The original P4s, and all of ours had a dual-arm, pantograph wiper system with a single blade that, because to the geometry of the mechanism, remains upright and parallel as the arms sweep in an arc across the screen. Our original wiper motor had just a single speed. It was adequate but struggled to comply with the IVA sweep cycle speed requirement.

Matt found this, more powerful, two-speed pantograph motor but it's much larger than our original one so locating it in the available space under the scuttle, above the pedal box will be a challenge. I started by making a cardboard box to the maximum dimensions of the motor - 180mm high x 170mm left to right and 110mm front to back. If I can manoeuvre the box into position under the scuttle without it touching any of the dash frame, air con hoses, steering column or pedals I may be in with a chance of success. I also measured and transferred the position of the chassis frames below the GRP onto masking tape on top. I'm awaiting arrival of the pantograph arm to mock-up and check the sweep angle and sweep area before I commit to drilling any holes.

It needed careful installation to optimise screen clearance and sweep angle, so I enlisted Matt to help. Here, we're mocking up the pantograph arm positions and checking the sweep angle. Even without the screen fitted we worked out the arm and blade lengths and hole positions for the motor shafts.

Even if I managed to install myself on my back on the cockpit floor, under the dash, I'd never get out. The last time Matt and I worked together on a car must be twenty years ago but he still somehow managed to get in there to check and install the new wiper motor as I drilled the holes from above.

The pantograph arm that fits the larger spindle taper on the new wiper motor is a heavy, industrial monstrosity designed for tractors and large trucks. But the smaller, more elegant size arm that is better suited to the P4 has a smaller taper that will not fit the new motor spindles. I measured the spindle taper angle and it's 10 degrees. An internet search for an affordable 10 degree tapered reamer drew a blank then I remembered that, somewhere in my drill drawers, I had a set of cone cutters. Luckily, the small one measured 10 degrees. Careful enlargement of the mounting hole gave a perfect fit on the motor spindle.

Here's the new motor, fitted right above the pedals on the front scuttle.

I found the old mould to make a light weight GRP cover that goes over the wiper spindles as they come through the scuttle. A nice little touch and aerodynamic to boot. I found some old black Gel Coat and used one of our Isopon GRP kits to 'knock one out'.

Things are starting to get dusty at this stage of the build as I trim and fit the various cockpit panels, so I gave the engine a good blow job with an airline, tidied and stashed all the management wiring on and around the engine and covered it with a  huge  polythene bag - tucked-in as much as possible underneath. I'll also drape some old towels over each suspension corner.

The front (cockpit) side of the mid bulkhead, behind the seats, comprises three panels - a left and right infill panel like the red one below, but in black gelcoat, which will be bonded and riveted behind the door reveals - you can see one Cleko'd in position, and a rectangular, removable centre panel (for access to the front of the engine, if ever needed), the width of the cockpit.  The top edge is bolted through the lower, mid window frame, the sides are secured with screws and rivnuts in the infill panels and the bottom flange overlaps the lower, aluminium cockpit panels, all secured with M4 screws into rivnuts in a chassis cross-tube. Problem is - the rivnuts are fitted but there were no matching holes in the GRP centre panel.

My solution was to turn the heads off of some M4 cap head screws and turn a point on them where the thread ends. Each one easily screwed by hand into its respective rivnut with the point sticking out by about 3mm. I offered-up the GRP panel and located it in its exact final position and lightly tapped along the bolt line with a hammer, marking a centre pop on the inside of the panel at each screw position, which I drilled through - first 2mm then opened up to 4mm.

I'll insulate the inside of the mid bulkhead and the inside of the infill panels  before final assembly - first with the self-adhesive, vibration-damping DYNAMAT XTREME, which is easily cut around a paper pattern and then with DYNAPAD, combined sound-proofing and thermal insulation.

