Dexko Global
How to Measure a U-Bolt
Use this guide to identify the U-bolt shape and collect the core measurements needed before selecting replacement U-bolts for a suspension repair.
Correct U-bolt fit helps keep the suspension clamped securely
U-bolts hold the spring assembly to the axle and help maintain proper clamping force. Getting the diameter, width, length, and shape right helps prevent loose hardware, alignment issues, and added stress on suspension components.
Clamping force
The right U-bolt helps secure the spring and axle assembly so the hardware can do its job under load.
Suspension alignment
Proper fit helps keep the spring pack positioned correctly on the axle seat and tie plate.
Hardware compatibility
Correct dimensions help confirm fit with the axle, spring, tie plate, nuts, and washers.
Ordering confidence
Recording the right measurements before ordering helps reduce returns and fitment issues.
Identify the bend style before measuring
The measurement approach is similar across U-bolts, but the bend style should be recorded so the replacement matches the application.
Round
Used when the U-bolt wraps around a round axle, tube, or similar rounded surface.
Semi-Round
Used where the top profile is partially rounded and the application requires a more specific fit.
Square
Used for square axles, rectangular tube, or flat-sided mounting applications.
Measure these four U-bolt dimensions
For most replacement U-bolts, record the threaded rod diameter, inside width, inside length, and thread length. Use inside measurements rather than outside-to-outside or center-to-center dimensions.
Threaded rod diameter
Measure the diameter of the threaded portion of the rod. Do not measure the unthreaded rod diameter by mistake, since it can be slightly smaller than the threaded portion.
Inside width
Measure from one inside edge of the U-bolt to the other. This is an inside width measurement, not center-to-center or outside-to-outside.
Inside length
Measure the usable inside length from the inside of the bend to the end of the leg, or to the point specified by your replacement part requirements.
Thread length
Record how much of each leg is threaded so the nuts can properly engage and clamp the spring, plate, and axle assembly.
Information to record before ordering
A complete U-bolt specification helps confirm the correct replacement. Record the required dimensions, bend style, application notes, and quantity before shopping or contacting support.
Round, semi-round, or square
Measure at the threads
Inside edge to inside edge
Inside bend to leg end
Threaded portion of each leg
Record total required
Axle, spring, or hardware notes
Use the appropriate torque guidance for the U-bolt type and finish.
Recommended U-bolt torque for cold-formed U-bolts
Cold-formed U-bolts that have been torqued to a set preload should be re-torqued after a short time to take up stretch in the material. Lubricated U-bolts with anti-seize will typically fall between plated and unplated values. These values are general guidelines; the OEM service manual for a specific model always takes precedence.
| Size | Material Grade | Max Torque Ft. Lbs. Plated | Max Torque Ft. Lbs. Unplated |
|---|---|---|---|
| 3/8 - 24 | 5 | 21 | 26 |
| 7/16 - 20 | 5 | 33 | 44 |
| 1/2 - 20 | 5 | 52 | 70 |
| 9/16 - 18 | 5 | 75 | 100 |
| 5/8 - 18 | 8 | 132 | 177 |
| 3/4 - 16 | 8 | 234 | 313 |
| 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 |
U-Bolts 
Plates Need help identifying a U-bolt?
Use your measurements to narrow your search or contact a Dexter representative for help selecting the right replacement.
