GD427 MK IV

GD427 MK IV
What my car should look like when finished - Stoneleigh 2015

Wednesday, 28 June 2017

Boot Lid Trial Fit

I thought that I would fit trial fit the boot lid since I wanted to see where the number plate light cable ends up so I can finalise the positioning of the rear wiring loom.

I bought the aluminium hinges from GD which I temporarily fitted and adjusted using some washers as spacers in place of the rubbers which I don't have yet.  I crawled into the boot and tightened the hinges up from there.  I just need to feed the wire into the boot skin to see where it lies.

I have started looking at the trim for the boot so may move onto that in the near future.....


Power Steering

I have deiced to install a power steering column from a Corsa including automatic speed control from the VSS.  I bought an adjustable column model from eBay and I have started to modify it ready to be installed into the body.

It requires the ECU to be removed and it has to be mounted remotely from the column.  I will only work out where exactly to put it once the column is in place.  One of the mounting ligs for the ECU requires to be cut off where it will pass through the bulkhead.  I polished the removed mount using a small power file.

I have been speaking with Mark T in regards to how he has installed his and he has kindly given me a good few pointers for how I can get mine to work.

I hope to get some metalwork from him to enable mine to mount securely instead of using the GD supplied cross brace which will require a lot of modification since it is designed for the Vectra column.



Side Repeaters

I finally fitted the side repeaters by drilling a 20mm hole.  I used the front line of the side vents to project a line up to the front edge of the repeater and 15mm up for the bottom edge.  These were pushed in through the hole and wired up with a 2-way superseal connector.  I will remove them and seal them with some sealant for a permanent fix.



Wiring, Wiring, and more Wiring

I started to put some of the wiring together for the body.  GD provided the harness for the body in two parts - front and rear.  I have thought long and hard about extra wires to put in, how to run the loom and where it can all fit.

I started by laying it all out and using the provided wiring diagrams and notes, tried to understand where it all goes and what additional items I would like.  In addition to the already added to engine loom (here), The list seems endless...............


  • The Aeromotive fuel pumps came with their own wiring looms which contains a 50A fuse and a relay along with all the supply / feed and trigger cabling.  These just needed a mounting location and the wires trimmed to length.
  • The Innovate Motorsports Wideband Lambda sensors require some additional fuses (5A per controller) and a relay(s) along with wiring.
  • Since the GD provided heater fan comes with 3 speeds, I wanted to have that availability so needed to add an extra wire.
  • The GD supplied fuse box comes as an 8-way unit which is already used up.  I bought a 16-way unit so all the fuses will need transferred to the new box and additional fuse wiring added.
  • In the GD build notes, it mentions about removing the green wire from the washer pump plug and replacing with an earth & the horn relay requires the purple wire removing and replacing with an earth on pin 85. 
  • I prefer a minimalistic look in the engine bay, so have decided to run all the engine loom plugs & earth in through the bulkhead along with the ECU wires / connector which will run behind the fuel pressure regulator.  Wires need extending to permit plugs to enter cockpit from engine bay, and the mating plugs re-routing back into passenger footwell.
  • Original holes for Engine loom connectors / fuse box requires filling and gel coat applied prior to sanding and polishing.
  • Additional ignition & permanent 12V supply wires run to the additional fuse box for future connections.
  • Earth & supply wires run from new relay for lambda sensors to fuse box and to controllers.
  • Additional 50A fuse supply inside cockpit - just one single 25mm² 12V hi-flex cable from the battery along with earth connection - require to solder all the 1mm² cores into a 25mm² through crimp and crimped on a 25mm² hi-flex cable to go to the battery.
  • Additional earth bar located inside the cockpit for future earth connections fed with 25mm² hi-flex cable.
  • Superseal connectors for all connections and convoluted conduit for protecting the cabling under the wings.
  • Additional wires for Coolant level switch which is located in the radiator feed hose, and for the heater control valve.
  • Spare wires for a switch mounted to the clutch pedal - to be wired up to the starting circuit so the clutch pedal has to be depressed to start.
  • The GD fuel pump wire will not be used, so will be a spare going to the rear of the car.  The CANEMS ECU will trigger the Aeromotive pumps - 1 master pump and a switch will control the 2nd pump.
  • 6mm² wires need to be installed for the Corsa Power Steering column from the 2nd 50A fuse.  VSS signals and others require to be run up to the power steering ECU.

The amount of times I have had the loom in, out, taped up, tape off, tape on, in, out is ridiculous!  It isn't far away now, so I will post what I have done so far.  I am waiting on some more convoluted conduit for the front indicators to finish them off.


Original GD Relay panel (7of)


Slot cut above heater to allow cabling to pass through


Wiring loom pulled in temporarily to check lengths prior to fitting superseal connectors


Loom near bonnet hinge


All front wiring passes through the bulkhead outside of the engine bay


Stainless battery tray supplied by GD - modified to allow fitment of slightly longer battery......


Relay holders and fuel pump relays / fuses mounted



Original 8-Way GD supplied fuse box


Additional relay (Twin) added for Innovate Lambda sensors


Additional 50A fuse holder added (with aluminium mount)


Earth bar mounted


Superseal connectors used and convoluted conduit used for protection


Wiring for O/S repeater



Windscreen Wipers / Vents / Mount

I removed the windscreen so I could mark and cut the demister vents, centre windscreen mount and wiper arms.

