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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: tscott77 on September 15, 2013, 05:21:52 pm
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Okay, forum gurus, I have a question. My 1984 Chevy K30 has a 4-speed(or 3-speed with a granny gear), and 4.56 gears, which means that not only do I get less than great fuel economy, but it also means that the top speed on it is roughly 65mph. Now, I understand that it is a big hauler, and that I might not be able to have my cake and eat it too, but when I get passed on the expressway by some dope in a one ton Ford with a Powder Choke, and he is towing a fifth wheel trailer while doing 80, I get the feeling that there just *might* be something that I can do to extend the top speed in my truck. Any ideas?
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3.43 gears and 31" tires will get you to 95mph, given that you can do 65 now.
With a "K" that means changing gears in two differentials. It also means you can't go to an overdrive after the transmission.
Basically, all transmissions are 1:1 in high gear, so you need to change gear ratios. Bigger tires can get you some of that.
The exception is an overdrive transmission, but I don't know of any stick overdrives. Someone else might.
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With your big rig I would go with a NV 4500 or something like that, it is made for a big truck transmission.
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lift ket and bigger tires (http://www.naioa.com/v2/modules/Forums/images/smiles/icon_twisted.gif)