The GRP side infill panels are Cleko'd in place

The infill panels are riveted to the tub with 4mm countersunk pop rivets and the removable mid panel is fixed with M4 stainless countersunk screws through countersunk screwcups into steel countersunk rivnuts in the infil panels.

Inside the drivers side sill is the front to back, 38mm aluminium radiator feed pipe - lagged with our #TEMPROTECT, the main positive battery cable, which I have protected with our #SPLIT2 split sleeving and marked with red insulation tape and the AIRCON refrigerant pipes to and from the engine-driven compressor. I moved the charging ports from the compressor to here for easier access and trimmed all the A/C hoses to length and crimped all the A/C unions. The A/C pipes will also be lagged with #TEMPROTECT

.... and here they are - this time lagged in blue TEMPROTECT from end to end.

Although the nose section has previously been 'offered-up' to the centre tub at a very early stage of the build I wanted to check clearance around the rads and all the pedal bulkhead components, but I mostly wanted to check the panel gaps and the critical alignment of these two major body components. It's been many, many years since I last fitted P4 body panels and I'd forgotten about all the procedures, techniques and development time I spent producing the mould and jigs so that it would all fit together accurately.  So, I took advantage of a quiet afternoon and spent three or four hours supporting and adjusting it's position with wooden blocks, shims, gaffer tape and aluminium angle in all three dimensions. I spaced and bolted the nose hinge to its chassis mounts - adjusting it's left-to-right position with washers before drilling through the mounting plates into the inner nose panels and bolting it in place. I'll machine aluminium spacers to replace the washers at the correct width later on. I needn't have worried. It sat in place level and square with neat, even shut lines. However, I've learned that GRP panels can become slightly misshapen during long storage periods depending on how they are supported during storage. So, I'll leave it at that and see how it settles before final fixing and fitting the gas rams and catches.

My build area is now feeling a little cramped so I may have to put the wheels on and move the car and lift a few inches further away from the benches.

The pipes, hoses and wiring that run from front to back inside the sills, have to make their way back into the engine bay, each side, through the chassis. But the valuable space at the rear end of each sill must be used - on the left, filled with  fuel pump, filters and swirl pot and on the right side with the engine wiring components. 

Problem is - it'll get mighty hot in those areas with the exhaust manifolds just a few inches away, so I'll have to make some closure panels to isolate them from the heat of the engine bay . Of course it would be possible to make aluminium panels in one piece but that would mean disconnecting all the hoses and pipes then fitting them back through holes in the panels. A major headache and not really necessary. Solution - make the panels in two or three parts, fitting around the pipes and hoses and rivet them together in situ.

I started on the fuel tank side, by measuring and cutting some rough cardboard templates, adding pieces with masking tape and cutting around the pipes and hoses where they pass into the engine bay.

Then transferred the shapes to 1mm aluminium - trimming and refining the shape and fit ...... until it was good enough to secure with Clekos

Finally fixing the panels together and to the chassis tubes with M4 Rivnuts and stainless screws. I also lined the hose cut-outs with our TRMU1 rubber 'U' channel. The panels can easily be removed if I need to make more holes through to the engine bay for, for instance on this side, fuel send and return and possibly wiring.

I have used our #AIRCON heat/aircon unit in this installation which is not fully automatic. The hot water flow has to be manually turned off when the A/C is on. As I previously described, the heater flow valve is in the hot water hose in the sill section, on the other side of this cockpit panel. I chose this discreet location for the 'push-pull' cable mount, under the left side of the dashboard panel. It's away from IVA zones but still in easy reach of the driver or passenger. A simple ali angle bracket riveted to the panel did the trick.

I decided to complete the brake plumbing by connecting the rear calipers. I ran the front to back line in our braided stainless flexible brake hose from the rear master cylinder, along inside the right hand sill then through into the engine bay to a brass 'Tee' piece bolted to the lower chassis frame with a M5 stainless bolt in a stainless rivnut. From the 'Tee' I formed and routed standard copper brake pipe to unions mounted in aluminium angle brackets mounted discreetly under the top chassis frame, and from there to the calipers on both sides with flexible.

