3.23 or 3.55?

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67DartGT340

67DartGT340

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I have a 3.23 sure grip in my 67 Dart now, but have been thinking about going to a 3.55 SG instead. Is it worth the change? any comments would be a help.
 
That is a hard question to answer without background.

what engine, what Transmission ?
what application ?
highway, or 1/8th mile ?
 
you will tell a difference but if i were making a change id go with 391s if you can hook it.that's if your looking at the performance aspect of it.thats my a thut.
 
I agree we need to know more.

If it is meant to be an around town car and track car with minimal highway driving, then 3.91s are the way to go.

If streetability and highway driving is the priority, then 3.55 is as high as I'd go...MAYBE 3.73 if you are running tall tires.

Some argue "but 4.10s were street gears way back when"...sure, but highway speeds are MUCH higher these days...I cruise at 75-80 mph just to keep up with traffic around some days, and I don't want the motor screamin to do it...racing is not nearly as important as drivability for me.

I run 26" tires and will be installing 3.55s before the end of the year...and I have a 518 so on the highway I will still be running a 2.44 final drive. :toothy10:
 
Hey guys sorry about that of course you need info:
69 340 bored .030 with Carter AVS
904 Torqueflight( tweaked a few years back)
25" tires (Goodyears) R60 in the back and R70 in the front

The car is basically used for the cruise nights and attending the mopar car shows around here. I have thought of 3.91, but there are times the car is on the highway. I have always heard 3.55 was the best of both worlds. My dad had an old 69 Dodge Truck with 3.73 and I remember the push those gears gave as well.
 
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Pretty car! What color is the interior??

I have 323's in my 69 Dart automatic with the 14" tires and it's a dream on the highway. I wish I had a Suregrip rear. :(
On the other hand, my last 72 Corvette had 355 gears from the factory with a 4 speed, and it too was a dream on the highway. The Vette had taller 15" tires though so I suppose that changes things.
I wouldn't be afraid of 355's for the street. They're an awesome gear.

Good Luck with that nice Dart.

George
 
I just went from 2.45s to 3.55s on my dart, and I don't think its enough gear. I'm running 205 60 14 all around. I think I could go 3.73 comfortably, but since I'm eventually going with an overdrive, I'll probably spring for 3.91s on the 8.75 rear I'm going to build sometime. I don't think you're gonna notice enough difference between 3.23s and 3.55s to bother with the gear change. But.. hey, its your ride and your wallet, so you gotta do your own thing, right?
 
My previous duster came with 3.23's i switched them out for 3.91's it was like night and day,what a performace improvement it was,as far as going from 3.23's to 3.55's i don't think you'll notice much gain,but i think a good compromise would be to run 3.73's,they becoming a pretty popular gear of choice with a lot of guys...
 
stroked 340 said:
My previous duster came with 3.23's i switched them out for 3.91's it was like night and day,what a performace improvement it was,as far as going from 3.23's to 3.55's i don't think you'll notice much gain,but i think a good compromise would be to run 3.73's,they becoming a pretty popular gear of choice with a lot of guys...
Click to expand...

Same here ('68 Dart GT, 383, 727, 15" tires, 3.91 SG)

Agreed on the 3.73.

My 3.91 are a PITA on the Freeway...
 
My 355's suck on the highway, it's 3200 rpm @ 60 to strung up I.M.O, The only highway driving i do now is a 60 mile roundtrip to the track, Which i dread now because i run 60 in the 65 now, Before i had 294's i'd cruise @ 75-80 at ease, Just depends what your doing with the car, Your not gonna gain much going from 323 to 355"s thou
 
I'm running 3.23's with a four speed and 29inch tires.

I run 2500 rpm in fourth gear at 70 mph, nice and smooth.

It launches well, maybe too well at times, and I have a low first gear, I forget gear ratio, but it is an all around great gear for me.

I'm sure I would get much better performance off the line with a 3.55 or 3.91 gear set, but I'm not racing the car, just having fun terrorizing the wusstangs and crumaro guys..LOL.
 
I am running the 3:55 set in my 360 powered Duster with 26" tires. I love the instant thrust these gears provide but in my opinion it's not much of a highway cruiser. I don't care to cruise it over 65mph, especially with the factory air on.

I almost went for the 3:23 gears, they are a better compromise for street duty. I would not open up that can of worms to swap 3:23's for 3:55's.

