Hi all Just wanted to get some opinions on my transmission/rear end set up. As many of you know I am bulding a 68 Skylark Vert for the wife. The chassis is done and now I am ready to set in the driveline. I am trying to decide whether to have the Turbo 350 rebuilt or use a 700R4. The car will be mainly driven around town to local shows and once or twice a year on roadtrips. Initially I thought the 700 was the way to go because of the overdrive and the added gas mileage, however since the car will not be a daily driver it will take a long time to save enough in gas to pay for the added expense of that transmission. I have used 350's in many cars over the years and find them to be bullet proof on stock or slightly modified cars. Also I would like opinions on what rear end gears to use with either trans. I want to be able to drive the car on the freeway without it taching real high, but still want to experience good acceleration from the signals. The engine is a basically stock 350 with headers, HEI, aluminum manifold and Edlebrock carb. Thanks for any thoughts and/or suggestions
If you have a choice more use the 200R. The problem is that you have something like a 2.73 ,8.2, 10 bolt. Getting a gear past a 3.23 may be hard so you may be forced to go to a 8.5 rear so you can go to a 3.55 or 3.73 to take avantage of the OD.
Below are listed the gear ratio's for GM transmissions ...TH350...TH400 Lo..2.52.....2.48 2...1.52.....1.48 3...1.00.....1.00 ..200-4R.....700R4/4L60E.....4L80E/4L85E Lo..2.78...........3.06.............2.48 2...1.57...........1.63.............1.48 3...1.00...........1.00.............1.00 4...0.67...........0.70.............0.75 The 700R4 is tough to beat with its numerically high 1st gear and 0.7 OD - plus it doesn't require any computer tie-ins. If you want to stick with the TH350, a ~2,000-ish stall converter and 3.08's or 3.23's would get you moving off the line yet keep cruising RPM's reasonable. Even after you select a gear, there is still "wiggle" room to adjust it by using anywhere from a 26" diameter tire up to 29"
The 700R4 requires an adapter because it was chevy only. The 2004R came in a universal or BOP. The 2004R is an easier swap because is was based on the TH350. The overall length, the driveshaft yoke, dipstick/fill tube, and the rubber mount are all the same as the TH350. It's also lighter and has a better overdrive than the 700R4. My 350 turns 2200 RPM at 70MPH with 200R4 and 3.73 gear. I love it but for what you want it seems to me that the stock trans and gears would be just fine. Better acceleration with no tradeoff(except cash) is the only reason I went with my combo.
Thanks guys for the information. It gave me what I needed to know. The decision was made today. I am putting a TH400 in the car. My rebuilder will do it for the same price as a 350 so what the heck. I know I'll have to do some work on the driveshaft, but not a big deal. Would you stll suggest using 308's with the 400? Thanks again
Th300 Vs 350 TH400 is heavier and bulletproof, but your car would be faster with the 350. Greg Gessler runs a 350 in his FAST car - less weight and less rotating mass.
I have a lower 1st and 2nd gearset in my TH400.....with 3.08's in the rear, it makes my 1st gear look like 3.42's, 2nd looks like 3.23's and of course third is 3.08. I call it a poor Mans' OverDrive o No: The gearsets aren't cheap though - I did it about 7 years ago and they were ~$400.
