The Garage (What did you work on today?)

[rehajm]

For anyone not familiar, Stark Industries has been making waves with their fully electric Motocross and Enduro bikes

I’m suffering bond villain fatigue. Does every product launch require a Steve Jobs copycat clutching an imaginary beach ball and pics of how you burned your first two rounds of vc? /end of rant

…Scout, please find an on brand, relevant way to launch, would you?

 

[rehajm]

its a way cool bike, btw

 

[Chavannigans]

Oh, wow. I would have been so mad.

Man… I really was. My main hesitation was that I don’t want to drive to Dallas or Austin for service.

But this dealership is brand new, so they are still getting their website updated and are still adding other brands. I think they are working on Ducati and just got their first shipment of Aprilias Friday night. So I’ll give them some grace.

 

[Chavannigans]

I’m suffering bond villain fatigue. Does every product launch require a Steve Jobs copycat clutching an imaginary beach ball and pics of how you burned your first two rounds of vc? /end of rant

…Scout, please find an on brand, relevant way to launch, would you?

Their launch video was pretty funny. I guess the CEO is doing the corporate song and dance to keep the money flowing.

 

[Chavannigans]

The low beam on my new Husqvarna is downright dangerous. Just a regular old halogen bulb in a large reflector. Just enough components there to say “it has a headlight”.

The evening after I got it I rode it to a wedding, and the ride back was pretty sketchy. I could see maybe 20ft in front of me at best. Monday morning I needed to get to work early so I left while it was still dark, and as I rounded a bend on the unlit highway I saw a flash which materialized into a vacuum cleaner.

I didn’t have time to go around it so I threw my body weight over the rear tire and yanked the bars up. I managed to pop over it without much drama but it scared the bejezus out of me.

So after I got the office I immediately ordered the first modification. A full LED projector headlight replacement.
View attachment IMG_0338.jpeg
View attachment IMG_0339.jpeg
View attachment IMG_0343.jpeg
Went for a little ride to make sure I had it adjusted properly and wasn’t blinding other drivers.

Very impressed. It has a wide throw so county roads will be a lot safer for late night runs.

Not only can I see, but I can be seen.

Next up is an exhaust shield. The factory muffler has a catalytic converter integrated and it gets OBSCENELY hot.

Within an hour of getting it I went to a friends house. I had let the bike cool off for 10 minutes and was fiddling with the seat when I briefly touched my arm on the exhaust can and… yeah… it was pretty bad.

Really want to keep the factory exhaust because it’s quiet, so I hope the shield will allow me to retain it and not crisp my bacon again. Also don’t want it frying my soft panniers.

If not I’ll be hunting for some quiet slip on mufflers, and it’s hard to find unbiased opinions when it comes to exhaust pipes though. Everyone thinks theirs is the best.

It feels great to be on a bike again though. I’ve only put about 200 miles on it so far and have felt a big boost to my mental health. No more panic attacks on the bike either.

 

[J Alynn]

The low beam on my new Husqvarna is downright dangerous. Just a regular old halogen bulb in a large reflector. Just enough components there to say “it has a headlight”.

The evening after I got it I rode it to a wedding, and the ride back was pretty sketchy. I could see maybe 20ft in front of me at best. Monday morning I needed to get to work early so I left while it was still dark, and as I rounded a bend on the unlit highway I saw a flash which materialized into a vacuum cleaner.

I didn’t have time to go around it so I threw my body weight over the rear tire and yanked the bars up. I managed to pop over it without much drama but it scared the bejezus out of me.

So after I got the office I immediately ordered the first modification. A full LED projector headlight replacement.
View attachment 10030
View attachment 10029
View attachment 10031
Went for a little ride to make sure I had it adjusted properly and wasn’t blinding other drivers.

Very impressed. It has a wide throw so county roads will be a lot safer for late night runs.

Not only can I see, but I can be seen.

Next up is an exhaust shield. The factory muffler has a catalytic converter integrated and it gets OBSCENELY hot.

Within an hour of getting it I went to a friends house. I had let the bike cool off for 10 minutes and was fiddling with the seat when I briefly touched my arm on the exhaust can and… yeah… it was pretty bad. View attachment 10032

Really want to keep the factory exhaust because it’s quiet, so I hope the shield will allow me to retain it and not crisp my bacon again. Also don’t want it frying my soft panniers.

If not I’ll be hunting for some quiet slip on mufflers, and it’s hard to find unbiased opinions when it comes to exhaust pipes though. Everyone thinks theirs is the best.

It feels great to be on a bike again though. I’ve only put about 200 miles on it so far and have felt a big boost to my mental health. No more panic attacks on the bike either.

OUCHHHH!!!! Holy F*#?! I can feel that sitting here. Hope you put a tissue and some duct tape on that monster

 

[SpaceEVDriver]

The low beam on my new Husqvarna is downright dangerous. Just a regular old halogen bulb in a large reflector. Just enough components there to say “it has a headlight”.

