Any recommendations for car design? Help appreciated...

[Speedster]

You are trying to go fast so lets talk about Physics for a moment. Physics is the science of Matter and its Motion. The best set up for a car with an extended wheelbase is 2 rows of 6, 1/4" tungsten cubes behind the rear axle slot and that will give 2 oz of weight behind the rear axle slot. That amount of weight will be the highest up the arc. Then, 2 rows of ? , (whatever it takes)1/4" tungsten cubes immediately in front of the rear axle slot. That keeps all your additional weight in as tight a package around your rear axle in a 1/4" car that looks like a Hersey bar. If you have 3 scales you can weigh how much weight is on each wheel. The search function will suggest how much weight is recommended to be on the Dominant front wheel. On a 1/4" high car, the remaining wood that can be cut out is very light. You might end up having to add tungsten putty up front to get your desired COM and to put more necessary weight on the DOM front wheel. Fenders of any kind look COOL but do they really help. Since this is your last year, I would forget the fenders.
Your car is going to go fast by what you do to the axles, wheels, and the tuning. I wish you the Best in finding a track to tune your car. That will be a definite advantage.

[whodathunkit]

Thank's Speedster!
I was hoping you would chime in on what I was driving at for the 1/4" thick body!

[derbypain]

Thank you both! Points taken... We are switching to the 1/4" tungsten.. Was not aware of the 3 scale system but it makes sense. Now time to get the process started... Still have not heard back from the district guy but will keep planning it out with or without him.

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[Speedster]

I'd like to clarify something.
The dominant front wheel is not only set with Positive camber, it is set with toe in. That's the way the car is tuned. The bend in the nail is pointed down toward the track. This will give you the Positive camber. If the mark you put on the axle head is exactly at 6 o'clock you will have Positive camber and "0" toe. If you turn the nail to 5 o'clock, you will now have Positive Camber and toe-in. When the car starts to roll the dominant front wheel will go to the rail and stay there because of the toe-in. The inside hub of the wheel will make contact with the car and stay there. It cannot migrate to the axle head.

It's early. I hope that's correct.

[derbypain]

I'd like to clarify something.
The dominant front wheel is not only set with Positive camber, it is set with toe in. That's the way the car is tuned. The bend in the nail is pointed down toward the track. This will give you the Positive camber. If the mark you put on the axle head is exactly at 6 o'clock you will have Positive camber and "0" toe. If you turn the nail to 5 o'clock, you will now have Positive Camber and toe-in. When the car starts to roll the dominant front wheel will go to the rail and stay there because of the toe-in. The inside hub of the wheel will make contact with the car and stay there. It cannot migrate to the axle head.

It's early. I hope that's correct.

I think that just helped me realize how to best make the dominant front wheel on a 4 wheel car. . If your statement is the case and I were to do, let's say 8 degree positive camber on dfw and move to 5 o'clock position what amount of negative camber and toe if any, I am assuming negative would you do on the NonDFW front wheel to start? Thanks as your statement helped me visualize the look of the DFW managing the system.

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[davet]

What if you bent the nonDFW axle about 6 or 8 degrees. Twist that axle until the wheel just touches the track. You could twist that and tune it but instead of for steer, you're tuning for touching the track. If the inspector says that there isn't enough weight on he wheel, even though it's touching the track, you could twist it down farther. I'm just trying to think of how to remedy a problem at check-in.

[davet]

I shimmed under my non-DFW with Post-It's until the car was perfectly flat (couldn't push any corner down). With 2 identical scales the DFW read .08 oz and the non-DFW read .55 oz. I'm not sure what this means other than it gives an idea of what the front weighs. Since the DFW weight with 3 wheels touching is .62 oz. , this seems to make sense.

Looking at this car I do think, if I had to run 4-wheels touching, that I would bend the non-DFW to same bend as the DFW. Then I would twist it down until that non-DFW side was barely touching the track and the wheel was toe'd in slightly. The toe-in would would mean air wasn't catching inside the wheel cavity and if that wheel did move over to the rail after a seam, it would only rub the very bottom front edge; just like the DFW does. If they gave me a hassle at check-in about that non-DFW corner being able to be pushed down I would ask to see if every car was perfectly flat. If you had to you could just twist it down some more until they were happy. I may be way off but it seems like this would work.

[Speedster]

I would research that 8 degree of camber. A common set up is 1 1/2 degrees on the dfw and 2 1/2 degrees on the rears. With the dfw nail bent 8 degrees I don't see how you could get any fine adjustment. I used the 6 o'clock to 5 o'clock times as a sample. In realty you might actually only move the nail .001 or .002. What do you see as an advantage to having that much of a bend?

[derbypain]

I would research that 8 degree of camber. A common set up is 1 1/2 degrees on the dfw and 2 1/2 degrees on the rears. With the dfw nail bent 8 degrees I don't see how you could get any fine adjustment. I used the 6 o'clock to 5 o'clock times as a sample. In realty you might actually only move the nail .001 or .002. What do you see as an advantage to having that much of a bend?

The DFW bend amount was something that davet had mentioned in an earlier post. Being that I am new to bending and setting this type of car up I can not comment on the benefit at this point. What have you seen commonly done on the non-DFW for camber if the others are 1 1/2 DFW and 2 1/2 for rears. Thanks.

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[Vitamin K]

I would research that 8 degree of camber. A common set up is 1 1/2 degrees on the dfw and 2 1/2 degrees on the rears. With the dfw nail bent 8 degrees I don't see how you could get any fine adjustment. I used the 6 o'clock to 5 o'clock times as a sample. In realty you might actually only move the nail .001 or .002. What do you see as an advantage to having that much of a bend?

