Following recent reports of a small number of wheel detachments on single axle Unicorn models I am writing to you with an update on our findings and the remedial action required to prevent this issue from occurring.
Examination of the Unicorn models which have experienced this type of failure has revealed no fault with the either the production process or the specification of individual components used. Further testing has shown however that, whilst the current configuration is robust, in certain extreme driving conditions where significant amounts of heat is generated in the wheel assembly, loosening of wheel bolts can occur. The larger single axle Unicorn models will be most susceptible to this problem given their relative size and weight.
After extensive research with the assistance of the National Caravan Council in a number of recognised test facilities and in consultation with leading automotive and commercial vehicle experts we have found that the following actions will significantly reduce the risk of any further wheel detachments :-
Replace the existing zinc plated wheel studs with new bolts coated in a dry lubricant (Delta Protekt 301). The purpose of the coating on the bolt is to reduce the friction between the wheel, hub and bolt thus doubling the level of tightness (technically referred to as ‘pre-load’) in the joint. As a result there is a significant improvement in torque retention and an associated reduction in the risk of detachment. Please note that no other lubricant (e.g ‘copa slip’) should be used in this regards
With the previous assembly any additional bolt torque would simply be lost as friction between the component parts and as such would serve little purpose in securing the assembly. With the new bolt coating the higher torque is converted into pre-load in the bolt and as such benefits the assembly. Consequently we are recommending an increase in the wheel bolt torque settings for single axle Unicorn models fitted with the new bolts. You will be notified of this higher torque value when the bolts are despatched week commencing 8th August 2011.
In the interest of customer safety we will therefore be issuing an immediate product recall on all Unicorn Valencia, Madrid and Almeria models. These corrective actions can be carried out by any Approved Bailey Service Centre or should they wish to do so at their own risk by the owners themselves. The cost of carrying out this exercise will be covered, on a without prejudice basis, by the Bailey manufacturers warranty. Unicorn Seville and Barcelona models have not been affected by this issue and are therefore not subject to this recall.