U-Bolt Protocol… Tips and Pointers when U-bolts are Involved

Lets face it. Most of us are on a budget. So If you are working with a set of leaf springs for your lift here are some quick tips and pointers to follow in regards to your U-Bolts. Whether you are installing a lift or doing a repair hopefully this helps you make the right decision and gives you some useful information…
First and foremost NEVER re-use U-bolts. Even if they are relatively new with a low amount of corrosion. The risk is actually much higher than you think for your old U-bolts to fail on you because they have already be torqued down to their previous specifications. Its the type of thing that if you have to remove them for a repair or upgrade you should get new ones.
Plated U-bolts don’t need to be torqued as much as non-plated U-bolts. So don’t over do it when torqueing them down. This same rule goes for the grade of the U-bolts you are using for your application. Grade 5 doesn’t need to be torqued as much as a grade 8 U-bolt. Torque specs should come with the parts for a lift or Repair kit, or you can find the OEM service manual for the original torque specs if all else fails. U-bolts that have been well lubricated with an anti seize compound will have a torque range somewhere between a plated and non-plated U-bolt. (SEE TABLE AT THE BOTTOM OF THE PAGE)
When tightening your U-bolts always use a cross pattern sequence.
1 4
3 2
So you tighten #1 then #2 to a partial torque. Then partially torque #3 and #4. Using the same sequence fully torque the U-bolt nuts to the recommended Ft. lbs. called out in your kit or service manual.
U-bolts that have been torqued to a set preload are recommended to be re-torqued after a short time to take up the stretch in the material. So after installing your new lift kit or replacing your U-bolts check them after a few hundred miles and re-torque them.
GENERAL U-BOLT TORQUE GUIDELINES
Size | Material | Grade | Ft. lbs Plated | Ft. lbs Non-Plated |
3/8″ | 24 | 5 | 21 | 28 |
7/16″ | 20 | 5 | 33 | 44 |
1/2″ | 20 | 5 | 52 | 70 |
9/16″ | 20 | 5 | 75 | 100 |
5/8″ | 18 | 5 | 107 | 143 |
5/8″ | 18 | 8 | 132 | 177 |
3/4″ | 16 | 5 | 190 | 253 |
3/4″ | 16 | 8 | 234 | 313 |
7/8″ | 14 | 5 | 304 | 405 |
7/8″ | 14 | 8 | 375 | 500 |
1″ | 14 | 8 | 758 | 1010 |
1-1/8″ | 12 | 8 | 848 | 1131 |
1-1/4″ | 12 | 8 | 1163 | 1551 |
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