Facts about Fasteners

Our highly engineered product must be fitted using high quality reliable fasteners.

All Witter Towbars are made from high strength structural steel plate, tube and section material and shaped into components using the very latest production techniques and processes.

Robot welding stations and highly skilled welders ensure that every product meets the exacting standards that are associated with Witter. Having produced a top quality Towbar it is essential that it is fastened to the vehicle by top quality components. In some countries, Towbars are welded to the chassis, but in Europe where advanced monocoque construction is the norm this is not possible. This means that our highly engineered product must be fitted using high quality reliable fasteners.

Witter source their fasteners globally in partnership with one of the UK’s largest and most experienced distributors of steel fixings. Our Quality Department visit all of the supplying factories to ensure that they meet and exceed our rigorous quality standards. This guarantees that you will only ever receive product that is to the highest standards.

In June 2007 the End of Vehicle Life Directive will come into force. This legislation has been enacted to help to reduce the amount of harmful chemicals being used in industrial processes and the environmental damage this can cause. Witter Towbars have already started to introduce zinc plated and Trivalent Chromium finished fasteners with a colourless passivation.

Witter are probably the first UK Towbar manufacturer to adopt these stringent new requirements.

All Witter bolt kits are supplied pre-packed, with a full list of contents clearly marked on the bag. Our quality assured partner company use the latest sorting and counting technology to ensure complete accuracy of the contents giving you the confidence that you will be able to fit the Towbar first time, every time.

Towbars are usually installed using grade 8.8 bolts although sometimes grade 10.9 is used. The grade is clearly stamped on the head of the bolt and identified on the Towbar fitting instructions. It is essential that all fasteners are tightened to the correct torque settings that are advised on the fitting instructions. A torque wrench must be used to do this as it is impossible to accurately and consistently estimate the applied forces using hand tools alone.

Torque is a measure of the force applied to rotate the bolt (or nut) to tighten the fasteners and create a pre-load in the bolt. This used to be measured in ‘ft lbs’, and now more commonly in the metric equivalent of ‘Nm’. The ‘ft lbs’ is perhaps easier to understand and relate to its definitions as it is simply the value in ‘lbs’ forces applied ‘1 foot’ from the centre of the axis of the fasteners. Most modern torque wrenches have scales in both ‘ft lbs’ and ‘Nm’.

It is quite normal for Towbar components to ‘bed in’ after initial use e.g. any small surface irregularities flatten, and therefore it is recommended that the tightness of all fasteners is checked after the first 500 miles of use, and thereafter every year. A question that we are often asked is; Can I re-use bolts or nuts? The answer is simply no. It is good practise to always use new fasteners if there is a need to remove, adjust or replace a component. In the case of Nyloc nuts it is essential that these are not reused. Replacement bolt kits are available for all current Witter Towbars.

Bolts and nuts are usually treated as an invisible friend. Always there and always ready to help out. Maybe it is because of this ‘invisibility’ they are taken for granted and relatively little is known about them. If you would like to find out more about Witter fasteners then visit FAQ section about fasteners.

A question we are often asked is; Can I re-use bolts or nuts? The answer is simply no.