The separate handbrake calipers are electric so will be part of the general wiring loom.

I may have mentioned in a previous post that the GRP dashboard moulding can be permanently bonded in place or, as we've done on a couple of builds - made removable for easier access to the heat/aircon, unit, wiper motor, pedals, instruments, i.c.e. etc.

I've detailed the procedure here because  other projects may have similar, mating GRP panels that may benefit from it.

The dash panel easily passes through a door opening and locates as far forward as the dash frame cross-tube will allow. The mating surfaces on the dash panel and the centre tub are moulded so that there is a gap between them to allow for inevitable, small variations in the GRP thickness. This gap can be filled with Filler or Fibre-fill along with mating GRP areas on the left and right forward door frames, to bond the dash in place.

However, to make the dash removable, the gap between the mating surfaces still has to be filled - but with the filler or GRP only bonding to one surface - the centre tub, not the dash.

There are two mating faces at ninety degrees to each other, around the forward curve on the centre tub - the Dashboard mating face - about 30mm wide and almost near to vertical and the windscreen bonding face, nearer to horizontal.

I cut a piece of cardboard to tape under the  gap so that any excess filler that I force through the gap doesn't drop down onto the cockpit contents or floor.

The Dash Mating Face is the part where the filler bonds to so I cleaned the surface thoroughly with Acetone to remove any remaining mould release. Then I abraded the surface with some 60 grit and cleaned it again to ensure a strong bond.

The mating face will, of course require the opposite treatment - no filler adhesion.  Here is the underside of the dash panel and the mating face. I first ran a D/A sander all around the mating face to level out any GRP fibres and high spots. I then applied clear tape (my old brain still calls it Sellotape) over and beyond the mating area, rolling out any wrinkles with a rubber Dynamat roller.

... and here's the dash panel in its natural position clearly showing gap to be filled. I taped the 'overflow' area on both sides of the gap to keep it clean of stray filler.

The filling begins. We're in one of the hottest periods of weather for years in the UK so the recommended filler/hardener mix would cure far too quickly for me to work the filler right into the gap. So, a reduced filler/hardener ratio will slow the cure time. But be careful - too little hardener will leave the filler soft. Experiment before you commit.

I use plastic business cards or old credit cards as filler spreaders. It's difficult to to judge when the gap is filled but better too much than not enough.

The filler has hardened and dash has been pulled away leaving the built-up mounting face with the excess filler flowed out of the bottom of the gap onto the cardboard beneath. I'll just trim off the excess with my multi-tool, remove all the tape masking and fill in the little gaps .

The dash is back in place and I've marked fixing holes all around the front edge. I'll tap them M5 directly into the GRP below, countersink the holes and secure with M5 countersunk stainless Pozi screws in countersunk stainless screwcups.

By the way, here's my invaluable cheap Chinese hand vacuum cleaner. It's small, lightweight, powerful and takes regular Makita batteries. No excuse for not cleaning up as I go. 

With the dash fitted, it's a good time to offer-up the windscreen to check clearances around it and to plan building up the support ledge. Here, I've applied 1" squares of our TRMR3 10mm thick self-adhesive foam as supports both under and around the edge of the screen. It's critically important that the laminated glass doesn't ever make contact with the GRP or there will be a danger of cracking the glass.

You can also clearly see the filler build-up around the dash and the countersunk screw and screwcup fixings.

It's now 18th July 2026 and the  manufacturing date on the windscreen sticker is 2003.

This is one of the two laminated glass windscreens that I've been lovingly cosseting for the last twenty three years. They've only ever been stored in two places, well away from any threatening activity so I was devastated to find one of them with cracks  around the front curve. How it happened is a mystery. The laminated screens were always strong and robust and I can't recall ever breaking or having to replace a one. Oh well - we still have one good one. 

