BETTER LATE THAN NEVER ?

[Spit131]

Well , at least there is now hope .

Mark at Race Ltd has managed to get some strip out done . However , lucky him , he is now in Bermuda for two weeks so I need to be patient for further work .

I have agreed to link the two tanks to save diverter valve complications . They will look exactly as was but just run one red top to the swirl pot but I will have the second pump left as a back up .

I have also reluctantly agreed to not fit an Accusump and heat pad just for start up as they insist it’s not needed. 

The entire electrics are going to be replaced by a Boing technician using Boing light weight aero components . 

The boys are also going to look at the rear leaf spring/upper A arm possibilities . Be interesting to see if they can come up with anything worthwhile .

They will be swapping out the Wilwoods for Caterham as in Dave’s build and they have a selection of VLs and a pair of adjustable upper arms .

They are going to source and fit the Tilton clutch hydraulics and fit the R160 with a Quaife initially .

Luckily they have a good fibreglass man who is going to come up with an efficient front spoiler together with any under chassis paneling to improve front stability . Also ensure the bonnet and drivers door fit well .

Early days but worth waiting for . Matt

 

 

 

 

[JohnD]

Matt,

No doubt your "fibreglass man" will have his own ideas, but may I offer a design I made and constructed, Gosh! Twenty years ago!  Some of this account you will know already, but please forgive me for not rewriting it!  And it may be useful to others.

A Spitfire Air Dam/Splitter.

    Most cars, and a Spitfire is no exception, are wing shaped in outline, flat underneath and curved on top.  As a result, airflow at speed tends to lift the car, just as the aircraft is lifted.  Tyre grip is reduced, the car corners less well and it may begin to be unstable at speed.  Much modern car design is directed at reducing lift, and for competition reversing it into actual downforce.  While an F1 or NASCAR car has so much downforce it could be driven on the ceiling, this was not a concept when the Spitfire was designed.  There are various lift reducing devices, but an airdam and splitter are easy to make, and can add to the car’s appearance.
An air dam reduces airflow beneath the car, reducing turbulence and lift.  A splitter is a horizontal forward extension of the bottom edge of the dam.  Because the dam causes an increased pressure in front of it, a surface in front of the dam will have a high pressure on top, providing actual downforce at the front of the car!

The design concept.
This design is based on the spoiler that I made for my Vitesse.  The Spitfire and Vitesse chassis are significantly different forward of the wheels, but the design method should serve for the Spitfire as well.

 
  The chassis rails under the engine are lower than the edge of the front valance.  A flat sheet bolted to the underside of the rails will come forward several inches below the valance, and a dam between the two completes the spoiler.
    Diagram ‘A’ is a view of the front of a Mk3 Spitfire with a flat sheet bolted to the under side of the chassis rails.  Between this splitter and the front valance is the gap filled by the airdam, and perforated by optional brake ducts and an oil cooler duct.  A plan view of the splitter is shown in ‘B’, with the splitter in position under a rolling chassis in ‘C’.  The actual dimensions will need to be found by fitting to the car.  They will not be the same as for the Vitesse, and I don’t have a Spitfire any more, so I have not given any measurements.  The general procedure will be the same.
 

 

 

Making the splitter.
    I used a sheet of ¼”(6mm) marine (waterproof) plywood for the base sheet.  A rough cutout for the wheel wells and for the part under the chassis rails will allow you to bolt or clamp the sheet in place and mark it out.  Make sure that the wheels are clear of the base sheet, from lock to lock and when the car rolls.  Decide where you will bolt the sheet to the rails.  You may find some small holes in the flanges of the rails.  If not, drill your own, as close to the edge of the rail flange as possible, without weakening it.
    The rearmost part of the base sheet needs to be wider than the width of the chassis rails (see below).  The two suspension turrets are bolted to rectangular brackets that project downwards below the rails, so that two rectangular cutouts are needed on each side.     You may also find that the antiroll bar (sway bar) mounts project downwards so that they need clearance holes to be made in the base sheet.  These are not required on the Vitesse, but may be on a Spitfire.  Mark the position of all the cutouts needed.

