ALKO Caravan Suspension Upgrade Installation Procedure

Safety first

1.       Please ensure that all safety procedures have been followed when jacking up the caravan, and ensure it is well supported on a flat surface area where it is not at risk from high winds or any other environmental risks

2.       Always ensure you are not putting yourself or others in danger when working underneath your caravan. If you have limited skills in this particular line of work, contact someone with mechanical skills who can assist to ensure you are not in danger

3.       Always take the caravan to a weighbridge before you start to ensure the van is not already exceeding its weight limit.

4.       Vantage RV cannot be held responsible for any damage to you or your caravan due to a DIY installation of these components. Substantial damage can be caused to a vehicle if the work is not carried out professionally. If you want a warranty, please arrange for us to do the installation

5.       When fitting the components, ensure you use thread lock on all the bolts and that they are not over-tightened or under-tightened

Warranty

The suspension upgrade has a one-year return-to-base warranty from the purchase date. Please check the product carefully before installation and contact us immediately if you find anything wrong. All products are thoroughly inspected before being packaged and dispatched.

Warranty covers

●       Manufacturing defects

●       Material faults

This warranty does not cover:

●       Damage resulting from incorrect installation

●       Improper use, modification, or misuse

●       Normal wear and tear

●       Labour costs any incidental or consequential damages resulting from poor installation practices.

Please note: These parts are intended for professional installation purposes. It is the purchaser’s responsibility to ensure correct installation. This warranty does not cover any damages or failure caused by improper installation.

If you believe a part is defective, don’t hesitate to contact us. We will do our best to replace the faulty part immediately.

How to install a Spring upgrade kit on a European caravan

Always take the caravan to a weighbridge before you start to ensure the van is not already exceeding its weight limit. Reduce the weight inside the caravan to keep it below the vehicle's payload rating.

 Before you start

Please check that you have the correct spring upgrade kit for your particular caravan. 

1. Has your caravan got a 5-sided straight axle going from side to side?
2. Has your caravan got pressed trailing arms held in place with three rubber cords within the 5-sided axle tube?
3. Does the backing plate at the end of the trailing arms have four bolts that attach to the trailing arms?

 Some additional anomalies may be different to a standard caravan axle; for example:

• Some models may have a rubber insert in the factory shock mount slot that needs removal,
• Some models may have a locking bracket on the LHS (if you want to maintain this feature, you will need to order the custom locking bracket adapted for the spring upgrade kit)

Lifting the Caravan

Choose a perfectly flat, concreted surface area to carry out this work.

Use only the axle to jack up the caravan and secure it with appropriate blocks or axle stands. Avoid jacking up an ALKO caravan using the chassis rails, because this may damage the lower flange or buckle the rail lengthwise. After jacking up the caravan, you can chock it using the chassis rails, as long as you spread the weight over the entire chassis

Stabilising the Caravan

Deploy the four steadies to stabilise the corners of the caravan.

Wheel Removal and Axle Rebound Check

1. Remove the wheels and check the trailing arm rebound.
2. Check the measurement from the underside of the caravan floor to the handbrake cable through the chassis rail cutout. With no weight on the trailing arms, the distance should be approximately 80mm.
3. If the rebound is less than 70mm, the rubber cords are worn, and the axle should be re-rubbered before proceeding.

Removing Components

Remove the one-shot nut that holds the hub bearings and the brake drums.

Remove the lower bolt from the shock absorber and discard the lower shock brackets.

Assembling components

Get acquainted with the components needed for this installation. See the main components in the image above.

The kit contains the following:

1.     Upper spring bracket (which attaches to the chassis)

2.     The inner and outer spring bracket (which attaches to the trailing arm shock absorber slot)

3.     The trailing arm brackets (which attach to the hub backing plate)

4.     The four spring locator washers that locate the springs

5.    Two springs 

6.     A selection of bolts, nuts, etc, and two large, galvanised washers (not shown in the image)

7.     Lateral restrain brackets (not shown in the image below

8.   

 You should also have left- and right-hand spacer brackets, as shown in the image above. This bracket links the combined inner and outer brackets to the hub. 

Security lock bracket (OPTIONAL)

If your model has a security lock on the LHS, you will need to remove it. (see image below)

If you still wish to retain the functionality of the ALKO locking system, we can supply a customised bracket to maintain it; however, your existing locking bracket must be sent to Vantage RV for remanufacturing, and we will send you a modified LHS locking bracket at an additional cost.

