Stretching U-Bolts are easily fixed. However, unforeseen issues can have disastrous consequences.

An excellent example of a caravanning problem is the humble u-bolt that clamps the spring to the axle. The bond between the spring and the steel beam prevents catastrophic events at high speed.

Therefore, it is of utmost importance to inspect the connection between the spring and the axle during servicing.

For example, the image below looks like there is something wrong. If you cannot pick the problem, I will help you identify the issues with comments under the photo.

Do you think the service mechanic noticed the nail or screw in the centre tyre?

Basic Observations

What is wrong?

  1. Leaf separation between leaf 2 and 3 indicates stretching u-bolts.
  2. Separation confirmed when looking between the axle pad and axle.

Solution

Did you notice the spanner on the ground and not a rattle gun?

Bright caravan and camper trailer service mechanics do not use rattle guns on u-bolts. Although a powerful battery rattle gun is available, in this instance, a spanner is the most useful piece of equipment to use.

Rattle guns create heat, causing the nylon inside the nylock to burn and become ineffective.

Steps and tips

  • Surprisingly the stretched u-bolts on this rig above will be OK.
  • Replace the nylock nuts.
  • Retighten the u-bolts in a diagonal rotation until the fishplate starts to bend.
  • Following these steps and your caravanning problems with u-bolts are resolved until the next service.

If you are unsure about checking these u-bolts, call your service technician to make a service booking before your next trip. It may just save your life.

Finally, did you notice the spring wrap from the main image below?

The spring wrap has opened a little. The spring warping causes this during reversing.

Broken Springs, Couplings and Jack-knife Trailers.

Tight u-bolts play a critical role in preventing spring warp. Tight u-bolts will prevent these spring wraps from opening.

Always mention u-bolt tightening checks to your service mechanic during your caravan services, and you will not experience these critical caravanning problems.

broken spring

There is also an excellent u-bolt article here.

Couplemate U-Bolts
A

Round U-Bolts

A

Square U-Bolts

B

Width

C

Height

Part Number
1 ½” (39mm) ½” (13mm) 4″ (100mm) U39R4GH
1 ½” (39mm) ½” (13mm) 4½” (112mm) U39R45GH
1 ½” (39mm) ½” (13mm) 5″ (125mm) U39R5GH
1 ½” (39mm) ½” (13mm) 5½” (137mm) U39R55GH
1 ¾” (45mm) ½” (13mm) 4″ (100mm) U45R4GH
1 ¾” (45mm) ½” (13mm) 4½” (112mm) U45R45GH
1 ¾” (45mm) ½” (13mm) 5″ (125mm) U45R5GH
1 ¾” (45mm) ½” (13mm) 5½” (137mm) U45R55GH
1 ¾” (45mm) ½” (13mm) 6″ (150mm) U45R6GH
1 ¾” (45mm) ½” (13mm) 6½”(162mm) U45R65GH
2″ (50mm) ½” (13mm) 4″ (100mm) U50R4GH
2″ (50mm) ½” (13mm) 4½” (112mm) U50R45GH
2″ (50mm) ½” (13mm) 5″ (125mm) U50R5GH
2″ (50mm) ½” (13mm) 5½” (137mm) U50R55GH
2″ (50mm) ½” (13mm) 6″ (150mm) U50R6GH
2″ (50mm) ½” (13mm) 6½”(162mm) U50R65GH
2″ (50mm) ½” (13mm) 7″ (175mm) U50R7GH
2 ⅓” (60mm) ½” (13mm) 5″ (125mm) U60R5GH
2 ⅓” (60mm) ½” (13mm) 6″ (150mm) U60R6GH
2 ⅓” (60mm) ½” (13mm) 7″ (175mm) U60R7GH
2 ½” (65mm) ½” (13mm) 5″ (125mm) U65R5GH
2 ½” (65mm) ½” (13mm) 6″ (150mm) U65R6GH
2 ½” (65mm) ½” (13mm) 7″ (175mm) U65R7GH
1 ½” (40mm) ½” (13mm) 4″ (100mm) U40S4GH
1 ½” (40mm) ½” (13mm) 4½” (112mm) U40S45GH
1 ½” (40mm) ½” (13mm) 5″ (125mm) U40S5GH
1 ½” (40mm) ½” (13mm) 5½” (137mm) U40S55GH
1 ½” (40mm) ½” (13mm) 6″ (150mm) U40S6GH
1 ¾” (45mm) ½” (13mm) 4″ (100mm) U45S4GH
1 ¾” (45mm) ½” (13mm) 4½” (112mm) U45S45GH
1 ¾” (45mm) ½” (13mm) 5″ (125mm) U45S5GH
1 ¾” (45mm) ½” (13mm) 5½” (137mm) U45S55GH
1 ¾” (45mm) ½” (13mm) 6″ (150mm) U45S6GH
1 ¾” (45mm) ½” (13mm) 6½”(165mm) U45S65GH
1 ¾” (45mm) ½” (13mm) 7″ (175mm) U45S7GH
2″ (50mm) ½” (13mm) 3″ (75mm) U50S3GH
2″ (50mm) ½” (13mm) 4″ (100mm) U50S4GH
2″ (50mm) ½” (13mm) 4½” (112mm) U50S45GH
2″ (50mm) ½” (13mm) 5″ (125mm) U50S5GH
2″ (50mm) ½” (13mm) 5½” (137mm) U50S55GH
2″ (50mm) ½” (13mm) 6″ (150mm) U50S6GH
2″ (50mm) ½” (13mm) 6½”(165mm) U50S65GH
2″ (50mm) ½” (13mm) 7″ (175mm) U50S7GH
2″ (50mm) ½” (13mm) 8″ (200mm) U50S8GH
2″ (50mm) ½” (13mm) 10″ (250mm) U50S10GH
2 ¼” (56mm) ½” (13mm) 4½” (112mm) U56S45GH
2 ¼” (56mm) ½” (13mm) 5″ (125mm) U56S5GH
2 ¼” (56mm) ½” (13mm) 5½” (137mm) U56S55GH
2 ¼” (56mm) ½” (13mm) 6½”(165mm) U56S65GH
3″ (75mm) ½” (13mm) 3″ (75mm) U75S75GH
3″ (75mm) ½” (13mm) 4″ (100mm) U75S100GH
3″ (75mm) ½” (13mm) 5″ (125mm) U75S125GH
3″ (75mm) ½” (13mm) 6″ (150mm) U75S150GH
3″ (75mm) ½” (13mm) 7″ (175mm) U75S175GH
3 ¼” (82mm) ½” (13mm) 4 ¾” (120mm) U80S120GH
4″ (100mm) ½” (13mm) 3″ (75mm) U100S75GH
4″ (100mm) ½” (13mm) 4″ (100mm) U100S100GH
4″ (100mm) ½” (13mm) 5″ (125mm) U100S125GH
4″ (100mm) ½” (13mm) 8″ (200mm) U100S200GH
1 ¾” (45mm) ⅝” (16mm) 6″ (150mm) CM600GH
2″ (50mm) ⅝” (16mm) 6″ (150mm) CM602GH
2 ⅓” (60mm) ⅝” (16mm) 7″ (175mm) CM604GH
1 ¾” (45mm) ⅝” (16mm) 6″ (150mm) CM601GH
2″ (50mm) ⅝” (16mm) 7″ (175mm) CM603-7GH

Stretching U-Bolts cause Caravanning Problems

© Steve Wotherspoon 28th June 2019