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Topic: Differential gears

in Forum: C3 Engines, Driveline and Handling


Differential gears

Posted: 6/29/08 10:51am Message 1 of 7
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Canada
Joined: 10/17/2007
Posts: 39
Vette(s): 1980 Silver, L48 Totally re-built at 52,000 KM Now 355 CI Edelbrock Performer package Dual exhaust
Hi All:
 
Just rebuilt the original block now has about 320 HP and 355 Torque.  Complete Edelbrock Performer package (Not RPM Package).
 
I find it is still slow off the line and will not spin the tires at all.  Once on the highway it runs great and has good pull.
 
The build sheet indicates it has 3.07:1 gears.  I know this is a tall gear  so I was wondering what would be the best selection for a rear gear set to get a little more power off the line but have good gas mileage on the highway?
 
Thanks in advance,



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Differential gears

Posted: 6/29/08 1:13pm Message 2 of 7
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HOWELL, NJ - USA
Joined: 5/18/2004
Posts: 6812
Vette(s): 1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.
A good factory gear set is 3.55:1. Much better than the 3.07 and still reasonable for cruising. I have a great contact for rebuilds  - sending you a PM. LukesVette2008-06-29 13:14:03


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Differential gears

Posted: 6/29/08 2:34pm Message 3 of 7
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20225
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas
Ya...3:55 or 3:36 would be a good choice.

Is this a 4 speed or automatic car?Adams' Apple2008-06-29 14:35:30


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Differential gears

Posted: 6/29/08 6:25pm Message 4 of 7
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VENTRESS, LA - USA
Joined: 10/8/2003
Posts: 87
Vette(s): 1971 Blue Roadster, sb400, cam, electronic ignition,10 disc CD changer, 2.5" chambered exhaust, 3.36 rear,tremec 5 speed from Classic Chevy, fiberglass rear spring and vintage air.
I've got 3:36 with 4 speed and would tach 3000 rpm at 70 mph. Put 5 speed in for mileage and reduce rpm. Now 2000=70mph.


Differential gears

Posted: 7/12/08 8:00am Message 5 of 7
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Falls Church, VA - USA
Joined: 3/22/2006
Posts: 232
Vette(s): 1975, 4 speed, L48, NOW Silver mist, Oxblood inside 2003 50th Av Torch RED little brother to 75
Good stuff I'm getting ready to have mine rebulit. This tread helps but 3000 RPM at 70 isn't that still a little to hi? I'm not changing the trany out like Ray. Any more Ideas guys about gear set up??? Thanks
 
sgm2003 AKA Guy



Differential gears

Posted: 7/12/08 9:37am Message 6 of 7
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Dorr, MI - USA
Joined: 8/21/2002
Posts: 2581
Vette(s): 71 Colonnade Hardtop Coupe Torch Red with black interior originally L48 built to push around 360hp
[QUOTE=Whtlitnin]I've got 3:36 with 4 speed and would tach 3000 rpm at 70 mph. Put 5 speed in for mileage and reduce rpm. Now 2000=70mph. [/QUOTE]
 
I'm at 2900 RPM 75 MPH Ray. Maybe one of us is off a little? I have 3.36, 4 spd. My motor is a built 383.  I can lite em up out of the hole, and still get 18 mpg. I am considering putting a 5 speed in someday.



Differential gears

Posted: 7/12/08 12:24pm Message 7 of 7
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WEST SENECA, NY - USA
Joined: 12/3/2001
Posts: 2381
Vette(s): 1981 Blue Ice Met. w/pearl ghost flames TKO500 5speed. LS1 Swap 3.45 Dana 44.
Well unfortunately '80 thru '82 Dana 44 "aluminum" rearend gear selection seems slim compared to '63-'79 "cast iron" rearends.
 
Factory gear sets available were 2.72, 2.87,3.07.
I've only seen 3.55 & 3.70 gear sets offered in the aftermarket for '80-82.
 
I had 2.72's in mine originally, and then later swapped in a '80 diff with 3.07's. I was a small improvement. I just recently put in a Keisler 5 speed kit. Now even with the 3.07's it launches like it has a 3.90 rearend gear. The overdrive gear help the car to acheive 22 mpg at speeds around 75mph on the highway.
 
So if the only other available choice up from a 3.07 is 3.55, then you'll probably have better off line performance with dismal fuel economy. So if you want the best of both worlds... I say overdrive transmission. Auto or Manual.
 




GEN III 5.7L "LS6" Engine swap
TKO500 5 spd.

3.54 Dana 44
'69 "N11" Sidepipes
Borgeson Steering Box
Born 8/1981
Sequence #3975




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in Forum: C3 Engines, Driveline and Handling


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