Fitting of wind deflectors - May 2008

At the Stoneleigh show I spotted that Trevor Bennett's recently completed Mojo had a rather neat pair of wind deflectors attached to the windscreen pillars.

Trevor Bennett's Mojo with deflectors fitted

Trevor Bennett's Mojo with deflectors fitted

The following week, after a typically damp Stoneleigh weekend, we had a bit of a May heatwave with temps reaching the low to mid 20s.  In these kind of conditions it can actually get quite hot driving the Mojo with the sidescreens fitted, especially once you drop below 40mph- My heater is rigged up to just be on or off and cannot be used to blow fresh air through the vents.  So after a couple of days of being cooked on the journey back from work, I left the sidescreens at home.  I had forgotten just what a difference this made - I was no longer being cooked, but instead my right ear was being buffeted to death!

I remembered Trevor's deflectors and dropped him a mail to find out how successful they were.  The answer was very positive so I decided to follow suit.  Trevor bought his deflectors as a bolt on kit from one of the kit car shows, at a cost of 40 with the mounting hardware all attached.  However, ideally I wanted to use the same hinges as used to mount my sidescreens to make for easy swaps between the 2 setups.

The main issue with using the same hinge brackets was that the deflectors need fitting such that they sit out at an angle, forcing the air flow further out and away from the driver.  I therefore needed to devise a way of locking the deflectors in a fixed position, whilst still allowing the opening of the sidescreens when fitted.  

My initial solution was to drill a small hole in the housing of one hinge bracket on each side, with a corresponding hole (or flat) in the pin of the hinge attached to the deflector.  A small grub screw could then be used to lock the rotation of the deflector.

With a plan sorted, I made up a template for the shape of the deflector using cardboard, approximately copying the shape of the ones used by Trevor.  I then attached these temporarily using tape, with a cardboard strut braced to the mirror to hold cardboard out at an angle, and went for a test drive to check the shape was successful.

High tech no expense spared prototype

High tech no expense spared prototype

The difference was very noticeable, I reached forward to release the bracing strut whilst driving at 60mph to confirm and the painful ear buffeting returned.  Amazingly, the cardboard moved around very little, it is obviously only changing the airflow a small amount, but enough to make a big difference to comfort.  I am convinced!

The next job was to source materials.  I managed to scrounge some offcuts of polycarbonate from Ruari (Fury Cossie owner who lives just around the corner) which although quite thin and flexible, may be up to the job.  I will try making one deflector and then do some testing!

I contacted Sylva to find out if they could supply me with just one half of the hinge (I only need the half attached to the deflector) but no such luck.  A full set is 18.  Being forever the true Yorkshireman, I wondered if there was a cheaper solution, and hatched a new alternative plan that was certainly worth a trial as it would cost nothing.  So, mounting solution plan B is as follows: 

  • Swap around the existing sidescreen hinge plates such that the half with the pin is now attached to the windscreen pillars
  • Make up some aluminium plates that attach to the polycarbonate, fold around the hinge pin on the pillar, and wrap around to the other side of the polycarbonate
  • The lower plate will incorporate a small lever arm that bears against the hinge plate on the pillar to stop the deflectors folding rearwards.

I think that probably calls for a diagram!

Hope fully that makes things a bit clearer.

So, the first step was to swap the existing hinges around, which was a fairly simple task.  I then set about cutting out the shape of a deflector from the polycarbonate offcuts, using a jigsaw and then finally wet and dry paper to achieve a smooth edge (being careful not to damage the front faces!).  The jigsaw left a surprisingly good finish (I used the finest toothed blade that I had).

At this stage I then held up the deflectors to the hinge brackets and realised that my Plan B would leave a gap between the windscreen pillar and the deflector.  I decided this was probably not ideal, so came up with Plan C!  This time the polycarbonate would sit in front of the hinge pins, with the aluminium brackets located behind, wrapping around the hinge pins.  I made up the first bracket without the additional arm to stop rotation and tried it out.  It turns out that the bracket was such a snug fit on the hinge pin when tightened up that the arm would not seem to be needed, so I made the second bracket identical to the first and then assembled the whole lot together, initially using rivnuts as nuts (but with the intention to set the rivnuts properly once I was happy).  Here is the result:

PICT0134.JPG (120440 bytes) PICT0135.JPG (83206 bytes) PICT0136.JPG (70462 bytes)

The deflector is not as flexible as I thought it would be considering the slim polycarbonate I have used, and shows no sign of rotating back on itself.  For the time being I am not going to bother making a second one as I so rarely drive the car with a passenger, and even more rarely with the doors off!

So, total cost of the project: 0 (i.e. everything was either 'in stock' or scrounged!).