Upgrade kit for M & S Hobbies' 1/24 scale 1993 Toyota Eagle MkIII

Text and images copyright Michael J. Fuller

M&S Hobbies 1/24 scale Toyota Eagle MkIII underfloor.  Flat as a flat thing.The M&S Hobbies Toyota Eagle MkIII kit is a fantastic model kit, however, it has its limitations.  And this is ground zero of those limitations, the underfloor.  Sure, most model builders probably don't care, and they're right inasmuch as this isn't an area of the car often seen.  But it was the principle...

The Toyota Eagle MkIII was the first race car to utilize a raised and narrow footbox, in conjunction with a front diffuser that managed air out the side of the car, with the aim at greater front downforce and better overall efficiency.  Every sports prototype racing today pays homage to the Eagle MkIII.

So it begged to be corrected on the M&S kit.  I initially toyed with the idea of going the scratch build route, and in fact I made a start.  But scratch building has its limitations (or, I have talent limitations...).  Anyhow, with access to modern 3D CAD, and a rapid prototype machine, I decided to completely redo the front diffuser/splitter, and while I was at it, redo the rear underfloor.  This upgrade kit is the result, it can be purchased here at my Shapeways store.
This is what the upgrade will give you.  Note the Shapeways pieces are manufactured using their Strong and Flexible brand of plastic, and they are produced by the SLA rapid prototype process.

Further note, the pieces in image here were produced using an FDM machine.

This page is the "instructions" to the kit.  It won't be Tamiya level by any stretch.

Any questions, suggestions, contact me.  
M&S Hobbies 1/24 scale Toyota Eagle MkIIISo the first thing that needs doing is the leading 50.5 mm of the standard M&S kit's underfloor needs to be removed, as well as a section 26 mm long closer to the rear.  The 26 mm long section is referenced from the start of the rear wheel cutout going forward.  

As you're removing major sections of the underfloor, and on this kit the underfloor drives the wheelbase, if you have any concern, prior to making any cuts, feel free to reference the wheel base by placing the underfloor on top of a piece of paper and marking front and rear wheel centerline.  Use this as your reference.  After all the modifications your wheel centerlines need to be identical to that reference.

Choopy choppy, get going, make sure your cuts are perpendicular to centerline.  Keep the rear bit as you'll need that later.

M&S Hobbies 1/24 scale Toyota Eagle MkIIIStarting with the underfloor upgrade, a further 21 mm (approximately) needs to be removed.  But more importantly, as this area is underneath the tub, you'll need to clearance this section at an angle to clear the underfloor leading edge.  Once this is clearanced, you can bond the new underfloor section on.  However, going back to your wheelbase reference, insure that this will correctly position the rear wheels. Test fit, test fit, test fit before you bond anything!  
Just a note, removing material from the tub to allow for tunnel clearance will mean the tunnels will form part of the cockpit floor.  
M&S Hobbies 1/24 scale Toyota Eagle MkIIIThe front bits.  You have the main diffuser/splitter (1), the wheel well exit pieces (2), the  mid tub pieces (3), and of course the radiator inlet ducts (4).
One small correction before you get going, and this will ease assembly later on, is you'll need to remove the bottom part (1) on the mid tub, and bond it to the splitter's trailing edge flange.  I initially envisioned the entire mid tub sliding up and into that flange on the splitter, but it made assembly even more difficult.  The sides (2) will be glued to the model.
M&S Hobbies 1/24 scale Toyota Eagle MkIIIThis shows the general alignment of the mid tub  (1) and wheel well exits (2).  Use the splitter as an alignment tool, and also make sure the wheel well exits are flat when they are bonded on.
Position the splitter with a 5 mm overhang relative to the leading edge of the bodywork.
M&S Hobbies 1/24 scale Toyota Eagle MkIIIGeneral arrangement, note how the trailing edge wings of the diffuser go either side of the mid tub piece.  Initially it seems like, with this being the case, the splitter won't then be able to slide into position.  But the model has some flex, and I simply spread it apart to allow the splitter assembly to slide into place.
Tips and techniques  

I prefer using super glue when bonding SLA rapid prototype to resin.  I use Loctite 454.  But the most important thing when bonding is to ensure the surfaces have "teeth."  And the best way to achieve that is to sand the surfaces to be mated with an aggressive sand paper.  100 grit or less (I tend to use 80 grit) will suffice.  Of course make sure you're not altering the shape of your surface, you're just trying to rough it up, not move heaven and earth.  Give it a flick with sandpaper and then clean the corresponding surfaces prior to bonding.  You can use acetone on the resin (if in doubt, test in an inconspicuous area), I'm uncertain if you can use same on the SLA parts.  I've also taken to drilling a couple of small diameter holes and inserting a corresponding diameter steel pin to make sure the two pieces stay together.  I also use steel pins to connect the diffuser to the nose while dry fitting.

Another thing, the main criticism of Shapeways Strong and Flexible plastic is that it comes out fuzzy.  It's certainly a "WTF" moment.  For starters, I'm using Strong and Flexible because of the reduced cost.  If I were to choose Frosted Ultra Detail it would shove the cost of the upgrade kit up approaching double.  But
don't be intimidated.  I've found the material can be tamed using multiple coats, with sanding between coats, of spot filler primer.  I prefer Dupli-Color brand, which can be found at most automotive parts stores in the paint section. 

ęCopyright 2016, Michael J. Fuller