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3.91 or 4.30 gears for the street and track?

Posted By: 67dodge67

3.91 or 4.30 gears for the street and track? - 03/10/10 10:59 PM

I've got a simple question here. 67 Coronet, 470, 727, 11" PTC converter, 28" tire. Which gears would you choose? 3.91 or 4.30? It will see both street and strip.


Opinions?

Thanks for your help.
Posted By: mopars_1

Re: 3.91 or 4.30 gears for the street and track? - 03/10/10 11:00 PM

3.91's would be my choice
Posted By: DaytonaTurbo

Re: 3.91 or 4.30 gears for the street and track? - 03/10/10 11:01 PM

With 4.30's and a 28" tire, you may run out of rpm before the end fo the 1/4 mile. And niether one of those gears will be the greatest on the highway but you can play with this calculator:

http://vexer.com/68rt/speed.html
Posted By: jvcuda

Re: 3.91 or 4.30 gears for the street and track? - 03/10/10 11:04 PM




Have a 3.91 in my '73 cuda,440,727,28" tire


Posted By: Dougsmopars

Re: 3.91 or 4.30 gears for the street and track? - 03/10/10 11:05 PM

3:91's. There not that bad on highway. 4:30's are way to much. Top speed on high way will be around 60 and taching around 3800 to 4000. I had 4:57's with a 4 speed. It was fun around town but forget the high way a prius will blow your doors off on the freeway. lol
Posted By: solidcam

Re: 3.91 or 4.30 gears for the street and track? - 03/10/10 11:11 PM

Posted By: KillerBee

Re: 3.91 or 4.30 gears for the street and track? - 03/10/10 11:14 PM

Between the 3.91 and the 4.30 I would pick the 3.91's unless you want evey tenth in the 1/4 but the 4.30 gear might be too much gear with a 28" tire.
If I had my choice I would go with 4.10, that's what I have in my Challenger with 28" tall tires.

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Posted By: 67dodge67

Re: 3.91 or 4.30 gears for the street and track? - 03/10/10 11:23 PM

Ok. So far it seems 3.91's are the better bet here. Thanks for the input!

By the way, nice Challenger!
Posted By: Dcuda69

Re: 3.91 or 4.30 gears for the street and track? - 03/11/10 12:41 AM

I did a 3.73 w/a 470" and a 4 spd in my 69 B'cuda w/a 26" tire. With your 28" tire I think the 3.91's will be a good fit for street/strip!!
Posted By: aarcuda

Re: 3.91 or 4.30 gears for the street and track? - 03/11/10 02:29 AM

i have 4.30's wit ha 28" tire, 10" converter. i love it. around town its a blast. i drive 60 miles to the track but i keep it at 60 mph. 65 max. at 60 mph im revving around 3300 rpm, at 65 around 3500 rpms
Posted By: 67dodge67

Re: 3.91 or 4.30 gears for the street and track? - 03/11/10 02:36 AM

Quote:

i have 4.30's wit ha 28" tire, 10" converter. i love it. around town its a blast. i drive 60 miles to the track but i keep it at 60 mph. 65 max. at 60 mph im revving around 3300 rpm, at 65 around 3500 rpms



Hmmm.... interesting.... I haven't committed to either gear set as of yet... a 10" converter makes a difference then... anyone else with a similar set up as well?

Thanks!
Posted By: terzmo

Re: 3.91 or 4.30 gears for the street and track? - 03/11/10 02:46 AM

a 28 inch tire may rub the wheel well. I put 29's on mine and the fit but rubbed on a bump so out they came. I would say 27's would work and the 391's would be fine...430's may be too much for the motor...what HP ?
Posted By: gd9704

Re: 3.91 or 4.30 gears for the street and track? - 03/11/10 02:57 AM

I run 3.91s....I would consider them "max" if you're going to do any freeway driving....
Posted By: Nick Mineau

Re: 3.91 or 4.30 gears for the street and track? - 03/11/10 03:39 AM

i vote 3.91 but 3.55 would be better if you plan on driving it a bunch. a 440 should have plentey of power even with 2.73"S LOL. you might loose .2 in the 1/4 but it will go down the road much better. it really sucks when your race car cant keep up with traffic
Posted By: Mr340

Re: 3.91 or 4.30 gears for the street and track? - 03/11/10 12:46 PM

Quote:

Quote:

i have 4.30's wit ha 28" tire, 10" converter. i love it. around town its a blast. i drive 60 miles to the track but i keep it at 60 mph. 65 max. at 60 mph im revving around 3300 rpm, at 65 around 3500 rpms



Hmmm.... interesting.... I haven't committed to either gear set as of yet... a 10" converter makes a difference then... anyone else with a similar set up as well?

