GD427 MK IV

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

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.

Footwell Extensions

I cut out for the footwell extension a while back, but never got around to fitting rivnuts to the cover, so I marked and drilled for 6x M6 rivnuts.  5 of these come through into the footwell, where 1 goes into the master cylinder compartment.  This was temporarily fitted, and will be finally fitted once the body shell has been put on.


Also, taking some pointers from Mark Turnbull's blog and Dale's blog, I decided to open out the footwell adjacent to the accelerator pedal.  I may need to slightly modify this once the accelerator is fully in place, however I copied what Dale had done here.  I will wait for the accelerator is in place and checked before applying glass fibre matting to the area.  Thanks Mark & Dale!



Pedal Box

I assembled the pedal box and mounted it to the bulkhead.

Using the engine bay ledge underside as a reference, the pedal box was mounted around 8-10mm lower that this line as Dale Cordingley did since he is roughly my size and confirms he is happy with his pedals.

I made up a cardboard template matching the alloy housing, and transferred the holes to the bulkhead before drilling with a holesaw and drill.  The pedal box was positioned in such a way that the accelerator pedal could still be removed while the clutch and brake pedal remained in place.

I then drilled and tapped holes for the brake light switch mount and also for a clutch switch in case I ever need it (Cruise Control?)  I will get another bracket and switch from GD just in case.




I mounted the brake and clutch pedals with the bias bar and master cylinders.  I calculated that I require a 10mm spacer under the brake cylinders to prevent cutting any threads off the push rods and to maintain a slight free play of the pedal on the housing.  For the clutch pedal, I require much more, however I decided to cut down the push rod by 20mm to enable a 10mm spacer to be fitted also.  I have drawn up a spacer using Solidworks and a local machining company will machine some spacers for me from 10mm aluminium.  I will post photos once finally assembled.

For the accelerator pedal, the GD and LS engines use a GM electronic pedal which requires a link rod to go through the bulkhead, or a re-designing of the pedal box housing to accommodate the GM pedal directly.  I decided to go down the link rod route.

Firstly I cut down the GM pedal so that it can fit inside the footwell compartment above the master cylinders.  I then drilled a 6mm hole to allow a rod end to be fitted.  Using some blogs for information, I copied Dale's blog for a distance of 43mm down from the top of the GD pedal to gain around 100mm of travel.  A 6mm hole was drilled through the GD pedal to allow a rod end to be fitted.

The tricky part was to drill a hole through the bulkhead in the correct location to allow smooth operation of the GD and GM pedals with the link rod.  I used 220mm long stainless M6 threaded rod to link the two pedals with the supplied female rod ends.  Once the pedal box is fully fitted, I will confirm the pedal travel and may have to adjust as required...

 



Anti-Roll Bar

I managed to get around to fitting the front Anti-Roll bar to the car.  This includes two drop links fitted with Rod-Ends linked to a bar that goes across the chassis mounted with plastic mounts.

I screwed the rod ends into the supplied drop links with around 1-2 threads showing above the lock nut.

The anti-roll bar was fixed to the chassis using the supplied plastic mounts and 6mm high tensile bolts to rivnuts in the bottom of the chassis.  Note:  Ensure you use hex head bolts since you can't get an allen key in for the upper wishbone.

I jacked up the front of the car and allowed the wishbones to drop down at full droop.  The rod ends were then bolted to the anti-roll bar and wishbone as follows to permit the softest setting:

Anti-Roll Bar - Hole Furthest Out (Furthest from pivot point)
Lower Wishbone - Hole Nearest Centre of Car (Nearest to pivot point)

Once bolted together the car was lowered.  Job done!