Caravan and Trailer Wheel Alignment

Caravan wheel alignment sounds like a complicated problem. How can wheels on caravans and trailers fall out of alignment?

It is common to find worn tyres and wheel bearings in older caravans and trailers. A lot of kilometres and a lot of shock loading is the prime cause of miss-alignment.

In a tandem axle setup, it is the rear axle that suffers the most significant wear and tear. If you take the time put a long straight edge across both tyres, I am sure you will be surprised!

It is far easier to correct the wheel alignment on a single axle trailer than tandem axle suspension systems..

How vital are axle pads?

Axle pads were first thought to align the spring on top or below the axle.

In many cases, axle pads have not been welded into position because many manufacturers did not require welding. U-bolts were thought to provide enough force to clamp the axle and spring into their correct location effectively.

In the past, it was recommended that only round axles needed to be welded. Read on to find the solution on how and why U-bolts cause misalignment and spring breakages.

U Bolts

U bolts installed on caravans and trailer are made from mild steel, generally. Mild steel stretches within the first 300 kilometres of installation and requires re-tightening.

What can happen if u-bolts are not re-tightened?

worn tyreLoose axle pads and loose u-bolts

Picture driving down the highway, west of the Great Divide and no doubt you have come across a pothole or two.

Both tow vehicle and caravan or trailer entering a pothole at 100 kph causes shock loading.

Shock loading transfers massive forces that try to push your axle or axle group towards the rear of the caravan or trailer.

If your axle pads are NOT welded into position, you might not have noticed the damage and continue driving.

What happens next?

Two things can happen to affect caravan or trailer wheel alignment:

  1. One wheel is now out of alignment. This will produce significant wear on your tyres. If you have an overlay or drop axle, it may even have twisted the drop or overlay. Contact your dealer if your tyre wear is excessive.
  2. Loose-fitting U-bolts and loose axle pads will cause the axle and spring assembly to fail progressively. The axle will develop vibration, and the spring will eventually break about 75mm from the back eye.

An article on loose u bolts and their effects can be found here.

50mm Square Lazy Axle AssemblyAxles without axle pads.

Couplemate dispatches dozens of axles daily. A small percentage have axle pads welded into position as requested by the customer.

The cost of an axle is between $600 and $1100 depending on the type of axle.

If replacing an axle, be sure to provide your chassis width so we can weld your axle pads into position. The cost is $25.

Axle pads welded into position make your axle much easier to install because of the axle centres itself directly over the leaf springs.

This article assumes the chassis or frame is straight and true.

Independent Suspension

Independent suspension is usually set up for full load at zero camber by the manufacturer.

Put a spirit level, in the vertical position of the tyre. More than a 5mm gap is a concern.

Most Independent suspensions have camber adjuster installed. The more rigid suspension like the Couplemate ICS does not require camber adjusters.

Loose Wheel Studs

A variety of factors cause loose wheel studs.

This is a rather comprehensive article on how wheel studs and what causes loose wheel studs.

Tandem Trailers

The very best way to check your tandem trailer is to place a piece of straight edge steel across the front of both wheels.

If the tandem wheels are not square, call your service agent for an alignment.

Finally, it is quite likely that your u-bolts have come loose, and your rig has sustained some shock loading during your travels.

© Steve Wotherspoon 24th November 2018

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