I've Got About 2 Weeks!

[Florida_Slotter]

The "Gearheads" here in Florida are all getting ready for "Daytona Speedweeks" which will soon be here.

The great part is that all types cars will be in action.

January 26th is the "official" start of the season is the premier endurance event, The Rolex 24.

I am a fan of the top tier of this series, the Daytona Prototypes.

A good friend of mine, Greg Walker, handed me one of the sample bodies he is coming out with. I placed an order with the fine folks at Slot Car Corner for some of the C.B. Design Wheels LMP wheels in gold color. They just arrived with the rest of my order.




What configuration of chassis will I build? Not sure at this time.

The plan is for a step x step build of the entire car.

Stay tuned.

[torquemutant]

Is there a class, for scratchbuilds, raced at Greg's "The Race Place" ? I too like building my own 1/32 chassis so my interest is peaked just waiting on your build up article, here on HRW. Is that body lexan and how thick is it?

[Florida_Slotter]

Torquemutant,

Actually Greg is developing a 1/32nd RTR car. It will be a very nice piece based on what I have seen. Greg & BoB from Pro-Track are working on this together. I can't share many details, but I have already placed my pre-order!

I am hoping to get a group of folks that like to build what they race going and having regularly scheduled races on Palm Bay in the near future.

[Florida_Slotter]

This AM I got a chance to do some "contemplation" on this project.




The first thing I did was to setup my jig for this build. I use the RGEO Super Jig. One of the many reasons I prefer this product over the others out there is that it meets all the requirements that I have for a jig. I race a lot of FCR cars, Flexi cars, 1/24 1/32 & 1/43 chassis. This one jig has met all of my needs, so it should meet any you might have. It is made with .750 thick commercial material. It sits perfectly flat on your workbench, so it stays flat, even after many builds. I had one jig that was made from .500 material and was supported by some nice little feet on the corners. I noticed all of a sudden that when I installed the wheels on the completed chassis, only 3 of them were making contact with my flat surface. I laid my flat surface on my jig and saw the problem. It was "Swaybacked" with the center of the jig lower then the corners. I have more than 200 builds on my Super Jig and the chassis are still flat.

To accommodate the 1/8 inch axles required by most Womp & FCR racing groups the Super Jig has 1/8 inch spacing between the axle locater pins, which are made from 1/8 inch material. You can buy 1/8 inch diameter stock at many places, so if you want or need more, you can make your own.

So how do you use this 1/8 inch spacing with 3/32 axles? Either I slide a piece of 1/8 inch round tubing over the axle, or in this case, I slid a piece of 5/32 inch over each of the 1/8 inch axle locator pins. I tend to like this method a bit more as it gives me more choices in wheelbase choice. Most of the tubing available K&S Engineering has .014 wall thickness. I can remove the tubing on the front locator pin and add a piece of 3/16 tubing over the 5/32 tubing on the rear axle locator and change the wheelbase by .014. This is very handy when building a chassis for a hardbody and you want it "right" rather then "close".


Before going any further, I'd like to address my theories on chassis parameters and how they affect the handling of the finished product.

"Shorter wheelbases NORMALLY handle quicker."

"Longer wheelbases NORMALLY handle slower."

"Shorter Rear AXle centerlines (RAX) to Guide Post Centerlines (GPC) NORMALLY respond quicker."

"Longer Rear AXle centerlines (RAX) to Guide Post Centerlines (GPC) NORMALLY respond slower."

Now let's discuss "drive configurations":

Inline - probably the most widely used drive configuration in all of slot car racing. It typically provides for a good handling chassis, can be made to have good "balance", but is not as mechanically efficient as a "sidewinder" drive configuration because of the 90 degree transfer of power.

Sidewinder - probably the most efficient configuration for the transfer of power as it is on the same plane. A sidewinder tends to place all the weight at the rearmost part of the chassis, but with careful planning, that can be overcome.

Anglewinder - this configuration came into being in 1968 in the commercial slot car racing world. Today it is the most popular as it provides a "compromise" between the inline and sidewinder configurations.

So. which should we build?

[torquemutant]

Anglewinder... Anglewinder. Please, Please, Please! :D

[Florida_Slotter]

After setting up the jig, I like to lay the body on it's top place the axles, wheels and tires in place and then see what I have to work with.

It looks like there will be a lot of room to put just about any configuration of chassis under this body.




Torquemutant - I have to apologize to you. I have all the parts necessary to build an inline chassis. Also that Fairlane is a sidewinder, and I have a Ferrari 512 with an anglewinder that has too much motor in it. But I think my motor solution will soon be here. This is not a one time happening.


