Stretching U-Bolts causes Caravanning Problems

Stretched u-bolts are easily fixed. However, insufficient safety knowledge and irregular checkups can result in disastrous consequences when towing a trailer or van – especially if hidden issues remain unresolved.

The humble u-bolt clamps the spring to the axle on trailers and caravans. This bond between the spring and the steel beam prevents catastrophic events at high speed. Therefore, it is of utmost importance to inspect this connection during servicing.

For example, in the image below there is something amiss. If you cannot pick the problem, keep reading for more information.

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

Basic Observations

The example image pictures an axle with the following specifications:

• Tri-axle configuration
• 60mm round 2t axles
• 12″ electric backing plates
• 60mm rocker roller springs
• Weight – challenging to ascertain (due to variable leaf-spring configuration)

What is wrong?

The following issues can be identified here:

1. The leaf separation between leaves two and three can indicate stretching u-bolts.
2. The space between the axle pad and the axle confirms stretching u-bolts.

Service Tip

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

Experienced 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.

Rattle guns create heat, which can cause the nylon ring inside the nylock nut to burn and become ineffective. Additionally, the power of the rattle gun can cause the nylon ring to pop out of the nut.

Solution

If you notice your trailer or caravan has stretched u-bolts, you can implement the following simple solutions:

• Replace the nylock nuts
• Retighten the u-bolts in a diagonal rotation until the fishplate starts to bend

Following these steps, each service will resolve caravanning problems with u-bolts. If you are unsure about checking the u-bolts, call your service technician to book a service before your next trip. It may just save your life.

Finally, did you notice the spring wrap from the main image below? It has opened a little. The spring warping causes this during reversing.

Tight u-bolts are critical in preventing spring warp and will prevent these spring wraps from opening.

In conclusion, we recommend to always request u-bolt tightening checks to your service mechanic during your caravan services, so that you do not experience these critical caravanning problems.

Find Heavy Duty U-Bolts Below

• 45mm x 16mm Square ElectroGal U-Bolt
• 50mm x 16mm Square ElectroGal U-Bolt
• 60mm x 16mm Round HD U-Bolts
• 65mm x 16mm Round HD U-Bolts

The Golden Rule is Do Not Reuse U-Bolts

• The used u-bolts will be stressed, and the threads will be rusted and damaged from the previous installation.
• A torqued u-bolt will suffer from distorted threads or stretched threads.
• Nylock nuts should be tightened once and retorqued, but never loosened and retightened.
• A used u-bolt may have suffered from fatigue and excessive stress since achieving accurate torque.

You can read another helpful article about the causes of significant highway accidents here, or learn more about broken springs, couplings and jack-knife trailers.

News Articles – Loose U-Bolts

• Loose Axle U-Bolts cause Highway Havoc
• Why U-bolts May be the Major Cause of Accidents
• How to Reduce Dangerous Caravan Vibration Fatigue
• Overview of Industry ADRs & Regulation Material

Links to Associated Administration Pages below

• Our Care, Your Warranty
• 60-Day Return Policy
• Shipping Policy
• Terms & Conditions
• Wholesale Application
• Submit A Review
• Overview of ADR 62/02 (Mechanical Connections Between Vehicles)

Stretching U-Bolts Causes Caravanning Problems

© Steve Wotherspoon 28th June 2019