    Take a plumbline, and hang it from the bottom edge of the front valance.  Move the line along the edge, marking the base sheet as you go.  This will mark the foot of the air dam.  Then take a length of stiff paper or thin card, a roll of spare wallpaper is good, and set this on edge along the line.  Use short lengths of tape to fix it temporarily to the base sheet, and as the rear edge of the front valance is curved, it will stand up by itself.  Trim the top edge of the paper so that it is just above the front valance edge.  Mark the paper at the valance.  When you remove this strip of paper, it is now a pattern from which you can make your mould.

    Now you must decide how far forward you want your splitter to project, in front of the airdam.  On the Vitesse about 4”(100mm), takes it to vertically below the front bumper.  The Spitfire front bumper is further forward, as much as12”(300mm) in front of the airdam, depending on model year and corresponding bumper.  This is impractical, as it will scrape on bumps and run into kerbs.  You must decide what looks best, and draw a smooth curve to form the front edge.  If you wish to find out the best design in terms of lift/downforce, book a session in a wind tunnel!

  Making the mould.
I made the mould in thin sheet steel, panel off cuts of 21g; about 1mm thick When cutting this out, I allowed a flange of about 1”(2.5mm) top and bottom.  The bottom flange was bent to a right angle, and the top to a lesser angle, so that it would lie inside the front valance.  Note that both flanges should be FORWARDS!  I then curved the ends of the sheet to match the line on the base sheet.  You cannot bend a sheet with a flange on it, unless you can stretch or shrink the flange.  If you do not have one of those little ‘shrinker/stretcher’ gadgets, you will need to cut slots in the flanges.
    If this is difficult to imagine, look at diagrams ‘D’ and ‘E’, or else try making the paper model (See end of article).  Even in thin printer paper, once the two parts are glued together, it becomes a fairly rigid structure.  Place the finished mould on the base sheet, on the original line.  Drill through the sheet and the bottom flange at several places and fix it temporarily to the base sheet with small bolts.  Don’t use screws – they will be very difficult to get at when the dam is finished!
Now offer up the base sheet and mould, and bolt it to the chassis rails temporarily.  Adjust the shape of the mould so that the top flange fits just inside the valance.  You are now ready to make the airdam/splitter!
  
Working with GRP.
     There are many books that go into detail about how to use GRP, so I will only do so in general.  Resin and hardener in the right proportions react chemically and become very hard, stiff and brittle.  Glass fibre is very flexible, but has high tensile strength.  Mix the two, and you have a hard, tough, flexible substance, Glass Reinforced Plastic, GRP, (called fibreglass in the US) that can be cast in a mould to any desired shape.  The glass fibres come in a mat that looks unsightly in the final result, so the top layer of a GRP fabrication, the one next to the mould, is usually made of resin alone.  This ‘gel coat’ will be as smooth as the mould it is laid up in.  You can add pigment to the gel coat, or paint the GRP; it’s up to you, and some GRP ‘tissue’, rather like a paper tissue, will help hold the resin in the gel coat.

    Resin is also a good adhesive, so unless it is to be a permanent part of the construction, you will need to prepare the mould so that the resin will not stick to it.  The traditional way to do this is to smooth the mould and then wax it with a non-silicone wax polish, or use a special “releasing agent”.  Release agent can be difficult to get, unless you buy your resin and matting from a GRP specialist.  Non-silicone wax polish is easier to find, but make sure that is non-silicone, or paint will never stick to the GRP!
    It is difficult to sand down a sheet of mild steel to a fine polish.  Unless you want a really perfect finish, the easiest way is cover the steel with that thin, brown wrapping tape, sold as ‘Parcel tape’, to which resin does not stick.  Check with a piece of tape and a blob of resin to make sure you have the right tape, and add a coat or two of wax to be sure.  When you tape the upper flange, fill the slots or the resin will fall through!  Use several layers of tape over the slots, as the tape is not strong or else use a stronger tape first, and cover that with ‘parcel tape’.  This part will be invisible, so irregularities will not matter.
At this stage, you should remove the mould from the base sheet again, so that you can apply a layer of GRP resin to both sides of the base plate first of all.   Resin alone, well soaked into the plywood, will form a hard, smooth, damage resistant surface.  Add glass fibre matting and the surface will be even stronger, but the matting will show through and leave a rough surface.  Make sure that the line for the mould is well marked.  To keep the holes open for later when you bolt the mould back on, leave a well waxed bolt, head underneath, in each bolt hole.  When the resin has cured, remove the bolts.  Sandpaper the surface on and behind the mould line to flatten any nibs and provide a key for the next layer.  Then bolt the mould back onto the base sheet.  

