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Endeavor

Sectioned and Channeled Pocher Alfa Spyder

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Posted (edited)

The kit cowl louvers are too tall and they are not really louvers.

 

In the foreground is a louver panel that was cut from one of a K73 kit’s hood (bonnet) side panels.  I used this panel to build new louvers.

 

The kit louvers are 34mm tall.  A section of the panel will be removed to reduce the height of the louvers to 27mm.

 

I cut openings in the cowl to receive panels incorporating the new louvers.  Here you see the section marked for removal.  

 

image.jpg

 

 

I removed the stock cowl louvers with a hobby knife.

 

The Pocher cowl “louvers” are just plastic lumps shaped like sections of quarter round. In the foreground, you see the kit cowl “louvers” and the much more accurate louvers from the kit’s bonnet side panels.

 

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This photo shows the left side of the body with the old louvers removed, the panel that will provide material for the new louvers, and a stock hood side panel like the one from which the panel was sourced.

 

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Another look at the two sets of louvers.

 

 

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A 7mm section was cut from the center of the louver panel.  While cutting, I stabilized the panel and the individual louvers by applying pressure on the panel with a ruler onto masking tape, sticky side up.  The cut might have been more precise if, in addition, I had applied double sided tape to the ruler to also stabilize the panel from above. 

 

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The final 15% of each cut was made with the panel mounted on two old sanding sticks wrapped with tape, sticky side up.

 

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I achieved a satisfactory result, but a great deal of of additional work will be necessary to join the louvers seamlessly.

 

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The two halves of the sectioned panels were joined using solvent.  While they were setting up, the panels were clamped to ensure that finished panels would be flat.

 

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Here are three sectioned panels of 27mm louvers and, for comparison, a section of bonnet side panel with stock 34mm louvers.

 

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This method was satisfactory for producing the five louvers for each side of the cowl.  This might not work so well for sectioning 7mm from the two bonnet side panels, each with 27 louvers.

 

 

Edited by Endeavor

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Kit cowl louvers removed.

 

111.jpg

 

 

Louver panels welded in place with solvent.  Hours of finish work lie ahead.

 

113.jpg

 

 

114.jpg

 

 

112.jpg

 

 

 

 

117.jpg

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Are you sure the louvres are set perfectly horizontal now? Right hand side ones seem slightly off..

 

Anyway this is a brilliant project I must say.

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5 hours ago, Roy vd M. said:

Are you sure the louvres are set perfectly horizontal now? Right hand side ones seem slightly off..

On my computer screen, I measure 32.10mm from the bottom edge of the body to the top of the trailing edges of both the front and rear louvers.

 

I used the third photograph as it has the least distortion due to the angle of the model to the camera.

 

Measuring the actual model in its current state, from the top of louvers to the top surface of the running board, there is a variance of 0.24mm.

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Posted (edited)
On 5/16/2018 at 5:21 AM, Codger said:

 Will you alter the hood panels or scratchbuild new? It may actually be easier and thinner material can be used - like brass.

Building the hood (bonnet) top and sides with metal would be ideal.  However, I have neither the tools nor the skill to build accurate louvered side panels. 

 

I'm just a shade tree mechanic.

Edited by Endeavor

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9 minutes ago, Endeavor said:

I'm just a shade tree mechanic.

SURELY you jest...shade guys don't know from measurements like 'point 24 mm'...........:rolleyes:

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In Case you ever wondered...                 (Adapted from an article in Road & Track)

 

You might think the word "Spider" (or "Spyder") is just a fancy word for roadster.  But where did the term “Spider” come from?

 

The name dates back to the 1800s, when horse-drawn carriages were a main mode of transportation.  Some lightweight carriages, because of their looks, came to be known as "Spiders".

 

As you can see from the photograph below, these carriages have a small body and large wooden wheels with thin spokes, which sort of look like spider legs. The term “spider“ transferred over to lighter, more agile, sporty automobiles, often with no roof over the cockpit.

 

The difference between "Spider" and “Spyder" is just the manufacturer's preference. Ferrari used Spyder in the past, but has switched to "Spider" for cars like the 488. Porsche still uses “Spyder” for it's most hardcore Boxster, while McLaren and Fiat use “Spider”.

 

Spyder.png

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Surely enough the difference is minor. 

 

I decided to run the photo through Gimp... really shouldn't do that because in the past almost without exception similar efforts (on another forum) were not met with much enthusiasm... I can only say, the better the modeller the nitpickier I'd like to be, aiming for the interpretation that such increased nitpickiness implies my increased admiration toward the builder. 

 

Hopefully agreeing on that, here are my findings.

 

Wheelbase versus louvres angle. 105 / 118 pixels are vertical measurements (=via the blue dotted lines) of the distance between the two green lines.  

