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Join Date: Mar 2005
Location: Jeannette Pa. near pittsburgh
Re: Thoughts On A Gear Ratio For My Rear End
Here is what I have. 1970 Nomad Sta. Wgn. 4380 Lbs. I built it to look like a SS 454, Its a very nice FRAUD.
My engine is a mild ( like the LS-5, 468)---Transmission- 700R4---Rear end---Chevelle 12 bolt with 3:07 gear, WHY a 3:07 gear?
My 700R has a 3:06 first gear ( Kinda like low range in a 4WD.). Mash on it from a dead stop and the Prius beside you will drive away while you are burning your tires down. While burning the tire it may or will go to second. ( burning tire and shifting under these conditions is not a smart thing to do with a 700.)
Why a 3:07 rear gear? G.M., Chevrolet used a lot of 3:08s with the 700R4 transmissions. So, Before I went to a 3:07 -12 bolt, I ran the 10-bolt 3:08 for a year just to see the results. I was a Happy Camper. So I built a 12 bolt with a 3:07. Here are some numbers. My 700 has a bit over 40.000 miles on it. first wagon engine 396 then a 454 now a 468. AND NO, I do not race it or mash on it a lot. WHY? My pea brain says, G.M.s 700R4 transmission were built for V-6s and small " TORQUE " V-8 engines.
Since I have GEESER statis,,, I know Dam well BIG TORQUE engines will find the " WEAK " link in the chain.
At 75 MPH in Electronic cruise. B.B. spins 1975 RPMs. & 18-19 MPG.----- W-A/C= 16--17.
At 65 MPH in " " " " B.B. spins 18?? RPMs & 20 MPG. W-----A/C=18--19
My tires a 225 X 70R X 14".
Not real good fuel mileage in traffic or going to a cruise,,, Its in first & second a lot. Fuel delivery= 1970 Q-Jet built for this engine.
If you want to beat on it? I would go with a T-400 or a 727.
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1970 SS LS-5/M-22 El Camino- Org. Owner-AACA 2016-Senior Grand National Winner---MCACN-GOLD-2013
1970 ( FRAUD) SS 468 Station Wagon - Driver.