You can call 'em weak links, design flaws, or whatever you wish. The fact is, there isn't a vehicle made that doesn't suffer to some degree from model-specific quirks. Some of these quirks rear their ugly heads after normal use, while others are the result of accumulated stress brought on by years of 'wheeling.
In this initial installment of Weak Links, Strong Fixes, we take a look at fullsize GM trucks and SUVs. Keep in mind that Chevrolet and GMC vehicles are almost identical, so many of these items apply not only to pickup trucks, but also to the Blazers, Jimmys and Suburbans. To help generate this list, we asked aftermarket GM experts at Missouri Off Road Outfitters and Off Road Design as well as some of the readers of ColoradoK5.com to share their experiences. The following reflect some of the more common problems that owners of GM trucks say they face. Without a doubt, there could be many more items included in this installment, but due to space constraints, we whittled them down to a reasonably sized list that includes the most important and compelling items.
We've tried to include information about which models the problem directly affects, what exactly happens when the component or part fails, and of course we would be remiss if we didn't include info on what you need to fix the problem and where you can get it.
ALL CRACKED UP
Weak link: Frame cracks around steering box
Models affected: Every straight-axle GM truck and SUV, though pre-'73 trucks don't seem to exhibit the problem as frequently as those built after 1973.
What happens: By today's standards, the GM frames of this era are fairly weak. This is one of the contributing factors to the notorious frame cracking around the steering box (shown).
Sturdy fix: Off Road Design offers a steering-box brace that can help avoid this problem. If cracking has already occurred, Off Road Design offers a weld-on repair kit.
Contact: Off Road Design.
WEAK AXLE
Weak link: The Corporate 10- and 12-bolt rear axle
Models affected: Late '60s-'91 1/2-ton
What happens: The pros say that these axles seem to handle a 33-inch-diameter tire with no problem, but depending on your driving style and equipment, 35-inchers and up require modifications. Common parts failure when running large tires on the trail include the factory limited-slip differentials, axles, axle bearings and the housing itself.
Sturdy fix: Install a quality locker, quality axleshafts like those available from Off Road Design, Green wide-repair axle bearings and a Missouri Off Road Outfitters Over The Top axle truss.
Contact: Missouri Off Road Outfitters, Off Road Design.
WEAK AXLE, 2
Weak link: The Corporate 10-bolt and Dana 44 solid front axles
Models affected: Dana 44 '78-and-older, 10-bolt '79-and-newer
What happens: With 35-inch or larger-diameter tires, expect to break a stock axleshaft, especially if using a limited-slip or locker. If you have a lot of weight on the front of your truck, like a snowplow, or if your vehicle sees hard off-highway use, the axletubes can bend. Most of the time the driver-side tube will bend where it enters the centersection. The earlier 3/4-ton Dana 44s had external-spline locking hubs, which are prone to working loose and breaking the bolts.
Sturdy fix: For use off-highway, the pros say that depending on driving style and equipment, the front 10-bolt and '44 can withstand a fair amount of abuse, if they're upgraded. Try installing a pair of chrome-moly or heavy-duty axleshafts and solid Spicer U-joints, and, if you're using a true locker, Warn fusible hub links. Missouri Off Road Outfitters offers a bolt-on under-the-axle truss for both the 10-bolt and the '44 housings, and the company offers its Rock Bruiser diff covers to guard against diff-cover damage (all shown in photo). To solve the hub-bolt breakage problem on 3/4-ton Dana 44s, either carry a wrench and check the bolts often, or swap the entire spindle-out assembly for a later internal-spline 3/4-ton setup.
Contact: Missouri Off Road Outfitters, Off Road Design, Warn Industries.