40370396170_d0f8c0dafd_b.jpg 

 

The next blue line spans between the tops of the front / aft tyres. Both lines cross, where in my view they shouldn't. 

27306013957_e966bc29cc_b.jpg 

 

Here the full image: 

 

40370396030_c5a5a44f55_b.jpg

 

So would you need to amend it? Surely not, almost nobody would. I only intend to hand you the information and it's up to you whether to use it.

 

It's going to be a great model either way. 

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Posted (edited)

I appreciate your interest, your desire to be helpful, and that you spent the time to generate this information.

 

I do not know what Gimp is or how to use it.  My ignorance of the technology may limit the value of the following....

 

To get reasonably accurate dimensions from a photograph, the camera must be pointed directly at the center of the body, both horizontally and vertically.   If you are attempting to determine dimensions of that part of the body that is between the wheels, the distance from the camera to each of the wheel centers should be equal.  The further elements are from the center of the photograph, the less accurate dimensionally those elements will be.

 

My measurements indicate that the louvers are level relative to the frame and bottom of the body, and that they are parallel to the leading edge of the cowl.  The frame rails are parallel to the ground due to changes I made to the mounting points of the front springs.

 

The photograph you rely on was taken from a low angle and is centered on the louvers because that was what I wanted to illustrate.  The limitations created by the position of the camera can be seen clearly by the fact that the front and rear wheels and tires appear to be different sizes.  The camera is not positioned properly to take photographs that can be utilized for sophisticated analysis. 

 

The grill shell and bonnet were placed loosely on the model for this photo.

 

 

 

 

Edited by Endeavor

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Posted (edited)

Before I could begin rebuilding the rear of the body, I had to properly position the spare tire mount. The first step  was to modify the fuel tank so it sits at the correct angle. 

 

Because the kit’s tank sits an an incorrect angle, an OOB K73’s fuel tank filler pipe is misaligned with the hole in the body.  Pocher knew the tank was tilted incorrectly and later K73 kits contained a filler pipe with a dog leg  so it would exit properly.  An incorrect superficial fix.

 

This modification tilts the tank forward and positions the  filler pipe so it exits the body correctly. More importantly, the correct position and angle of the fuel tank is necessary because, unlike an OOB Spyder, the spare tires will be mounted against the tank, like the prototypes.

 

The Pocher Spyder’s fuel tank is held in position by two 2mm rods. The rods run through the spare tire mounting bracket, through two molded-in guide tubes inside the tank, to two metal blocks attached to a tubular cross member. This setup positions the tank in a too-vertical position.

 

To tilt the tank forward, I drilled two holes in the forward side of the tank 5mm above the two factory holes. I modified the guides inside the tank so that the rods pass through the new holes and into the blocks. The blocks were reversed to further increase the forward tilt of the tank. A bit of work on the spare tire mount and it all went together. The spare tires are not yet at the correct height or vertical but it’s much better and can be corrected.

 

image.jpg

 

 

Here is what the mount looks like after measuring, adding styrene, grinding, and filing. I’ll do something about its appearance later.

 

The lines drawn under the model are reference points used to position the top and bottom of the first spare in relation to the rear axle.

 

DSCN1223.jpg

 

 

I used the styrene triangle to determine the correct angle for the tire mounting bracket.  I used measuring sticks to determine the height of the top and bottom of the first spare in relation to the ground and chassis.

 

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The spare tire in relation to the body. Now I can plan the changes I will make to the body.

 

 

image.jpg

 

 

 

Edited by Endeavor

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Serious stuff this... thanks for taking the time to explain your techniques. They might come in handy when I'm ready for them in like ... oh, 20 years 😉

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7 hours ago, Endeavor said:

The photograph you rely on was taken from a low angle and is centered on the louvers because that was what I wanted to illustrate.  The limitations created by the position of the camera can be seen clearly by the fact that the front and rear wheels and tires appear to be different sizes.  The camera is not positioned properly to take photographs that can be utilized for sophisticated analysis. 

QED!

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The three styrene pieces stacked on the rear deck show the planned height and slope of the new rear deck. The forward edge of the rear deck will be very slightly lower than the cowl, 3.5mm lower.

 

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The first steps taken to modify the rear of the body were to remove the spare tire well, alter the mounting of the fuel tank, and to attach the spare wheel mounting bracket to the fuel tank at the correct height and angle.

 

The next steps were to re-build the spare tire well and fit it into its new position in the modified body. The position of the well establishes the length and slope of the rear deck.

 

The kit's spare tire well is too deep at its bottom, is too wide, and has no depth at all at its top.  I removed excess material from the bottom of the well and attached that material to the top of the well to give it shape and depth.

