Anyone who has seriously wheeled anything with a Dana 30, Dana 44, or Chevy 10-bolt front axle has probably replaced at least one Spicer 5-297X U-joint. The ol' 297 served admirably in most 11/42- and 31/44-ton American trucks for the last 20 or so years. So when we heard some time ago from High Angle Driveline's Jess Jaynes that Spicer was pulling the plug on one of its most-produced U-joint parts and replacing it with part number 5-760X, we wanted to know why.
Why the New Part?
We spoke with DaimlerChrysler's Development Engineer of Jeep TJ vehicle development, David Yegge. Yegge was one of those ultra-cool engineers that dreamt up the Rubicon Wrangler. He told us that the Jeep engineers realized that given the torquey 4.0L six, 4.10 gears, 4:1 transfer case low range, and front locker in the new Rubicon, they shouldn't be using the same front U-joint that's used in the front of Malibu Stacey's four-cylinder Wrangler's Dana 30. Spicer was asked to build a stronger U-joint, and the 5-760X is it.
Is It Better?
The cross of the 760 is cold-forged, while the 297 is hot-forged. The cold forging makes for a denser product. Yegge told us that under cyclical bench testing, the new 5-760X outlasted its 5-297X predecessor by 10 times. While this doesn't mean that the new U-joint is 10 times stronger, it does mean it's 10 times more durable. We had High Angle Driveline send us a few of the new joints for some real-world testing. Using stock Spicer shafts, we ran the new 5-760X in the short side of a Dana 44 and the old 5-297X in the long side. What we found was that in three different circumstances, when the axleshaft failed the new 760 joints survived and were able to be reused, while the 297s failed at the trunion.
Is It the Ultimate?
While the 760s are the deal of the century at about $20 a pop, they're still not as strong as the better aftermarket U-joints on the market such as those offered by CTM and the Ox joints from Drivetrain Direct. Would we put off getting CTM or Ox U-joints indefinitely? Probably not. Would we rush right out and replace our 297s with 760s? You bet.