Thanks!


Same set up here but with a 340. I instaled a 416 last year and with the added torque I'm thinking of switching to a 3.91.
How tight do you want to turn that 470?
The 4.30 is fun stop lite to stop lite and if your not in hurry Ok on the freeway but I think the 3.91 will be more liveable.
Posted By: challenger70

Re: 3.91 or 4.30 gears for the street and track? - 03/11/10 03:48 PM

Quote:




Have a 3.91 in my '73 cuda,440,727,28" tire






Same combo I have in my challenger, fun on the streets and ok on the highway below 70.
Posted By: 2boltmain

Re: 3.91 or 4.30 gears for the street and track? - 03/11/10 04:35 PM

I had a Challenger with 29" tall rears and 4:10s. I did not like to drive on the highway. Too many RPMs to go 60mph.
Posted By: terzmo

Re: 3.91 or 4.30 gears for the street and track? - 03/11/10 05:04 PM

I have 29 inch tires on My bee with a 4 speed and turn just a hair less than 65 at 3000 rpm. 440 and 410 dana

The stock wheel well on 66 and 67 coronet and satellites don't accept a real big tire. I've seen 275 width the most with special offset wheels. BUT...try and fix a flat on the road with them. The wheel well on a 68 on up will accept much bigger tires/wheels.
Posted By: Barnstorm

Re: 3.91 or 4.30 gears for the street and track? - 03/11/10 05:56 PM

Surprised several years ago a buddy talked me into replacing my 3.91's with 3.23's. Ran 12.20's and 112 w/3.91's and 12.40's at 111 w/3.23's. Mileage went from 9 to 13 one the road, 65mph. Motor makes 511hp 580tq 500in...it doesn't care much for a deep gear. Torque motor.
Posted By: 67dodge67

Re: 3.91 or 4.30 gears for the street and track? - 03/11/10 06:11 PM

Quote:

I have 29 inch tires on My bee with a 4 speed and turn just a hair less than 65 at 3000 rpm. 440 and 410 dana

The stock wheel well on 66 and 67 coronet and satellites don't accept a real big tire. I've seen 275 width the most with special offset wheels. BUT...try and fix a flat on the road with them. The wheel well on a 68 on up will accept much bigger tires/wheels.



Going with the 3.91's. I mini tubbed my car a while back so I have added room for tires. Before I did that, I was able to get 255x70x15's in it but wanted a wider tire so I now have 275x60x15 mt drag radials.

Now I'm wondering which converter to use... I have an 11" now, but thinking a 10" or maybe a 9.5" would be better.

Thanks again for all the input.
Posted By: aarcuda

Re: 3.91 or 4.30 gears for the street and track? - 03/11/10 07:05 PM

Quote:

Surprised several years ago a buddy talked me into replacing my 3.91's with 3.23's. Ran 12.20's and 112 w/3.91's and 12.40's at 111 w/3.23's. Mileage went from 9 to 13 one the road, 65mph. Motor makes 511hp 580tq 500in...it doesn't care much for a deep gear. Torque motor.



you lost a 1/4 second with the gear change! thats a lot!!!!
Posted By: Stroked65Belv

Re: 3.91 or 4.30 gears for the street and track? - 03/11/10 07:07 PM

I run a 496/440 stroker, currently with 4.30 and 727 with 3000 stall. I had a 28" tire, @55mph 3000rpm. Went to a 29" tire and dropped approx. 150-200 rpm at same speed. I plan to switch to 3.91 myself and have a lil more driveability in the car. The 3.73 is also an option as well. The more cubes(stroker) = more torque. I dont think you need 4.30 as others suggested here youd run out of motor at the end of the strip. Keep the motor in its powerband longer other then way upstairs where you may come up short. The taller tire (29x11.50x15 Hoosier DOT slick 15x8"rim) in itself helped me a lot. Slightly taller and more rubber on the street. Blows away drag radials.
Try a dyno, possibly will find your powerband target zone and help you decide better.
Good luck.
Posted By: Barnstorm

Re: 3.91 or 4.30 gears for the street and track? - 03/11/10 07:56 PM

Don't care...tough to tell the diff...car is much more driveable on the hiway...I can still go rounds at 12.40.
Posted By: Exit1965

Re: 3.91 or 4.30 gears for the street and track? - 03/11/10 11:14 PM

Quote:

Quote:

Surprised several years ago a buddy talked me into replacing my 3.91's with 3.23's. Ran 12.20's and 112 w/3.91's and 12.40's at 111 w/3.23's. Mileage went from 9 to 13 one the road, 65mph. Motor makes 511hp 580tq 500in...it doesn't care much for a deep gear. Torque motor.



you lost a 1/4 second with the gear change! thats a lot!!!!