Wheelbase, or RAX-FAX=3.497, FAX-GPC=.150 & RAX-GPC=3.647. While short in the Guide Lead, the overall length is long for a 1/32nd car, other than a stock car. The track is right at 2.5, so overall it should handle well.

The effects of a short Guide Lead can sometimes be offset by allowing some side to side movement in the front wheels. I'll make a note of that and make sre I provide some.

My thoughts are to build a multi-wire chassis using .032 wire. This is like having flat wire and works pretty well. I hope to get this project into high gear tomorrow.

[Florida_Slotter]

I was taught and still believe that the most important part of a slot car chassis is the 'triangle' that starts at the Guide Flag and ends at the rear wheels. If you build this section so all parts are straight, flat and square you will have a fast chassis. Many times I have had a fast chassis that might not have handled as well as desired, but once I either changed the pans or pan mounting system, I then had a "killer" chassis.

Something I always try to do, whenever possible, is to use a rear axle tube of 7/32 round brass tubing. The logic here is to put the bushings / bearings as close to the wheel as possible, My belief is that you will bend / break far less axles this way as you eliminate the added leverage created by the distance between the bearing / bushing and the wheel itself.

To do this you must open up the 3/16 holes in the motor bracket to 7/32. I have a set of step drills that make this a very simple task. One of the benefits of using a motor bracket like the RGEO unit is it is made from .050 half hard brass, While this particular piece is designed for building IRRA Retro chassis, I find it is very adaptable to 1/32 cars as well. If you use .8125 diameter rear wheels, it will provide you with .050 clearance under the chassis. When I build, I use "Jig Wheels" on the rear that are .712 in diameter. A reason I use 'round' wheels is that I have tactile feedback as to how much traction each wheel has with the surface of the jig.




After I prepped the motor bracket I cut a piece of 7/32 round brass tubing to 1.400 inches in length. Then I assembled the motor bracket, axle tube, build axle, bushings and jig wheels into a complete assembly. Next I centered & squared everything and finally soldered the axle tube in place. I like using the step drill to open thr 3/16 hole in the motor brachet up as it also chamfers the hole and the solder will flow all around the axle tube.




Next I bent 2 "U" shaped loops of .032 wire. The first measured .750 inside, the second .814. Then I cut a piece of .032 x .750 brass strip to fit between the two .032 rails from the front of the motor and .250 behind the back edge of the GP.




The final step tack solder it all together.

[Florida_Slotter]

Let me start this section with an apology for such a long delay. I awoke about 2 weeks ago with what felt like a sprained wrist. After a couple of days of ice, then heat, then ice, I called my doctor and went in to find out what was going on. He reached around to my shoulder and stuck his finger under the shoulder blade. It was one of those experiences that you both like and hate at the same time. There was this large shock that went through my body followed by a lot of relief. He said I had a pinched nerve due to the start of bursitis in my shoulder! However the pills he prescribed were quite enjoyable. After almost 2 weeks off due to the fact that I could not bend any wire by holding a pair of pliers in my right hand, I am back on task.




I added the two missing main wires from the 8 wire chassis I am building. Over in the retro racing world of 1/24th, I am seeing a paradigm in chassis design. It was not too long ago where .078 wire - 1 per side - was the basis for a good handling chassis. Now the more the merrier seems to be the way to go. So I decided to give this theory a try in a 1/32nd chassis. The idea is that you are essentially creating the equivalent of a piece of flat wire.




Rather then making a larger loop, I chose to use the rear of the main wires to form the start of bracing to the rear axle tube. I simply bent the wire up, then out. Awhile back I bought a set of miniature pliers from Harbor Freight. I got this one pair of pliers that has a flat bill on it. Call it pure dumb luck, but the spacing is such that it makes the bend right where I need it for this build. Once I had the wire bent up, then I used those pliers to bend it out towards the end of the axle tube.

The two outside wires proved a front and rear brace on each side of the axle tube. I will add a triangulation type of brace to support the rear axle tube to prevent bending from a side impact.

Something I want to say is that once you finish working for the day, you need to make a trip to the sink to wash off the remaining flux residue off of your chassis. If not, it will age very quickly. Rust will quickly appear and take away from all the hard work you have done.

Tomorrow we will add a guide tongue, front axle and then start to design the pan system.

It feels good to get back to bending wire and soldering.

[HomeRacingWorld]

Looking outstanding.

