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July 2008 4x4 Truck Tech Questions - Nuts & Bolts

Posted in How To on July 1, 2008
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Confused? E-mail your questions about trucks, 4x4s, and off-roading tech using "Nuts, I'm confused" as the subject and include a picture (if it's applicable). Digital photos must measure no less than 1600 x 1200 pixels (or two megapixels) and be saved as a TIFF, an EPS, or a maximum-quality JPEG file. Also, I'll be checking the forums on our Web site (, and if I see a question that I think more of you might want to have answered, I'll print that as well. Otherwise drop it old-school style with the envelope addressed to the address below. Letters published in this magazine reflect the opinions of the writers, and we reserve the right to edit letters for clarity, brevity, or other purposes.

Nuts & Bolts
4-Wheel & Off-Road
6420 Wilshire Blvd.
Los Angeles, CA 90048-5515
fax 323.782.2704.


AMC 700
Question: Do you know about adapting an AMC 401 to a 700R4 transmission? I want to run this combo in my "new" '88 Waggy. I've found lots of info on a 360 to 700R4, but not much on a 401. A buddy is selling a 401 and my 360 may be blown, so this is a no-brainer.
Phil F.

Answer: Novak Adapter (877.602.1500, has the adapter to go from AMC engines to GM TH350, TH400, TH700R4, and 4L60E automatics. Simply call them to discuss the options when adapting to a 401. However, the 700R4 was never offered behind any GM big-block and may be maxed out in your Wagoneer depending on how fresh the 401 is, how heavy the truck is built, and how big a tire you are running. I would rather see you go with a TH400 or 4L80E with an aftermarket controller like the Compushift from HGM Electronics (877.744.3887,

Low-Buck Locker
Question: I have a '94 Ford F-250 that I've been wrenching and wheeling on for about two years. I installed a 4-inch lift and 35s. It has a 460 big-block with a manual five-speed and 4.10 gears, so it gets around OK on regular trails but still leaves me hanging on the serious rocks and mud. I read your tech articles, including the tests on suspension travel versus lockers, but I'm still not sure if a locker is right for me. It's a daily driver, not to mention my pride and joy, and I don't want serious axle wear during on-road use. I also lack serious flex because of my stiff front and back leaf springs. What would you recommend? I'm on a 17-year-old's budget.
Michael S.

Answer:Get a Detroit Locker for your rear Sterling 10.5-inch axle. It will probably cost around $600 depending on where you get it, and you'll need someone to install it, so figure an additional $300 to $500 depending on shop fees. However, the Detroit Locker is tough as nails, less expensive than a selectable locker, and won't seriously add to axle wear. It's not the cheapest locker available, but it will survive just about any tire-and-engine combo you throw at it, and it will keep your tires turning when you start lacking traction from your stiff suspension. Just remember to keep your rear tires aired up to the same pressure to defer any odd on-road characteristics.

On The Right Track
Question: I have an '89 F-150 pickup. I removed the junk TTB in favor of a Dana 60 that I am putting in place with a radius-arm kit from Cage Off-Road. With the coil springs, I was wondering if I need a traction bar or will the antisway bar keep the axle located side to side without any problems?

Answer:You don't need a "traction" bar, but you do need a "track" bar. A traction bar is very similar to a radius arm and is usually found on a rear axle in order to control axlewrap, whereas a track bar (also known as a Panhard bar) is mounted from the frame to the axle along the same angle as your steering draglink. Your sway bar will not work as a track bar because it has flexible links at each end that will not control the massive forces trying to move your axle side to side.

Bow Tie Cummins
Question: I have a '71 Chevy 3/4-ton with plans to put in a 5.9 Cummins with an SM465 transmission. Does a company make an adapter to mate the motor to this tranny? I'm also looking for a 30-percent overdrive splitter box. Do you have any suggestions?
Adam T.

Answer:Actually there is a Cummins factory adapter that allows you to bolt up a GM transmission. Your best bet is to look in old box-style delivery trucks. Many of them came with six- or four-cylinder Cummins diesels and they both use the same rear adapter, and some even had manual transmissions behind them. I found one years ago that had been in an old Frito Lay potato chip delivery truck. However, one problem is that the factory Cummins adapter leans the transmission over between 15 and 20 degrees. For an aftermarket adapter contact Destroked (303.945.7570,, as they specialize in adapting Cummins engines to a variety of transmissions and they offer an adapter without the angled mount.

A Ranger gear-splitter overdrive box from Advance Adapters (800.350.2223, to go with your SM465 could help reduce the engine revs of the Cummins at highway speeds, but it is only rated to 420 lb-ft of torque, which isn't quite enough for the Cummins. A better option might be ditching the SM465 and getting an NV4500 five-speed manual with overdrive. Plus they can easily be bolted to the back of the Cummins.

