167 replies to this topic

[Alan Draht]

I also worked on a vintage dragster motor project which produced a half dozen 6 volt Kemtron/ Ram/ Pittman hybrids for use in future dragster projects I have planned.

 

 

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[Alan Draht]

Other items on the "to do" list include grinding the motor's field laminations to reduce weight and optimize magnetic force...

 

**  Fabricate and install a gear guard

**  Drill an eight-hole pattern in the 69-tooth spur gear to reduce weight

**  Replace the existing guide with a vintage Cor-Ben guide flag

**  Power wiring between the guide flag and the motor

**  Pour/ install lead nose weight (1 oz. +/-)

**  Replace existing drop arm's spring with a heavier-gauge spring

**  Mount and true new tires

**  Polish magnesium side rails and apply clear coat

 

When I last posted here late November 2020, I was working on fabricating a gear guard for this car.  This was machined out of a piece of 0.10" thick magnesium sheet:

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[Alan Draht]

Gear guard installed:

 

 

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[Alan Draht]

Next on my "To Do" list is the item to "Drill an eight-hole pattern in the 69-tooth spur gear to reduce weight":

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[Phil Smith]

That's really nice manual mill work.

[Alan Draht]

One of the big tasks in building the Maldonado dragster that's not on the "To Do" list is body building.

 

Initially I planned to fabricate the body out of a single piece of sheet aluminum.  I needed a thin piece of sheet aluminum 12.5" long x 2" wide.

 

The big challenge with this car's body is the Z-bend at the nose where the aluminum panel sweeps up from the tip of the car towards the front axle, doubles back for 1/4" and then bends back towards the body's rear.

 

I tried working with three types of aluminum sheet.  First was K&B, 0.0160" thick x 10" long.  The 10" length meant that I couldn't fabricate a single body panel 12.5" long.

 

Second, I tried working with a 0.0075" thick piece of aluminum cut from a 4" round dryer exhaust duct.  Length wasn't a problem and it is very lightweight compared with the K&B material, so I had high hopes of being able to fabricate a body out of this material.  There is an issue with its malleability which I discovered when I tried to crease or fold it sharply as in the Z-bend or at the tip of the nose.  This material is stiff and when it's creased/ folded, it cracks and splits.  No bueno.  This material cannot be used for anything other than relatively flat or gently curved body panels, such as everywhere except the nose of the car, including the Z-bend.

 

Third, I tried working with 0.0180" thick sheet aluminum cut from a large sheet, so length wasn't a problem.  It's the thickest of the three aluminum material choices, so it's relatively heavy, which is a strike against it.  When I found out that it too is stiff and cannot be creased/ bent as needed, I put that material aside.

[Alan Draht]

Thanks, Phil.  The gear guard is tricky to make.  I don't know how the Pro's made theirs in the 1960's.  On full-size mills?

[Alan Draht]

Back to fabricating the Maldonado dragster body...

 

I was focused on the Z-bend and soon realized that in order to make the body out of a single panel, the first step in the process, after cutting out a 12.5" x 2" piece of aluminum, was locating the Z-bend on the flat panel and then bending it back and forth neat, square and precisely where it needed to be located front-to-back.  Then, I figured you bend the nose piece sharply to fold it underneath the front of the car.  And, if all goes well, you go on from there...

 

However, in order to make the critical second fold of the Z-bend, I had to modify my mini-metal bender, "The Bender".

 

I had to mill a large angled notch in the bender's base so that the 2" wide aluminum sheet with its first fold could be positioned close enough to the tool's steel die's centerline to make the second bend 1/4" from the first bend, but in the opposite direction, to complete the "Z".

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[Dave Crevie]

You can get .010 aluminum strip stock 1" wide. For the sharp bends, anneal the material in the area of the bend with a propane torch. You won't see a color change like you would with steel, so practice on some scrap until you have a feel for how hot you need to get the strip. 

 

A local guy cut the clearance for the gears with a hole saw. He laid out the hole centers, and center drilled them. Then cut the big hole with the hole saw. Then he drilled the hole for the pinion, and finally did the outer contour. I just did mine with a Lil' Crafty hand grinder and a half round file.

[Alan Draht]

The result:

 

 

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[Phil Smith]

Thanks, Phil.  The gear guard is a tricky to make.  I don't know how the Pro's made theirs in the 1960's.  On full-size mills?

 

Alan, I think everything would be easier on a full size mill. The accuracy is at the least the same as a small mill. and the mass and rigidity is a big advantage. That you did yours on a small mill is a more impressive accomplishment.

[Alan Draht]

A lot of trial and error:

 

 

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[Alan Draht]

At one point I thought I would make the body out of two pieces, the nose and everything rearwards of the Z-bend as far as 10" would stretch, out of the more malleable 0.0160" thick sheet, the end of which turns out to be conveniently located at the "hump" where the driver sits in front of the motor.  The tail piece I'd make out of the thin 0.0075 material.  The front and rear panels would be joined with  a small piece of aluminum duct tape applied to the underside of the assembly.

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[Alan Draht]

Finally, I decided to make just the nose piece out of 0.0160" thick material up to through the Z-bend and make the rest of the body from the Z-bend rearwards out of 0.0075" thick material.

 

Not only is this a doable approach, but the heavier body material belongs at the front of the car where it contributes to the extra weight needed to counteract motor torque forces from lifting the nose and front wheels up off of the track's surface. 

 

I fabricated two complete bodies.  One body will be painted.  The other body will have a clear-coated brushed aluminum finish as pictured.

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[Alan Draht]

Next, I cast a set of low-temp lead alloy nose weights ranging in weight from 0.50 oz. to 1.0 oz.

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[Alan Draht]

Rod & Custom magazine's 1966 slot car drag meet rules stipulated that the Gas Top Eliminator and Fuel Top Eliminator dragsters must have "...a driver and a steering wheel.  Drivers must have arms and helmets."  Also, dragsters must have "...a roll bar, though not necessarily attached to the frame."   

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[Alan Draht]

Power wiring came next:

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[Alan Draht]

Driver and roll bar installed:

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[Alan Draht]

A 0.50 oz. nose weight is installed.  Before and after:

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[Alan Draht]

Here's the car without the driver or the body:

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[Alan Draht]

With the driver in position for racing...

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[Alan Draht]

Rear section of the body installed:

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[Alan Draht]

Complete body:

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[Alan Draht]

Now, if you'll excuse me, I have a bunch of vintage dragster wheels, tires, and Graupner donuts to prep, glue, mount, cure, cut, trim and true before I can take these dragsters to the track.

 

And, I need to finish the Maldonado dragster by disassembling it, polish the outside face of the main rails and other exposed magnesium frame components, clear coat them, and finally, re-assemble the car.  The driver needs to be painted/ detailed...

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[Jesse Gonzales]

Very nice work! I assume you are using Graupner rubber so tire don't "Explode" upon start up?

 

Jess Gonzales