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make the front axle a piece of allthread, put a wingnut on it and something that keeps it from rotating all the way around (can be the body of the vehicle or a string/piece of wire)

How to I make a measuring device to make sure my car breaks at the tight point? Are we allowed to put the car on the end line and then just roll it back to the start point to set up the braking system?

Pranoob wrote: ↑November 2nd, 2019, 3:37 pm How to I make a measuring device to make sure my car breaks at the tight point? Are we allowed to put the car on the end line and then just roll it back to the start point to set up the braking system?

That's what testing is for, you test the car before competition and write measurements down so that you can set the car to the desired measurement at competition.

As for rolling the car I would think it is allowed but don't do it, I got called out at an invitational by another schools parent who wanted to give me a hard time when I simply was 'unlocking' the wingnut from the stopper by rolling it back a few cm after the first run. (Rule 5.g. is meant to say that you cannot test the car on that flooring before you actually compete, however it could be extended to mean that you cannot roll your car on the floor during the competition itself).
Moreover if you roll it back, it would not be accurate since you would need to take into account skid as well as the distance the car travels on the ramp.

https://www.docfizzix.com/products/part ... 60df.shtml
Would the doc fizzix braking system be good for this? Also, how do I make sure my threaded rods don't slip out of my ball bearings?

Pranoob wrote: ↑December 20th, 2019, 11:53 pm https://www.docfizzix.com/products/part ... 60df.shtml
Would the doc fizzix braking system be good for this? Also, how do I make sure my threaded rods don't slip out of my ball bearings?

That's the braking system that I have used with much success in the past, although you could easily make it yourself for less than that. I particularly like the track, which doesn't allow the wing nut to remain stationery relative to the rod when the axle is spinning no matter which way the rod is spinning.
Unfortunately, I can't help you with the bearing bit because I don't use 'em. However, the threaded rod he sells has the brass axle tubing slid over it, which provides a conventional round axle to attach to your bearings.

I've always used a wing nut system. It has worked with scramblers and battery buggies. Now it can be inconsistent but it is a good system to start out with.

I've been having a problem with my vehicle where it twists when the brakes are triggered, displacing the dowel horizontally. I'm using a wingnut system and the vehicle has very little linear skidding, it just twists to the left about 30 degrees when the wingnut locks. My vehicle is 1100 grams, the vehicle itself is 500 grams and there is 600 grams of added-on mass that can be moved back and forth on the vehicle. I've tried moving the 600 gram mass to every spot on the vehicle but no matter where the mass concentration is, it still seems to twist. I tried running the vehicle without the 600 gram mass as well and I got the same result. The only thing I can think of now is slowing down the vehicle because it gets times around 2.5 seconds. Any suggestions?

MTV<=>Operator wrote: ↑February 4th, 2020, 12:07 pm I've been having a problem with my vehicle where it twists when the brakes are triggered, displacing the dowel horizontally. I'm using a wingnut system and the vehicle has very little linear skidding, it just twists to the left about 30 degrees when the wingnut locks. My vehicle is 1100 grams, the vehicle itself is 500 grams and there is 600 grams of added-on mass that can be moved back and forth on the vehicle. I've tried moving the 600 gram mass to every spot on the vehicle but no matter where the mass concentration is, it still seems to twist. I tried running the vehicle without the 600 gram mass as well and I got the same result. The only thing I can think of now is slowing down the vehicle because it gets times around 2.5 seconds. Any suggestions?

You can try making it so your wingnut is triggered by something on the axle. Perhaps you can add a couple of hex nuts more in the middle so the wingnut locks against those and not the side of the vehicle. You can also try softer wheels (green banebots wheels if you're not using those already).

CPScienceDude wrote: ↑February 4th, 2020, 12:14 pm

MTV<=>Operator wrote: ↑February 4th, 2020, 12:07 pm I've been having a problem with my vehicle where it twists when the brakes are triggered, displacing the dowel horizontally. I'm using a wingnut system and the vehicle has very little linear skidding, it just twists to the left about 30 degrees when the wingnut locks. My vehicle is 1100 grams, the vehicle itself is 500 grams and there is 600 grams of added-on mass that can be moved back and forth on the vehicle. I've tried moving the 600 gram mass to every spot on the vehicle but no matter where the mass concentration is, it still seems to twist. I tried running the vehicle without the 600 gram mass as well and I got the same result. The only thing I can think of now is slowing down the vehicle because it gets times around 2.5 seconds. Any suggestions?

You can try making it so your wingnut is triggered by something on the axle. Perhaps you can add a couple of hex nuts more in the middle so the wingnut locks against those and not the side of the vehicle. You can also try softer wheels (green banebots wheels if you're not using those already).

I would definitely try this first. Another possible solution though would be to have your wingnut break against a softer and more cushiony material.

Vortexx2 wrote: ↑February 4th, 2020, 12:19 pm

CPScienceDude wrote: ↑February 4th, 2020, 12:14 pm

MTV<=>Operator wrote: ↑February 4th, 2020, 12:07 pm I've been having a problem with my vehicle where it twists when the brakes are triggered, displacing the dowel horizontally. I'm using a wingnut system and the vehicle has very little linear skidding, it just twists to the left about 30 degrees when the wingnut locks. My vehicle is 1100 grams, the vehicle itself is 500 grams and there is 600 grams of added-on mass that can be moved back and forth on the vehicle. I've tried moving the 600 gram mass to every spot on the vehicle but no matter where the mass concentration is, it still seems to twist. I tried running the vehicle without the 600 gram mass as well and I got the same result. The only thing I can think of now is slowing down the vehicle because it gets times around 2.5 seconds. Any suggestions?

You can try making it so your wingnut is triggered by something on the axle. Perhaps you can add a couple of hex nuts more in the middle so the wingnut locks against those and not the side of the vehicle. You can also try softer wheels (green banebots wheels if you're not using those already).

I would definitely try this first. Another possible solution though would be to have your wingnut break against a softer and more cushiony material.

Thank you both. The wingnut currently brakes on two 70A washers and a nut, but I will try moving these closer to the middle of the axle. I'll also try 40A washers instead because it seems like the 70A ones aren't doing much. I'm using the orange banebots 2 3/8" T40s right now because the greens were out of stock and still are. I'll switch whenever the greens come back in stock.