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7. Continuing with body mods

   Alright, alright, I know I said at the start that this would be a long term project but even I can't believe that my last post on the P4 build was eight years ago give or take a week or so - about the same time as the launch of the iphone 5 ! Where the bloody hell did that time go? Well, I guess life just got in the way - I had seven intense years with my pub-rock band  'The fabulous Grandads', I built the NORVIN project bike, made some progress with the Berkeley and have been helping my Son, Matthew with the steady growth of Car Builder Solutions. Sadly, the P4 became neglected and assumed the status of a bench in the workshop as the years sailed by. Then, along came Covid19 and with most of the CBS staff furloughed I was back in the warehouse - busier than ever picking and packing orders 12 hours a day, six and a half days a week. As I write this post on 11th october 2020, Covid is still around and threatening a savage return but all CBS staff are back and for now, my pressure is finally off a little. 

I'll be sixty seven next birthday and although Matthew is more than capable of finishing the P4 if I bite the dust prematurely, I'm thinking that I should, at least, complete the one, big outstanding engineering challenge before my old brain goes doolally - making the flywheel. Big problem though - my Mojo had got up and gone. I'd got out of the habit of working on a project for a couple of hours each evening and the lure of dozing off in a comfy chair after a hearty evening meal became the more attractive option. Getting my Mojo back was essential if the P4 was to progress and the first task was cleaning up the workshop and sorting out twenty five years-worth of never-to-be-used-again parts and tools. 

I can recall my Dad telling me that, as a young man, he would just dive in and tackle a task and then sit back and wonder how he did it. Later in life he would spend more and more time staring at it and wondering how to do it. The older I become, the more I can relate to that but with the added prerequisites of a tidy, orderly, warm and well-lit environment in which to work. 

So, after four weeks brutally clearing out half a skip-load of surplus 'stuff', I had a workshop environment in which I could feel comfortable, relaxed and ready for a Mojo hunt to focus again on the last P4 - thirty years after the first one.

Although manufacturing a flywheel was the prime goal of this new spurt of activity I have to complete the reshaping of the tail first.  I'd left it with the hinge fitted, sitting in position on the tub and secured with a few aluminium plates and Clekos. Most of the cuts and shuts had been lightly fibre-glassed together on the outside - enough to hold it all together but not enough to make it a strong, structural panel again. This will have to be done by glassing from the inside which can only be achieved properly by flipping it over. Problem it - the forward end of the tail will be very floppy when removed from the main tub and would not retain it's correct shape. Glassing it on the inside would only stiffen the panel in whatever shape it relaxed to upside down - not necessarily the correct shape to match the mid bulkhead. 

I moved the joining plates around to gain access to the cuts beneath them, Here I've removed a plate to reveal the cut line below, 'V'd' the cut most of the way through the panel with my Powefile and used CBS 'Fibrefil' to fill and repair back to surface level. 

I decided to make a wooden frame which would 'lock' the shape of the tail 'hoop' while it was removed and inverted. I used 25mm ply - glued and screwed and fixed it to the panel in six places with aluminium brackets and Clekos.


Here it is- fitted across the tail before all the joining plated were removed.

I supported the wooden frame on two axle stands while the tail spoiler rests on a block of wood on the gearbox. A 'three-point' support like this puts no twisting or uneven forces on the panel and allows it to 'float to it's natural position - in theory !!

If you zoom in to this overhead view you can see the 25mm wide return all along the front edge of the tail (nearest to the camera). There are cuts through the return every 30mm along the whole centre curve which allowed me to freely reshape it. This is the most important edge to repair and strengthen but you can see all the other, lighter coloured areas where the red gel-coat has been removed on the other side. They've all been re-glassed on the outside and await reinforcement on the inside. You can see here where the two black vertical inner wheel arch panels and the forward three-quarters of the engine cover panel have been removed. These will have to be reglassed in their new positions. More on that later.

I'm not as tolerant of glassfibre dust as I used to be so I take steps to minimise airborne dust. All my sanding tools are connected to a powerful workshop vacuum cleaner while I work and the big yellow ducting is connected to a massive extractor fan which does a great job of removing the rest. 

