As the header states, I'm running a Stage 1 455 & TH400 in my GN. Current gears are 2.41, and the car doesn't accelerate too well. I've had this engine in my GS California for several years and was running a set of 3.31's. I have a set of gears already, and want to put them in the 7.5 that the car currently has. (26 spline axles, I know, weak). I can swap them in using a ring gear spacer and have tons of torque multiplcation, but wondering on highway speed RPM and shift points. My other option is to get a rear from a Monte SS (known 3.73's) and do the whole unit swap. Either way, should improve the performance greatly. Bottom line, is this too much gear for street use? Jim GN Clone
It is funny how rodders think about different things in different times.... back in the 60's if you were not running 4.11 or lower you were not running a gear.... 4.56 and 4.88 was common ... and I am talking on the street.... the most popular street/strip set up was 3.90 to 1.... now.... with all that said, I would go for the range of 3.55 or 3.73 for a street/strip car...
without a overdrive i would look for a set of 2.93-3.08 i have 2.73 and its good for the streetbut not so good at the track just my opinion scott
how tall are your tires? We run 3.42 in red car, and I put 3.08 in my convertible. Had 4.10 in race car and went back to 3.42. We run 28" tall rear tires. The 455 has plenty of torque to run a 3.42 gear and have good mix of power and still drive on highway.
The problem is soft performance on take off (2.41 gear set). Feels just plain mushy on the launch. I already have the gear set & would need to get the spacer to make this "work". Running a 235/60R15 (all round) which I believe is a 28" tall tire. I'd like a set of 3.42's, but since I have the 3.73's.... BTW - had the same issue when running the BBC & SBC, take off is lacking, but top end is awesome. Jim
3.73 are alot of fun on the street. Make sure your cooling system is up to the task and more importantly your wallet. Most people do highway and city driving. If your highway driving is 40% or more of you total driving, you might wanna rethink the 3.73.
Had them in my MC SS, lots of fun, but also had OD. Thinkin' this will run in the 2800-3200 range on the highway. Since it is a "fun car" and not a DD, that is gonna be OK. Radiator is a new Desert Cooler, brand new & plenty thick. Also have a heater, but might end up deleating it again. Just gonna send all the parts with it when it sells. I'm gonna let this thread run over the weekend and decide next week. Jim
Those rear ends are really weak. So are the Monte Carlo rear ends. The GN rear end is the one you want.
I'd cast my vote for anything in the low 3's. I've got 3.08s which are perfect in the Pontiac, 3.23's in the 65 which allow me to drive back and forth to the track and still run quick, and 3.42s in the 73 which are a bit revvy at 80 mph. I have 3.55s in the corvair, and I'm running 4500 -5000 rpms at 90.. in that car it's ok, but in anything else I'd avoid them.... Like Doc says, interesting how attitudes have shifted...
A 235/60-15 is 26" tall, not 28". 3.73 is a good gear, although its not that highway friendly. I would reconsider putting a 7.5 behind a 455 and a turbo 400.
I ran 4.10s in my daily driver for quite a long time. With 255/70R15 I turned 3500@70 It was a blast until I had to drive an hour to school or 2 hours to the drag strip. After 2 years, switched to 3.73s and it was a little better. With 275/60R15 I turned 3200@70. If you don't drive long distances or have a cam/torque converter/cooler combo that can handle spinning that speed you can do it. I still have 3.73 and 275/60R15 but I have a turbo 200-4R now and turn 2200@70.