Laying up in the mould.
You are now ready to lay up the GRP.  Follow the maker’s instructions to mix   resin and hardener, and apply a thin coat of resin to the mould, as a gel coat.  Let the resin go off (harden).  Cut a piece, or more likely, pieces of glass fibre matt to cover the back of the mould and the strip of base sheet two to three inches behind it.  Apply another coat of resin onto the mould and to the base sheet.  Lay the glass matt on to the wet resin, folding it round onto the base, and apply more resin, stippling it in with a paint brush.  Make sure that all the matt is wetted, especially where it overlaps itself, and that there are no air bubbles.  Let this layer go off overnight.  The next day, put on another one or two layers of resin and glass, allowing the first to go off, and you are finished!
 
Leave the splitter for another day or two to really harden.  Then remove the bolts securing the mould, and prise it loose.  This may be harder to do than you expect, but persevere, levering from the edges and bending the mould rather than product.
The curvature of the airdam makes the structure very rigid from side to side, but some front to back strengthening may be needed between the ‘dam and the rails.  As you have cut the base sheet wider than the rails, you can add a ridge of GRP along the edge, from the rear corner straight forward to the ‘dam, outside the rails.  See diagram ‘B’.  Anything that will raise up a ridge of GRP will do, a wooden dowel, a piece of plastic tube or cardboard.  Place this where you want the ridge, lay up another coat of GRP over it, and the sheet will gain enormous rigidity.

Buy the cheapest possible brushes for laying up GRP, and throw them away; they are impossible to clean afterwards!  Also buy yourself some disposable rubber gloves and throw them away frequently.  Resin on the hands is very sticky and can cause dermatitis.  Glass fibre can leave tiny irritant pieces in the skin for days afterwards.

Mounting the splitter.
    The bolts into the chassis rails are into the flange on the inside edge of each rail, to give you access to the nut on top of the flange.  I use cheap, dome headed roofing bolts, with little square nuts.  The dome head minimises the possibility that it will catch on kerbs and bumps.  The rail flange is quite narrow, and the nut will need to have a millimetre or two cut off one side, so that the bolt hole is not too close to the edge of the flange.  If the nut edge is right up against the inside wall of the rail, it will be semi-captive, making fitting the splitter much easier.
    Once the base sheet is bolted to the rails, with the lip of the airdam inside the valance, it will be self supporting.  The curvature of the dam, and its’ long base on the splitter, will make it very strong, like a wing.  If the ‘wingtips seem to flap, add a piece of 6mm threaded rod behind the dam between ‘wingtip’ and a bracket inside the valance, or the internal bumper bar.  Drill through the base sheet and use a washer each side to spread the load.

Additional options.
    Because of the high pressure in the ‘stagnation zone’ above the splitter and in front of the dam, this is a very good place for cooling air intakes, for brakes or an oil cooler.  You can make your own, or like me buy them ready made from a performance shop or by mail order.  Demon Tweeks in the UK have a selection.  If they are fixed in place on the mould before lay up, they become part of the dam, or you can cut holes and resin them in later.
 
Some books on how to use GRP.
- Books on GRP for boats; the techniques are the same – see Amazon.
- Competition car composites by Simon McBeath, Pub.Haynes.
    
- Ch.7, ‘Glass-fibre bodywork’, The Car Bodywork Repair Manual,
                             by Lindsay Porter, Pub.Haynes.
- The West System is a range of very high quality GRP products for boat building.  Their “Technical Manual/Product Catalogue” is full of useful information and techniques for using GRP to build anything, and used to be FREE, from:
Wessex Resins & Adhesives Ltd.
189/193 Spring Road, Sholing
Southampton   SO19 2NY
Or:    Gougeon Brothers Inc.
    Bay City
Mitchigan, USA

Acknowledgement.
I am very grateful to Mike Nelson of Omaha for his help in translating my Vitesse experience into Spitfire possibilities.

