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October 2011 Nuts & Bolts

Chevy 3500
Fred Williams
| Brand Manager, Petersen’s 4Wheel & Off Road
Posted October 1, 2011

Colorado Spring-Over Swap, Suburban Drivetrain Swap, and More!

1⁄2 Full or 3⁄4 Empty?
Q In almost every issue of 4-Wheel & Off-Road, it is stated that IFS is weaker, wears out quicker, and is less useful off-road overall versus a solid axle. Would it be feasible to take a Chevy 1500 4x4 and install the complete suspension from a 3500 4x4? The 3500 components are stronger, more durable, and made for a heavy-duty truck, whereas the 1500 is lightweight. Would the pros of the 3500 suspension overcome the worst of the 1500’s IFS cons? And even though it would still have IFS, would it be much better off-road?
Tyler S.
Holmen, WI

A Although your idea is good, the later-model IFS trucks are just not as easy to convert from 1⁄2-ton to 1-ton as you would hope. The mounting points are much different, and in the end you’ll be doing as much fabrication work as you would be if you were swapping in a solid front axle. Is it possible? Yes. Is it worth it? Not really. Yes, the 3500 IFS will be stronger than the 1500, but it will still be hindered by all the moving parts that can wear out and cause issues with the IFS. However, the 3500 parts usually have more gearing and locker options available and stronger aftermarket support, so I’d recommend starting with a 3500 truck rather than trying to swap the parts over.

We are currently exploring a heavy-duty IFS in our Ultimate Adventure F-150 buildup (see page 70), so stay tuned to see how that comes out. Developing a front independent suspension that will be strong enough (we hope!) for serious off-road use will be just as expensive (or more so), time consuming, and elaborate as swapping in a solid front axle.

Over the Canyon
Q I have an ’06 GMC Canyon 2WD Z85 and am in the process of lifting it more than the 2-inch lift coils and shackles I have on it currently. I will be getting the 5-inch CST spindles soon to bring the front up more, but how would I do the spring-over axle so I can gain those extra inches to level it out? I’d rather it not be leaning back like a lowrider. Where can I go to in Southern California to get this done?

A The look you are talking about is called the prerunner look, where the bed is low and the nose of the truck is high, reminiscent of some desert race trucks. For some reason a lot of the southwestern guys like this look. Oddly enough, most desert race trucks do not sit like that anymore. I’m not a huge fan, as it makes forward visibility harder, but the low bed makes it easier to load your cooler!

As for the rear spring-over conversion, you will need to relocate the spring perches, change the pinion angle, and attach longer shocks and longer brake lines. The spring-over is more likely to have spring wrap, as this configuration can increase the leverage against the springs. A simple online or Yellow Pages search will show you many 4x4 and off-road shops in Southern California depending on where you live exactly. Be sure to ask if they have ever done a spring-over conversion. It shouldn’t be too difficult, but will require some welding and new parts.

Low-Tech Tow
Q My newest project, besides one of my eight Jeeps, is to build a low-tech, old-school tow vehicle. One with no computer, no automatic transmission, no power windows, and the like. I purchased an ’84 Chevy 4x4 standard cab dualie from my old fire department. It has a 350 V-8, an SM465, an NP205, a Dana 60 front axle and 14-bolt rear with 4.56 gearing, and 30x16 tires. The only problem is that it has a top speed of about 58 mph, which makes it unsuitable for towing a Jeep to Moab.

I could have the axles regeared, but I really hate to, as the truck only has 9,000 miles on it and they are just broken in. Since I’m not fond of the nonsyncronized granny gear (but could live with it if necessary), I was thinking about a more modern five- or six-speed overdrive stick-shift tranny instead to gain the top speed I need.

What would be the easiest and/or cheapest tranny to swap in? Or is there some kind of overdrive unit to install between the gearbox and the transfer case?
Glen D. B.
Orlando Jeep Club

A Your truck sounds awesome! Simple, basic, and tough. I would have to agree that keeping the tow rig simple and reliable is a great goal. The tow rig doesn’t need to be a project truck. Little things like a camper shell, a leveling kit, and a light bar all make sense. But a huge lift, over-the-top engine upgrades, and giant rubber can make a tow rig into a large headache.

The truck needs higher gearing, and you have three choices. First is a Ranger overdrive between the engine and transmission from Advance Adapters ( These cost about $1,300 and put a 27 percent overdrive and additional shifter in front of your SM465. This swap will also require moving your transmission and transfer case rearward 71⁄2 inches and shortening and lengthening your driveshafts, which can be very expensive. The Ranger is a great option built to handle 420 lb-ft of torque and a GVWR of 25,000. It does, however, have some gear whine in overdrive, but I use one in my Dumpster M37 project with great results.

The second option is the infamous NV-4500 five-speed manual transmission. I have used a few of these and find them expensive, annoying to drive, and weak. I have seen many failures, though there is a supposed fix on the market to keep the overdrive gear from coming apart. Any manual gearbox that requires fancy $100 gear oil to fill it, on top of the $2,000-plus initial purchase price, doesn’t interest me. Again, you will need new driveshafts, which are more expensive than many people realize. I’ve been there. Although a lot of people like this transmission, I have only found it enjoyable behind the big Cummins diesel we put in the ’07 Ultimate Adventure Jeep we built because that engine has the power to pull through the odd gear jumps of the NV-4500.

Your third and best option is a simple gear swap and tire increase. If you were to go up to 4.10 gears with a 32- or 33-inch tire, I think you’d be pretty happy with the truck. If you want to keep the smaller rubber, jump up to a 3.73. The V-8 and granny First gear of the SM465 should have no issue getting a Jeep on a trailer up and moving, and then you won’t have to mess with new driveshafts and so on. You will have to change the carrier in the axle, as there is a carrier change at 4.10 to 4.56, but from the outside the rest of the truck will not change. I would guesstimate that the gears, carriers, bearing kits, and installation would be around $2,000 or less, depending on where you get it done and what grade parts you use. No driveshaft adjustments are needed, and you only need to upgrade to larger tires when your old ones wear out.

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