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10 Bolt Off Road Design’s 4340 Chromoly Axles

Bang!! Pow!! Crack!!

No, it’s not the sounds of Bruce Wayne stomping out evil in a Batman episode. It’s the horrible sound of a good day of wheeling gone bad. If you’ve done enough hard-core wheeling it’s a sound that you’re probably familiar with. Tempting fate is something we all do to some extent when we head out for yet another round of off-roading with stock drive train components in our rig. That’s exactly where I was with my ’87 full-size Blazer. I’ve taken this rig on some extreme trails in Arizona and in Utah, all while using it as my daily driver. For the last three years it’s sat on 33 and 35 inch tires, stock 28-spline axles, 4:56 gears, and two lock-rights calling home to front and rear corporate 10-bolt axles. Luckily, when Bruce Wayne decided to stomp out the evils in our axles, I was only 2 miles away from home. We were out just to take measurements on a new suspension system that was to be installed and, while on the side of a hill powering up it, the bang, pows and cracks let out with a vengeance. This was the sound of a front axle snapping. At the same, the left rear axle broke at the neck of the spines. Talk about your bad days.

This brings us to our first of 3 articles that deal with strengthening corporate 10-bolt axles.

Fortunately, we know Stephen Watson, owner of Offroad Design in Carbondale, Colorado, who specializes in beefing full size rigs. Stephen has jokingly taunted me about my stock axles and their inevitable fate. Well, it was now time to give Stephen a call to try out his 28-spline, 4340 chrome moly front axle shafts. While talking with Stephen he told us that a corporate 10-bolt front end is basically the same strength as a Dana 44 and not too far behind a corporate 12 bolt axle. Further, the front 10-bolt’s weakness lies mostly in the stock u-joints and with proper driving techniques, a well maintained differential carrier and upgraded u-joints, a 10-bolt should hold up well to 35 and 36 inch tires. He cautioned us that heavy throttle action will surely be the demise of a 10-bolt while running large tires. Knowing that my driving style is more of finesse and patience, I felt pretty comfortable with the 35″ tires and upgraded axles installed.

 Stephen’s design process is well thought out to increase the axle shafts durability, strength and reliability. The axles are forged, heat-treated, and are machined in such a way that they are the strongest axle shafts available for our application. And here’s the guarantee- Offroad Design stands behind them 100%. If you should break one, the axle will be replaced at no charge. The durability of the Off Road Design axles comes from the lack of the strength-reducing taper near the splines, which is incorporated in the factory axles. The tapering associated with stock axle shafts account for a for a 40% reduction in strength. It’s no wonder that’s why ours broke in this location. The Off Road Design axles are also machined for a full snap ring around the u-joint cups to help prevent the possibility of u-joint failures. While apart, we decided to replace the outer stub shafts. We couldn’t see strengthening the “inner” axles and leaving the weaker “outer” stub shafts. The chrome moly stub shafts are 60% stronger than stock, so I think you’ll agree with our decision. The only weak link left was the u-joints themselves, and for those we chose Spicer u-joints per Stephen’s recommendations.

Read how our install of this strength increasing process, for the drive train of your GM 10 bolt or 12 bolt, went. We think you’ll agree these Off Road Design chrome moly axles are worth every penny. 


Step 1
Luckily, we had the opportunity to use an automotive lift to do this install. We also enlisted the help of an ASE Master Technician to assist us. The process first starts off with removing the tires, locking hubs, and bearings. We recommend the use of a spindle nut removal tool (an oversized, thin- walled socket) to remove the spindle retaining nuts, instead of using the old “hammer-screwdriver trick”.

Step 2
Disassemble the front brakes including the rotors, and unbolting the calipers and swinging them out of the way. Take care in doing this so that the brake lines are not damaged, and remember to not let the calipers hang from the brake lines by themselves. Once the rotors are off, you’re left only with the backing plate and spindle. These are held on with six bolts and once they were off, we took the time to clean the area well.

Step 3
Next, carefully slide out the axles. “Carefully” is the key word because there are axle seals located on the inside of the differential housing tube, not at the end by the knuckle. This is only true of the front of our corporate ten-bolt housing; the rear differential has them at the outer ends. Once the axles are out, it’s now time to retrieve the broken piece that was left in the right side of our carrier. As expected, the stock axle broke at the weakest point as mentioned previously; at the taper behind the splines. We were able to slide a telescoping magnet down the axle tube and pull the broken piece out. Before installing our new Off Road Design chrome-moly axles, we took the time to remove the front cover and inspect the ring and pinion. We also checked inside the differential tube to check for any debris that may have been in there from the broken axle.

Step 4
While we had everything apart, we figured this would be the best time to replace all of our bearing and axle seals. This is where having a Master Technician really came in handy. We will be the first to admit this is not an easy job to do due to the location of the seals in the housing.

Step 5
During our disassembly, we took the time to lay everything out in a n orderly fashion. This really serves two purposes; 1) it keeps you from loosing parts and 2) when it comes time to assemble the rig or any new parts, it’s much easier to do. We started by assembling the stub shafts and the axle shafts with the new spicer u-joints and then ensuring that they moved freely. Even though the u-joints come pre-lubed, we took a few minutes to push a bit more grease through them just to make sure.

Step 6
Next, we assembled the axles shafts with the Spicer u-joints. When inserting your axles remember to install the new backing plate that goes behind the rear bearing seal on the spindle. (These plates fit on the outer stub shaft.) Time should be taken to slowly line up the axle to go through the inner axle seal without damaging it, and then into the side gear on the Lock Right locker. Once the new axle is bottomed out, reverse the original order of removing the spindle, backing plate, bearings, rotor, caliper, and locking hub assembly and reinstall. Torque all nuts inside the hub to factory spec; reinstall the tire, torque the lug nuts and you’re set for a test drive.

Off Road Design
Web Site:http://www.offroaddesign.com
Email: support@offroaddesign.com
Phone: (970) 945-7777


Description Notes Rating
Ease of Install As stated in our install, if you haven’t done this type of job, make sure you enlist the help of a friend or professional shop that has.
Ease of Use N/A N/A
Performance No difference can be felt compared to stock, except that you can have piece of mind with the strength improvement you’ve made.
Durability With the inner axles 40% stronger and the outer stub shafts 60% stronger over stock, I think we’ve said it all.
Appearance The appearance of machined 4340 chrome-moly is a work of art in itself. Too bad they are hidden in the axle housing.
Drivability N/A N/A
Comfort N/A N/A
Price in comparison to related products Less expensive than other brands.
Tools Required You’ll need a good assortment of wrenches and sockets, a gasket scraper, a GM hub removal tool, snap ring pliers, torque wrench, and some screwdrivers. Air tools are nice to have with a job like this.
Editors Notes After deciding to go with Offroad Designs axles, I am convinced that you would be just as satisfied and impressed as we were…TS

About Rick Webster

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