© John R.Davies, February 2001

 

PS  Here's another pic of the airdam fitted and in action:

Edited December 6, 2024 by JohnD

[Spit131]

Can not thank you enough John .

I will try and take this all in over the weekend .

Harry , one of the owners of Race Ltd did come back and say they can definitely sort out a good splitter but I will definitely pass on all of your very generous information . 👌👌👌👌

[Escadrille Ecosse]

I f you are planning on using GRP then go to a proper supplier where you can get everything you need. Life is a lot easier with the proper stuff, like mould release wax that works.

For glassfibre materials I would highly recommend East Coast Fibreglass Supplies https://www.ecfibreglasssupplies.co.uk/

Have a look at their website. They also have a learning area with basic how to videos.

For sealing a large mould like this don't use packing tape. The styrene in the resin/gel will tend to attack the tape at the edges which leaves lots of stickly lines on your finished part that will need cleaning and/or filling afterwards.

If using plywood you will need to seal the surface sufficiently to take release agent/wax. Well cured polyurethane varnish will resist the resin/gel and will take the release/wax.

Or for large areas you can simply use thin film poyethylene sheet (like decorating sheet) which you can stick to the wood using spray can adhesive.

Alternatively you can do what I do and use Correx board. The stuff used to make estate agent signs amongst other things. It can be cut easily with a Stanley knife and will go round curves. Large flat areas can be supported with bits of wood.

It can be stuck together using a hot glue gun. The hot glue will also stick it to metal or glassfibre/plastic parts, like the valence and quarter panels.

It has a decent surface that will take release wax and the hot glue will allow it to come apart and off the car when you're done. And won't damage paintwork.

Despite what is says above brushes can be easily cleaned. Only use brushes intended for glassfibre. Most other ones tend to get attacked by the styrene and fall apart or melt. Wood handled laminating brushes of 1.5" or 2" are perfect.

Get these from the GRP supplier and get some acetone at the same time. You should not attempt any large glassfibre job without having a can of acetone to hand. It is also an excelent general purpose solvent/cleaner and you will wonder how you ever managed without it. Just keep it well clear of paintwork.

Incidentally you should thoroughly mask off any parts of the car in the general vicinity of where you are working with poly sheet and masking tape otherwise the WILL get splashes of resin on them which WILL cause varying levels of inconvenience/damage.

For brush cleaning you want a couple of acetone resistant pots, polyethylene or polypropylene. I use ice cream tubs, the round ones not rectangular. Keep the lids.

Put a couple of inches of acetone in each pot. One of these is now the dedicated 'dirty' cleaning pot. After removing as much resing as possible from the brush with a paper towel stick it into the first pot and wash off as much resin as possible before drying the bruch on a paper towel. Then clean the brush a second time in the 'clean' cleaning pot, wipe of with a clean paper towel and leave the brush to dry. Doing this thoroughly and the brush will last a long time.

When the acetone in the second pot is getting too used to fully clean the brush, tip out the 'drity' pot, replace it with stuff from the 'clean' pot.

Wear gloves. Always. For cutting glassfibre I wear thicker Marigold kitchen gloves as these are better for handling the mat and minimise the 'itch' from microscopic bits of glass getting into your skin. Or even larger puncture injuries.

For handling resin get a box of disposable latex gloves and change these regularly as they get too sticky and/or covered in goey glassfibre strands.

You can use the thin vinyl gloves but they are attacked by syrene and more so by acetone and fall apart quickly.

For mixing the resin you can use plastic pots but I find that it is better to make up multiple small batches of resin/hardner than one large batch which will go 'off' faster due to the bulk heating effect. For mixing then I use disposable paper cups again bought cheaply from the glassfibre supplier. Get some mixing sticks too. Again if you keep these cleaned with acetone after use they last almost indefinitely.

Finally styrene is nasty stuff. And as you need to work at a minimum of about 15 degress C then unless its summer you will be inside and the vapour will accumulate. So you need proper respiratory protection in the form of a half mask and charcoal filters. I would also suggest you have a separate set of clothes/overalls that you wear for glassfibre work, remove before you go into the house and wash separately.