1/5th the way I calculate it. For the mileage increase, and possibly feeling better when taking it on the freeway, not that bad of a sacrifice..
Posted By: dOrk !

Re: 3.91 or 4.30 gears for the street and track? - 03/12/10 01:35 AM

A diff spin on all this .....

Big torque motor .. not a super heavy-weight car ...... and a real "streeter" ? ...

....GO WITH the shortest gear possible ... ie 2.76.

Your short-times(60 foot) will suffer a TAD but you will LOVE the driveability on the highway.

HOW would you like to a ZR1 Corvette from a 100-roll ? ..

Posted By: Barnstorm

Re: 3.91 or 4.30 gears for the street and track? - 03/12/10 02:17 AM

We don't have and 2.76 pumpkins around, but I'd try one if we did. purpose built torque motor for the street...give me 400 less rpms at 60 and maybe I can get 16mpg and now run 12.60's.
Posted By: dOrk !

Re: 3.91 or 4.30 gears for the street and track? - 03/12/10 02:34 AM

Quote:



...give me 400 less rpms at 60 and maybe I can get 16mpg and now run 12.60's.



THERE ya go ... Now I have a lite-weight 62 Belvedere, just a basic-HP rebuild, iron manifolds ... 276 gear ..

and it should run 12.30's and get near 20 mpg(if not more).
Posted By: Barnstorm

Re: 3.91 or 4.30 gears for the street and track? - 03/12/10 03:05 AM

Maybe Slantzilla has some thing that runs 12's and gets 30mpg.
Posted By: 67dodge67

Re: 3.91 or 4.30 gears for the street and track? - 03/12/10 05:21 AM

wow! this is interesting how my initial post has changed! haha no worries.... i'm following this and trying to get anything from it. hmmm...
Posted By: Anonymous

Re: 3.91 or 4.30 gears for the street and track? - 03/12/10 05:25 AM

I gave up on deep gears years ago after putting 4.56 gears in a street car and hating them.

Big surprise, went back to 3.23's and really didn't change e.t. at the strip!

Deepest I'll go with a street car now is 3.55's.

If I want better e.t.'s I'll throw a buttload of stall in the convertor at it.
Posted By: dOrk !

Re: 3.91 or 4.30 gears for the street and track? - 03/12/10 05:29 AM

Quote:

Maybe Slantzilla has some thing that runs 12's and gets 30mpg.



Hey HAY ...was this a jab ? ....

I had a junk-yard 440 in there ...and it ran 12.80's and got 17.

So THERE ....

And slant ...with his 'Tona ....maybe could get 40.
Posted By: Von

Re: 3.91 or 4.30 gears for the street and track? - 03/12/10 05:29 AM

Quote:

3:Top speed on high way will be around 60 and taching around 3800 to 4000. I



Unless you have 24 inch tall tires your converter needs help........
Posted By: 67dodge67

Re: 3.91 or 4.30 gears for the street and track? - 03/12/10 05:33 AM

OK... so that leads to my next question then.... why would you overkill your converter if your powerband is between 2600 - 5800? I'm going by what I have experienced driving it on the track... not the true numbers.

SOOOO my converter as of now is a PTC 11" and rated at 2800 which is AWESOME now. SOOOO would a 3000 or 3500 stall be that much better? That would be a 10" or a 9"? Sorry, converters are not my best subject (recap on my set up: 470, 727, 3.91, eddy rpm heads, rpm intake, 830 quick fuel, voodoo cam 513 intake, 533 ehxaust)

I'm open to any and all suggestions.
Thanks!
Posted By: terzmo

Re: 3.91 or 4.30 gears for the street and track? - 03/12/10 06:38 AM

converter also maens better efficiency of transferring power from motor to trans...on down

I have a 69 bee with a 30 over 440 6 pack setup and 410's but will run My plymouth...67..with a 498 stroker..auto...355's..with a 2200 to 2800 stahl...If I don't get into 11's I will first improve the converter

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