New member

[Cation]

Hi

I'm new here My son's first PWD was last year, but pop pop had to help because my mom was dying and died two weeks before the race. He got second place in his group and was happy but he wants to win this year and his siblings want to win the siblings race. Last year they were pretty good but they had huge divots underneath that I'm sure slowed them down (biggest divots had slowest time .

I've got that blue jig but from what I'm reading it looks like the acrylic one or the SBD are superior. What is the advantage of the SBD? I don't see any description of what angles it uses to cant the wheels . Is there any reason to get it over the the clear acrylic one? Is the 3 degrees better than the 2.5 with the blue jig ?

I also have that "hand lathe" but the mandrel for it is rough and not smooth so it looks like it will damage the bore which comes mirror shiny . I'm wondering if I should not use that one . I just saw a yt video that showed the same flattening shaving using the drill press and a mandrel .

We can sand with a mandrel to remove mold lines but that's supposed to be it .

Finally why do most people put the weights right on the bottom of the car instead of high at the top? (assuming similar center of balance ) it seems like as high and far back as possible would give better potential energy.

One last question is does the rounding the front to get a little quicker start off the starter actually work ?

Thank you for your help and listening to a bunch of bunch of simplistic questions.

 

[flockshot]

First of all there are a lot of folks here with more knowledge than myself.
Weight with 2 oz behind the rear axle. Some like it higher and some like it lower. I like it lower.
Rear axle cant angle . I have a Silver Bullet Extreme that drills them a 3 degrees. It is more important that they be the same angle on both sides, I believe, than what the angle is.
Hand Lathe. I have one and I hate it, but have shaved some descent wheels with it. Keep it sharpened at the 5 degree angle and take very light cuts. I suggest buying extra wheels to find the roundest, smoothest spinning, wheels available. DD4H has some legal scout wheels, that have been trued on a lathe with no other alterations.
Mold lines. I don't think these wheels still have mold lines, but I have the same rule. It allows some truing of the axle tread to the bore.
Make your body 'thin to win'. Aerodynamics means more than I thought it did. A thin light weight body with the weight in the rear will be the faster car than other configurations.

 

[flockshot]

Also, I polish the wheel bores with the DD4H "Black Ice" 3 step process and after polishing axles I spray them with SailKote. There are other ways to do this, and other products available, but this is the best I have found so far. As for graphite (If you are allowed to use oil this may be all wrong) I also use the DD4H or Hob-e-lube. I think DD4H is finer texture.
Our race was canceled to to virus concerns, but perhaps we can get it in later in the year. My grandson did win his pack last year and this years car is better. The more cars you make the more you learn about making cars.

 

[Thinkin'Bout Racin]

Hi

I've got that blue jig but from what I'm reading it looks like the acrylic one or the SBD are superior. What is the advantage of the SBD? I don't see any description of what angles it uses to cant the wheels . Is there any reason to get it over the the clear acrylic one? Is the 3 degrees better than the 2.5 with the blue jig ?

Finally why do most people put the weights right on the bottom of the car instead of high at the top? (assuming similar center of balance ) it seems like as high and far back as possible would give better potential energy.
.

Welcome.

A good quality drill jig is a must to help build a fast car. Which one? There are a number of people that will have an opinion on that.

Where to put the weight ...think about it this way ....picture your car on the track at the starting gate. Which point of the car is the farthest from the finish line. The answer is the bottom rear corner. That is the highest point of the car on the hill.

Placing weight high in the car has two disadvantages. The weight is high off the track. So the car has a higher COM. This promotes a car that is less stable than a low COM. Think about all the race cars you see. They are low to the ground. Also, placing the weight high in the car actually moves the weight forward when the car is on the hill. Therefore giving it less potential energy.

Clear as mud?

 

[Roadrunner]

Thinkin’Bout Racin - nice explanation about weight placement. Thanks

 

[Cation]

Welcome.

A good quality drill jig is a must to help build a fast car. Which one? There are a number of people that will have an opinion on that.

Where to put the weight ...think about it this way ....picture your car on the track at the starting gate. Which point of the car is the farthest from the finish line. The answer is the bottom rear corner. That is the highest point of the car on the hill.

Placing weight high in the car has two disadvantages. The weight is high off the track. So the car has a higher COM. This promotes a car that is less stable than a low COM. Think about all the race cars you see. They are low to the ground. Also, placing the weight high in the car actually moves the weight forward when the car is on the hill. Therefore giving it less potential energy.

Clear as mud?

Thank you very much for help that makes a lot of sense about weight placement. I already was weary about the high COM but didn't really visualize the farthest distance from finish .

 

[Cation]

Also, I polish the wheel bores with the DD4H "Black Ice" 3 step process and after polishing axles I spray them with SailKote. There are other ways to do this, and other products available, but this is the best I have found so far. As for graphite (If you are allowed to use oil this may be all wrong) I also use the DD4H or Hob-e-lube. I think DD4H is finer texture.
Our race was canceled to to virus concerns, but perhaps we can get it in later in the year. My grandson did win his pack last year and this years car is better. The more cars you make the more you learn about making cars.

Thank you for your help! I really appreciate it Yeah, our race was postponed indefinitely due to the virus, but I figure it is more time to prepare fast cars.

Yes Graphite is allowed.

I really appreciate it..