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1985 Chevy 1/2-ton & 1980 Ford F-250 4x4 - Mail Box

Posted in Features on October 1, 2000
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Editor's Note: If you have any questions, comments, rants, or raves, please feel free to contact us at OFF-ROAD magazine, Mailbox, 774 S. Placentia Ave., Placentia, CA 92870. You can e-mail us at joem@mcmullenargus.com.

Right Tires; Right GearsI own an '85 Chevy 1/2-ton with a 406ci motor that's running a little less than 400 hp. The stock 3.73 gear ratio is currently in the axles, but I was wondering if I should go to a lower gear ratio such as 4.11. The tires on the truck are 32x11.50/15 Wild Country Mud Terrain, but they're wearing out and I'd like to replace them with 33s. I'm not a hard-core mudder, but I do use my truck in the mud occasionally. I also do a lot of hunting in the sand hills of Nebraska, so I need tires that would work well in the sand as well as in the mud. Is there a tire that you can recommend that does well in the sand, the mud, and during everyday driving? What tire and gear combination would be best for minor towing? Any help you could give me would be great. Keep up the good work on OFF-ROAD magazine.Patrick McMullenvia e-mail

You're asking a lot if you're seeking a tire that excels on the street, in the mud, and on the sand; technically, it's impossible for any single tread design to do it all. For the street, a tire with a large contact patch and large tread blocks is preferred since maximum tread in contact with the pavement normally produces maximum traction. During rainy conditions, that same tire wouldn't work quite as well; it would need spaces between the tread (voids) to channel the water away from the area between the tread and the pavement to prevent hydroplaning. For sandy conditions, a wide tire on a wide rim is the best choice since such a setup provides flotation over the sand. A good sand tire would also feature a tread with a large contact patch and a small amount of voids since flotation is the goal. Many tires, such as Mickey Thompson's new Baja Claw and Goodyear's Wrangler use traction lugs or ribs on their sidewalls, which is a benefit on the sand since some amount of traction is provided even when the tire starts digging in. For mud, you need a tire that's aggressive, incorporating large, sharp-edged lugs and large, open voids to channel away the mud so the lugs can grab the maximum available traction. The previously mentioned sidewall traction elements on the Goodyear Wrangler M/T and the Mickey Thompson tires are also very useful in muddy conditions; they provide additional traction even if the tread is clogged with mud or if traction isn't available at the tire's main tread area. Our suggestion is to go with an all-terrain type of tire and select a set of wheels that maximizes the tires' width; a set of 33x12.50R15s on 15x10 wheels will be a good compromise, as illustrated by the accompanying photo of a BFG All-Terrain T/A. If you really need tires that deliver mud performance, you'll need to go with a true mud-terrain tire. If using a mud-specific tread, go for the wide tire and wide wheel setup that was previously described; the mud tires will show some decent flotation characteristics on the sand as well as deliver above-average traction on the street. However, using a mud-terrain tire for everyday driving is expensive; the aggressive tread lugs don't wear as well as an all-terrain tire, and the mud-terrain's widely spaced lugs and large voids contribute to tire noise, which may or may not be of concern to you.

As for gearing, we can provide you with a general recommendation; however, it sounds as if your truck's small-block is modified with an intake and camshaft that accents midrange torque. If this is the case, overall gearing should be chosen to place the engine in the fat part of its powerband during normal operation. To run 33s, we suggest a ring-and-pinion gearset with a ratio of 4.11; if your engine is set up for midrange power, go to 4.56 gears.

Our friends at JET Performance had an answer for your question. JET builds automatic transmissions for all manner of high-performance trucks, including high-horsepower 4x4s, so its recommendations are worthwhile. The first aspect of your transmission swap to consider is the actual amount of power your built 460 will produce. A JET-modified Ford C6 three-speed automatic transmission is stout indeed. The C6 can routinely withstand plenty of abuse, such as the type that occurs off-road or on the dragstrip. The only drawback to the C6 is debatable: some enthusiasts find the C6's three speeds sufficient; other enthusiasts aren't happy with the C6's lack of an Overdrive Fourth gear. The JET C6 tranny uses performance bands with superior friction materials, a performance valve body, an adjustable modulator, and is designed to handle 550 hp. The C6 is a direct bolt-on to the 460ci engine. You can special order JET's C6 4WD transmission under PN 500109.

For a more expensive option, JET also manufactures a high-performance E40D electronic overdrive automatic transmission. The four-speed E40D is for trucks without a transmission computer, which is ideal for your '80 F-series. JET offers the E40D with a five-pack clutch set, heavy-duty drums and clutches and a performance valve body. The E40D is set up by JET to withstand the rigors of towing, built engines, and off-road abuse. Typically, the JET E40D will handle 600 hp in a reliable manner. To get the JET E40D physically hooked up to a 460ci and the existing Ford NP208 T-case, you'll need to special order JET's E4 4WD transmission (PN 650121); otherwise, it's a direct bolt-in. For more infor-mation, contact: JET Performance Products, Dept. OR, 17491 Apex Cir., Huntington Beach, CA 92647, (714) 848-5515, www.jetchip.com.

Upgraded TransmissionsI own an '80 Ford F-250 4x4.I bought it fairly roughed up; the motor was blown and the body was thrashed, so I've been fixing it up little by little. Instead of rebuilding the 351M engine, I'd like to drop in a built 460 ci. My question is: What automatic transmission should I use? Is there a specific automatic transmission for a big-block Ford engine? Is there a certain automatic Ford transmission that is correct for a 4x4 truck?Darren ThomasMacomb, Illinois

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