I dont know if anyone will be able to help me...but I will give it a shot. I have a 1969 Pontiac Firebird with a 3:11 rear end. When it comes to these ratios I know NOTHING! The car is great in the quarter miles and off the line, but the top end is pretty limited. I want to change the raio in the rear end to get alittle more top end but I still want that off the line low end. Anyone help me with what kind of gear ratio I should stick in it?! Thanks alot!

With 26" tall tires ( kinda short ) you'd be turning around 2400 rpm at 60 mph, or 5500 rpm at 136 mph in top gear ( 1:1 ). How fast are you going? You might go faster, and quicker as well, with 3.5:1 gears. A lot depends on your motor's power band and tire size. Give us more info.....

I blew out a tire so I had to buy all new tires and my dad put them on...so as far as I know the tires are no bigger than 16 inch. The car runs about 3200 rpm at 60 mph...so it tops out pretty quick at that 5500 rpm range! Thanks again for any help!

It has an original motor, which is a 350/350, but it is bored out and runs very close to 400 HP

can anyone help me?

my knowledge is somewhat limited too, but basically you have a 3.11 ratio. If you go higher(like a 3.5:1) you will increase bottom end, and lower top end speed. Thus you probably want something like a 2.75:1 ratio, taking away some low end grunt, but giving you better overall top speed.

Steve

PS those ratios are not available, I just made them up for demonstration.