3.22 gears, you can smoke them. Plus it will be better on the highway with 3.23s.
 
harrisonm said:
If you have a built 340 with a stock converter, then you already have a problem, in my humble opinion. Before converting my 69 Cuda to a 4 speed, I built the 340, and kept the stock converter. It didn't like to idle, and it fell on its face from a stop until about 2000 RPM even with the 4.56 gears it came with. I picked a 2400 stall, and my car drove GREAT while it still had the automatic. I eventually switched to 3.55 gears. FIRST, I would think you'd need to get a higher stall converter. Then I would highly recommend 3.55 gears. That being said, you can not only "chirp" your tires with 3.22 gears, you can smoke them. Plus it will be better on the highway with 3.23s.
Click to expand...

Probably the most constructive post yet! Actually her car idled fine. It's just it is a dog on the hole shot. I'll definitely think about a torque converter... but right now I'll get on the gears first. (Cheaper of the two)
 
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