Your factory gearset will be quieter than the aftermarket set you replace them with. My 78 350 powered Crumaro has a 3:08 gear and it is perfect for a cruiser.

A stout limited slip diff. and ss springs will help you make good use of your power from a standstill with your 3:23's.
 
3:73's or 3:91's and an OD trans for a street/highway cruiser. Quick out of the gate and low rpm and good fuel mileage for highway cruisin' toolman
 
why not put the lower gear in, and have 2 sets of tires? Some 26, some 31?
Change the ratio that way.
 
"Some argue "but 4.10s were street gears way back when"...sure, but highway speeds are MUCH higher these days...I cruise at 75-80 mph just to keep up with traffic around some days, and I don't want the motor screamin to do it...racing is not nearly as important as drivability for me."

Got to call BS on that one. Speed limits were at least as high when these cars were in production, at least up until 1975 or 1976, when speed limits were reduced in a typical government knee-jerk effort to save fuel. Sure, a bunch of earlier cars were built with 4.10 rear ends under them, but they weren't installing 6.95 x14 inch tires with those 4.10 rear ends, either. The bigger circumference of those tires pretty well cancelled out the effects of the slower rear ends.

If you want a higher ratio rear end for quick get-aways, why not bolt up an overdrive transmission in there? That way you can raise all the hell you want, and when playtime is over, shift into overdrive so you can hear yourself think!
 
I run a 391 gear on the street I like it.I run that same gear on the highway also.323 to a 355 i don't think it is worth it.
 
C39 said:
"Some argue "but 4.10s were street gears way back when"...sure, but highway speeds are MUCH higher these days...I cruise at 75-80 mph just to keep up with traffic around some days, and I don't want the motor screamin to do it...racing is not nearly as important as drivability for me."

Got to call BS on that one. Speed limits were at least as high when these cars were in production, at least up until 1975 or 1976, when speed limits were reduced in a typical government knee-jerk effort to save fuel. Sure, a bunch of earlier cars were built with 4.10 rear ends under them, but they weren't installing 6.95 x14 inch tires with those 4.10 rear ends, either. The bigger circumference of those tires pretty well cancelled out the effects of the slower rear ends.

If you want a higher ratio rear end for quick get-aways, why not bolt up an overdrive transmission in there? That way you can raise all the hell you want, and when playtime is over, shift into overdrive so you can hear yourself think!
Click to expand...

Overdrives are a great idea but dont work for every car. Try making one work with 4:10's and a 3500 stall. Might if you can get a locking tq...

I like the idea of and overdrive though.
 
I guess I was thinking of 833 overdrives. Automatic overdrives can be beefed up to handle the power. toolmanmike
 
Thanks for the info guys, these are great ideas. I do not really race the car so 4.10 are not an option. It is mostly street and the odd highway trip. I actually bought a very nice set of 3.55 gears out of a 70 Duster for $80.00 just to have. I have not fully decided which way to go yet, but i have to pull the pumpkin, because by gears are howling like crazy from the bearings. Might just throw the 3.55 in for a little to try them anyway. Keep the posts coming they are great!
 
My 2-cents. On my '68 Cuda 340 727, just changed over from 3.23's to 3.55's. I noticed very little diference driving around town. On the freeway at about 60 mph I'm revving about 500 rpm more. My opinion, keep the 3.23's if you do much highway driving.
 
green1 said:
why not put the lower gear in, and have 2 sets of tires? Some 26, some 31?
Change the ratio that way.
Click to expand...

That works too. I ran 24.5" rubber with a 3:08 for a while and they felt like 3:55's. With 27" rubber they feel like the car has overdrive.
 
I drove my 69' 340 Dart GT to Spring Break in Daytona FLA. from Buffalo,N.Y.
with 3:55 gears. I also raced the car in the 1/8th mile turning times in the 8.90's ...I love the gear, but would consider 3:73's if I had no plans on regular long distance driving.I think you will love the 3:55's !
 
You can always buy a 3.91 chunk like my buddy has and install it before going to the track then put the highway chunk back in when the season is over.

I was thinking of doing the same just because I love the 3.23 gears as they have really great street manners, but I am very curious what a set of 3.73 or 3.91's would do to my world and I am always keeping my eye open for a 742 case'd 3.91 sure grip chunkeroonie.
 
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