The Stovebolt Site Forums The Shop Area Engine Shop REAR AXLE RATIO

Hello Stovebolters, need some help, I have a rear axle housing from 81 Camaro with 2.41 ratio. Question: I intend to run a 350/350, with 215/70/15 or 225/70/15 tires. This is going to be a daily driver, but still would prefer power over mileage. Another option I have is use a S-10 T-5 transmission. So just wanted to know if anyone else has had any experience with the "tall" gear set up and what do you think? Thanks in advance.
Phil

Do a check of the web for gear ratio calculator. There are a lot of them out there. Just feed your numbers in them and see what happens. Also, what trans did the Camero have? What tire size did it have? Joe

That '81 Camaro was probably a 350/350 or maybe a 305/350. What are you building and how will it be different than the Camaro?

Assuming you're working on an old truck performance is going to be similar to the Camaro with the same engine mods and tires.

Here is the calculator I like.
http://www.drivetraindirect.com/t_gear_calculator.htm

I use it to find rear axle and overdrive ratios that work together to give me the cruising down the interstate speed I want at an RPM that gives the engine the best economy and a long life.

If you find a transmission that works well with the rear ratio you have you can still have the lower gears needed to race from light to light, and the top gear for good fuel mileage.
Grigg

True, if the weight of both are close.

If your truck is much heaver you may want lower gears in the rear to help haul the extra weight.

Grigg

I would think that 2:41 would be OK with a 350 or any other 1 to 1 tranny.But with an overdrive unit you would need to go somewhere around a 3:73 gear.I am running a 350 SB,and 700R4 OD tranny,with 3:90 gears.It gets decent performance and gets 20 MPG all day long.I am sure you will get other opinions here,but that is how I would go.

Yeah I rashly assumed a 1/2-ton pickup that's not likely to weigh even as much as a bloated Camaro, but is also unlikely to weigh a lot less.

I made that assumption in part because if its a bigger truck that Camaro rear is a mistake...

I've had an '81 Z28 since I was 19. It came stock with 350/350 and 3.08 gears. It weighs pretty close to 3600 pounds. Base coupes were a few hundred pounds lighter and Berlinettas were in between.

Advance Design 1/2 ton pickups weigh approx. 3100 lbs. Suburbans: 3600 +-, 3/4 ton pickups: 3480 +-
Weights vary slightly from year to year.

Sounds like they are about the same weight. I just assumed a sporty car would weigh less than a pickup.
Grigg

I think it would be geared too high. The o-drive would be useless. I run a 350 with 700-4r & 3.08 rear end in my 70 stepside. It is just right but could not handle anything higher.

I'm going to run 350 w/ T400 tranny and 3.08 rear end. Given the calculator I've used on Randy's Ring and Pinion web site, I should be cruising right along at about 2200 rpm's at highway speeds. Looking forward to getting the differential put on the truck.

I run a 250 six with a 350 trans 3.08 gear and 235/75R15 tires, mine gets 18 to 19 mpg and can run 70 mph all day long. Its a little slow pulling a trailer but still gets down the road! Joe

Well, with those gears you are definetly on the economy side. I would think you would find it difficult to pull a load, or climb a grade. If you ever plan to use it like a truck, you would want to get a lower geared rear end. 3.08 without overdrive, or 3.55 - 4.11 with overdrive should give you "the power" that you are looking for.

3.08, 3.40 or 3.73....... 2.4 is pretty highly geared
you'll be great on the freeway but hills may be interesting..
my.02

Think about the gears themselves too. With a 2.41, even a 3.08, the gears themselves get pretty thin. If you ever want to haul anything, it will be a dog, and the gears have a lot more strain on them (not as strong).

My 327, 2 speed automatic with 3.73 gears will haul and go 75mph. Gas mileage takes a crap at those speeds, but I can take off pretty good too. Mileage around town is going to suffer with too high ratio also.

2.41 IMHO is way to high.

Hard to believe you have a 2.41 in a Camaro...most V8 Camaros had 3.40 and up rears. With that high a ratio you'll be lucky to get up your driveway and you'll certainly never get that motor going enough to use any OD gear...that's a true flatland only gear!