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09-18-2014, 09:20 AM
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#1 |
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Registered User
Join Date: Sep 2014
Location: Granite Bay, CA
Posts: 11
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Final Drive Questions
I am in the planning stages of a crate LS3/trans swap into my 68 stepper. Currently it has 3.73 gears in the rear. At 60 MPH the truck is really winding out. I need recommendations for my final drive ratio based on the following:
1. Freeway cruise speed of 70-75 MPH 2. Economy with some spirit 3. 4L70E top gear ratio of .70-1 On the crate powertrain combo I am considering, (CPSLS3764804L70E) The converter is a lock up with a stall of 3000-3400 RPM. Is this a good stall for a truck that will be my daily driver? Any help would be really appreciated. Thanks Last edited by Guss; 09-18-2014 at 09:31 AM. |
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09-18-2014, 09:36 AM
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#2 |
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Registered User
Join Date: Dec 2007
Location: Nanaimo B.C.
Posts: 604
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Re: Final Drive Questions
3.73x.7=2.61 looks good to me
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I was hooked on these trucks since 1982 when I drove my budys fathers 1968 Custum GMC 396 automatic dana 60 rear with a power lock diff what a ride more fun then we will we can ever tell!! |
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09-18-2014, 10:14 AM
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#3 |
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Registered User
Join Date: May 2009
Location: Motor City
Posts: 9,179
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Re: Final Drive Questions
3.73 is perfect for me with a .70-.73 overdrive trans.
K
__________________
Chevrolet Flint Assembly 1979-1986 GM Full Size Truck Engineering 1986 - 2019 Intro from an Old Assembly Guy: http://67-72chevytrucks.com/vboard/s...d.php?t=342926 My Pontiac story: http://forums.maxperformanceinc.com/...d.php?t=560524 Chevelle intro: http://www.superchevy.com/features/s...hevy-chevelle/ |
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09-18-2014, 10:38 AM
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#4 |
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Registered User
 
Join Date: May 2013
Location: WEST PALM FLORIDA
Posts: 1,174
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Re: Final Drive Questions
I agree with the other posters , the overdrive trany you are installing should work great with your combo on the highway , wish I had one in my ls equipped truck [see tag line] , tire size makes a big difference also my lowered 68 has tires around 27 inches tall , building a 67 now with 31x10.5x15 tires , its a big difference post some pictures please
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68 Long Fleet , ly6 , turbo 350 , 3-5 drop , original paint , front discs 67 Small window , 7 foot bed , tweaked 6.0 LSX 2004R Medium Olive 58 Apache fleet , 235 , offy intake , dual exhaust , 4 on the floor , red/white 69 Long Fleet , Custom , 6.0, 4l60 , AC , Medium Olive |
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09-18-2014, 09:29 PM
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#5 |
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Registered User
Join Date: Sep 2014
Location: Granite Bay, CA
Posts: 11
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Re: Final Drive Questions
Thanks for the replies everyone. Here are some pics as requested.
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09-18-2014, 11:08 PM
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#6 |
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Registered User
Join Date: May 2013
Location: WEST PALM FLORIDA
Posts: 1,174
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Re: Final Drive Questions
That truck is GORGEOUS
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68 Long Fleet , ly6 , turbo 350 , 3-5 drop , original paint , front discs 67 Small window , 7 foot bed , tweaked 6.0 LSX 2004R Medium Olive 58 Apache fleet , 235 , offy intake , dual exhaust , 4 on the floor , red/white 69 Long Fleet , Custom , 6.0, 4l60 , AC , Medium Olive |
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09-19-2014, 07:22 AM
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#7 |
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Registered User
Join Date: May 2009
Location: Motor City
Posts: 9,179
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Re: Final Drive Questions
Ooh. I like that.
K
__________________
Chevrolet Flint Assembly 1979-1986 GM Full Size Truck Engineering 1986 - 2019 Intro from an Old Assembly Guy: http://67-72chevytrucks.com/vboard/s...d.php?t=342926 My Pontiac story: http://forums.maxperformanceinc.com/...d.php?t=560524 Chevelle intro: http://www.superchevy.com/features/s...hevy-chevelle/ |
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09-19-2014, 08:15 AM
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#8 | |
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Account Suspended
Join Date: Jan 2007
Location: Tucson
Posts: 2,183
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Re: Final Drive Questions
Quote:
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09-19-2014, 05:52 PM
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#9 |
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Registered User
Join Date: Jun 2011
Location: United States
Posts: 158
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Re: Final Drive Questions
I have 3.73 gears behind an LS-equipped T56 with a sixth gear ratio of 0.63. It ticks over around 1,600rpm at 70-75mph with a 27-inch tire. You should be very happy with the ratio you mentioned. My supercharged LS gets around 14mpg around town with the A/C on; I would expect closer to 20 in a crate engine'd situation, FWIW.
We've done a handful of crate LS swap (engines & transmissions) in our tech center and they're hands-down the easy way to do an engine swap. It's literally all plug and plug and the ECUs that Chevy provides controls the ignition, fuel, and transmission, which is very nice. No messing about with different ECUs, etc. I would leave the engineering up to GM as far as the torque converter specs go, but that's just me. They've considered way more things and put way more thought into the package than any of us could imagine. Hope that helps! |
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