I have a 70'F-100 with a 9" rear end. I want to know what year of fords I can get a rear end that will bolt right in. I was told all 1/2 ton rear ends are the same. But someone else told me only 67-72 will fit. I was also considering just changing the whole gear assembly and replacing the outer bearings. Will any 9" gear assembly bolt right in? Please help!
Andy, In 73 Ford widened the frame rails just behind the cab. They also widened the rearend to make it track the front that was widened in 65. To answer your question, your choice for whole rear set up stops at 72. Your truck has a 9 in. "rear gear" and will interchange with any 9 in. if you want to change ratios.
Hope this helps some.
John
66 F100s
In the still cool hours of the night, you can hear chevys rusting away.
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In the cool still quiet hours of night, you can hear chevies rusting away.
John is absolutely correct. I put a set of '73 axles under my '72 by mounting a different set of springs pads on the axle just inside where the original pads were mounted to get it to match up to the '72 springs.
Thanks for your help, and the quick response. I want to change to a much lower gear ratio so when somebody takes it for a test drive it will roast the tires. What gear ratio do you think would help achieve this? The truck has a 79' 302 2bbl with a C-6 tranny. I just slapped on a set of 235/75/15's. Do you know what vehicle with 9"rear ends came with very low gear ratio's? Thank again.
Andy, Tis pleasure to offer quick turnaround help. My advice, leave the rear alone, the 302 isn't known as a power house in the trucks anyway. You will kill any fuel mileage that it gets.
John
66 F100s
In the still cool hours of the night, you can hear chevys rusting away.
__________________
In the cool still quiet hours of night, you can hear chevies rusting away.
If you are looking at trucks, your best bet will be 6 cylinder F100 models for the highest numerical ratio. In cars, full size station wagons are a place to start. Then try cars such as Thunderbirds or other large vehicles with V-8s.
I have two F100's that both have around a 3.50 rear ratio. One has (had) a 302 with Edelbrock 4V and aluminum manifold,C6,and a 9inch. It was tough to spin the tires on this. I also have a F100 with 390,4sp,and a Dana limited slip rear also w/ about a 3.50 ratio. I kinda figured the 390 should be able to smoke the tires good, but not so. I talked to the speed shop guy and he said that higher gear ratio's would make spinning the tires easier. Drag racers like low ratio's because it translates torque into movement down the track instead of wasting time by spinning the tires. Of coarse the drag racers still smoke the tires because they have a ton of HP. I have a 89 Camaro with a TBI 305 5sp 3.08 rear. It is only factory rated at 170HP but w/ 116K miles, it easily smokes the tires. Granted it is lighter than the truck. Also 6 cylinder trucks didn't neccesarily have a high gearing. My 76 originally had a 300 w/3sp and 3.50 gears. I've got a buddy with a 80 300 w/3sp and 2.75 gears. He's raves about both the get up and go on the hiway and pretty decent mileage. Seems like changing the rear to facilitate selling the truck is of questionable value. If you do anything put taller gears in it. Better yet sell it as is.
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