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Copyright 1996-2004 Dan Wentz
Rear End Swaps |
quick liNksmaintenanceSpecifications modificationsF-Series historyCanadian Ford & Mercury Trucks Early F-Series in Film & Television Online ToolscommunityMy 1950 f1 |
The rear gear ratio on an F1 is 3.91:1. On heavier trucks it's even lower. If your truck works hard (towing, or other things that require enormous torque) then this is good for you. If you don't use your truck to pull out tree stumps you might not like the gear ratio. If you drive your truck on the highway them I'm sure you hate the gears. Personally, I used to drive my stock truck on the freeway and the engine would be wound out at about 3000 rpm, and I'd only be going 55mph. Common sense says you can change out the stock gears for a better ratio. The problem with that is they don't make replacement gears. I know of 1 outfit that will do it, but it costs around $800. Most people just opt to replace the whole rear end. This has added advantages of using stronger parts and having better brakes. What's available? Every car and truck has a rear end. Some of them are of a size that will fit under your truck. Your mission is to find the one that works for you. The common swaps are the Ford 9" and GM 10 bolt (that is what it's called, isn't it?). Of the 2 the 9" is much more common. It is the gold standard. The problem with it is that it's so popular it could look like you didn't put much thought into your project and just copied what the magazines did. The other problem is that they are getting harder to find, and junkyards tend to want a pretty penny for them. In the last couple years I have seen a rise in popularity of Ford 8 and 8.8 inch rear ends. These are newer and are used in Mustangs and trucks with V8 engines. From what I know they are strong enough to take about any engine. They use C clips to hold the axles on though, so they could be prone to spectacular failure (unlikely though if you don't abuse them). BonusBuilt.com suggests: If you have an F1 your best bet is the 9" out of a 68-72 F100 or F150. They are the same length as your original rear. They also have the same bolt pattern, so you don't have to get new wheels. The cherry on top is that the spring perches are in the exact right location, so you don't have to weld on new ones. You will probably have to shim the pinion down a few degrees though. They come with a 3.50:1 ratio, but that is easy enough to change--just put in any other 9" 3rd member. How do you do it? Pretty easy. It requires some measuring and usually some welding. First you have to set the pinion angle, then weld on your spring perches (the things that the truck will sit on, via the springs), then weld on shock absorber mounts. From there you just have to bolt the thing in, hook up the brakes and driveshaft and you're set. A word about driveshafts--you will probably have to lengthen or shorten your driveshaft after installing the rear end. Any common problems? Not really. If you don't have it bolted down tight or if the pinion angle is incorrect you'll get bad vibration. |
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Copyright 1996-2004 Dan Wentz |