camper trailers tech tips

Vehicle Mounted Rear Stone Guard





Stone Protection


vehicle mounted rear stone guard

    As soon as we travel off bitumen roads the threat of stone damage to vehicle and trailer increases significantly.

    We can put in place all sorts of protection measures but just how effective are they, the ultimate would be to bubble wrap your vehicle in the garage and stay home. None of us want that so where do we start and what can we control, effectively.

    The problem starts when the rubber leaves the road taking with it stones often quite large and the throwing them away not just at your mud flap but often in all directions. Most of us fit stone guards to the front of our trailer and this helps to protect the trailer from our stones although they are sometimes deflected back onto the back of our vehicle.

    In preparation for our next “out back” trip I decided to move closer to the source of the stone problem and the following is what I came up with.

    A full width (almost) flap for the back of the tow vehicle. I wanted it to be easy to fit and remove without drilling or welding the vehicle or tow bar.

    My answer was to use purpose made U bots to hold the assembly to the tow bar.
The materials for the support assembly: 25 x 25 x 1.6 steel tube, 32 x 4 flat steel, 10mm round rod, 25 x 3 flat aluminium bar (I couldn’t get steel locally).

    The flap is rubber matting from that rubber supplier it is about 10mm thick with 15mm holes, which I trust, will let some of the air through and stop most stones.

    The Patrol is fitted with a standard Nissan tow bar, this is a 75 x 75 mm cross member with end brackets to the chassis. I found that the end brackets project about 8mm below the bottom face of the cross member therefore I used some short lengths of 10mm rod as spacers to clear the ends.

    I also found it necessary to fit an extra piece of stiffening across the cut-out for the engine exhaust.

    When fitting I used an extra (lock) nut to cover the exposed thread and protect the thread from stone damage.

    The next step now is the field testing, scheduled to start in 18 days.


bits & pieces


the guard

extra stiffener

Thanks to Ian Wilkin for this article

 june 2008