higher ratio rear end
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higher ratio rear end
Hello everyone!
I am new to this site and want to ask a question about my 1975 Ford f150. I recently put a new engine in my truck but I want some more get up and go. Should I consider changing out the rear end with a higher ratio? The truck tops out beautifully but it just does not pull off very well.
J L Hart
I am new to this site and want to ask a question about my 1975 Ford f150. I recently put a new engine in my truck but I want some more get up and go. Should I consider changing out the rear end with a higher ratio? The truck tops out beautifully but it just does not pull off very well.
J L Hart
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higher ratio rear end
Sorry for not giving out all the necessary info. My 1975 ford truck has a 302 engine with a fmx automatic tranny and the rear end ratio is 3.25. Like I said it has more than enough pulling power and plenty of top out cruising power but it does not have get up and go from the start. Is that part of being the truck it is?
J L Hart
J L Hart
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Joined: Dec 1999
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From: Copley, OH
higher ratio rear end
a 3.25 rear end is a good compromise between performance and cruise, especially with a non-OD tranny like an FMX.
Assuming 29" tires your RPM at 65 MPH with various rear axle ratios:
2.73 2135
3.08 2410
3.27 2560
3.55 2775
3.73 2920
4.10 3215
Those are 8.8" ratios, but the 9" equivalents are close enough. A bigger gear will give you better aceleration, but don't expect much, it's a truck. You have to decide how hard you want to rev the engine at highway speeds. I'd be inclined to leave things as they are
Assuming 29" tires your RPM at 65 MPH with various rear axle ratios:
2.73 2135
3.08 2410
3.27 2560
3.55 2775
3.73 2920
4.10 3215
Those are 8.8" ratios, but the 9" equivalents are close enough. A bigger gear will give you better aceleration, but don't expect much, it's a truck. You have to decide how hard you want to rev the engine at highway speeds. I'd be inclined to leave things as they are
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