Glassfibre dust seems to aggravate me more these days - not only the irritant thing but general cleanliness around the workshop is important. Yeah - I know - sad old git. My big extractor does a great job but i've made a few mods to my tools that help deal with sanding dust at source. Almost every power tool I use these days is from the fantastic Makita 18volt cordless range. Their orbital sanders come with a little dust collection bag which is ok for the odd small job on wood. I've modified the stub where the bag fits to accept a 32mm hose from my Industrial vacuum cleaner. Waaaaayyy better. 

You can also see in this picture the inside of all the cut lines. These will all be 'V'd out to the new glass on the ouside and then filled and reinforced with new glass on the inside. More of that later.


Likewise, my Black & Decker Powerfile has a push-on filter cartridge which is all but useless. I connected a short length of rubberr hose to it with a narrow band hose clip. Again, my vacuum cleaner hose pushes straight on to it.


Much better, but the dust collection hole is in the body of the Powerfile, where the belt enters he motor. It's very small and a long way from the nose of the tool where most of the action takes place. Much of the sanding dust still misses the inlet so I made a larger collector from a 75mm plastic funnel, trimmed it to fit around the inlet hole.....

Three or four layers of chopped strand mat and resin over all the inside cut lines and a couple extra on the long curved return on the forward hoop. (Note to self: Must find a new home for the BSA and it's lift before I take the engiine out again. It's getting a bit crowded in here.)

It seems half a  lifteime ago that I surgically removed the flat GRP inner wheel arch panels (2) and the flat(ish) engine cover (1) which were all glassed to the inside of the tail. The tail has, of course, changed shape so they must be trimmed to fit and re-glassed in their new positions, significantly reinforcing and bracing the new shape. There's a great temptation to just bond them in whilst I have the tail upside down but if they're not in the correct position the front lip of the engine cover (3) will not follow it's mating curve on the rear of the mid bulkhead.

You can see here the imm thick aluminium brackets and Clekos holding the inner wing panels in place and clekos holding the rear of the engine cover panel back in position where it will be rejoined with glassfibre once I've trial fitted the tail again and I'm happy with the general fit.

You can also see in the bottom right corner of the picture that I've taken the opportunity to mark more accurately the cut-out for engine's induction chamber. This will eventually have a dome.

I 'V'd out all the cut lines on the outside face of the forward return - right back to the new glassfibre on the inside and filled them with fibrefill. Fingers are the best tool for this job so it looks a little untidy - but it'll sand down and clean up OK.

Sucess !! Support frame removed and tail re-mounted. The fit is about as good as I could expect at this stage. That's all I need to do on this area for the time being. Final filling and flatting will be after the tub is permanently mounted to the chassis and the tail catches are fitted.

While the tail is on and the car is on my lift I may as well do a few more jobs at a comfortable working height. Waaaayyy back , for some reason, we added another pair of recesses for quad tail lights. I've decided to return this car to the simple, twin, tail light layout of the original P4. 

The original P4 rear lamps are no longer readily available and anyway, this won't be a faithful replica so my options are open. This is our new RL136 LED Stop and Tail lamp with a sequencing Indicator bar. It's stylish, modern and certainly a candidate. (There's a video of them sequencing on our online listing).

Here I'm using my Makita oscillating Multi-tool with a circular saw cutter fitted to cut away the two inner lamp recesses. These brilliant tools cut by oscillating the blade to and fro very fast by just a millimeter or two so you can 'plunge' the cutter directly into your material. Compared to a rotary cutting disc, they thrrow out far less dust but they just weren't around when we were manufacturing these cars. I can remember searching for a similar tool that was used in hospitals for removing plaster casts without risking injury to the patient's skin but they were either too expensive or just unavailable.   

Another, relatively new piece of kit is this cordless 75mm mini angle grinder. I've fitted a sanding disc for this job but it also accepts 1mm thick cutting discs for steel - (Great for cutting stainless overbraid). This 12 volt example is made by 'Parkside' and cost only about £25 online. It's very fast and has no dust extraction so it's messy but very handy for smaller jobs on GRP, like feathering these hole edges ready for the blanking disc to be bonded to the inside.

I cut eight, 7 inch discs of chopped strand mat.....

..... and laid up two stacks of four with resin on a thin sheet of stainless steel on a flat sueface. When the resin is cured and the steel sheet is bent slightly, they'll just pop off and will be about 2mm thick.

I've bonded the discs on the inside with fibrefill. When it's cured I dress down the rough bits and lay up the outside.


