This blog is intended to document the build of my Gardner Douglas Mk4 Cobra; partly as IVA evidence, bit primarily to help others learn from my mistakes and/or successes.

I will endeavour to post as often as possible, with a view to entering a single post for a particular element of the build process, however inevitably some things may not be completed in one go. All posts will be tagged so it should be easy enough to find the information you seek.

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Tuesday, 23 August 2016

No More Bling

I never really wanted a Cobra with loads of shiny Chrome as I'm trying to build a modern alternative, but didn't think there was any other option for certain things such as the windscreen so just settled for it.

After recent discussions with fellow builders, I have decided I am going to go 'bling free' after all. The chrome/shiny bits I already have are:
- Windscreen frame and stanchions
- Fuel filler cap
- Headlight surrounds
- Wiper spindle ferrules
- Wiper arms and blades

The wiper arms and blades haven't been fitted so I will see if I can return them to GD and I'll buy black ones, I think Classic Mini ones fit.

I have made enquiries with a few local powder coaters and the consensus it that Chrome can be coated after being shot blasted to ensure good adhesion, and cheaper than I was expecting too.

I now needed to remove bits from the car, the headlight surround and wiper spindle ferrules just unbolt and the Aston filler cap needs a couple of roll pins knocking out but the tricky bit was the windscreen.

The powder coating process involves oven baking which isn't good for the rubber seals which meant the glass had to be removed and after speaking with Brasscraft (they make all the UK Cobra screens) I was assured it was possible.

The frame is made of two sections, the lower bit that sits across the scuttle and the rest. These are held together by 2 flat head screws at the bottom of each side. A sharp flat object needs to be run around between the seals and the glass, I used a 6" steel ruler. I then used a flat head screwdriver to prise the lower corners apart, I could then gradually ease the two sections apart.

The top frame is more difficult as it wraps around 3 side so there is more friction in the seals, I had to resort to a nylon faced mallet here! Whilst holding the glass, I lightly tapped the corner of the frame outwards each side, then upwards from the bottom.

This process was repeated gradually each side until I could pull the frame off the glass, thankfully with everything still in one piece. Now the seals can be removed for reuse when it all goes back together.

Two roll pins for the hinge and catch removed with a hammer and punch

Glass removing tools! 

This shows the two screw holes at the lower edge on each side. I'd already removed the lower frame before I remembered to take pictures. 

Prising the seal off the glass, a Stanley blade would probably have been better in hindsight. 

Two parts of the frame ready for the powder coaters 

Saturday, 20 August 2016

Fuel Filler Cap

I actually fitted the fuel filler a while ago but never wrote it up.  GD offer 2 types of filler, Aston Style and flush fit, I went for the Aston style.  This is a decision that needs to be made at the body order stage as the relevant recess need to be bonded in place.

The first thing to do was rub down and polish the fuel filler recess, this was done by hand due to the confines of it.  The centre of the mounting surface was found and an 76mm hole was cut with a holesaw.  

The Aston filler cap comes in two parts, the threaded flange and the cap itself.  The two parts were separated and the flange bolt holes drilled to 5mm (these were already pre-marked on the underside) and countersunk.  With the flange held in position on the car I then drilled through for one of the mounting holes, then bolted it in place to drill the rest.  The flange was then removed again to make the gasket.

I used countersunk Allen head bolts, but you could use button heads.

I bought a large roll of 1mm thick rubber gasket material off ebay along with a tool to cut circles (basically a compass with a blade attached) and some punches for the bolt holes.  I then made my gasket at 135mm diameter with a 76mm diameter hole in the middle, remember to cut the outer dimension first otherwise you'll have no centre left for your compass point!  With the ring made I placed it on the car under the flange and marked bolt holes which were then punched out.  I used an M6 punch just to give a bit of wiggle room for the bolts.

Gasket cutting made easy with cheap tool (left)
Bolt holes punched and gasket offered up (right)

The flange and gasket were then bolted to the car and the cap screwed on.  Initially it didn't tighten up in the right place.  The cap comes with several shims, the thicker red ones are 1mm think and the thinner blue ones 0.4mm thick.  After some experimentation I needed the 3 thick ones to get the cap to sit in the desired position.

Bolted on to car, looking lovely (although I may still get it powder coated black yet....)

Rear wiring loom

There are four main looms for the car:
1. Front
2. Rear
3. Dash
4. Engine

The Font loom has already been installed, although not exactly as per the GD manual, see this link for the blog post.  The dash loom can be purchased from GD (which is probably preferable if using the standard layout) however I will likely create my own as my layout will be different.  I already have an LS3 engine loom, that will stay in the cupboard until I get the engine.

To start with a pilot hole was drilled from the boot in the bottom left hand corner above the rear axle tunnel, this appeared behind where the passenger seat will be. I then opened this out to around 15mm and cut a strip out below this to allow the loom to fold downwards.

The loom is then fed through bit by bit from the cockpit, around the near side and behind the boot latch striker plate. The front part goes down the rear bulkhead, along the transmission tunnel then half way up the front bulkhead where it will meet the front loom behind the dash.