 

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I used styrene sheet and Milliput to construct a more accurate well, and I removed the center of the well with a hobby knife.

 

image.jpg

 

 

 

image.jpg

 

 

Edited by Endeavor

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Do you do all the cutting with a hobby knife or do you use other tools as well?

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Excellent! I imagine another surgery is planned for the rear small covers too...

 

captur29.jpg

 

captur28.jpg

 

We are all plastic surgeons, but you are a master!

Dan.

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6 hours ago, JeroenS said:

Do you do all the cutting with a hobby knife or do you use other tools as well?

When possible, all straight cuts were made with the flush cutting saw shown in some earlier photographs.  A flush cutting saw's teeth have no offset.  They are be used, for example, to cut a wooden dowel flush without marring the surface.  The lack of offset makes the saw ideal for making narrow precise cuts.

 

For cutting curves, I use the back side of the blade of a hobby knife.  The back of the blade is much easier to control than the front of the blade.  The task is  a bit easier when the contours of the plastic make it easier to guide the blade.  Cutting out the tire well from inside the body was easier than it would have been to cut from the outside.

 

When I can't use the saw to make straight cuts, I guide the hobby knife along the edge of a metal ruler.

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4 hours ago, PROPELLER said:

Excellent! I imagine another surgery is planned for the rear small covers too...

 

Yes.  

 

The new hatch openings will be on a higher, flatter, and wider deck.  This will enlarge and change the shape of the hatch openings so the hatch covers, like the those on the prototypes, will wrap down over the sides to cover the larger openings.

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The photograph of this prototype shows that the bottom section of the well is a separate concave panel that runs from the tail of the car toward the rear frame crossmember. I don't know the shape of the upper section of this panel or how it is attached. It will be difficult to make an accurate representation of this panel.

 

Some prototypes lack this lower section of the well, leaving the bottom of the spare tire exposed. At this point, I have only etched the intersection of the two panels into the flat plastic panel. I will decide later how to complete the well.

 

image.jpg

 

 

The part of the body behind the rear wheels must be shortened and the panels surrounding the spare wheel well must be reshaped. The lower body panels must be at the correct height so that both sides of the bottom of the body will intersect the wheel well at the correct and symmetric locations.

 

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A 10mm vertical section was marked for removal.

 

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The body with the 10mm section removed.

 

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The spare tire well installed. The cut pieces were adjusted and re-attached and the body surrounding the spare tire well was filled and shaped with styrene pieces and Milliput.

 

image.jpg

 

 

image.jpg

 

 

Edited by Endeavor

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Some of the K73 Spyder's inaccurate features are caused by Pocher's use of the frame from the Monza kit. The Pocher Spyder's front springs and spring mounting points are those of a prototype Monza rather than a prototype Spyder.  You can see some of the differences between a Monza and a Touring Spyder chassis in the two photographs below.

 

image.jpg

 

 

image.jpg

 

 

In addition to the different mounting points, notice that the front wings on the Spyder prototype above, unlike the Spyder prototype pictured at the beginning of this thread, are attached to the inside of the frame rails, rather than the outside.  The importance of this will become apparent later.

 

The Spyder prototypes' front springs are longer than those of the Monzas, so the length of the K73's front springs and their front mounting points are incorrect. The correct mounting points for the Spyder's spring shackles are at the center of the leading edges of the frame rails.

 

I raised the mounting points for the front spring shackles and moved them forward to a position like that of a prototype. The new front mounting points are 6.5mm higher, which lowers the front of the frame. The frame cross member under the radiator is now about 2mm lower, making the top of the rails parallel to the ground. The stock Pocher frame slanted upward toward the front of the model. This change makes a surprisingly obvious difference in the built model.

 

Below is the model with the radiator installed.  In its earlier position, the bottom leading edge of the Monza radiator shell almost touched the third row of louvers. Now it is about 8.5mm back.

 

In the three photographs below, the front mounting points have been raised but not yet moved forward.  The front shackles are mounted in the center of the frame rail, rather than in the brackets that are located directly under the new mounting points.  In these three photographs, you can see the result of moving the front crossmember back and raising the front mounting points for the stock MMC springs.

 

The next steps were to remove the old mounting brackets, modify the front of the frame, and build longer spring leaves.

 

image.jpg

 

 

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Below is an unmodified Spyder frame rail.  The mounting point for the front shackle is the hole in the bracket on the right, which is beneath the frame rail.

 

DSCN2760_2.jpg

 

 

Below is one of the modified frame rails. I removed the bracket that hung below the frame rail and drilled a mounting hole close to the leading edge of the frame rail. The hole immediately to the left of the new correct hole was the temporary attachment point for the shackles in the photographs above.

 

I also modified the inside of the frame rails to obtain clearance for the tubular front crossmember.

