Bent Axle tubes
02-15-2008, 10:02 AM
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Bent Axle tubes Just bought a used 10 bolt 3:42 to replace my 2:73 with. (I don't want to hear from all you Moser and 9" guys about what a piece of S*** the 10 bolt is either) The axle tubes were bent both on a vertical plane and a horizontal plane. I measured using a 6" steel rod bolted to the brake mouting plates(not backing plates) and found that it was bent 1/2" toward the front of the car and 1/8" toward the ground. The axles were out of the rear end when we did this.
I couldn't find anyone in Atlanta that could straighten it and the costs I got on line were stupid(it's a 10 bolt and I am not dumping much $ into it) So, I started researching bent tubes on line. Seems like ALL tubed axles are prone to bending. If you check out the off road blogs, a lot of them are bending tubes. According to one shop, well over half of the rear ends (YES, this includes the famous 9") they rebuild have bent tubes.
Anyhoo, we use large hydralic presses to run fatigue and destructive testing on Transit System components in our testing lab here in Atlanta. So I set my rear end on the table below the Hydralic jack ram with the outside edges of the axles on jack stands and the Yoke end up. We carefully pressed down on the center casting .125 to .150" at a time. We would back off the cylinder and measure as best we could and then start again, adding another .125 to .150 inches. The tubes retain some memory, so you actually have to carefully bend them in the opposite direction slightly to get them to return to neutral. Over a period of about 30 minutes, we took almost all of the bend out of it(visually, it looks straight and a level shows it straight. Not perfect, but it does show the bend going away) We flopped the rear end over and pressed on the casting with the yoke parallel to the ground and took out the bend in that direction. We had to bend one side slightly more than the other, so we first got one side straight using the jack stands on the ends of the axle pressing on the center section. We then moved the jack stand under the straight side to a postion under the edge of the casting where the tube enters it and pressed down on the center of the casting with the jack stand on the bent side at the end of the tube. Using the same method, it straightened the tube very well. It may not be straight within .001s, but it is much, much better than it was. We'll weld the tubes in a couple of places, replace the axle bearings and seals and put the axles back in and see how she goes.
One question: What affect does bent axle tubes put on the carrier bearings?
I couldn't find anyone in Atlanta that could straighten it and the costs I got on line were stupid(it's a 10 bolt and I am not dumping much $ into it) So, I started researching bent tubes on line. Seems like ALL tubed axles are prone to bending. If you check out the off road blogs, a lot of them are bending tubes. According to one shop, well over half of the rear ends (YES, this includes the famous 9") they rebuild have bent tubes.
Anyhoo, we use large hydralic presses to run fatigue and destructive testing on Transit System components in our testing lab here in Atlanta. So I set my rear end on the table below the Hydralic jack ram with the outside edges of the axles on jack stands and the Yoke end up. We carefully pressed down on the center casting .125 to .150" at a time. We would back off the cylinder and measure as best we could and then start again, adding another .125 to .150 inches. The tubes retain some memory, so you actually have to carefully bend them in the opposite direction slightly to get them to return to neutral. Over a period of about 30 minutes, we took almost all of the bend out of it(visually, it looks straight and a level shows it straight. Not perfect, but it does show the bend going away) We flopped the rear end over and pressed on the casting with the yoke parallel to the ground and took out the bend in that direction. We had to bend one side slightly more than the other, so we first got one side straight using the jack stands on the ends of the axle pressing on the center section. We then moved the jack stand under the straight side to a postion under the edge of the casting where the tube enters it and pressed down on the center of the casting with the jack stand on the bent side at the end of the tube. Using the same method, it straightened the tube very well. It may not be straight within .001s, but it is much, much better than it was. We'll weld the tubes in a couple of places, replace the axle bearings and seals and put the axles back in and see how she goes.
One question: What affect does bent axle tubes put on the carrier bearings?
Last edited by carman53; 02-15-2008 at 05:05 PM.