I was reassured to find the fit was about what I expected. The screen doesn't touch the GRP anywhere and the gap beneath it varies from about  5 to 10mm. This will be OK to inject Screen Bond in stages as the foam support pads are removed later. Matt reminded me that we often built-out the reveal  around the screen hoop with filler to make an even gap of about 6mm around the edge of the screen - and built up the 'A post' on both sides to raise the screen reveal flush with the glass all round. Back into storage. A job for much later in the build.

There's a lot of glass-fibre work coming up. The weather is hot and sweaty and there's nothin worse than the itch and irritation of the fibre dust on my skin.  So, I keep my powerful Nilfisk workshop vacuum cleaner at hand and I use it whenever there's likely to be dust in the air and to clean up after each cut or trim of a panel. I've extended the hose to around six metres long so I can reach every corner of the car without dragging the cleaner around. Back in the day, I modified it by taping a rather dodgy on/off toggle switch near the nozzle and taping a two core cable all the way along the hose, back to the machine, where I broke into the mains cable neutral wire and connected the toggle switch. I could then switch the cleaner on and of from the nozzle - saving endless steps to and from to the on/off switch on the machine.

Fast forward twenty years and I found this remote controlled mains socket and its little battery powered transmitter on amazon for about fifteen quid. Plug the socket into a live mains output, switch on the vac cleaner and tape the transmitter to the business end of the vac hose. 

There's a void, inside the tub sill sections, on each side of the dash, just behind the front wheel arches, below the fuel filler caps.  It is here that you'll find the welded tubes and plates that mount the door hinges and door gas struts that hold the doors in the open position.

Each kit was supplied with two, three-sided GRP infil panels  (left and right) that would close off the area perfectly, collecting rain water in a little dome, from where it would drain through a tube to the road.

Now, if the door mounting tubes weren't there these panels would fit perfectly - bonded in  around all the edges with carefully laid strips of GRP mat and resin. Problem is, the fuel filler hose and door hinge support tubes are in the way so the panels have to be cut into three, along the fold lines, trimmed to fit around the hose and tubes, then bonded together again.

As usual the easiest way to determine the cut lines and shapes is to make stiff cardboard patterns first. If they all fit without forcing or bending there's a good chance  the GRP panels will. They are quite complex shapes that took a while to perfect with scissors, knife and tape - then transfer to the GRP panels which I cut and shaped with my bandsaw, powerfile, and panel saw.

Here are the cut GRP panels, in position, in the same orientation as the two pictures above, temporarily held together with little 50mm x 25mm  x 1.5mm aluminium plates and Clekos. They will eventually be bonded together from below, blended and sealed to the tub and around the tubes.

I wheeled my Makita bandsaw round to the P4 while I'm cutting and trimming fibreglass panels - just to save a lot of leg-work to and fro between workshops.

The right side took a while longer due to slight dimensional changes but here are all the parts Cleko'd together in situ. Both sides will come out while I mount the hinges and trim the doors.

Here's the left side door hinge, mounted on it's rod ends through the holes in the side frame pillars, and with it's gas-spring fitted to keep the door in the open position. It's quite tricky to mount and set-up the doors because they open 'up and out' at about 45 degrees and there are three planes of adjustment. The door outer panels are untrimmed and are 3 or 4mm too big all round.

I'll have a go at explaining how it all works. There are three 6mm thick steel lates about 150mm x 40mm. The centre plate assembly has two tapped M10 holes where two 80mm lengths of M10 studding, are silver soldered into the threads about half way along their length.

The other two plates each have two, aligning, 10mm clearance holes - so all three plates can be sandwiched together on the studding. The plate on the right in the picture has two 3mm welded 'ears' with 8mm holes for mounting the two M10 stud, forming the 'hinge'. It also has a central 'ear' where one end of the gas spring mounts. The other end of the gas spring is mounted to the chassis hinge frame.

