By: Matt Dubbin - 11/1/2002, Photos by Matt Dubbin
Prevent spun axle tubes!
One of the many areas for upgrades on a Jeep vehicle beyond that of the simple bolt-on after market is an axle upgrades. Over the last couple years it has become popular to install a Ford Explorer 8.8 axle into the rear of a Jeep. The advantages are many: similar width (only 1" shorter than a stock YJ/TJ), 31 spline axle shaft (most stock Dana 35 axles have 28 splines), the wheel bolt pattern is 5x4.5 (same pattern as on the YJ and TJ) and if you get an axle newer than 1995 you get disc brakes. Several after market companies sell all the required parts to install this axle into your Jeep.
|Figures 1 and 2|
|Figures 3 and 4|
|Figure 5 shows the three sheared off pins, front and back.|
|Figure 6 shows where the welds are located on a Dana 44 front axle.|
|Figures 7 and 8 show how Mark's 8.8 center casting was welded to the axle tubes.|
Recently, I assisted my friend Mark with a complete trail truck buildup. The starting platform was a stock 87 YJ with the 4.2L engine, Peugeot tranny and NP 231 T-case. Other than the frame and tub, everything went. Installed was a fresh Chevy 350, SM 465 tranny, Atlas II T-case, custom narrowed high pinion Dana 44 front end and a Ford 8.8 rear axle from a 1999 Ford explorer. This new creation sits on a new set of Super Swamper 36" TSL SX tires. Believe it or not, when it was all finished it actually drove down the road quite well at 65 MPH.
The first trail action the truck saw was at Camp Jeep in Branson, Missouri. During the first day of trail riding, Mark took it easy getting a feel for the new conglomeration of fixed and moving parts hoping that the fixed parts stayed fixed and the moving parts kept moving. All went well the first day. The second days trail was more technical with Mark beginning to stretch the limits of the truck, which he found, near the end of the trail. Mark said the sound he heard and initial damage assessment was that of a rear u-joint failure. The u-joint had broke and the u-joint flange was split. It wasnt until the vehicle was back on level ground that it became evident what had happened. The center section of the differential broke free of the axle tube and spun, breaking the drive shaft flange, u-joint and bending the rear drive shaft.
The Ford 8.8 axle relies on three pins per side that are pushed into three predrilled holes in the case and axle tube. Figure 1 is a photo of the front passenger side of a Ford 8.8 rear axle. Figure 2 is a close-up photo of the one of the three pins used to keep the axle tube from spinning. Due to the deformation of the pin (see Figure 2) it appears the pins are near molten stage when they are pressed into the axle.
When enough torque was applied, such as with Marks truck, these pins sheared off between the tube and the case. Mark was able to easily remove the portion of the pin that was attached to the case. Figure 3 below is a photo of the back of the axle, drivers side. Figure 4 is a close-up photo of where the pin had been located. Figure 4 shows that the axle is not quite aligned. The tube needs to be rotated backward and slid out slightly.
The Dana axles I have examined have holes drilled in the cast case that are used to weld the tube to the case. I have seen anywhere from 5 to 8 welds per axle tube on the Dana axle. Figure 6 shows a photo of the Dana 44 front axle. Notice the two welds on each tube. This assembly had 6 welds per side.
Once the axle tubes were re-aligned, Mark welded each of the holes and the contact point where the tube enters the case. Figure 7 is a photo of the left side of the axle tube after it was welded. Notice the weld placed in the location of the factory pin. Figure 8 below is a photo of the right side of the axle tube after it was welded.
A year ago I installed the 8.8 axle into my 93 YJ. I run 33 MTRs, stock T-case, tranny and 4.0L engine. I installed a Loc-right locker and other than a leaking axle seal, I love the axle. Since Marks unfortunate find (better him than me) my axle will soon get a fresh weld. Simple insurance. So, if you have an 8.8 in you truck or plan on installing one, take a few minutes and weld the axle tubes to the case. It would have saved Mark $300 in drive line repairs and the slightly bent passenger side rear springs.
Specials thanks to Mark for allowing me to photograph his truck and pass along his story