Cutaway of AAM Upper Ball Joint** from 2005 Dodge Ram 3500 4x4
** Upper Ball Joint is really a floating King Pin
|Dan the Gear Man® Tech Note:
Premature Ball Joint failures on 2003-up Ram Trucks is a reoccurring problem that will probably plague these trucks for their entire life due to the size of the Ball Joints and the steering geometry of the AAM 9.25" axle. Average Ball Joint life on these vehicles is only 50,000-75,000 miles regardless of the brand of stock type greaseable or non-greaseable ball joints used. Yes, some folks luck out and get 200,000 miles on a set of but the vast majority of owners get a whole lot less.
The Upper and Lower Ball Joints on these axles are at different angles, in other words the vertical axis of the Upper and Lower Ball Joints are neither inline or parallel to each other. To compensate for the different arc of each Ball Joint during turns, the modest sized, straight shank, 7/8" diameter stud of the Upper Ball Joint is vertically free-floating in a 1" long sleeve. Consequently, the Upper Ball Joint does not support any weight, it merely keeps the knuckle in place. On the AAM axle, the upper Ball Joint is not really a Ball Joint at all, instead it is a floating King Pin that is about the same diameter as the King Pins found on 1966-1981 Ford F100 4x2 1/2 ton trucks and light 3/4 ton trucks with GVW's of 4,700 lbs-6,900 lbs..
The Lower Ball Joint is load bearing, in fact, the two Lower Ball Joints carry 100% of the front axle weight on your 2003 or newer Dodge Ram truck. Dimensionally, the outside diameter of the Lower Ball Joint is only 4% larger than the Ball Joints used on 1972-1986 Jeep CJ's (and other light-duty models of that era) which has somewhere between 1/4 and 1/3 of the front axle weight of the Dodge Ram, plus both the Upper and Lower Ball Joints on the CJ are load bearing. In addition, the Ball Joints used on older models like the Jeep CJ and 1994-1999 Dodge Ram 2500 and 3500* shared the same vertical centerline axis and were pre-loaded to compensate for wear. With the AAM front axle steering geometry using differing Ball Joint angles, no preload is possible, therefore, any wear means loose Ball Joints.
I found it very interesting that the 2003 Dodge Ram Truck Service Manual does NOT give any specifications for allowable Ball Joint movement or looseness, yet later manuals allow for up to an amazing 0.090" of vertical movement and 0.060" of horizontal play. You can interpret this information any way you want, but my experience has been that anything more than a fraction of the amount of play Dodge says is permissible will adversely affect steering and tire wear on the AAM 925 axle. (Note: 1/16" = 0.0625")
*1994-1999 Dodge Ram trucks with the Dana 60 Front Axle have Lower Ball Joints that are nearly 10% larger than the AAM axle. Average Ball Joint life for 1994-1999 trucks is close to 150,000 miles or 7 to 10 years. All 4 Ball Joints for those years carry weight and are pre-loaded to compensate for wear and dampen steering shocks.
Dodge AAM 925 Beam Type 4x4 Front Axle:
2004-2010 Ram 1500 Mega Cab
2003-2012 Ram 2500, Ram 3500