83 replies to this topic

[dc-65x]

I’m lucky to be able to do another MESAC build, this time it is from the Super-Coupe class of cars. 

 

This was made possible by the keeper of the MESAC legacy Victor Ferguson and my good friend Rodney Chew.

 

Below is a link to Victor’s MESAC Facebook page:

 

MESAC Slot Car Club

 

 

Below is an article from Modeler Magazine August/September 1975 that tells about this cool class of cars:

 

 

 

 

 

Slotblogger Todd Messinger (n9949y) was a MESAC member and raced in this class. I believe the number 15 Lotus Europa in the picture below is his car. 

 

Sadly I've been told that Todd has passed away. I am sure we would have all appreciated his insights he could have shared with us.

 

 

Victor has these 8 Super-Coupe body molds:

 

Greenwood Corvette

BMW CSL

Ford Escort Mk1 (maybe?)

Camaro 74 75

Lotus Europa

Porsche RSR

Ford Capri

Alfa GTV

 

Victor was kind enough to pull a body for me from one of these molds.

 

 

Can you guess which one I said I’d really love to have?   

[Bill from NH]

Rick, Todd Messinger passed away about five years ago with ALS. He was always posting photos of his Pelican Park cars. I'm guessing you'd love to get the Porsche RSR. My favorite would be the Greenwood Vette & one of their red, white, & blue paint jobs.

[dc-65x]

I'm sorry to hear about Todd and I've edited my post.

 

When I did a search for MESAC on Slotblog his posts came up and I was looking forward to hearing any stories he must have had. A sad loss and thanks for letting me know Bill.

[Martin]

The Greenwood Corvette has some sexy lines. The RSR Porsche would work for me too    

 

Looking forward to seeing what you did pick. 

 

 

 

[dc-65x]

Hi Martin.

 

I really like the Lotus Europa but......I am totally smitten with this original survivor MESAC Porsche RSR:

 

 

I love those HUGE fenders filled with fat tires:

 

 

A much appreciated beauty from Victor:

 

 

Gota love that whale tail rear wing:  

 

 

Here the body has been roughly trimmed out.........

 

 

 

..........and on the setup block to start planning chassis construction:

 

[Larry Horner]

Damn ... I was really rooting for the Lotus Europa!    But the Porsche was my second choice and those wheel flares are really stunning.

[Martin]

Not that you need inspersion Rick. see pics.

 

 

I was working on 4 IROC 911s for friends and I to have equal cars to race. 

 

[Bill from NH]

The first IROC races were with Porsche coupes. I think they were only used for the first season. Building modified Camaros was cheaper.

[dc-65x]

I really like the Lotus too Larry but the fat fender Porsche won out.  

 

There sure are zillions of pictures of RSR race cars for inspiration Martin. I'll be doing a "fantasy livery" like the MESAC guys were doing in the 70's.

 

Bill, it amazing that the first little 1963 Porsche 911...........

 

 

...........10 years later evolved into this fantastic race car:

 

[Dave Crevie]

Right. Starting with the basic unibody;

 

 

They made a few changes;

 

[dc-65x]

Hi Dave,

 

Boy, they didn't mess around did they!  

[Martin]

When I was working on the plan for my 911 IROC cars, for a minute I played with the idea of putting the motor behind the axle ala Porsche 911  .

Why does Porsche do it that way? and they just will not give it up.

 

I would think it would make a terrible tail happy slot car. But I wanted to prove it to the die hard Porsche fans as a joke really. 

What's your thinking Dave and all ?

[dc-65x]

Here are the pictures of the the very successful MESAC Porsche RSR from Victor. Sorry Martin, it's rear engine but not behind the rear axle.

 

This is the design I will be using for my "inspired by" build:

 

 

 

My version will have a 3 5/8" wheel base, 5/8" guide lead and is 2 1/2" wide with a 3" track width:

 

[Martin]

No need to be sorry Rick, It was a joke to prove a point that putting the weight behind the axle sucks. 

 

I look forward to your build.

[Bill from NH]

The only slot cars I've seen with motors behind the rear axles have been wheel-standers for drag racing. And I've only seen a couple of them. The dual red can cars, by I think Buzco, doesn't count.

[Martin]

...and to clear Rick. In Porsche speak, you are building a MID motor chassis.  911 Porsches are rear engine.

Didn't MID motor mean in the middle (e.g.Cheetah) at one point? Now it means behind the driver but in front of the rear axle ( I am speaking of real cars now)

I would love an engineer to explain how Porsche ever went with that design, and it works somehow    

[Dave Crevie]

The 911 floorpan layout is a carryover from the very first cars Dr. Porsche designed, and the factory's ideology to "not fix what ain't broke". As long as they were building race winning cars, there was no incentive to change. You do drive a 911 a little different than a mid-engined car, due to what racers call the "dumbbell" effect. Imagine a weightlifter's dumbbell, and how once it is spinning, it is hard to stop. This is due to the heaviest parts of the dumbbell being far from the center of where it is spinning. The same physics makes it harder to recover from a spinout in a 911 than with some other cars. You steer into the slide like you would if sliding on snow or ice. But chances are, you will over-correct in a 911, and get the car spinning in the opposite direction. 

 

Let's consider two objects. One, a dumbbell , and the other a bar with the weight in the center. Both are rotating on their center of balance.

