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1988 Chevy Blazer - Bug-Out Blazer: Part 2

Posted in Project Vehicles on January 12, 2015
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If you’re the type who likes to roll the dice with your fullsize rig by running lockers and 37-inch tires on your ½-ton axles, we’re betting our chips on you being one good “bounce” away from breaking a carrier or ring-and-pinion, or snapping an axleshaft. Them’s the facts: Your ½-ton axles were never designed for the shock loads applied by the combination of a big ’n heavy fullsize rig, big tires, serious off-roading, and a heavy right foot. When it’s time to romp on your 4x4 like your life depends on it, nothing will put you mind at ease like a pair of 1-ton axles slung underneath your ½-ton truck. Of course, you’ll want to make sure the rest of your drivetrain is up to the task, but if you’re running large tires with a heavy right foot, the factory 10-bolt axles strapped to your second-generation Blazer will undoubtedly be the main ingredients in a recipe for game-ending driveline failure.

Our target tire size for this build is somewhere between 37-40 inches, and this level of rotational mass meant 1-tons were high on the priority list—especially with the increased shock loads that are possible with B.O.B.’s manual transmission. Given our aim of making our ’88 Blazer into a sledgehammer-reliable escape pod for an apocalyptic scenario (or a pretty bitchin’ wheeling, camping, hunting rig until said s#!t hits the fan), we’re giving our ½-ton axles the heave-ho in favor of the proven, venerable, and easy-to-swap Dana 60 front and 14-bolt rear combination. Drawing comparisons between the corporate 10-bolt axles currently living under B.O.B., the 1-tons are bigger and stronger in every respect, better supported by the aftermarket, and better serve the bulletproof objective we’re striving for.

Some ½-ton rigs can provide some challenging roadblocks when going 1-ton, but with the ’67-’87 ½-ton pickups or ’67-’91 Blazers and Suburbans, it’s more or less a cakewalk. If the donor axles were pirated from a GM K30, its Dana 60 front shares the same exact spring-pad width as the fullsize Blazer/Jimmy and K10/K20 series of trucks. If possible, you’ll want to snag the factory spring plates that came with the Dana 60, but the aftermarket has you covered if they’re MIA. The steering and sway bar (should you choose to keep the latter in there) even bolt up. The front-driveshaft U-joint size is the same (1310), and depending on lift height, you may or may not need to have your driveshaft shortened to accommodate the longer pinion of the Dana 60. Overall, it’s a walk-in-the-park swap.

Out back, strapping the 14-bolt in is a bit more work, but the difficulty level isn’t prohibitive for most weekend wrench turners. If you happen to find a ¾-ton full-floating version, its spring-perch width is identical to the ¾-ton, making it a no-brainer, bolt-in proposition. However, the 1-ton versions have a narrower perch width and different shock-mount locations, so you’ll be welding on new perchs and shock mounts to make the swap it work. If you’re working with a ’67-’72 truck or Blazer, you’re in luck: The spring perch width is a perfect match, both front and rear. Conversion U-joints are offered to mate your existing driveshaft with the 14-bolt, and again, you may or may not need to have the shaft shortened.

If you can find them, a Dana 60 and 14-bolt from a mid-’80s military CUCV K30—like our modified M1028 pictured here—will kill three birds with one pull of the trigger. Not only are you getting the inherent strength of the axle assemblies themselves, these particular 1-tons were also equipped with 4.56 gearing (a good match for our target tire size), as well as a Detroit Locker in the rear—all of which could save you a good chunk of time, effort, and money in the end.

So, where does one find a set of 1-tons? Well, depending on how many $100 bills you have buried in the backyard, you can always look to an outfit like Dynatrac to build you a set of bombproof axles assemblies, spec’d out to meet your exact requirements. It’s tough to go wrong with this option if your financial means permit. However, in the Northeast—where copious amounts of road salt are laid down each winter—you can usually find a perfectly good set of 1-ton axles lurking under a pile of rusted sheetmetal that previously resembled a truck. A lot of these trucks are still being put into use as “yard trucks” to plow snow during the winter and are sold accordingly on places like Craigslist. Outside of the off-road community, it’s pretty uncommon to find a seller who actually knows his rusted-out, not-fit-for-the-road K30 is worth much more than scrap value, so scoring a decent deal in the rust belt might be easier than elsewhere in the country. The only kicker is that you might have to take the entire rusty enchilada to get the axles.

When searching, avoid axles that came from a dualie—the rear is too narrow and the front too wide. If that’s the hand you’ve been dealt, you can make a Dana 60 front axle from a dualie work by swapping out the hub and rotor assemblies from a non-dualie axle, but it’s an added expense. Used parts are few and far between, but a brand-new hub/rotor package can be purchased directly through the folks at Offroad Design to the tune of about $300 a side. The rear 14-bolt from a dualie is about 4 inches too narrow. You could always swap out hubs from a single-rear-wheel axle, or run spacers to make up the difference, but thankfully, standard, full-width 14-bolts can be found cheap in nearly every boneyard in the continental U.S.

As Stephen Watson from Offroad Design recently put it, the second-generation fullsize Blazers are the “Lego equivalent” of the truck world, meaning you can easily mix and match parts from all years and tonnage capacities. The 1-ton, K30 Dana 60 (top) is a prime example and a literal bolt-in in place of

If you can find them, the crème de la crème of GM 1-tons are found beneath the mid-’80s CUCV (Commercial Utility Cargo Vehicle) Chevy 1¼-ton military trucks. That’s exactly what we’re sliding underneath B.O.B. These axles are generally low-mileage units (ours had under 40,000 miles), and not only did they have 4.56 gears—which is close to perfect for our target tire size—Uncle Sam spec’d out the 14-bolt with a bulletproof Detroit Locker. The front CUCV Dana 60s have an open diff, unless it’s an M1028, which was equipped with a limited slip.

Now that you know everything you need to about CUCV axles, here’s some more info: All of the CUCV pickup variations—the most-common M1008 cargo truck, the M1010 ambulance and single- and dual-wheel versions of the M1028 shelter carrier—got the good axles, but the Blazer version (M1009) was fit with the same 10-bolt axles found in the standard civvy versions. Complete trucks can be found in private hands across the country, as well as online venues like govliquidation.com in various states of running and disrepair. Ours came from a beat-up and rusted-out M1008 being parted out on Craigslist, and at $1,100 for the pair, they were a pretty smokin’ deal. A quick Craigslist search while writing this yielded even better deals—they’re out there.

Even though our 1-tons represent some serious beef for our ½-ton Blazer, the overkill angle we’re striving for with B.O.B.—as in “beyond-the-shadow-of-a-doubt, kill-it-with-an-RPG” overkill—dictates that we go waaay overboard in the strength department. We have a choice selection of bombproof parts in store for these axles, but you’ll have to wait ’til next issue to witness the level of lunacy our apocalyptic-preparedness has reached.

B.O.B.s ½-ton 10-bolt front axle. With a 37-40 inch tire on the checklist, we’ll no longer be able to count on the 10-bolt to serve reliably, so the Dana 60 represents a must-have.
PhotosView Slideshow

Sources

Offroad Design
970-945-7777
www.offroaddesign.com
RCV Performance
Loves Park, IL
815-877-7473
RCVperformance.com
Reid Racing
Pleasant Hill, CA 94523
925-935-3025
http://www.reidracing.biz/
Ruff Stuff Specialties
916-600-1945
http://www.ruffstuffspecialties.com

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