 

image.jpg

 

 

I made three brass leaves for each front spring set, which replace the three longest MMC leaves. The new leaves are 9mm longer than the old. I retained the other six MMC stainless steel leaves.

 

These changes will make it possible to build front fenders (wings) and a front apron that will be faithful to the look of an original.

 

Here is the result.

 

image.jpg

 

 

image.jpg

 

Edited by Endeavor

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The third stage of body modifications

 

The first two photographs of an OOB body - looking from the rear toward the cowl - show the contrast between the cowl section, wider at the top than at the bottom, and the rear section of the body, wider at the bottom than at the top.  The photographs reveal the fundamental flaw of the rear body and they also explain why the kit's doors are so inaccurate and, despite their compound curves, do not fit. 

 

DSCN2768_2.jpg

 

 

DSCN2775.jpg

 

 

It is not possible to build fenders that look correct with the OOB body.

 

The two photographs below show why. The first photo is the K73 body after I eliminated the "Coke bottle" shape. Stock fenders are bolted to the left side; fenders I had begun to work on are bolted to the right side. The width, height, and overall shape of the rear body are still the way Pocher made them. The large gaps between the fenders and the body are due to the errors in both.

 

The cowl is wider at the top and therefor flows down slightly inward.  The leading edges of the doors flow down slightly inward.  The body from the rear doorjamb back flows outward because it is wider at the bottom than at the top.

 

The K73 body narrows 0.5" or 12.75mm from the rear door jams to the top leading edge of the rear deck, and narrows a further 0.25" or 6.4mm from the leading edge of the deck to the area over the rear axle. These measurements were made at the height where the body is widest. Because the rear body is narrower at the deck than at the frame, there are large gaps between the body and the fenders.  The shape of the fender, wider at the bottom, contributes to the gap.

 

image.jpg

 

 

The Touring bodied 8C 2300 below, provides a contrast. There is no gap.  

 

The prototype body, in 1/8th scale, would be 0.1" or 2.7mm wider at the rear door jams than the Pocher, 0.6" or 15.2mm wider at the leading edge of the rear deck, and 0.55" or 14mm wider at the area over the rear axle. The difference in the shapes of the bodies is as important as the difference in the dimensions. The prototype's rear body is wider higher up and slopes inward as it flows down toward the frame. As the prototype's rear fenders flow down and inward to the frame, they are almost parallel with the body panels  In contrast, even when the K73's rear fenders are pulled inward  toward the frame, they form a "V" shaped gap with the outward sloping Pocher body.

 

Looking at the hatch openings and the top of the seatbacks in the two photographs, you see that the prototype deck is much wider and flatter. 

 

.image.jpg

 

 

Widening the top and and reshaping the top and sides of the rear body will make it possible to build accurate rear wings that will fit with the body like the prototypes.

 

I raised the leading edge of the rear deck, inclined the top of the deck down from the seat to the spare tire well, made the deck flatter, reduced the radius of the curves that flow down from the deck to the sides, widened the top of the deck behind the seats, and made the sides of the body flatter and slope inward as they flow down to meet the frame.

 

I began with styrene strips and sheet, then layered on Milliput to achieve the basic shape. I applied Metal Glaze, filed and sanded, and repeated the process a few times.

 

image.jpg

 

I enlarged the hatch openings and I will build larger hatch covers which will wrap down over the sides a bit. it's a work in process. This is not the final shape.

 

 

image.jpg

 

 

Some net changes to the K73 body thus far. These measurements were taken with the body mounted on the rolling chassis.

 

Reduced the cowl height- 0.34"/ 8.7mm

 

Reduced the rear deck height at the seat back- 0.21"/ 5.3mm

 

Reduced the body width at the front door jams- 0.22"/ 5.6mm

 

The body width at rear door jams is unchanged except that the trim was removed

 

Increased the body width over the rear axle- 0.41"/ 10.4mm

 

Increased the body width in front of the spare tire well- 0.31"/7.9mm

 

Net change from the front door jams to the rear axle- 0.63"/ 16mm

 

image.jpg

 

 

image.jpg

 

 

 

 

 

 

Edited by Endeavor

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It was hard enough  for me getting a Monza body to fit the chassis, and remove all the moulding distortion. This is on another level.

 

If you hadn't already done so much work on the rear, would it have been possible to insert a wedge along the centreline of the rear deck?

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That is an interesting idea.  After I achieve the final dimensions, I plan to make a second body.  I will be open to other methods.

 

The primary problem, I think, would be that adding material in the center will not increase the height of the top edges of the deck or reduce the curvature of the sides of the rear body.  It might an interesting starting point, however.  Something to think about.

 

Thanks for the idea.

 

David

Edited by Endeavor

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