The plate on the left has the two 10mm clearance holes and is fitted over the studding,  inside the door through an access hole. The door inner skin has a reinforced, angled section with two, 15mm, clearance holes that, when the door is fitted, allow it to float around on the studding. This is the first plane of adjustment. M10 nuts on the inside of the door are tightened to tighten the door in position against the centre plate.

The second plane of adjustment is via the two M10 studs that pass through the right hand (hinge) plate. M10 lock nuts allow up to about 15mm of adjustment at 90 degrees to the 'floating' door movement.

The third plane of adjustment is on the rod end threads, allowing up to about 15mm movement on each of them.

 

...and here's the door mounted on the hinge mounted on the chassis.

When I widened the roof many moons ago I knew that the day would come when I would have to cut down the door window frames and rebuild them to the new shape and profile of the reveal. I've done this job a couple of times in the dim and distant past so there's been some considerable 'sleeping on it' time.

I left the bottom 150mm  of the frame on the doors because the curvature hasn't changed significantly. Here, I've started to trim the upper parts and tape them in position

3mm aluminium plates and 4mm Clekos temporarily hold it all together in about the right shape.

All of this trial / pre-assembly has to be done with the door latches and strikers fitted and adjusted to maintain the 'shuts', position and size. Also the rubber door seals must be fitted because a degree of 'pre-load' is needed all round the seals to make them weather tight. I'm using our #TRMDR hollow door seal all around the reveal.

Here's a longer stainless striker made to replace the standard one supplied with the Bear Claw door latches.

The window frame area around the top of the doors is a reinforced, 'T' section moulding to maintain it's strength and shape and prevent distortion when the door is closed on the rubber seals. Where I have cut and re shaped the  upper window sections I'll have to rebuild the joints with new glassfibre. This means hollowing-out the inside of the 'T' sections on each side of the cut to accept new GRP matting inside and across the joint.

One one section I have to 'relax' the curvature of about 150mm of the frame to match the mid bulkhead curvature. Here, I've drilled through the 'T'  section and I'm opening up the gap with a coarse saw blade so I can force the resin/choppie mix down into the .

On my bandsaw, I then cut through, almost to the gel coat, across the whole width of the frame at about 30mm spacing. This will allow the frame section to flex and straighten enough to bring it inline with the mid bulkhead curvature whilst the glass and resin infill cures. It only needs to straighten by about 6mm in the centre of the curve.

I've 'hollowed-out' the inside of the joining  'T'  mouldings to a depth of about 50mm and the little spacer. My plan is to embed a 100mm length of stainless M8 studding across the joint using a 'Choppies' resin mix down into the T section with a thin steel rule.

'Choppies' are individual, 6 or 8mm lengths of glassfibre. Mixed with resin, they form a very strong paste that has many uses in repairing and strengthening glassfibre components. 

In this instance I'll fill the hollowed out ends of the window sections and force in the studding so that it spreads around the studding and joins in the middle.

I'll bond just the top joint first. I've taped some cling film over the roof and door seal in case any 'choppie' resin escapes the joint. I've cleko'd the top, centre joint with it's aluminium plate, reassembled the two side plates to lock the frame in the correct position and clamped the right hand side of the frame to correct the curvature and set it all slightly under-flush in the reveal to simulate the pre-load required.

I'll take the top section off again to fill the  sawn segments section with choppies. I'll use half the usual amount of hardener in the resin to prolong the cure time while I re-cleko it and clamp it to straighten the curved section by 6mm.

Then it's off again and back on the bench for tidying and filling any voids with more resin and choppies. 

There will be a lot of GRP work coming up so I bought 2 litres of resin for starters. Here I'm adding some Talcum powder to 'bulk-up' the viscosity of the resin.

All filled and rubbed down to the first stage of prep, and a quick splash of Matt Black aerosol. I'm holding a few off the sections that I cut out of the frame.

That'll do for now and off we go on the driver's side.