I hope you are ok, I know those things can hurt!

Ahhh, prescriptions!

[cagee13]

Glad your back at it. Very nice work so far.

[dreinecke]

Wow! That is some really nice work!!!

[Florida_Slotter]

As promised, I added a guide tongue, front axle tube and rear axle bracing. Basically this finishes up the center section of the Daytona Prototype chassis I am building.

Let's get to it.




I made the guide tongue from a piece of .064 x .500 brass strip. I simply found the centerline of the strip, drilled a 3/16 hole and then radiused the front so the guide flag will fit and move smoothly. Then I soldered it on the centerline of the chassis.




Next I cut a 1.6 inch long piece of 1/8 inch round brass tubing to serve as my front axle tube. I like to use a tube as running a solid front axle with the wheels turning on the hard front axle will eventually "waller out" and start to flop about. To set the proper height for the front axle, I used a pair of rear jig wheels that set the height of the chassis to .050 clearance with .8125 wheels and tires on the front. During truing that will diminish, but we have a 1 mm (.039) clearance rule, so I have room to spare.




This is the piece of .055 wire that I bent to make the front axle tube support. Why did I choose .055 wire? Well when I grabbed a piece of short wire from the 'short wire holder' a piece of .055 was what I grabbed. So I bent it and used it to solder the front axle tube in place on the chassis.




Since I had a really short piece of .055 wire sitting on the work surface, it was time to make a rear axle tube brace to save the integriy of the rear axle tubes / motor bracket in the event of a side on wreck. I mean these are cars that are meant to race, are they not? Two quick approximately 70 degree bends, then solder it in place and trim off the excess. You will also notice that I removed the center section of the rear axle tube.




Okay, now it's time to do the QC check on your work. Go back and look at all the solder joints. Do they all have a smooth, shiny surface to them? If so, they're all good. If not, now is the time to go back and make them like that.

A couple of things I do prior to calling a center section "done" is to make some measurements and tests of the chassis. First off I use my calipers to measure wheelbase side to side to make sure it is right on the money. On this chassis it was so no adjustments were necessary. Then I will take the chassis off the jig and turn it over with the jig wheels in place. I then place a small amount of pressure on the chassis and then try to move each of the jig wheels. If they feel like there is a similar amount of effort required to move each of them, then the chassis is flat. Finally I mount the wheels and tires on the chassis that will be used when it is complete and let it roll across my work surface. If it rolls straight, all is good. If it pulls left or right, then you need to correct this. If you do not, you will be using some of your motor's power to fight the resistance of the guide in the slot as the chassis is always turning in a direction rather then going straight.




This is what your chassis shoule look like at this point.

Don't those gold LMP wheels from Slot Car Corner look awesome? I sure do think so!


Next up we're going to build the pans. I've got an idea about doing something different than I have ever done in the past. I want to try a new concept that I've been thinking about, "Mass Centralization". If you have ever ridden a sport bike by Honda, they talk about this all the time. I hade the opportunity to ride one of their liter bikes one day and it was one of the most nibble bikes I've ever been on. Hey, one of the great things about building your own chassis from wire and brass is that you can come up with something that is different and might just work a bit better then your friend's car that you are racing. Oh yeah, that's what racing is supposed to be about, ain't it?

[torquemutant]

This is a wonderful build, Marty. You are extremely articulate in your directions and back it up with super illustration photography that even a novice, like me, can understand. Question; to set the ride height on the front axle you used the rear jig wheels… what was used on the rear axle, at that time, to keep the rear axle at proper height while you set up the front? “Mass Centralization”… I can hardly wait until you let us in on that. The podium awaits you, professor.

[Florida_Slotter]

Since the rear has already been soldered, it should be laying flat on the jig with the rear jig wheels in place. So you can simply move them to the front and re-use them. Or if you are lucky enough to have more than a single set of jig wheels, then you can keep the rear jig wheels in place and grab the rear jig wheels from the other set.

Okay, now I'll answer your question of "Why do you have 2 sets of jig wheels?" It is a very simply matter; the first set I bought did not have set screws in them and I got tired of chasing those little suckers around on the floor. The new set has set screws in them so when I pick the chassis up off the jig, I no longer have to think about those jig wheels going on an adventure. Do you know how fast and far those heavy metal wheels roll on a tiled floor? If some of my slot cars were as fast, I'd be very happy.

Thank you very much for the glowing comments!

[bill from nh]

Marty, the set of jig wheels without set screws could be drilled & tapped for 4-40 screws.