Rear Half of Roll Cage Fitted

The previously made template was used to accurately mark out where the holes needed to be cut for the rear bracing tubes.  A hole saw and a curved file were used for this.

What I hadn't appreciated was that these bracing tubes were at a slight angle.  Meaning that the holes had to be widened to get the ends through, before the rear half of the cage could be lowered in to place.  Covers will need to be made for these.  Probably out of aluminium sheet sprayed white.

The feet were then bolted on to the bracing tubes and holes drilled in the rear of the chassis to accommodate the fixing bolts.  All in all not too bad a fit, the fabrication tolerances probably within a few millimetres.

Luckily the off-side bracing tube clears the fuel filler by about 10mm and also the filler pipe below.  Phew!  That was a close call.

After fitting I tried to get in the boot.  Oh dear, we have a problem.  Looks like the boot on the Avon Mk2 bodywork will only open to about 45 degrees with the roll cage fitted.  Never mind, access is still pretty good.

Next on to the front half of the roll cage...

Delivery of Full Race Cage

Yesterday my full race cage arrived.  This was delivered on a pallet direct from the manufacturers Caged Laser Engerineering.  It is comprised of a braced roll over bar with the main part of the cage bolting to this and the side chassis rails.

It is very substantial and quite heavy.  Much tougher than the chassis by the looks of it.  Which I suppose is reassuring and whole point of fitting the cage.  The quality is very good and it comes complete with a fixing kit.  We'll see how straightforward it is to install.

Holes need to be cut in the top of the rear tub to allow the diagonal braces to pass through.  The feet are bolted on after passing through the braces through the holes.  This helps keep the holes as small as possible.

I've made a cardboard template to establish the location of the holes.

I'll use this template to transfer the dimensions across to the top  of the rear tub.  I am praying that fuel filler is not in the way and does not need to be moved.  Once I've got the old roll over bar off, and the template offered up, I'll know for sure.

0-60 (well 0-62 actually) in 4.66s!

Finally got round to trying out the acceleration timing feature on my digital dash.  It has three modes 0-62mph (0-100km/h), 62-0mph and 0-400m (1/4 mile).  I had a few runs using the 0-62mph setting.  My best time was  4.66 seconds.

I think technique and gearing are big factors in setting a good time.  After a few practice runs I was getting better at getting the power down without lighting up the rear tyres.  In second gear the engine is getting near the red line at 62mph, but it just makes it.  I think with some more practice I could knock a bit more off this time.  With a better road surface, i.e. a track/airfield, as opposed to my slightly bumpy deserted country lane, further fractions of second could be knocked off.

Anyway, just over 4.5 seconds to 62mph is very satisfying, especially for a car that you've built yourself, and a level of performance equaling cars many times more expensive.

Must get round to trying the other two timing features.

Stone Guards

Like most (all) Sevens, my Tiger Avon was starting to get a lot of stone chip damage on the fronts of the rear arches.  A lot of this comes from stones that are thrown up by the front wheels.  Some people fit mud-flaps to the front cycle wings, but I don't really like the look of these - too much like a rally car.

I decided to follow the crowd and add stone guards to the front of the rear wings.  These also help prevent damage when getting in/out of the car.  To make these I used cardboard templates to transfer the dimensions to the 1mm aluminium sheet.  The shapes were then cut out using a guillotine (lovely straight edges that can't be achieved with tin snips or a jigsaw).

The aluminium was then shaped to the curvature of the arches by gently bending around a cylindrical plastic kitchen bin.  Holes were drilled for the rivets and then 2 or 3 coats of spray etch primer were added.

Thinking that most paints would chip off I decided to try using an automotive stone chip paint.  Black Hycote Stone Guard spray paint to be exact.  One 400ml can was enough to do about 2-3 coats.  The formula of this paint contains particles of rubber.

Once dry the stone guards were riveted in place using black head pop rivets.  I've been out for a spirited drive down some country lanes and the paint seems to be holding up very well - no chips yet.  Let's see how they handle some high speed motorway driving.

Brands Hatch Novice Track Evening

Tonight I've been to a novice track evening at Brands Hatch Indy race circuit.  I was very lucky with the weather and had a fantastic time putting the car (and myself) through its paces.

Seeing the photos has made me realise how inadequate the roll-bar is.  The next day I placed an order with Tiger for the full race cage.  Hopefully, this will be delivered and fitted soon.

Radiator Leak Repair

Since first getting the car on the road there has been a very slight leak from the radiator bleed bolt.  I'd tried tightening it up a number of times, including using PTFE tape on the threads, but it always continued to leak.

I tried one more time, but unfortunately this time I overtightened the bolt and stripped the thread in the radiator - turns out the tread is just tapped into the aluminium so is very weak. My solution was to re-tap the  hole to a larger size (M10 x 1.5mm thread) and use a spare cap head bolt of the same thread that I just happened to have spare.

Once the bleed bolt was fixed I could get back to investigating the leak.  Upon closer inspection it was not the bolt that was leaking at, but a pin hole in the weld around it!  With the engine running drops of coolant would slowly form.  I decided to leave this for a while as the coolant was only coming out very slowly.

Many miles later I got a coolant overheat warning from the Webcon ECU.  Turns out there was air in the top of the radiator and the coolant was no longer flowing properly.  The cause was air being sucked back in through this tiny pin hole each time the engine cooled down.  Something had to be done to fix this. I took the front of the car apart and removed the radiator.  This was when I discovered that the pin hole had turned into a crack, probably about 10mm long.  The body of the radiator was starting to split.

I quickly took the radiator to the friendly local welders who re-made the weld over the area where the crack was.

I'm happy to report that after a few hundred miles of use there is no longer a leak in the radiator.  This gives me added confidence for longer runs, particularly with another trip to northern France booked for later in the year.

Brake Light Switch Upgrade

I've never been truly happy with the existing brake light switch, the one supplied by Tiger.  This is a pressure switch that screws into one of the spare outlets on the brake master cylinder.  It is not very reliable and sometimes requires quite a bit of pedal pressure to light the brake lights.  Being a small, low car it is essential that people following behind, sometimes too close, are given maximum warning when I am slowing down.  I was reminded of this when being tailgated in London city centre last weekend.

To ensure that the brake lights come on as soon as the brake pedal is pressed I've introduced a microswitch on the brake pedal assembly, just the same as would be fitted to a normal production car.  Here is the microswitch mounted using a piece of cut and shaped aluminium L-section.

Floor mounted brake pedal re installed and wiring connected up.

The microswitch has been wired in parallel with the existing pressure switch - adding a level of redundancy.  Now, when the brake pedal is depressed just a couple of milimetres, the brake lights come on.  Likewise, now the lights also go out with a very positive action.  Next on the to do list is to investigate a high level third brake light installation on the roll bar.