A. because the smell of the styrene REALLY clings and will make your house smell and B. because your clothes will be covered in tiny glass particles from the chopped strand matt that will then spread to the house, carpets, and any other clothes that get washed with them.

I also have a pair of slip on shoes that I keep in the garage and get worn for glassfibre work. Because you will drip resin on the floor and you will drop glass fibres on the floor and the soles of the shoes will pick all this up. Alternatively you can use shoe covers.

[Spit131]

No shortage of education here ! 
Very grateful , however , luckily , I am not going to be participating myself . I will however watch the videos you recommended out of interest .
The exceptional skill of some of you people on here is enough to convince me to keep out of the kitchen and instead to rely on experts . 

[Escadrille Ecosse]

5 minutes ago, Spit131 said:

however , luckily , I am not going to be participating myself

[JohnD]

You've  has done more glassfibering (is that a word?) than I have, so thanks for that, Colin!

My approach to mixing pots is to use TWO disposable cups/glasses, the clear kind, one inside the other.    This allows you to graduate the outer one previously by adding measured quantities of another liquid, so that you know how much resin you have and hardener to add.    Then throw away the inner glass/cup after each session.  IMHO however useful Colin's advice on brush washing, life is too short to wash out a disposable cup!

John

[Escadrille Ecosse]

2 hours ago, JohnD said:

IMHO however useful Colin's advice on brush washing, life is too short to wash out a disposable cup!

Bloody right. Hence the use of disposable cups. Dead cheap from the GRP people. I buy them in bulk. Use once only.

For big and simple jobs you can get plastic tubs of various sizes from your GRP supplier of choice for mixing up resin. These don't need cleaning either as once any residual resin has cured it can be 'cracked' out of the flexible tub.

As for measuring, catalyst addition is specified as a percentage usually around 2% volume MEKP to weight of resin. So 2cc MEKP per kg polyester resin. A bit more if it is cool or a bit less if it is warmer.

Easiest way to do this is with a cheap set of electronic kitchen scales for weighing the desired amount of resin in the disposable cup. The big ones will take up to 700g or so. Weigh out as many cups of resin as you think you'll need. Then add the required quantity of catalyst using a syringe and mix throughly as and when you need more resin for the job.

Or if you are doing anything more than one small job it's worth investing a couple of quid in a measuring bottle dispenser this graduated in cc's. Very quick and easy to use, especially when time is of the essence, you are a bit sticky and you are making up that last wee cup of resin to just finish the job before the laminate goes off.

The additional and most valuable advantage of the dispenser is that when (and not if) you knock the thing over you'll only ever spill a small amount of catalyst (nasty stuff). Unlike the knocking over the catalyst bottle.

And I also put the scales in a plastic bag to protect them from the inevitable drips of resin. Also in there is a tile for the scales to sit on so I don't need to worry too much about the surface I put the scales on.

Edited December 8, 2024 by Escadrille Ecosse

[Spit131]

Post Xmas work has begun .

 

[Spit131]

A quick catch up . Fully stripped out , Engine/gearbox mounts now welded up , seems welded , boot , cabin and engine bay repainted . Four ears added to spring plate and a visit on Monday to finalise  decisions on upper arm arrangement  .

 

[Spit131]

Oh , and I bought an electric heater to save the complexity/weight of a water system . It’s only just over 1KG .

Edited February 23 by Spit131

[zetecspit]

2 hours ago, Spit131 said:

Oh , and I bought an electric heater to save the complexity/weight of a water system . It’s only just over 1KG .

A 600w 12v electric heater? That will draw 50A, I hope you have a big alternator!

Even then 600w is not a lot for a car heater, I reckon my Spitfire heater must be 3kw from temp and airflow. Of course, it will depend on what your intended use will be. 

[Sigma hurricane]

12 hours ago, zetecspit said:

A 600w 12v electric heater? That will draw 50A, I hope you have a big alternator!

Even then 600w is not a lot for a car heater, I reckon my Spitfire heater must be 3kw from temp and airflow. Of course, it will depend on what your intended use will be. 

