I currently run a 350ci and a TH350 trans, non overdrive, with a 3.73posi axle ratio , 255/60-15 tires. I dont race, mostly cruising and stoplight stuff. I find that the 3.73 rpms me a bit too much for my tastes. I run out of gear real quick when I floor it from a standstill. It gets up and goes, but I dont really like the rpms I achieve at hi speeds, the occasional highway trip. Anyhow, I am considering a ratio change this winter, and am looking for thoughts on 3.23 and 3.42 ratios. I guess I can do the math to find rpm ranges to suit me, but the best way to know the difference in a seat-of-the-pants sense is to try the ratios. So I thought Id ask the ppl who have experience running these gearsets for their thoughts? I'll probably end up trying all the ratios eventually..... Ken G.
I went from a 3.08 to a 3.73 in my GS and think a 3.42 would be a great all around setup. I have a 700R4 with a lock up converter however. Mike D.
Ken, going from a 3:73 to 3:42 isn't really going to change the driveability and rpm too much. I would go for the 3:08's which will improve your highway driving rpms, and the car will still have some giddy up.
My GS has a 3.08. I race mine a little and wish I had a little more gear on the strip, but for the street the 3.08 is fine. After years of driving cars with O.D., it seems that even the 3.08 buzzes the engine a little much on the highway with the THM350. I keep expecting it to shift again. It still has plenty of acceleration with this gear. I've been running 14.50 et's with the car, which has a '70 sp code 350, basically stock except for a mild cam and 2.5in exhaust.
If you can find a tire about 2" taller, you would get about the same net effect as changing to a 3:42 (assuming your tire is about 26.5 in tall). Maybe you can borrow some from someone and try them out to see if the 3:42 is enough change, which is about a 10% reduction in cruising rpm.
That is what I had to do when I went with 3.42's, the rpm's were too high on the freeway, so I went with taller rear tires to comensate.
The GS350's came stock with 3.23's in 69, I would have to think that Buick probably put a lot of that into it and figured these were a pretty good all around gear for the 350.
Rather than change the rear end, why not install a 200-4R tranny and this will give you the best of both worlds. The 3.73 is great for acceleration, and with a ,67 overdrive ,you will end up with a better cruising gear than either of the ratios you are looking at
Me too! The Old Guy beat me about the head and shoulders for about a year on which tranny to go with, finally got tired of the abuse and put a 200-4r in and will never go back. I run a CZ code (SS Monte Carlo) with a mild build in a 12 second Lark. With a stock 350 you can go with a stock trans.
In a nutshell- The more important highway driving is, the taller gear you'll use. The more important the "strip" and takeoff is, the shorter gear you'll use. I love my 2.56s. You'll really have to answer for yourself though. -Bob C.
The one thing I can say about this hobby of mine is that you learn something from every build. I learned that a 3.42 ratio is the best all around gear for a car without overdrive and put that ratio in most of my builds now. I just finished my 1970 malibu build up and went from a stock 2.73 to the 3.42, also swapped the lame 307 for a 327 I built myself. Wow, no longer feels like grandma's car! I believe the 3.23 would make the best gear for your situation, it would make a big enough change to help your cruise rpm. Steve
