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Ask for the "Extreme Discount"
www.4xshaft.com
 | Excessive angles are also a big problem. Often it is necessary to relief grind portions of the driveshaft or the attaching yokes to allow for extra momentary articulation through the driveshaft. This should only be done to allow for things like axle droop, spring wrap and frame flexing and not as a cure-all. As the U joints operate at greater angles, they'll create increasing axial loads on the retaining yokes of the driven shaft. This will cause the joint to rip out the end of the driven shaft. This is a result of the tendency of the U joint to transmit torque in a plane that is perpendicular to the driving shaft. At the transfer case end, the driveshaft is the driven shaft. At the differential end, the driveshaft is the driving shaft. I often equate this to using a flex socket at the end of an extension. In a straight line it will work well, but at an extreme angle it will be difficult to keep the socket on the nut or bolt. The most common failures are the U joint pulling out of the driveshaft itself at the transfer case end and breaking the retaining strap and bolts on the differential pinion yoke. This type of failure is especially common in lifted, short wheelbase Jeeps such as the Wrangler and CJ's. | |
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Make sure that you have no binding interference's in the driveshaft at all extremes of shaft operation. It can be difficult to simulate the extent of suspension travel and frame flexing in your garage, driveway or even on a ramp. On the highly modified suspensions that we are seeing these days, I recommend that you at least try. Allow a little extra margin for things that you can't simulate. For example, you'll driving down the highway and your rear end gets airborne because of the stored energy from compressed springs and their recoil effect. Your differential may fall well below what it would if allowed to hang freely from the vehicle. | 
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