Nuts, I'm Confused
Minimal Lift
Question: I have a '93 Chevy K-1500 with 150,000 miles, and I want to install a smaller lift kit. I'd like to run bigger tires, but I'm 50 years old and still need to get in and out of it. It also needs new shocks and I'm wondering what you would recommend? Is this a swap I can do myself as I'm new to off-roading? And what type of price difference would there be between a suspension and a body lift?
Craig S.
Lansing, MI

Answer:I get tons of requests each month from readers looking for huge suspension lifts to clear massive tires, but I'm sure there are just as many readers out there looking for a slight lift that will clear a more aggressive tread, but still make the truck livable. Now don't tell anyone, but I've recently been driving a few trucks that are lifted with just a short 2- or 3-inch lift and it's quite enjoyable not needing a grappling hook to climb in and out of the cab. When you only add a slight lift to your truck it keeps all the suspension components that much closer to stock and more in line with what the OEM engineers designed. This in turn increases longevity of CV and steering joints. I found a 21/2-inch suspension kit for your truck from Skyjacker (318.388.0816, and Rancho (734.384.7804, Both come with new shocks and are sold through 4-Wheel Parts (800.284.9905, for around $750 dollars. In addition, both kits use rear add-a-leaves, which I prefer to lift blocks. I would have no issue recommending either to you, and the Skyjacker kit is a little less expensive than the Rancho, but I prefer the Rancho shocks from my experience. Both kits should clear 33-inch tires, and with a set of tools, a jack, and some jackstands you should be able to install it in your driveway.

A body lift is a different bird than these kits altogether; costing between $175 and $300 depending on which kit you go with, and most of these are 2- or 3-inch kits. I wouldn't personally go above a 2-inch body lift and I prefer no more than a 1-inch since you are adding leverage to the mounting bolts and not really gaining any ground clearance. That being said, a body lift does leave the suspension alone and keeps it within factory geometry, which isn't bad especially on a truck that sees a lot of street driving. Also the new body lifts are much more complete than in years past when you were lucky to get a box of old hockey pucks with holes drilled in the middle.

Building a truck with a short lift seems contrary to the years of upgrades guys have been doing to their 4x4s, but it's not really a bad idea, especially as fuel prices increase. A truck with a short lift, some mud tires, and a rear locking differential can still take you down many off-road trails, and though it's not going to cross neck-deep mud or vertical rockcrawls, it doesn't mean it won't be fun to wheel and explore.

You've earned this month's "Nuts, I'm Confused" award by asking the question that many of our (how do I say this nicely?) less extreme and less agile (aka older) readers want to know. As much as I like a tall truck on 37-inch or larger tires, I know the many pitfalls and costs that come with building a big truck on big tires. AEM (310.484.2322, has for you a Brute Force intake with the only dry performance filter on the market. These intakes are engineered to draw in a clean fresh-air charge for your engine at up to 1,350 cfm, while filtering down to a single micron. The brackets for mounting the intake are fully TIG-welded, the tubing is aircraft-grade aluminum, the coupler hoses are made of noncracking silicone, and the kit comes complete with hardware for easy installation. Best of all, these kits have been submitted to CARB for 50-state legal use. Thanks for writing in.

Tired Tracker
Question: Do you know of any place where I can get info about putting in a Chevy 4.3 V-6 or a 350 V-8 in my Geo Tracker (aka Suzuki Sidekick)? I really need to know because my engine is starting to go.

Answer:Lightning Conversions (800.839.6150, has a plethora of GM V-6 and V-8 conversion kits for Suzuki Sidekicks and Samurais and Geo Trackers. Most of these swaps also require some major drivetrain changes to deal with the added power and torque.

Stumped On Shackles
Question: I was just wondering why the shackle is always at the back of the spring? I'm making a Ford Ranger with a solid front end and I really don't want to put the shackle in the back because it would throw my pinion angle off too much. I know that I could just raise the chassis up, but I want it as low to the ground as possible. I'm going to be running 35s on it with a Chevy 350.

Answer:Not all front leaf-spring shackles are on the rear of the spring. In fact, most open-top Jeeps that run leaf springs have the shackle in the front. Throughout the years there have been many companies offering shackle-reversal kits on the theory that when you hit a ditch at speed, the natural rearward motion of the shackle as the suspension compresses gives a better ride. With a front shackle, on the other hand, when you come up to a rock you want to climb and the suspension starts to compress, it actually forces the tire into the rock and (again in theory) aids in traction.

The problem you are having with your pinion may be solved by changing the angle of your spring perches. But if you are using an axle with a cast-in spring perch on the differential housing, it is more difficult. Some people use shims, but I'm not a fan of that on a front axle. I'd rather see you cut or machine the housing to a different angle, but this opens another can of worms with the mounting bolts. If going with front shackles solves your problem, I wouldn't see it being a major loss versus using a rear shackle.

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