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Moparmike

Frame cracked questions

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I have 3 ed mack 2 2000 and 1 2001 why do everyone of these trucks frame crack at the back by the rear end running the long way ..dot told me park it dont lif it back on the road its dangerous smh

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If you are talking cracked at the frame flange bend, top or bottom it is generally rust spreading a double frame, or even on a single frame at the trunnion stand at the bottom.    terry:MackLogo:

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+1 on the rust, gotta disassemble frame, sandblast and paint before it gets to cracking point. You could probably still take it apart and weld it back together if it's the horizontal flange crack by the trunion. Mack frames want 100,000 pound tensile welding rods, 3/32nds for frame repair. I think 10018 rod? Took my dad and I about a week and a bit to do our 95 rd. Well worth it, but we didn't have any cracks yet.

Because the DOT caught you you might have to show them the truck to be put back on the road, or sign that it's been fixed.  Once it's been welded, bring it so you can't tell it's been welded.

Edited by JoeH

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10018 rod is good but so is a gas shielded cored wire for the task in the proper rating. Either stick or wire, the frame should be temperature elevated in the weld zone with a torch to about 350 degrees or a bit better and welded up and allow a slow cooling to not set up stresses in the steel that cause cracking. 

 

Probably should add the crack needs to be "Vee" grooved out to get a full penetration weld also.

Edited by Rob
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