My son was complaining that his new to him had no get up and go. I kept telling him it was probably geared high. Well tonight I confirmed that, it's 7 1/4 rear end has a 2.2 gear. I didn't know they put that high a gear in one. All that being said, what gear ratios were available in these cars?

Factory ratios offered include but are not limited to:

2.26:1 - Used in many civilian M-bodies over the years
2.76:1 - Used in 80s Dakotas
2.93:1
3.21:1 - Used in 90s Dakotas
3.23:1 - Used in many Slant 6 cars from 1963-1969, and 80s Dakotas
3.55:1 - Used in 80s Dakotas
3.90:1 - Used in 90s Dakotas
3.91:1 - Used in 67 Formula S Barracudas with power-lock
4.11:1

Aftermarket gear ratios available include but are not limited to:

2.26:1
2.76:1
2.94:1
3.21:1
3.23:1
3.55:1
3.90:1
4.10:1
4.11:1

source: http://www.dippy.org/forum2/index.php/topic,73.0.html

Might already have one but the wide ratio 9xx transmissions do help some.

Heavy car and small engine doesn't help.

Being it's a Mirada it will already have the low gear 904 trans in it. There wasn't much that could be ordered different mechanically than what you have, but Diplomat cop car parts will bolt right in. Go find a Diplomat fleet car, fender tage code A38 (pre 1983), or AHB (1984 on up). They all came with 8.25" rear axles and could be ordered with up to 2.94 gears and Sure Grip. Grab the rear springs, and both the front and rear sway bars while you're at it. Your driveshaft will probably have to shortened.

On the cop car 8.25 axles, definitely check to see what ratio is in the axle before buying it. Some of the non-pursuit cop cars were set up for economy. If I'm not mistaken, for a year or two the 2.26 axle was available in the cop cars. These cop cars were used for administrative duties, etc.

I had a 1983 Grand Fury years many years ago. It had a 318 with a 2 bbl carburetor and the high gears in it. I discovered it was used at a prison. The car had the police package on it. In fact, it was the nicest driving M body ex-cop car I ever drove.

I believe they also made an axle with 2.4? gears as well in some years. I believe I may still have it in the parts stash.... I believe that axle came out of a Aspen.

Pretty sure my 1980 Mirada, 318 car had a 2.45 ratio. Got great mileage, but so sloooowwwww

Robert

Ordered a new Mirada in 1980 360 4bbl. 2.5 gears standard 2.9 was the only option.

I think the cars that had these 2.26 axle ratios were equipped with them partly because the 904 based 999 transmissions had the lower 1st gear. They were still 3 speed NON overdrive transmissions so I suspect that this was an effort to end up with a similar final drive you might get in a car equipped with a .70 overdrive and a 3.0 series gear.

You nailed it, Frankenberry! When these cars were being specified, Chrysler didn't have an overdrive automatic. They also didn't have enough money to build a new transmission, being nearly bankrupt at the time.
So in typical Mopar Engineering fashion, they put the 3 speed transmission in front of a ridiculously low numerically gear ratio. The torque converter would have to do more to get the car rolling. To help with this problem, a lower First gear set was specified for the A904 variants they were using.

This whole system change was done for one purpose only; to help them meet CAFE standards. My mother's Fifth Avenue had such a setup and would get phenomenal mileage on the highway. Off the line it was a dog, but the Fifth was built for old people who wanted a rear wheel drive car, formally styled.

There was a sizeable number of automotive engineers who thought optimum mileage could be reached with a big engine and a tall rear gear. Our family's '69 Olds had a 455 with a 2.56 gear. It'd run 90 forever. Mileage was better than the car it replaced. My Dad had the opinion that a 2-barrel carb got better mileage, so our 455 had a 2-barrel on top. Our neighbors bought the same car with the Quadrajet and claimed 2 mpg more than we were getting.

R.

My thought too. So heavily smogged it's a wonder they even ran.

Thanks guys. I will try to find him an 8 1/4 with a better gear.

Really? a 455 with a 2 barrel? Was that stock? I have never heard of an engine that large with a meager 2 barrel carburetor!