In the league circuits, they pretty much say to put as much bend on that axle as possible so long as you can still insert the axle into the bore.

My theory is this: The DFW has two surfaces to contend with: The bottom of the track, and the rail. Now, the wheel contacts the track in such a way that it is rolling down the track, thus not incurring much friction loss. When the inner edge of the wheel contacts the rail, however, if there is not enough bend on that axle, what happens is that the flat edge of the wheel gets pushed into the rail, and you incur sliding friction, which is much greater. If, on the other hand, there is enough positive camber on the wheel, only the very edge of that wheel contacts the rail, which means that you get rolling friction along the rail as well as the track.

Just my theory, mind you, but we use a similar amount of camber (7-9 degrees).

[davet]

-- One regular winner at league races says he does like VK mentioned and goes as steep as he can and still get the axle through the wheel without damaging the bore. He and I have had our disagreements but he is regularly at the top of the rankings.

-- I remember hearing the points VK just made but also heard you can run less steer with the steeper angle. We didn't have a way to test any different angles, just went with what the pros recommended.

--Also, I believe that with the steeper angle, the very bottom front edge of the wheel makes contact with the seams rather than higher up on the front of the wheel. This should mean less disruption to the car at the seams, especially if you hit a bad seam.

--A steeper bend also means less of the inner hub face is contacting the body all the way down the track.

--I'm not sure if 1.5 degrees of bend would even overcome the axle to bore clearance to lift the outer tread off the track. I've bent rears at 2 degrees and couldn't even tell that the outside edge of the tread was off the table.

Tuning the steer (drift) is a delicate action. It sometimes feels like you didn't even twist the nail.

[derbypain]

-- One regular winner at league races says he does like VK mentioned and goes as steep as he can and still get the axle through the wheel without damaging the bore. He and I have had our disagreements but he is regularly at the top of the rankings.

-- I remember hearing the points VK just made but also heard you can run less steer with the steeper angle. We didn't have a way to test any different angles, just went with what the pros recommended.

--Also, I believe that with the steeper angle, the very bottom front edge of the wheel makes contact with the seams rather than higher up on the front of the wheel. This should mean less disruption to the car at the seams, especially if you hit a bad seam.

--A steeper bend also means less of the inner hub face is contacting the body all the way down the track.

--I'm not sure if 1.5 degrees of bend would even overcome the axle to bore clearance to lift the outer tread off the track. I've bent rears at 2 degrees and couldn't even tell that the outside edge of the tread was off the table.

Tuning the steer (drift) is a delicate action. It sometimes feels like you didn't even twist the nail.

Great detail to get an education on thank you.

Those small adjustments are why I want to make sure we can create the k-groove in the axle head. My son and I are getting excited with the possibilities. Thank you all for adding to the excitement of possibly one of his last races.

You guys have me wanting to join a league in the Dallas area.. My bachelor and masters degrees are in math and statistics so I am eating up this information and logic. Thanks for making it fun for all of us.

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[whodathunkit]

I'd like to clarify something.
The dominant front wheel is not only set with Positive camber, it is set with toe in. That's the way the car is tuned. The bend in the nail is pointed down toward the track. This will give you the Positive camber. If the mark you put on the axle head is exactly at 6 o'clock you will have Positive camber and "0" toe. If you turn the nail to 5 o'clock, you will now have Positive Camber and toe-in. When the car starts to roll the dominant front wheel will go to the rail and stay there because of the toe-in. The inside hub of the wheel will make contact with the car and stay there. It cannot migrate to the axle head.

It's early. I hope that's correct.

Thank's speedster!

I was hoping he would catch on to why toe was needed to hold the wheel hub to the body and steer the car.. with out it who knows what might happen.

[Speedster]

Vitamin K and davet are correct. With a stock wheel and axle 1 1/2 degrees of Positive camber will not raise the dfw to run on its outer edge. The wheel runs straight up and down on the guide strip because of the clearance between the wheel and axle. Unfortunately, our rules state the wheels must be straight up and down. I still run Positive camber hoping the small advantage Positive camber might provide would still be better then using Negative camber. derbypain does not have to deal with my problem. He has a much more difficult one.

I would not put toe-in on the non-dfw. I suspect no matter how much toe-in either wheel has they are both going to go to the rail. That would not be good. The slightest amount of Negative Camber and toe-out should be the best. The non-dfw would then be helping the dfw do its job even if it is in a very small way. I think it is Derbytalk member "sporty" who detailed this set-up and it would be in the Search function.

[derbypain]

Vitamin K and davet are correct. With a stock wheel and axle 1 1/2 degrees of Positive camber will not raise the dfw to run on its outer edge. The wheel runs straight up and down on the guide strip because of the clearance between the wheel and axle. Unfortunately, our rules state the wheels must be straight up and down. I still run Positive camber hoping the small advantage Positive camber might provide would still be better then using Negative camber. derbypain does not have to deal with my problem. He has a much more difficult one.

I would not put toe-in on the non-dfw. I suspect no matter how much toe-in either wheel has they are both going to go to the rail. That would not be good. The slightest amount of Negative Camber and toe-out should be the best. The non-dfw would then be helping the dfw do its job even if it is in a very small way. I think it is Derbytalk member "sporty" who detailed this set-up and it would be in the Search function.

Since I have the four wheel rule I was thinking per your and davet's earlier comments that dfw and NonDFW would have opposite camber and toeing (one positive/in and negative/out respectively) of course different degrees of bend/toeing for each. Glad to see my logic was not seeming to be totally out of alignment with all of you guys experienced thoughts. Thanks guys.

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