The evening after I got it I rode it to a wedding, and the ride back was pretty sketchy. I could see maybe 20ft in front of me at best. Monday morning I needed to get to work early so I left while it was still dark, and as I rounded a bend on the unlit highway I saw a flash which materialized into a vacuum cleaner.

I didn’t have time to go around it so I threw my body weight over the rear tire and yanked the bars up. I managed to pop over it without much drama but it scared the bejezus out of me.

Great reflexes!

Not only can I see, but I can be seen.

Almost more important than being able to see...

Next up is an exhaust shield. The factory muffler has a catalytic converter integrated and it gets OBSCENELY hot.

Within an hour of getting it I went to a friends house. I had let the bike cool off for 10 minutes and was fiddling with the seat when I briefly touched my arm on the exhaust can and… yeah… it was pretty bad.

Oh, that’s not good. I hope it heals without complications.

It feels great to be on a bike again though. I’ve only put about 200 miles on it so far and have felt a big boost to my mental health. No more panic attacks on the bike either.

One of the best things for my mental health was my motorcycle. If it weren’t getting colder here, I’d consider taking it out for a ride a few more times. That said, I do enjoy taking my Mustang out too.

 

[Chavannigans]

Dang it I didnt realize my photos were too big for thumbnails!

OUCHHHH!!!! Holy F*#?! I can feel that sitting here. Hope you put a tissue and some duct tape on that monster

I slapped a 2nd skin bandage on there after it opened up. Its now a Thunderdome for my white blood cells.

Great reflexes!

I think moments like that are when ADHD is a super power. I thrive in a crisis.

Almost more important than being able to see...

It really is when people spend a majority of the time looking at their phone when they drive. Someone still merged into me this morning on my commute and was of course watching Tik Tok videos

One of the best things for my mental health was my motorcycle. If it weren’t getting colder here, I’d consider taking it out for a ride a few more times. That said, I do enjoy taking my Mustang out too.

With great shame, I must I started drinking a lot more after I stopped riding. Its so hard to explain to people that dont ride, but its like a "mental break" in a meditation kind of way. All of your senses are being stimulated at once. You are fully engaged and harmonized with the machine so you dont have the bandwidth to think about the stresses of every day life. When I get off the bike its the same mental clarity I get from yoga.

Not sure what the weather is like there, but I used to ride year round. Even when there is ice on the roads or snow. Dual sports probably handle that better than cruiser bikes though.

I wear thermals under my Klim riding suit, a thin neck gator, and had heated grips on my Norden. If you have never had heated grips, its an absolute game changer!
I also have a cold weather modular helmet that has a removable nose guard and chin cover so it traps my breath in there and keeps my pin lock from fogging up. Then I can take all of it off when its warm and have a normal helmet.

I am going to be ordering another set of Oxford heated grips and a new helmet soon.

Amazon.com

 

[SpaceEVDriver]

With great shame, I must I started drinking a lot more after I stopped riding.

Nah, brother. We don't do shame for things like this.

Its so hard to explain to people that dont ride, but its like a "mental break" in a meditation kind of way. All of your senses are being stimulated at once. You are fully engaged and harmonized with the machine so you dont have the bandwidth to think about the stresses of every day life. When I get off the bike its the same mental clarity I get from yoga.

One way I've put it to people before:
On a bike, you have to ride in the right part of the moment. It takes all of your attention and all of your senses to keep your mind on the road at the middle distance. You have to look just far enough ahead to see the oncoming road, but if you're too focused on the immediate issues, you'll never make it through the curve. If you're looking too far ahead, you won't even see the curve. The mental clarity you achieve is unparalleled, in my experience.

Not sure what the weather is like there, but I used to ride year round. Even when there is ice on the roads or snow. Dual sports probably handle that better than cruiser bikes though.

I wear thermals under my Klim riding suit, a thin neck gator, and had heated grips on my Norden. If you have never had heated grips, its an absolute game changer!
I also have a cold weather modular helmet that has a removable nose guard and chin cover so it traps my breath in there and keeps my pin lock from fogging up. Then I can take all of it off when its warm and have a normal helmet.

I am going to be ordering another set of Oxford heated grips and a new helmet soon.

Amazon.com

Mostly my riding was decreased because of the ice and snow. There's none right now. Hmmm...

 

[Logan]

One way I've put it to people before:
On a bike, you have to ride in the right part of the moment. It takes all of your attention and all of your senses to keep your mind on the road at the middle distance. You have to look just far enough ahead to see the oncoming road, but if you're too focused on the immediate issues, you'll never make it through the curve. If you're looking too far ahead, you won't even see the curve. The mental clarity you achieve is unparalleled, in my experience.

In mountain biking, we call this the "flow state". Its definitely a thing. So much going on, that you have to pay attention and react to, but it has to be instinctual, without second guessing yourself (hesitation is dangerous on some of the big features).

https://www.flowresearchcollective.com/blog/what-is-flow-state

On topic for the thread here, I had my Tucsons driver side window explode on me the other day. I have no idea what caused it. Driving down the road at ~40mph, and BOOM, window shattered. The Heat/AC wasn't on (no HVAC at all was on, it was like 55f, and I had the heated seats on low). A vehicle or two had passed a moment ago.

