Stock wheelbase cars

Secrets, tips, tools, design considerations, materials, the "science" behind it all, and other topics related to building the cars and semi-trucks.
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Speedster
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Stock wheelbase cars

Post by Speedster » Sat Feb 11, 2017 11:38 am

I'm planning a car for next year's "Sponsor" race. It will be built in the warm summer months so I can do a lot of testing.
It will be a 1/4" Hershey bar car. I will be using the Falcon body from Derby Evolution and they will cut the slots. Maximum Velocity 4094 axles will be used and Derby Evolution BSA wheels made round. No other modification on the wheels. The car is being designed so the 1/4" cubes can be moved to different locations.

I know 1 1/2 ounces is the recommended weight behind the rear axle slot for a stock wheelbase car but is it the best amount? Some of you have done 2 ounces. It will be a 3 wheel rail rider. How much weight should I keep on the dfw? What's the maximum COM for a Best track?
I know I would ultimately find an answer to my questions but it would take a tremendous amount of time. Some of you might already have the answers.
Is burnishing the wheel bores worth doing?
Thank You Racers.



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davet
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Re: Stock wheelbase cars

Post by davet » Wed Sep 20, 2017 8:21 pm

SPeedster, I'm waiting for someone to chime in also. I'm cutting cars for a church workshop and have settled on everyone gets a wedge. I have 2 stacks of pennies alongside each other behind the rear, stock slot. I t gives me 2.25 oz behind rear slot and a DFW weight of .91. THis seems like a very safe DFW weight but I've only run extended wheelbase cars but have gone as low as .58 on the DFW. I'll have to try and test run it somehow before I cut them all the same way.

BTW! You were right about MaxV wheels. THese kits are really nice. SAme weight for 4 wheels and axles as BSA stuff. TIghter bore to axle also. I plan on just having the kids use metal polish on the axles. SHould I hit them with 3000 grit first?



Speedster
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Re: Stock wheelbase cars

Post by Speedster » Thu Sep 21, 2017 9:21 am

duvet, let me share the specs on my penny car. All pennies do not weigh the same. a 1980 penny weighs 3.15 gr. and a 2014 penny weighs 2.50 grams.

I drilled the rear hole 1 1/2" deep with a 3/4" spade bit and the front hole 1" deep. The rear hole holds 20 pennies (1.85 oz) and the front hole has 13 pennies (1.21oz ).
I needed to drill 2 holes in the bottom of the car, one 1/8" deep and one 1/4" deep which was probably for fine tuning at the time. The COM is about 3/4" and it travels safely on the "Best" track. To start, I drilled the holes and then cut the car to a wedge. I sanded the penny area to almost going through the wood. The height of the car measures 0.81" over the pennies. The car is complete less filler, paint, decorations. It weighs 137.84 grams.
I wouldn't do anything with the axles. Oil them up.
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davet
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Re: Stock wheelbase cars

Post by davet » Thu Sep 21, 2017 11:03 am

THx Speedster. Great info as u usually give me. My wedges are cut diagonally, corner to corner but 1/8" from the actual corner so the fronts have 1/8" bumper. I see how u got ur low COM with fewer pennies behind the axle by shaving the wedge much thinner than ours.
I'll have to go look at a block again but how do you have a 1 1/2" deep rear hole and have .81" above those pennies, yet still be able to almost see through it?

ALso, what kind of glue are u using for the pennies?



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davet
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Re: Stock wheelbase cars

Post by davet » Thu Sep 21, 2017 11:06 am

Disregard all questions. I should've read my e-mail first. Your pics answer all my questions.



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davet
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Re: Stock wheelbase cars

Post by davet » Thu Sep 21, 2017 11:08 am

I'm going to have them polish axles with metal polish just to give them something fun to do with a drill and see how they shine up. INstant gratification.

I'm going to have some duct tape but also will be printing off images onto photo paper that they can glue on if they want.



Speedster
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Re: Stock wheelbase cars

Post by Speedster » Thu Sep 21, 2017 2:31 pm

I like that photo paper. That really sounds like Fun. I've never seen that done before. When is your workshop?



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davet
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Re: Stock wheelbase cars

Post by davet » Thu Sep 21, 2017 2:56 pm

Oct 7, 14 and an optional day on the 21st depending on how many racers we get. The car in my avatar is a photopaper project. It's easy and clean when done at the right point in the build process. I'm using your duct tape idea to save us from paint globs and smell.

I'll try to get a pic on here of the test car but I've since seen your pics and will go that route instead. Easier drilling. My drill was 2 vertical holes behind the rear slot. Each held about 12 or 13 pennies.

The bondo you're using, is it the red finish stuff in the tube? I've got some from a Jeep project yrs ago. It sticks to the wood OK and keeps the pennies from falling out?



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Re: Stock wheelbase cars

Post by Speedster » Thu Sep 21, 2017 5:43 pm

Red stuff in a tube sounds like "Glazing Putty" and that takes forever to dry. You don't want that. The body Filler is usually white, comes in a quart or gallon can, and then "red stuff in a tube" (specifically designed for the white stuff) is added and that activates the white stuff and it will dry in one or two minutes. I form it over the hole to look like the top of a Hershey Kiss and keep touching it until it reaches a spongy stage. At that point I cut it with a razor blade and scuff it quickly with a piece of 80 grit sandpaper. You're done. This year we are having the Girl Scouts color the sides of their wedge cars and a bit on the top with a BIG Sharpie. The ink dries almost instantly and then the Duct tape will be cut to 1 5/8". That will leave a clean line and a stripe on each side of the tape. They can then put any decorations on the car when they take it home.
Our most time consuming activity, and I think the most important, will be wheel prep, especially bore prep. We will be using Novus 2 and pipe cleaners. They will lube with graphite since all their councils use graphite. It won't matter what kind of job they do but that they do it. When they later build their special car with their adult helper they will know the product to use and how to do it. As I've mentioned before, this Activity is designed to be Science, speed, speed, speed. That is why we are using wedge cars from Hodges Hobby House that I just ordered yesterday. I understand your activity is different and you will make it lots of Fun. My Hat goes off to you.



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