Installing the brackets

Install the outer trailing arm bracket by inserting the right-angled tab through the rectangular hole on the underside of the ALKO trailing arm (this is the same slotted hole where the shock absorber would typically be connected to the trailing arm).

Install the inner bracket similarly by inserting the tab and pivoting it into the rectangular slot.

Use a 12mm flange nut and bolt to secure the inner and outer brackets directly below the tabs, which should securely lock the two brackets into the rectangular slot of the Alko trailing arm.

You may need a G-clamp or similar tool to align all the holes properly. This is a press fit, and the two plates will not align until bolted together.

Installing the spacer brackets and trailing arm brackets

1. Place the spacer between the backing plate and the outer bracket.
2. Feed three long M12 cap bolts through the backing plate. Be cautious not to overtighten the top and bottom bolts; stop if any distortion of the packer or rotational movement is noticed.

 Installing the Lower Spring Support Plate

Before adding the lower spring support plate, install a 12mm flange nut and bolt through the inner and outer brackets at the bottom rear. Now, bolt on the lower spring bracket with spring locator washers. (See image below)

Our office will have determined which axle type you have and supplied you with the correct offset for your vehicle.

Installing the Upper Spring Bracket

Using the M10 cap bolts, bolt together the thick red spring support disk and the galvanised upper spring bracket.

Hold it up against the chassis rail. As shown in the image below.

The upper spring bracket can sit anywhere along the chassis bracket, but it is very important to position it correctly and ensure it is aligned with the travelling arc of the trailing arm. 

Measure 80 mm on the chassis from the rear of the axle bracket. (see image below) Hook the lower edge of the upper spring bracket around the bottom of the chassis flange, using a jack and a piece of timber to position it correctly.

Drilling Holes into the chassis

Drill three holes using a 10mm drill bit. Clean up any swarf between the bracket and chassis with compressed air to prevent future rust.

Insert the three M10 bolts and flange nuts, and apply thread locker before tightening.

NOTE. If you're using the Vantage RV-supplied lateral restraint brackets, ensure they are fitted at this point, as they are mounted with the two front bolts.

 Setting the spring location

Using the slotted hole, align the centre of the upper spring locator disk with the lower spring bracket attached to the trailing arm. It is best to have the spring vertical, but if that is not possible, it can be slightly closer to the chassis rail at the top than at the bottom; in other words, it can be off-plumb towards the top.

 From the side of the vehicle, the spring should align with the arc of the trailing arm's motion. Next, from the rear of the vehicle, the spring should sit as vertically as possible so the bottom support bracket can be adjusted using the slotted hole and the round spring locator washer, as you did when fitting the top bracket. Check that you are happy with the way the spring sits sideways, and from the rear, it is vertical. This is important because the forces on the chassis should be vertical, not sideways.

The spring locator washers should be tightly seated within the spring's inner diameter at both the top and bottom of the spring. It should be an effort to get the spring between the locator brackets. 

 Ensure you use a thread locker during assembly.

 Install the springs

If the existing suspension rubbers have good rebound, the springs can be inserted by hand. The springs will be captive due to the upper spring support and the lower spring locator, but they may be slightly loose and rotate when no weight is on the wheels.

 Installing the Lateral Restraint

When fitting the lateral restraint bracket, cut the galvanised tube to fit between the two brackets. Spray the cut ends with Cold-Galve to prevent corrosion. Clamp it into the bracket to eliminate gaps, drill the tube with a 6.5mm drill bit, and secure it with six structural rivets on both sides.

You will need a hydraulic rivet gun to pull these structural rivets up.

 IMPORTANT NOTE:

The lateral restraints should always be fitted before lowering the caravan onto its wheels.

 Brake Inspection

This is a good time to inspect the brakes and make any necessary adjustments, or to perform servicing while the hubs are off.

 Reassembly

Check that the trailing arm brackets are bolted firmly with thread lock through the backing plate to the spacer bracket. Refit the drums using new one-shot nuts, tightening them to 290 Nm.

Final Steps

Refit the wheels and check the clearance between the wheels and the spring brackets; check all other clearances.

Make any final brake adjustments if necessary.

Lower the caravan back onto its wheels and confirm clearances once again.

Take the caravan for a short test drive. Once again, check that everything is tight and operating correctly.

 Maintenance

 We recommend a check-up after six months or after the caravan's first extended trip to ensure everything operates properly.