Luggage space has always been minimal in the P4. There is some room behind the seats and inside the sill sections - depending on fuel tank location but that's about it. There are, however two large, empty cavities in the tail behind the rear wheels. Check out some of the previous pictures. They're not entirely waterproof but ideal for storing lightweight items like bags of clothes or a car ccover. To make access to them I must make doors - and whilst the car is on the lift at a good working height I may as well make them now.

There's only really one place to put a door and that's in the vertical panels on each side of the tail hinge frame. This is where the tail hinge and the tail gas-rams are mounted so maintaining their structural integrity is important. The hole must be big enough to push a soft bag through but not too big as to weaken the panel. Here's how I made them.

You can see in this picture the tail hinge mount in the bottom left and the angled line on a piece of tape  which represents the position of the gas ram when it is fitted. I settled on a size of about 180mm wide x 220mm high with one corner cut off to clear the gas ram. I cut a piece of paper to the size, taped it in the optimum position and sprayed it's silhouett with an aerosol. I then marked the edges with masking tape and added radiused corners.

Before making any cuts in the panel I made the hinges from our Stainless Piano hinge. Marker pen makes the lightly scribed lines easier to see and our Self-striking centre punch positions the holes. 3mm rivets will be fine for fixing the hinge.

I drilled the holes, radiused the corners, taped the hinge in place as a template and drilled the holes through the GRP adding a 1/8" Cleko one at a time. This guarantees perfect alignment of the door later on.

With the hinge removed I used my multi-tool to carefully cut all the straight lines through the panel. The blade is less than 1mm thick so even if I wander a little I can dress the panel and the opening later for a consistent 3mm gap all round.

I then used a 2mm drill in my Dremel to make a series of close holes around the radiused corner lines. With a little sideways pressure the drill will cut through between the holes releasing the panel. 

So now we have a hinged door, perfectly fittedly in it's opening. We now need a stop and some sort of latch. 

I cut a piece of 1.5mm thick aluminium sheet about 25mm bigger all-round than the opening, centralised it inside the cavity behind the hole, marked, drilled and fixed it with evenly spaced Clekos. I marked a line on the aluminium about 8mm smaller than the door, removed the panel and began cutting out the middle.

Here I'm using a step drill to radius the corners ......

..... then a jigsaw between the holes......... (the little lug at the top of the picture is where a Dzus fastener spring will be mounted)


...... then files to clean it up.

Here's the rear view of the Dzus fastener and spring before being fixed to the aluminium with rivets.

... and the finished job. Countersunk 3mm aluminium rivets secure the aluminium frame and 3mm dome ones for the hinge. The Dzus fastener is a simple captive fastener.

Here it is open. You can see the  Dzus button, the inside of the rear light nacelle and the louvres in the tail wheel arch. I'm not sure about the finish yet. Maybe Heatmat.

Of course, there are other ways to make a door in a panel but this way leaves a flush finish and the aluminium frame goes some way towards maintaining the structural integrity if the panel.

This picture is of an original, aluminium-bodied P4. They had twin fuel tanks with a huge Aston filler set into a recess on each side of the scuttle. Each recess was skilfully crafted in aluminium with a hinged lid and little securing brackets for an 'R' Clip or the like.

Our tub has only one recess on the nearside. I recall a customer once asking for twin fillers so I made a mould for an offside recess. It's been outside in the weather for around fifteen years - but that's the great beauty of glassfibre. A quick scrub up in the kitchen sink and some minor surface repairs with filler will have it servicable again. 

Six layers of CSM and resin should be enough. It's not a structural part and only has to bear the weight of a fuel cap. I'll leave it to cure overnight.

I've cut the hole and trimmed the new moulding so that it fits flush on the underside of the scuttle panel, at the same depth as the one on the other side. I've propped it up with a wooden stick and laid up a few pieces of GRP on the inside to bond it in place. The tub will have to be removed and inverted later on so I'll complete the job when it's upside down. Much easier.

Here's an aerial view, looking down on the windscreen reveal and scuttle. Like the original hand-made P4s, the left and right side are not symmetrical. Look carefully and you'll see that the distance between the fuel cap recesses and the windscreen frame are quite different - about 20mm different, in fact. There's nothing I can do about it but that's Ok.

I used a 75mm flap wheel and my trusty Powerfile to dressthe hole flush to the inside of the new moulding. A little filler and some hand-drressing will make a neat job. I'll aim for a 2.5mm radius around the top edge for IVA 'sharp edges' compliance.

