Topic: Differential gears
in Forum: C3 Engines, Driveline and Handling
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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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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. LukesVette 2008-06-29 13:14:03
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Ya...3:55 or 3:36 would be a good choice.
Is this a 4 speed or automatic car?Adams' Apple 2008-06-29 14:35:30

Is this a 4 speed or automatic car?
Joel Adams
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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.
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
[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.
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.
in Forum: C3 Engines, Driveline and Handling
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