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U-bolts and the saga goes on. The 1/2 u-bolts on the Montys and other rigs are only of grade 5 quality ( may be lower if Made In China) on axles up to 7000 lb ratings. Another area where axles, springs,u-bolts, shackles etc. should be of better quality when carrying a rig that can gross 15,000 lbs plus. We are all running on the EDGE. When you jump to 5/8 fine thread the u-bolts are of grade 8 or better quality, many now on trucks at grade 12. To change to a 5/8 u-bolt one would have to ream out each hole on the spring pack hold down plate; a total of 16 holes; quite a job indeed.
To conclude; as one retorques the grade 5 bolts they will stretch and stretch until they let go, commonly at the bottom thread. This is called going beyond the yield point of any mechanical stress.
Price of a 1/2 u-bolt at any spring shop is about a $1.50 each so go figure the quality??? 5/8 will run about $10.00 and up.
To conclude: if you find that each time you retorque; you can get a fraction of a turn to arrive at spec. your bolts are stretched or are strectching to a point of failure!!
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