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PostPosted: Fri 21. Oct 2016 05:23 
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Joined: Sun 13. Apr 2014 01:02
Posts: 263
Location: Sedona, AZ USA
Here are a few pictures of my 2006 Chevrolet Montecarlo. It is a converted SCX slot car which I bought on eBay. I built this car primarily to see how Chassis Kit CK2 would work with NASCAR bodies. Works fine but the car doesn't handle like an LMP.

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This is the second car I built using Chassis Kit CK2 which is available at https://www.shapeways.com/shops/magracingunlimited
This version of CK2 is slightly newer than the one I used to make my 1998 Mercedes CLK-LM. The main difference is that in the case of this newer one, the distance between the motor and the rear axle can be adjusted after the motor is glued to the motor plate, to precisely mesh the gears.

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The wheels and tires are from the slot car.

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The body by itself weighs 29 grams. The entire car with the battery weighs 87 grams.

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The rear axle is from the slot car. The front stub axles are made from 3/32” diameter x ½” long stainless steel rivets. The gear on the axle is from gears I had on hand.

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All of the extra holes in the chassis are to reduce weight and printing costs. This build uses spring copper strip for battery terminal connectors instead of magnets. The chassis can accommodate protected as well as unprotected batteries. There is no need to remove any insulation from the battery and the battery does not need a magnetic positive (+) terminal.

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The body is held to the chassis with 3 magnets. There is a bumper in front and a stop behind one of the rear magnets that prevent the body from shifting on the chassis. This car does not handle as well on my road course compared to most of my other cars, probably because of the relatively long wheelbase, narrow front and rear track, and higher center of gravity. Without the body the chassis runs much better.

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Both of these cars were built with Chassis Kit CK2. The silver Mercedes has a shorter wheelbase and a wider track.


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PostPosted: Sat 22. Oct 2016 00:06 
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Joined: Wed 10. Aug 2016 00:44
Posts: 37
Location: Bethlehem, Connecticut USA
Hi Ned,

You said both the Monte Carlo and Mercedes were built using the same chassis. What gives the Mercedes the wider track, just wheels and tires, and width of rear axle?

While on the wheel subject, I have yet to tear apart the slot cars I have, but the Slot it LMP cars that I have seem to have relatively narrow wheels/tires. I suppose I can just find anything wider to get more meat on the road? And it's my understanding that all the slot car wheels are simply pressed onto the axles and that's it. I see other aluminum wheels with an allen head set screw to hold them on, nice wheels but I would think the plastic are lighter.

With tires, because the magracers run on the tracks that everyone builds for themselves, I wouldn't think that all those fancy silicone tires you can get would make any difference one way or the other over the rubber tires that come with the slot car, which maybe could use some improving on grip by switching to something else when you're running on a plastic track surface.

Any thoughts. Just wondering if you've experimented with any of it. Kind of got away from my original question.

Brian


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PostPosted: Sat 22. Oct 2016 04:59 
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Joined: Sun 13. Apr 2014 01:02
Posts: 263
Location: Sedona, AZ USA
The width of the front wheels including the hub determines the front track. To reduce the distance between the front wheels, remove some of the hub. If needed, remove all of the hub. If that's not enough, reduce the width of the wheel and tire also. The track in the rear is determined by the width of the wheels and the length of the rear axle.

Wider front tires will probably not help handling and cornering. It will probably hurt. Magracers seem to run best when they run on the inside edges of the front tires, that's the main reason I designed negative camber into the front ends of my chassis.

I would not be concerned with the weight of wheels. I would be extremely concerned about how round the wheels, and especially the tires are. Many slot car tires, mounted on wheels when new, are not round. They're not a perfect cylinder. Perfectly round front tires are probably more important in magracing than in slot racing. All of the plastic wheels I've seen are pressed onto the axles. Aluminum wheels are typically held on with a set screw through the hub. Aluminum wheels are probably more accurately made. Better quality I suspect but much higher price. I don't have any experience racing slot cars. Maybe the guys with slot car experience could chime in here. My best wheels and tires were made by SCX for an SCX PRO 2003 Audi R8 slot car. That's an LMP race car. The wheels are aluminum and the tires are very high quality, rubber I think. The tires are .353" wide.

I wouldn't consider silicone tires for my cars and track. I'm not sure what is the best tire compound. It partly depends upon the smoothness (gloss) of the track surface and the cleanliness of the surface. Experienced slot racers, like Keld, would know much more than I.


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