Was wondering what RPM's I should be turning at 65 MPH in Overdrive with my 2004r trans with 3 different gear ratios/ I bought a set of 3:55, Thinking about 3:91 or 4:11. The rear wheels are 27" tall. 2004r trans and a 383 stroker. What is the highest RPM you would want to run going down the highway @65 if gas mileage meant nothing to you. I was thinking around 2500 rpms would be about the max for a long haul. Does anyone have the conversion chart for this. Also is the rear out of an 81 the same or different then my 72. I found a set of 4:11 for an 81.
Vette(s): 1981 Blue Ice Met. w/pearl ghost flames
3.45 Dana 44.
From the info you gave, I ran some numbers through an online engine rpm calculator. The 200R4 I believe has a .67 overdrive ratio. At 65mph a: 3.55 = 1924 rpm approx. 3.91 = 2119 rpm 4.11 = 2227 rpm
'80-'82 differentials are the aluminum DANA 44. These are weaker that the cast iron units. Gear sets from '80-'82 will not work in the older cast iron '79 and older corvette differentials.
Some guys with '80-'82 vette are adapting the cast iron units to the aluminum "batwing." Good upgrade if you going to be pushing some power.
Speaking of diff's. Not to get off the subject. I'm waiting for my differential for the '81 to come back from a fellow in Texas. I had him machine a left bearing cap out of billet steel and fit a C4 carrier w/posi unit. These are a weak points in the Aluminum Dana 44. I'm going with 3.54 gears. This should work good when I swap over to the "Baby LS1" engine.
|UPDATED|5/26/2012 7:04:00 PM (AZT)|/UPDATED|
GEN III 5.7L "LS6" Engine swap TKO500 5 spd.
3.54 Dana 44
'69 "N11" Sidepipes Borgeson Steering Box Born 8/1981
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
Personally, I'd go with the 3.55, but the 3.91 would be ok too. I would not go to 4.11 if planning on running very many highway miles. Low ratio gearsets like that tend to get hot in use. I think Darryl's RPM/Gear ratio "chart" is prolly correct. Also correct in that you cannot use gearsets designed for the Dana(aluminuminum) carrier in the iron carriers.
____________________________________ Joel Adams C3VR Lifetime Member #56 My Link
Thanks for the replies. I will start to look for a set of 3:70, 3:90 or 4:11. If I dont find any of these by the time I pull mine apart I will go with the 3:55 gears I bought. The overdrive looks to make a huge difference. Thanks again for the responses Rodney
Corvette is a registered trademark of the General Motors Corporation(GM) &
Chevrolet Motor Division. Vette Registries, LLC is responsible for all site content (except for member submitted content or where otherwise
noted) and does not claim or imply that Chevrolet or
GM is responsible for Official C3 Vette Registry content. Vette Registries, LLC is independent from GM and is not affiliated
with, sponsored or supported by GM. Copyright/trademark/sales mark
infringements are not intended, or implied and are in fact used to support
GM, Chevrolet and Corvette.
Official C3 Vette Registry content is Copyright 2001-2017, Vette Registries, LLC. Content may not be reused without written consent. All Rights Reserved. NS
Corvette (Vette) Model Years on this site: 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982