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Rear end gears #2551352
09/18/18 01:16 AM
09/18/18 01:16 AM
Joined: Sep 2018
Posts: 257
NC
7
70charger512 Offline OP
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70charger512  Offline OP
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NC
Hi, I have decided to use the lunati voodoo 60303 cam for my 440. It is a daily driver that I want to obviously have good power (500+). Since its a daily I was wondering if 3.73 gears would still have good street manners over 3.55, or should i compromise the low end torque and get the 3.55s for much better street manners?

Re: Rear end gears [Re: 70charger512] #2551360
09/18/18 01:38 AM
09/18/18 01:38 AM
Joined: Jan 2003
Posts: 32,882
Grand Prairie,Texas
stumpy Offline
I Win
stumpy  Offline
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Grand Prairie,Texas
daily driver would be better with the 3.55 gears and still have plenty of go fast.

Re: Rear end gears [Re: 70charger512] #2551371
09/18/18 02:57 AM
09/18/18 02:57 AM
Joined: Aug 2003
Posts: 43,007
Bend,OR USA
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Cab_Burge Offline
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Bend,OR USA
The difference in those two ratio is only .049 %, less than five percent, from the 3.73 to the 3.55 shruggy work
That would reduce your RPM cruising at 2000 RPM down to 1900 RPM, at 3000 RPM down to 2850, correct work


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Rear end gears [Re: 70charger512] #2551418
09/18/18 10:50 AM
09/18/18 10:50 AM
Joined: Jan 2003
Posts: 1,331
Oregon
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earlymopar Offline
pro stock
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Oregon
What rear tire diameter, transmission, car weight?

- EM

Re: Rear end gears [Re: 70charger512] #2551485
09/18/18 01:39 PM
09/18/18 01:39 PM
Joined: Sep 2018
Posts: 257
NC
7
70charger512 Offline OP
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70charger512  Offline OP
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NC
Sorry about not mentioning that hahaah, 26.61 tire, tko600, and chargers weigh around 3600 lbs correct?

Re: Rear end gears [Re: 70charger512] #2551487
09/18/18 01:46 PM
09/18/18 01:46 PM
Joined: Nov 2003
Posts: 2,936
GA
roadrunninMark Offline
master
roadrunninMark  Offline
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GA
If I am looking at the right gearing of your trans, a 2.87 1st and .68 5th, the 3.55 gear would put you at about 10.2 to 1 first gear ratio and a final of 2.41. If you already own the 3.73 gear, I would keep it, no need to waste money for such a small change. Otherwise, get the 3.55. It will give you a little better cruising RPM in overdrive.

Re: Rear end gears [Re: 70charger512] #2551505
09/18/18 02:17 PM
09/18/18 02:17 PM
Joined: Nov 2006
Posts: 2,252
IL
furious70 Offline
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IL
As the owner of a car with a cammed 440 and a .68 OD ratio with a 4.10 dana, my perspective is I still don't have enough gear to make effective use of OD until I'm going 70mph. Of course it screams in 4th gear at 65. The tremec gear splits don't work great with cammed up street cars IMO, 1st gear is already granny gear, if I put any more gear in it I'd never use first, less gear and I'd only use OD when I can go 80 on the freeway. If you go with a 3.55 I don't think you'd often find yourself in 5th gear.


70 Sport Fury
68 Charger
69 Coronet
72 RR
Re: Rear end gears [Re: 70charger512] #2551729
09/18/18 11:44 PM
09/18/18 11:44 PM
Joined: Jul 2011
Posts: 953
Chicago
PurpleBeeper Offline
super stock
PurpleBeeper  Offline
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Chicago
Furious is giving you some really good advice. No overdrive, then 3.55's or 3.23's. With overdrive, 3.73, 3.91 or 4.10


70 Roadrunner convt. street car 440+6, NOS, 4-spd, SS springs '96 Mustang GT convt. street car '04 4.6 SOHC, NOS, auto, lowered "Officer, that button is for short on-ramps"
Re: Rear end gears [Re: 70charger512] #2551734
09/18/18 11:51 PM
09/18/18 11:51 PM
Joined: Jan 2003
Posts: 32,882
Grand Prairie,Texas
stumpy Offline
I Win
stumpy  Offline
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Posts: 32,882
Grand Prairie,Texas
This might give you a basic idea for a gear selection. I haven't been able to find the VEXER one. https://www.reillymotorsports.com/speed-tire-rpm-calculator.html.
Another one. http://www.crawlpedia.com/rpm_gear_calculator.htm

Re: Rear end gears [Re: 70charger512] #2551737
09/19/18 12:01 AM
09/19/18 12:01 AM
Joined: Nov 2004
Posts: 25,050
Texas
GoodysGotaCuda Offline
5.7L Hemi, 6spd
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5.7L Hemi, 6spd

Joined: Nov 2004
Posts: 25,050
Texas
I'd run a 3.55 in a non-OD application.


With a 0.63spd I've actually considered going from 3.91 to 3.73 for just a hair lower cruising rpm [I probably need to dig into the diff anyway], but it's not really necessary. I knocked down 20mpg on the last road trip at 80mph.


1972 Barracuda - 5.7L Hemi, T56 Magnum 6spd - https://www.facebook.com/GoodysGotaHemi
2020 RAM 1500
[img]https://i.imgur.com/v9yezP9.jpg[/img]
Re: Rear end gears [Re: 70charger512] #2551870
09/19/18 11:22 AM
09/19/18 11:22 AM
Joined: Jan 2003
Posts: 1,331
Oregon
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earlymopar Offline
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Oregon
I have an almost 31" tall tire, also have the TKO600 and running 3.91 rear end ratio.

- EM

Re: Rear end gears [Re: 70charger512] #2551881
09/19/18 11:48 AM
09/19/18 11:48 AM
Joined: Nov 2006
Posts: 2,252
IL
furious70 Offline
top fuel
furious70  Offline
top fuel

Joined: Nov 2006
Posts: 2,252
IL
I should have said I've got 28" tires.
A 5.7 hemi is going to feel very different about the 'lugging' rpm, the heads are far more efficient than the old stuff.


70 Sport Fury
68 Charger
69 Coronet
72 RR






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