ring &pinion

[grandmas73rocket]

I have a 73 cutlass with a 350 rocket. It has 273's in the rear and I wanted to give it more punch. everyone is telling me to put 373's in it. I mainly take it out to go cruising locally with one or two trips to the shore a year. will 373's be too much or should I go with 355's? I know there's not that much diiference in the two but I want the most punch from the get go and still be able to take it up to 60-65mph. any info would be appreciated.

thanks
c.b.

[jimfulco]

I went from 2.73 to 3.45 in an 88 T-bird with 302. MUCH more fun, but if I didn't have overdrive, it would be running around 3200 rpm at 70mph.

[Oldslover]

I have a 73 Olds Delta 88 with a 350 Rocket engine and I need to know what ring and pinion is available for that year modle? I have no idea what gear is in it now, because the tag is gone. I would like to get more speed and lower rpms then what I am getting now. I need to know how low and how high the gears are available for this car.
Thanks

[Oldsguy]

I drive a '69 Delta, 455 engine, TH400, 2.73:1 rear. The car turns 2150 rpm at 70 miles per hour. The car could handle 3.73:1 or even higher but the trade off would be higher rpm at the same highway speeds. For the 455 I have decided 3.73:1 would be as high as I want to go. A 350 wouldn't mind the constant higher rpm as much as a 455 so you need to consider that. Also, my carrier is a type O 12 bolt, not the same as the GM corporate 12 bolt. I have been told it is a little more difficult to find ring and pinion sets to fit it. I am not sure what type carrier the '73 Delta had but of course you would have to get ring and pinion sets to fit whatever carrier it was. There is some info over at Realoldspower.com if you do a search and prepare to read a lot of posts you will find some good info. Try using key words like "type O", "12 bolt", "ratio", etc. Good luck to you both.

[PetChemMan]

My 1962 Olds Starfire came from the factory with 3.42 rear axle gears. It has 14 inch. tires, and can cruise at 70 miles per hour without excessive rpm. I think that for the street anything up to a 3.90 ratio is suitable. The extra kick from numerically high gears is great, but of course fuel economy and engine noise and wear are the tradeoffs. Most American V-8s can safely cruise at 3500 rpm , so get out your calculator, measure your tire diameter , and find out what rpm you'll have at your maximum sustained cruising speed. You can assume your torque converter has negligible slip at cruising speed. I ran the numbers out, and you can use the following to calculate vehicle miles per hour. (Assuming that your transmission is in high gear, and has no overdrive).
First, divide engine rpm by the axle ratio to obtain wheel rpm. Then, multiply wheel rpm by tire diameter (in inches) , and then multiply that amount by .002972. That will produce vehicle miles per hour. Lets calculate the following example; Engine rpm = 3500; axle ratio = 3.73; tire diameter = 27 inches. First we find wheel rpm = 3500/3.73 = 938.33 rpm. Then multiply 938.33 times 27 inches times .002972 = 75 miles per hour.

[Oldslover]

I have a 1973 Olds Delta 88 and it has a 308 gear in the rear end. I am looking for a 256 gear for it. e-mail me at vickiekellisor@bellsouth.net if you can help me.

[ November 23, 2005: Message edited by: Oldslover ]</p>