Not to mention it always helps when your running the car hard to avoid overheating 🤣

 

I guess if using something like dynomat as well for sound deadening the actual heat loss of the car won’t be much. 

[Escadrille Ecosse]

5 minutes ago, Sigma hurricane said:

I guess if using something like dynomat as well for sound deadening the actual heat loss of the car won’t be much. 

Except for the big hole where the roof isn't . 

But I'm interested to see how this does as it certainly helps the plumbing.

[Spit131]

It will only be needed for Debra for the first ten minutes on cold days ( perhaps more psychological than ‘ full heat ‘ ) because after that the cockpit located dry sump tank will take over . There will be a pre-start 240V heater pad strapped to the tank and some insulation/burn protection on top of that .

I am asking Harry today to fit a high output lightweight alternator so should not be an issue . I am not intending to fit sound deadening or carpet , just a couple of rubber mats , but only time will tell if she can deal with that . 

Once it’s finished , run in and a few hundred miles shake down , we are looking to take a trip down to the Italian lakes and Tuscany with Debra’s brother and his wife . The only way to do it though is if we book a hotel or two to be based in and then Debra and Karren would fly down with their suitcases and jay in his Exige and myself in the Spit drive down there . Be fun being able to visit various places each day .
All I could fit in is a 4” spare , some basic tools/spares behind the seats and a couple of holdalls and odd items stuffed in corners and strapped to the roll bar . 

what could go wrong ?!

[Sigma hurricane]

1 hour ago, Spit131 said:

It will only be needed for Debra for the first ten minutes on cold days ( perhaps more psychological than ‘ full heat ‘ ) because after that the cockpit located dry sump tank will take over . There will be a pre-start 240V heater pad strapped to the tank and some insulation/burn protection on top of that .

I am asking Harry today to fit a high output lightweight alternator so should not be an issue . I am not intending to fit sound deadening or carpet , just a couple of rubber mats , but only time will tell if she can deal with that . 

Once it’s finished , run in and a few hundred miles shake down , we are looking to take a trip down to the Italian lakes and Tuscany with Debra’s brother and his wife . The only way to do it though is if we book a hotel or two to be based in and then Debra and Karren would fly down with their suitcases and jay in his Exige and myself in the Spit drive down there . Be fun being able to visit various places each day .
All I could fit in is a 4” spare , some basic tools/spares behind the seats and a couple of holdalls and odd items stuffed in corners and strapped to the roll bar . 

what could go wrong ?!

I hadn’t realised pre heating the oil sump tank was a thing. The sigma going in mine is dry sumped too so there goes my morning looking into that now 🤣. 

[Sigma hurricane]

16 hours ago, Spit131 said:

Oh , and I bought an electric heater to save the complexity/weight of a water system . It’s only just over 1KG .

Might be worth also considering a lithium ion car battery as you would drain a standard spitfire battery in 40 mins from full with that? Would allow a lot larger capacity battery for the same size/weight

[Spit131]

This is the current battery position so be good to use the same size if something appropriate is available 

[Spit131]

I would have had a heating pad on the accusump so hot oil injected before start up but now that Harry has talked me out of an accusump at least incoming oil after start up is coming in warm . The accusump was only going to be there for that purpose .

[Spit131]

OK , just left Race Ltd .

The GT40 ( one of three being built for the same customer ! ) is coming along nicely . Beautiful period orange massive wheels . The Aston Martin vantage is also nearing completion . Also in the shop today was a beautiful old racing Jag and a V8 Caterham .

It seems we have agreed on the top A arm arrangement . Basically , my wider diff arrangement , Harry’s two tubes welded together joining idea and my two rose joints within the upright top bracket keeping it narrow enough to avoid the spring .

Ill do a basic drawing when I get home .

I also requested a seriously loud horn and the 90 amp race alternator .

[Spit131]

Halibrand wheels I believe ? 

[Spit131]

If anyone has a 3 1/2” x 13” Spit wheel for sale , let me know please . 

[Spit131]

[egret]

That looks like it's going to be very special.  I particularly like the dashtop and dial cluster.  My youngest commented on how my dashtop had deteriorated and was hinting that I should really do something about it soon!

[Spit131]

Dash actually done by a previous owner in Alcantara but yes I love it .