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November 1998 Willie's Workbench

Posted in Features on November 1, 1998 Comment (0)
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November 1998 Willie's Workbench

One neat thing about Jeep vehicles is that throughout the years (since 1941, to be precise), and five different parent companies, they've retained the same style 1310-series U-joint in the front and rear driveshafts. There are some exceptions to this, of course: Some early Wagoneers used a "Detroit'' joint, the Jeepster an unusually small two-piece front shaft, Grand Wagoneers a CV-joint, and the 1994-95 YJs a 1330-series yoke. While seemingly small, these 1310 U-joints are quite strong and hold up well for all uses, other than perhaps racing.

The U-bolt-style yoke to the right is a direct replacement for the broken strap-style yoke to the left.

Around 1980, Jeep and Dana/Spicer (who supplied the axles) switched over to the strap-and-bolt-style yoke instead of the conventional U-bolt-style yoke. This was even used on the AMC Model 20 rearends and front output yokes on the New Venture/New Process transfer cases.

The strap type yoke (generally Spicer Part No. 2-4-6901-1X) has a bad reputation for failure, and serious Jeep owners often switch over to the seemingly stronger U-bolt-type yoke. Most Dana 30 frontends, Dana 35 rears, and Dana 44 fronts and rears use a similar 26-spline pinion shaft. The strap type yokes can be exchanged for Spicer Part No. 2-4-8091X yokes that use the full U-bolt clamping style of retention. The U-bolt kit is Part No. 2-94-28X. For AMC Model 20 rearends, the replacement Spicer part, which used a 28 spline yoke, is Part No. 2-43741. The Dana 300 transfer case's front and rear yokes, as well as the NP 207 and NV 231 front yokes, can be converted from the strap style to the U-bolt-style by using Spicer yokes (Part No. 2-4-2461X) and U-bolt kit (Part No. 2-94-28X).

Jason Bunch, owner of Tri County Gear (Dept. FW, 1143 W. Second Ave., Pomona, CA 91766, 909/623-3373) who supplied the information and part numbers, says that one really shouldn't totally condemn the strap-type yoke. Breakage usually occurs for two reasons: either the U-joint binds from excessive angularity (caused by modified suspension systems), causing an excessive load to be placed on the strap; or the U-joint itself gets worn and allows unequal loads to be put on the strap.

Jason does consider it good insurance to replace these straps (Spicer Part No. 270-18X) whenever a U-joint is changed out. If you're reusing the old bolts, a dab of blue Loctite isn't a bad idea. Torque specs are 13 to 18 pounds, just about what you can pull up to with the standard length 12-point end wrench.

On some of the strap-type yokes, Jason notes, you can drill out the threads and use a milling machine to spot-face the back side so that it'll accept the U-bolt-type hold-downs.

Jason and his crew build a lot of custom Jeeps and driveline components, and have discovered that the unusual 1994-95 Dana 35 yoke (Spicer part No. 2-4-7631-1) can actually be a good thing. It's about 5/8 inch longer in overall length and can make up the necessary needed difference in driveshaft length on some lifted Jeeps. It uses the slightly wider 1330 U-joint, but, when combined with a driveshaft that takes a 1310-series U-joint, it provides excellent clearance for high-angularity applications. A special combination joint (Spicer Part No. 5-134X) must be used. This yoke can also be drilled and milled to accept U-bolt-type hold-downs.

Most people don't grease their U-joints often enough, especially when they operate at higher angles than they were originally intended. Grease is cheep . . . but unnecessary replacement of U-joints isn't. Always put in the U-joint so that the grease fitting and the hole are in compression, not tension. I've found that U-joints without the grease hole are a bit stronger than those that are greaseable. In fact, it just may be better to use the "lubed-for-life'' style-not only are they stronger, but the seal around the bearing cap is better about keeping contaminants out.

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