Within the boot, the loom follows the corner down the axle tunnel, across the floor and along the rear edge finishing at the offside rear lights. There are 3 main bunches of wires:
  1. Fuel system (fuel pump, level sender)
  2. Nearside rear lights
  3. Offside rear lights
There is also a lead just as it enters the boot for the number plate light and provision for reverse and fog are available at either side rear lights.  The loom comes with crimped bullet connections but I've changed these for Superseal connectors (for the lights at least) as they lend themselves better to being disconnected/reconnected repeatedly and offer a more OEM look.

Drilling hole in to cockpit area

Loom behind passenger seat position (looking rearward)

Number plate light lead just inside boot

Fuel system bundle

Nearside lights

Loom goes behind boot latch plate to offside lights

Superseal plugs

Rear loom connects to front loom behind dash (black & white plugs)

Windscreen Washer

Now that the daunting bit of fitting the wiper spindles is done, I turned my attention to the washer system.

In an effort to keep the engine bay as clutter free as possible I have decided to install the washer bottle in the offside wheel arch compartment (idea shamelessly stolen from Rob's blog), I may also install a float switch to tell me when it's low.  The bracket for the bottle is fitted to the inner wing and the bottle just clips in.

Like many others I've opted for a single washer jet in the centre and this was install 40mm back from the rubber seal of the windscreen. A simple 8mm hole and nut on the back, the hose then follows the wiper bundy tube and enters the wheel arch compartment above above the pedal box. The wiring will also follow the same route for the pump.

Tube will be cable tied to Bundy tube

Tube enters wheel arch compartment above pedal box

Bottle fits snuggle in wheel arch compartment
Washer nozzle looking neat and tidy

Tuesday, 16 August 2016

Windscreen Fitting

I like a good 'shape change' to show progress so it was time to fit the windscreen. I removed the support legs from the windscreen by undoing the 4 screws each side then put the screen back in a safe place. I've read a few blogs where jigs had to be made and bonded to the body to transfer the mounting holes to the legs but my legs were already pilot drilled.

There is also a drawing within the build DVD files so I transferred these measurements on to the legs to check the pilot drill holes. This showed that they were the right distance apart but slightly off the centre line. I figured that I could elongate holes if need be so opened up the holes to 8.5mm, slowly and with light pressure to avoid the drill grabbing the brass.

Next I cleaned and polished the scuttle area before drilling a line of holes where GD had already marked the scuttle each side. These were then filed to a rectangle and gradually opened out until the support legs slid through easily and the mounting holes lined up. I then removed them and refitted to the windscreen before sliding the whole thing back in, this can be done on your own by standing in astride the transmission tunnel but it is much easier with a helping hand.

I had to shim the legs out a bit with penny washers between the legs and mounting points each side. There needs to be about a 6mm gap between the outermost points of the lower frame and the scuttle and 930mm from the top of the windscreen and the rear bulkhead return, the rake angle can be adjusted slightly by elongating the mounting bolts slightly if needed but mine was spot on. I also measured the distance between the edge of the frame and the top rear edge of the door opening, both sides should be similar and again mine were pretty much spot on.

The centre stay bracket is awkward. I first placed the lower piece on the scuttle lining up the screw holes in the frame and marked where it will sit. Next the screen was removed and bracket laid in place so I could mark and drill the holes. The two brackets and centre stay was then installed on the screen before putting it back on the car, the tricky bit was getting the button head bolts through the scuttle, but needle nosed pliers helped here. These will require a cut down allen key when I finally tighten them up, but for now they are left loose as the screen will come off for safe storage.

The screen will stay fitted for now while I mark up for the windscreen wipers and washer jet, then  it will be removed and the gaps around the stanchions filled with silicone. 


Stanchions were already pilot drilled, markings are as per the build manual

Stanchion slots were pre-marked by GD, these were chain drilled then opened out with a file

Nearside stanchion installed
Looking more car like now

Centre stay fitted

Windscreen Wipers

I have been putting off fitting the wipers but it was time to bite the bullet and get on with it so the screen could be removed and stored safely again.   

The build manual states that the spindles should be 415mm in from the outside edge of the screen stantions and 5mm forward of the screen rubber seal so these measurements were marked on the scuttle. I then used one of the rubber gaskets to mark the elliptical hole. This left a measurement of 512mm between spindle centres.

I then assembled the wiper motor, bundy tube and gearboxes on the bench after bending the bundy tube to the curve of the scuttle.  The measurements between the spindles on the bench proved to be within a couple of millimetres so I was happy to proceed.

Using one of the outer ferrules as a guide I pilot drilled the holes in the scuttle, gradually opening out up to 12mm.  The holes were finished with a round file until the spindles fit through. The inner ferrules weren't the right angle so needed filing down to match the outer one, which also allowed for enough thread to protrude. 

With everything reassembled it was installed on the car, initially with the spindle gearboxes facing forward but the motor didn't seem to want to line up very well so I turned them around and moved the motor further forward on the mount. I'm still undecided on which way is best so may come back to this again later.... 

The motor is installed on the lateral under dash bar with a strap and rubber pad using M8 bolts. It may need to come ofc again yet as can't judge where the park position is until power is applied. 

Measurements transferred to scuttle 

Bench assembly

Near side spindle fitted 

Gearboxes facing forward.. 

.. and rearward. The jury is still out on which way is better.