rear axle ratio change
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09-13-2003, 07:51 AM
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rear axle ratio change
#2
09-13-2003, 09:02 AM
Postmaster
rear axle ratio change
Shaun: Changing the ratio can be as easy as just changing a chunk or "pumpkin" out of the rear, or by buying new gears and having your current one rebuilt.
Here are the issues you will face;
1. 9 inch rears are very common still; they were used up to '86.
2. There are 2 sizes of axles used: 28 spline and 31 spline. Yours is most likely a 28 spline. If you use another chunk with 28 spline axles, you will be able to take yours out and just drop the new one in. If you for some reason want to use a 31 spline axle, they will have to be cut to the narrower length of your '64 rear end, and then re-splined. Not recommended.
3. Your input yoke is probably the smaller one. Ford used 2 U-joint sizes, so if you plan to replace yours straight up, it will go easier if you get one with the same size U-joint yoke. Otherwise, you have to have the chunk "set up" any way, so you aren't saving any money or time.
To replace your chunk, follow these steps:
1. Jack up the rear of the truck (don't forget to chock the front so it won't roll) and remove the rear wheels and drums.
2. Remove the 4 backing plate nuts though the hole in the axle plate. Don't remove the backing plate, or take any brake parts off.
3. Remove the axles with a puller. You can reverse the drum and use it as a puller.
4. Remove the rear U-joint and the driveshaft.
5. Remove the 10 nuts on the chunk.
6. With an oil pan under the chunk, break the seal, and let it drain.
7. Now, slide the whole chunk off. BE CAREFUL. IT IS HEAVY!
8. To install the new one, clean the old gasket off the mating surfaces. You will use RTV instead of a gasket.
Use this opportunity to change the rear axle bearings, and change the seals. You will have to have a machine shop press the bearings off and on, but it is cheap insurance.
Pry the old seals out with the very tip end of the axle.
Tap new seals in evenly. When you re-install the axles, keep the axle shaft off the seal as much as possible.
Here are the issues you will face;
1. 9 inch rears are very common still; they were used up to '86.
2. There are 2 sizes of axles used: 28 spline and 31 spline. Yours is most likely a 28 spline. If you use another chunk with 28 spline axles, you will be able to take yours out and just drop the new one in. If you for some reason want to use a 31 spline axle, they will have to be cut to the narrower length of your '64 rear end, and then re-splined. Not recommended.
3. Your input yoke is probably the smaller one. Ford used 2 U-joint sizes, so if you plan to replace yours straight up, it will go easier if you get one with the same size U-joint yoke. Otherwise, you have to have the chunk "set up" any way, so you aren't saving any money or time.
To replace your chunk, follow these steps:
1. Jack up the rear of the truck (don't forget to chock the front so it won't roll) and remove the rear wheels and drums.
2. Remove the 4 backing plate nuts though the hole in the axle plate. Don't remove the backing plate, or take any brake parts off.
3. Remove the axles with a puller. You can reverse the drum and use it as a puller.
4. Remove the rear U-joint and the driveshaft.
5. Remove the 10 nuts on the chunk.
6. With an oil pan under the chunk, break the seal, and let it drain.
7. Now, slide the whole chunk off. BE CAREFUL. IT IS HEAVY!
8. To install the new one, clean the old gasket off the mating surfaces. You will use RTV instead of a gasket.
Use this opportunity to change the rear axle bearings, and change the seals. You will have to have a machine shop press the bearings off and on, but it is cheap insurance.
Pry the old seals out with the very tip end of the axle.
Tap new seals in evenly. When you re-install the axles, keep the axle shaft off the seal as much as possible.
Last edited by banjopicker66; 09-13-2003 at 09:05 AM.
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