 Our original P4 body moulds had a long and busy life and had begun to show some signs of it. Plasticene is often used to repair damaged areas and smooth-out joints between mould panels berfore the fibreglass guys can begin laying-up the panels. Traces of the Plasticene remain in the panels after removal from the mpoulds so I use a fine stainless steel wire brush and thinners to remove it all before work begins on any area - like around the nearside filler recess. (left).

I'm not happy with the large radius around the top of it so I'll build up the edge with filler and reshape the radius to sharpen up the edge.

First job is to key all around the area with 40 grit abrasive. (right)

Then apply our P38 filler to square-off the edge all round (left) , rub it down flush and form a nice 2.5mm radius. I've half finished it here (right), splashed on a drop of satin black aerosol and dropped in our #AST35KIT filler cap and neck, although the catch will not pass IVA as it is. The final colour will probably be red, but you get the idea.

A few more jobs to do before the tub comes off again. This shot was taken from the front, looking through the windscreen into the cockpit. The original roll-over hoop was cut off to allow for the roof chop. A new one was made to follow the new roof curvature. Here it is tack-welded in place. The four holes you can see in the square cross tube are threaded bushes for shoulder harnesses.

Another job is to make a start on reshaping the top of the doors. The lower part, below the window is fine because nothing has changed. But I have widened and lowered the roof so the door window frame is now too long, too high and the wrong shape to fit neatly in the new reveal. The shape of the windscreen hoop is unchanged so mods to the leading edge of the window frame should be relatively simple. But the curvature of the mid bulkhead has changed drastically so the trailing edge of the window frame will need lots of cutting and shutting.

The doors/windows are two piece mouldings with the inner and outer skins moulded seperately then bonded together. You can see on the left that there is a wide bracing web all around the inside of the window. This makes the frame very strong and rigid - quite important later on, when I fit our rubber door seal all around the door reveal.

In the right picture you can see a shallow reveal for the 3mm thick, moulded acrylic window pane. I've made the first cut about 120mm up the window frame.

I can now offer up the top part of the window frame to the reveal and see what we have. Both doors have been trimmed oversize. If you zoom into the picture you can see a raised line a few millimetres in around the edge of the door. This is a guide for final dressing oif the shut gap - pretty much irrelevant now.

And that about as far as I can take the doors at this stage. I'm satisfied that it'll all work Ok. Final door work will have to wait until the tub is permanently fitted and bonded to the chassis.

Finally the tub is flipped over to work on the inside. You're looking in from the front with the sill sections at the top on each side. The red bit is the part that I greafted in when the roof was widened. 

 The black arrows indicate the original roof width. The red section was cut from an old roof-lining panel that was supplied with the kits. It's about the same curvature as the roof so it was grafted inbetween the two door-top sections when they were split in two to widen the roof. The red arrows indicate the two areas where the door reveal has to be rebuilt. Aluminium templates are Cleko'd in the reveal as formers for laying up new Glassfibre 

The red section is slightly under--flush so I cut a piece of 3mm Coremat to exactly rthe same shape and glassed it in (left). Another piece of Coremat, which covers the whole of the roof and mid bulkhead, was glassed in over the top, reinforcing the whole area. You can see new GRP around the door reveal to form the new corners and even-out inconsistencies in the thickness. This is the edge where push-on rubber door seal will be fitted.

The banana-shaped opening is the reveal where the mid window will eventually fit. Although this area of the roof and mid bulkhead will sit over (but not touch) the roll-over bar it has been heavily cut and reshaped in the roof chop. Some reinforcement is in order so I curved a length of 8mm steel rod to fit perfectly in the channel at the top of the mid window reveal (Don't forget that you're looking at the tub upside down) and embedded it in the channel with fibrefill. I've also reinforced the lower edge of the mid window reveal with a strip of Coremat. 

Well, that's about it for this post. The tub is off and the sheet of polythene that's been covering the engine for the past eight years has been consigned to the bin.  Apologies for any repeated information from previous posts - I'm know that there's a lot of stuff I've forgotten since we built this chassis in September 2008 but there's also a lot that I have learned since then. Other thiings have changed - including availability of better and more suitable components and the quality of the pictures - now taken on my iphone 11.

I'll be tackling mechanical challenges in the next post - including making the flywheel. 

Thanks for hanging in there.

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Hello sir,

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