 

         Largest areas of mass farther away from center of rotation                         Largest area of mass close to center of rotation

 

 

Now we have to stop the rotation. Figure A will be the most difficult of the two to do this, since it's mass is farther away from the center of rotation. 

 

 

Now consider the placement of the motor in a slot car. The motor is the heaviest single component of the chassis. Let's call the guide flag post the center of rotation. Once the car enters a turn, it is beginning to rotate around that axis, and it will act like one half of the dumbbell.  

 

 

And just like with the dumbbell, the farther from the center of rotation the major mass is, the harder it will be to stop the rotation. 

 

So, with all this, one wonders why the motor has to be in the rear of the chassis at all? Tires need some downward force to get traction. That downward force comes from the weight of the motor. (Plus some from the body) It becomes a balancing act. You want enough weight in the rear to gain grip, but not so much as to make the car spin out of the slot through the dumbbell effect.  

[dc-65x]

The motor for the MESAC Super-Coupe class was the Mura C-can with an NCC20 armature. 

 

Below is a new old stock (NOS) Mura C-can, an aluminum block to support the can when it's clamped in a vise, Champion motor bracket that needs lots of work to flatten it out and a pair of 2-56 stainless steel machine screws:

 

 

I modified my C-can and used it with a junk endbell for my jig motor. Modifications included notching out the can (red arrow) to make room for a motor bracket to rear axle brace:

 

 

I like to machine the can nice and flat so the motor bracket seats flush. I took less than .005" metal removal. This is the first "fuzz cut" showing how bad the surface was:

 

 

Using 2 machine screws, with flat surfaces on the motor and bracket makes motor installation and gear alignment easy and precise.........and most of all I like doing it this way.   

 

 

Here's the jig motor in the Rick's jig and soldered to the axle tube with its typical relief cut modification:

 

 

I've set the motor up to clear the axle with a 9T (Sonic) - 45T (vintage Fass) 64P gear set. I can easily switch pinions to a 10 or 11 tooth to have ratios from 5:1 down to about 4:1:

 

[dc-65x]

The good old Parma 1 1/4" drop arm was cut down to 7/8":

 

 

The mail rails were the tricky part to bend:

 

 

A notch was filed for bottom motor screw clearance. The motor bracket will act as a gusset for strength:

 

 

The drop arm, main rails and both rear axle braces........

 

 

............in the jig and ready to go:

 

[dc-65x]

Everything soldered up but those soldering iron "drag marks" have to go:

 

 

That's better:

 

 

 

Motor bracket, main rail motor screw notch and axle tube brace:

 

 

A view of both rear axle braces:

 

 

 

[dc-65x]

Here's the front axles and wide MESAC style tires on the original car:

 

 

After staring at this photo for a LONG time I've decided on how to make my front end.    

 

But first I need some wide MESAC style front wheels and tires for a 1/16" axle.

 

I decided to use Russkit Rear Road wheels and tires that came on the Cooper and Ferrari F1 hard body kits:

 

 

These are 1/8" axle set screw wheels shown on the right.

I bored out the wheels to 3/16" and made a gizmo with a 1/16" hole to slip fit inside shown in the center. 

On the left the finished wheel.

 

 

The gizmo spins on the axle and is permently attached to it like a regular "pin wheel".

The Russkit wheel slips over the gizmo and attaches with its setscrew:

 

 

The front wheels and tires finished at 7/8" diameter, spin dead true and will be easily removable from the chassis:

 

 

Time for those front axles.........

 

 

[Larry Horner]

Lovely job cutting the rain grooves into the fronts after you cut them down! Did you make extra "gizmos" for next time I need to sleeve some front wheels down to .0625? 

[dc-65x]

Thanks Larry,

 

These gizmos are custom cut to slip fit in the wheels after their hole is bored out.  

 

I thought about making 1/8" diameter gizmos so I could use the existing holes in the wheels. I was worried that tightening the wheels set screw would distort the resulting thin wall thickness on the gizmo and cause it to bind on the axle.

 

I finally broke down and bought a set of gage pins to check the size of small holes in projects like this one:

 

[Dave Crevie]

Thanks Larry,

 

I finally broke down and bought a set of gage pins to check the size of small holes in projects like this one:

 

71kWHeJfgiL._SL1500_.jpg

 

The only way to do it. Too easy to make a mistake measuring with a telescope or small hole guage. And the price of a guage pin set is low enough that, if you figure your time, and possibly cost of material, to fix a mistake. Well worth the price. 

 

Just for your readers who might be contemplating getting a set of pins;

 

 

Class ZZ is as fussy as we need. Don't need laboratory grade here. You'll want the  - minus set, you can't put a .250 dia. pin into a .250 dia. hole. A .250 minus pin actually will measure a tiny bit undersize, depending on the size of the pin.  The .061 to .250 inch diameter set will cover anything a slot racer is going to build. And for sizes over .250, you can buy individual pins. You will find yourself checking things like axle bushing holes to fit ball bearings, pinion bores for fit to an arm shaft, axle holes in wheels and gears. You can get affordable sets on e-Bay;

 

 

And from Amazon;

 

[Bill from NH]

Gage pins were available individually, maybe they still are. I think it was cheater who mentioned using them when setting rear bushing heights on a flexi.