I first ensured that the windscreen was sitting correctly, 930mm from the back centre to the body behind the seats.  The screen sits roughly 3mm above the scuttle at the corners.  This made the rubber seal look correct over the width of the car.  I then made sure that it was sitting with even spaces at both sides.  This was all tweaked and setup ok.  The centre bracket was positioned against the pre-drilled holes in the screen and slight adjustments were made to the bracket to allow it to fit.  The holes were then marked in the scuttle and drilled.


I used some measurements from Dale for the demister slots, however I mis-interpreted his description, but it is well within tolerance of the GD build notes:  30-40mm from the back of the screen.  I used 80mm from the roll of the scuttle to the centre of the slot.  Dale's measurement was actually from the rounded edge extremity ie furthest rearward of the scuttle, where I assumed that it mean where the rounded edge met the flat piece of the scuttle.  The outer holes were positioned 220mm in from the windscreen mounting slots.  The stainless escutcheons were used as templates and the holes / slot was drilled and cut using a Proxxon angle grinder.


The windscreen wiper spindles were drilled using the build notes - 415mm in from the outer edge of the windscreen stanchion and 3mm clear of the windscreen rubber.  The cowlings were used to drill the holes at the correct angle, and then were filed out to ensure the spindle fitted through.

I plan to sand down the scuttle polish it before bolting the escutcheons down and fitting the screen.



Fuel Tank Modification

You may remember that I said about modifying my fuel tank to accept the Aeromotive Phantom system for my twin pump setup (here).  I played around with some templates to ensure that the tank could still fit into the boot through the opening.  This is quite tight, but with some cardboard and string attached to the GD tank, I managed to find a shape that could still fit in to the boot, and fit the Phantom baffle / basket.

You can see from the pictures, the folded pieces temporarily attached show the proposed profile.  This was tested in the boot and it just fits.  I obviously have to sacrifice some boot space, but at least I may be able to travel further with the added fuel capacity!  I just need to fabricate the entire back of the tank along with new sides.  This will be leak tested once complete.




A quick reminder of what the Phantom baffle / Basket looks like:












Thursday, 4 May 2017

Heater Assembly

Since I was on a roll, I decided to tackle the heater box.  There have been many posts regarding the modification and placement of the heater box, but I will run through what I have done.

I started by removing the mounting flanges from the ends by partially drilling the spot welds and then chiselling them off.  I then used a flap wheel on the grinder to polish down the surface before coating it with satin black paint.  In hindsight, you probably only need to cut remove the N/S flange since there is room for it on the inner side.

I then used previous blogs to calculate where to mount the rivnuts.  I placed the top ones in line with the top screws for the extract pipes, and 30mm in from the edge.  I then drilled the bottom ones 8mm up from the bottom so that the rivnut clears the heater matrix.  Just ensure you use the correct length of set screw to prevent puncturing the heater matrix!

Once I drilled the 9mm hole to take the M6 rivnut, I found that the rivnuts I have don't like the 1mm thickness of the heater!  The rivnut couldn't grip.  This was only for the top ones, since the bottom ones were located through a double skinned part.

I decided, that the only thing to do was to drill out the attempted nut and fit a coupled more rivnuts, with a stainless plate in between the two to prevent them from spinning.  So I drilled another 2x 9mm holes in line with the bottom screws and 30mm in from the sides.  I then made a small plate linking the 2 from 1.5mm stainless so that the rivnut could grip properly.

A bit of extra work, but at least they now grip!  There may have been an easier method, but it's all I thought I could do with what I had in the garage......  There are some scuff marks on the newly painted sides due to the number of trial fits!  I had my daughter helping to screw in the set screws while I held the unit from the wheel arch....  (also in this photo you can see the 60mm hole cut for the ECU wiring loom.)






I then made a template from card marking the holes to be drilled along with the discharge pipes.  The heater assembly (minus motor and matrix) was then placed inside the N/S compartment and held up to the bulkhead and the rectangular hole was marked through to line up the holes.  I found that by keeping the bottom of the heater box inline with the top of the side vent was roughly the correct height.

I then drilled through the mount holes and discharge pipe holes.  I have just used the top and bottom rivnuts and 25mm long M6 set screws.



Then by leaving the matrix out and the side off the heater box, I could transfer the position to the engine bay.  I then used the side plate with the 2 cutouts to locate the hose position.  I then removed the heater box, drilled a 3mm hole through from the inside and drilled the 25mm hole through from the engine bay to align for the hose.  I could then measure and drill for the 2nd hose which is a 90 degree elbow fitted to the rearmost connection.

While I was at it, I drilled the 44mm hole for the wiring loom, and the 2x 10mm holes for the battery connectors.


I need to drill a hole through the bulkhead next to the heater box to allow the fan wires and other wires to go from the dashboard area into the battery compartment.

I also require a short piece of 16mm pipe to join the silicon hose as seen above to another 90 degree elbow to connect to the fixed pipe on the chassis.