My 1970 Ferrari 512 S

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Ned
Posts: 315
Joined: Sun 13. Apr 2014 01:02
Location: Sedona, AZ USA

My 1970 Ferrari 512 S

Post by Ned » Wed 13. Apr 2016 17:49

Here are a few pictures of my 1970 Ferrari 512 S. The body and rear wheels are from a Fry slot car I bought on ebay.

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The front & rear Fry wheels are made for 3/32” (2.38mm) axles. Reducing the diameter of the hole in the wheels, and keeping the holes centered, was not easy for me. I was able to do it for the rear wheels but not for the front wheels. So I’ve used stock front wheels painted gold with stock stub axles.

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Although this car has rubber tires, it certainly cannot run wide open around the corners on my track without crashing. It still takes considerable skill to achieve good lap times.

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The rear axle, gears, and motor are stock magracing parts.

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The white plastic chassis parts I designed using 3D modeling software. They are all slightly different from stock parts and were printed by Shapeways. The grey plastic chassis parts are stock.

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The wheelbase of the chassis can be adjusted to get a precise fit. The body is held on by 4 magnets which are glued to the body with 2 part epoxy. They are attracted to the four #2 self tapping screws in the chassis which are made of regular steel, not stainless steel. This method makes it very easy to precisely adjust the height of the body. The front bumper is made from .182” thick foam board. It prevents the chassis from sliding forward relative to the body upon a frontal impact during a crash.

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This car runs like a champ. No front end shimmy at all. Not even at the end of my 24’ long straight. Lane changes are more reliable than any of my other 5 cars. I think that the lack of any front end shimmy is primarily due to the fact that the front end is designed with 1.7 degrees of toe in (positive toe). Secondly, I eliminated much of the front wheel wobble by eliminating most of the taper in the stock front wheel bore. Reduced wobble may also contribute to less front end shimmy.

The next time I want to use slot car wheels designed for 3/32” axles, I plan to use 3/32” axles front and rear. Enlarging the holes in the chassis and the spur gear to accommodate the larger rear axles should be easy. The problem may be finding something to serve as the front stub axles. Does anyone know where 3/32” headed pins can be purchased? The diameter of the stub axles is critical. My experience suggests that the diameter of the stub axle should be .001” - .002” less than the diameter of the hole in the hub of the wheel. If the axle is too small relative to the hole, the wheel wobbles on the axle and probably contributes to front end shimmy at high speeds. Of course if the axle is too large, the wheel won’t spin freely.

kiklo
Posts: 175
Joined: Mon 9. Nov 2015 11:49
Location: Norway

Re: My 1970 Ferrari 512 S

Post by kiklo » Wed 13. Apr 2016 18:14

Lots of fine work ! Nice to hear you got a good running car.
Racing Regards

Kim K.

Ned
Posts: 315
Joined: Sun 13. Apr 2014 01:02
Location: Sedona, AZ USA

Re: My 1970 Ferrari 512 S

Post by Ned » Sun 18. Sep 2016 05:28

Here is a short video of the car running on my outdoor track. This is the first car I built using a chassis I designed and had printed at Shapeways.
The Y intersection in the upper right corner is difficult to navigate. I have a portable barrier there to force cars to go to the right since the track is not finished.


vmibert
Posts: 53
Joined: Mon 30. Dec 2013 00:25
Location: Oro Valley, Arizona - U.S.
Contact:

Re: My 1970 Ferrari 512 S

Post by vmibert » Thu 22. Sep 2016 04:13

Very impressive!

How much more do your cars weigh than the original Mag Racing cars? Is this a problem for going up a slope?

Does the added weight add some stability to your cars?

Now all we need for this hobby is a sound module like electric R/C airplanes:

https://www.modelsoundsinc.com/index.php

Bert

Ned
Posts: 315
Joined: Sun 13. Apr 2014 01:02
Location: Sedona, AZ USA

Re: My 1970 Ferrari 512 S

Post by Ned » Fri 23. Sep 2016 14:06

This car with battery, ready to run, weighs 10 grams (about 15%) more than an original stock mag racing car. The extra weight does not present a problem going up a 10% grade. Top speed is the same assuming same motor, gear ratio, and rear tire diameter. I would expect run time on a fully charged battery to be about 15% less. The extra weight is not an issue for casual racing but would be for serious long races as Keld has pointed out elsewhere. I think the extra weight might improve stability a little. Rubber rear tires certainly do help overall performance.

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