Highest stock gear ratio in 9inch rears?

What's the highest (numerically lowest) ratio put in 31 spline truck 9inches. I've got a 3.0 in my 9inch at the moment and don't really like it for highway cruisin. I've got what I believe to be a 2.20 something (?) in my 56 chevy truck with a gm 10bolt underneath it. Something similar to stab in my 9inch housing would definitely be sweet. Oh, and if anyone has anything close to what I'm looking for, I'll probably be interested in buying...if you're selling.

 

i'm thinking maybe 2.56?

 

i've been looking for a 2.79 (28 spline) but i'm not sure if they're made for 31 spline.

 

2.80's are the tallest 9" gear I know of. I'll check my books.

 

I had a 2.73 31 spline 9" with the SMALL 5x4.5 bolt pattern under my '82 F100 stepside pickup. It was a pretty wierd deal and part of an econo package I think. It got the light duty smogged out 300 with the aluminum SROD 4 speed OD out of the GT Mustang, and it came with the car bolt pattern front and rear from the factory.

It was a dog... until I made that 300 scream. Economy went down the ****ter though lol.

 

I run 2.47s in my Bonneville car. Common 70s big car smog gears.

 

2.47, 2.50, 2.75, are the high speed 9" gears

 

Well, sweet. Thanks for all of your input so far. I guess now what should be said is that I'm looking for a third member with 2.47s...for a 31 spline

 

I don't think there is any such thing stock, you'll have to combine a 31 spline carrier with the awful gears. You can find the 2.47's in late 70's Lincoln Versailles and full sized Lincolns but those are all 28 splines.

 

Why? Im not trying to be an ***. I am really wondering why you would want anything more than a 3.00 in a street car. I had 3.08s in my model A and it would cruize nicely at 75 mph.

 

I have a set of 2.47 gears on the shelf, may not need

 

I had a '79 S/W with factory 2.25s Don't recall if 9" or not.

 

That was my initial thought. But maybe the tires are really short or the transmission's gears are less than optimized for highway driving.

 

How tall are your tires?

 

I had a 2:75 9 3/8 in my 66' Galaxie with stock C6, 15in wheels. It would auto shift 2nd to 3rd gear with the pedal on the boards at 80mph. Top end... scary. But the bottom end was doggy with 428, 6barrels, mild cam, headers. With a 3:89 posi it would run 14.0's in the 1/4 mile. It's all about compromise. Whatcha guna do with it.

 

2.47's with 31 spline axles are common in the mid 70's big Lincoln 9" rear ends.

 

Just to put this in perspective, Currie Enterprises lists "good used 2.50 ratio ring and pinion" sets for the Ford 9" for about $100.

Yeah, I expect you can do better than that if you are willing to do some legwork, but at least that gives you a starting point in terms of pricing.

 

I'm running 7.00 15s out back and a th350 for a trans. 3.0 isn't bad, I don't have a tach in the car right now but I know of friend's cars with 3.0 that turn around 3000 rpm at 70ish mph. The truck I was referring to earlier with what I believe to be around a 2.20something gear cruises around 2000 at 70mph, and I love it.

 

2.5 to 2.75 is a good place to be if you don't have overdrive, and you like going fast on the highway, and your engine has the torque to pull it. I've put a lot of miles on a set of 2.75 gears in my 55....having a mild blown big block makes the soggy bottom end not an issue. especially with the switch pitch torque converter.

 

I don't think so...something is really not right there.

I had 3.23's, and a very short 25" tall tire and was only about 3000rpm at 70mph. You are running a much taller tire, so you would be several hundred rpm lower.

 

http://www.richmondgear.com/streetcalculators.html

this gear calculator may be helpfull

 

Without trying to sidetrack the thread too far, what's the highest gear anyone's seen in a domestic rear axle? I always thought 2.20s were as high as they got but once bought a ten bolt out of a 79 police car.....the ****er had 2.13 gears! Yikes!

 

I think two teens is the lowest number I've seen. caddys had them before OD came along...late 70s was a great time for "high speed" rearend gears.

 

My truck has a camaro ten bolt not sure of the ratio (the only reason I ***umed they were around 2.20 because I had a 79 malibu with a ten bolt with a ratio around 2.20) with 235 75's in the rear and I turn around 2000rpm at 70ish mph. Been driving it for like 6 years now...been all over the country. I know what rpms that truck cruises and at what speeds.

 

The formula I use; DxRPM/Rx336
D=tire diameter
R=ratio

This will give you the speed for your gears and tires. The numbers can be moved around to give all 3 variables.

 

check out some of the nascar used parts sites, better gears cheap

 

The used Nascar gears usually howl pretty good. They grind a crown in them for the optimum contact pattern, and they make some serious noise. I have bought several sets, and for race cars they are great, but they will drive you crazy on the street.

 

A few of us swapped one of those lincoln center sections 2.** range into a '58 Ford with a 352 interceptor and got in the 20's on MPG on the way to MOKAN one year. Not much good on the strip then, but the highway is what counts these days IMO.

 

You know what I would suggest!

 

My 81 F150 came with 2:79 ratio 31 spline, 300 six and C6. I think the last year for the 9 in.