All I can think is maybe I got hit by a random BB gun?

I've never done a window repair before, but after finding some videos, and a service manual, I've now got the door apart, and have gotten to the stage where I'm cleaning out the door. Just wanted to make sure I could get into the door before I ordered the glass. But I think I'm at that point now.

Also, working on some pinewood derby cars with the kids.

 

[cyure]

In mountain biking, we call this the "flow state". Its definitely a thing. So much going on, that you have to pay attention and react to, but it has to be instinctual, without second guessing yourself (hesitation is dangerous on some of the big features).

https://www.flowresearchcollective.com/blog/what-is-flow-state

On topic for the thread here, I had my Tucsons driver side window explode on me the other day. I have no idea what caused it. Driving down the road at ~40mph, and BOOM, window shattered. The Heat/AC wasn't on (no HVAC at all was on, it was like 55f, and I had the heated seats on low). A vehicle or two had passed a moment ago.

All I can think is maybe I got hit by a random BB gun?

View attachment 10040

I've never done a window repair before, but after finding some videos, and a service manual, I've now got the door apart, and have gotten to the stage where I'm cleaning out the door. Just wanted to make sure I could get into the door before I ordered the glass. But I think I'm at that point now.

View attachment 10042

Also, working on some pinewood derby cars with the kids.

How scary! Good luck fixing it.

I remember pinewood derby cars. Such fun. Did you ever do the boats in the rain gutters? That was fun too!!

 

[SpaceEVDriver]

In mountain biking, we call this the "flow state". Its definitely a thing. So much going on, that you have to pay attention and react to, but it has to be instinctual, without second guessing yourself (hesitation is dangerous on some of the big features).

Yeah. Hesitation or loss of focus is a big cause of losing control on a curve while riding a motorcycle.

https://www.flowresearchcollective.com/blog/what-is-flow-state

On topic for the thread here, I had my Tucsons driver side window explode on me the other day. I have no idea what caused it. Driving down the road at ~40mph, and BOOM, window shattered. The Heat/AC wasn't on (no HVAC at all was on, it was like 55f, and I had the heated seats on low). A vehicle or two had passed a moment ago.

All I can think is maybe I got hit by a random BB gun?

View attachment 10040

Yeah, that’s definitely a “point source” kind of “failure.” I’m sorry this happened.

Also, working on some pinewood derby cars with the kids.

Fun!

 

[Chavannigans]

In mountain biking, we call this the "flow state". Its definitely a thing. So much going on, that you have to pay attention and react to, but it has to be instinctual, without second guessing yourself (hesitation is dangerous on some of the big features).

https://www.flowresearchcollective.com/blog/what-is-flow-state

On topic for the thread here, I had my Tucsons driver side window explode on me the other day. I have no idea what caused it. Driving down the road at ~40mph, and BOOM, window shattered. The Heat/AC wasn't on (no HVAC at all was on, it was like 55f, and I had the heated seats on low). A vehicle or two had passed a moment ago.

All I can think is maybe I got hit by a random BB gun?

View attachment 10040

I've never done a window repair before, but after finding some videos, and a service manual, I've now got the door apart, and have gotten to the stage where I'm cleaning out the door. Just wanted to make sure I could get into the door before I ordered the glass. But I think I'm at that point now.

View attachment 10042

Also, working on some pinewood derby cars with the kids.

As Jerryrigeverything says “Glass is glass, and glass breaks.”

Glad you are okay man.


The shopvac will be the real MVP here. If you leave just a few pieces in there it will drive you nuts as they rattle around in there.

That sucks though. Sometimes glass breaks on its own from a defect. Sometimes a small stone or pebble strike is all it takes. If the cars passing by picked up something it could bounce up there.

Usually you need to nose the front portion in first then line it up once it’s all in there. You got this dude!

We have Pinewood Derby coming up too. I wish Uncle @SpaceEVDriver could come help. Past few years our cars haven’t performed too well, but the kids still love it so and that’s the point, right? Lol

 

[cyure]

As Jerryrigeverything says “Glass is glass, and glass breaks.”

Glad you are okay man.


The shopvac will be the real MVP here. If you leave just a few pieces in there it will drive you nuts as they rattle around in there.

That sucks though. Sometimes glass breaks on its own from a defect. Sometimes a small stone or pebble strike is all it takes. If the cars passing by picked up something it could bounce up there.

Usually you need to nose the front portion in first then line it up once it’s all in there. You got this dude!

We have Pinewood Derby coming up too. I wish Uncle @SpaceEVDriver could come help. Past few years our cars haven’t performed too well, but the kids still love it so and that’s the point, right? Lol

Right (but it’s so fun when they get that plastic trophy)

 

[J Alynn]

As Jerryrigeverything says “Glass is glass, and glass breaks.”

Glad you are okay man.


The shopvac will be the real MVP here. If you leave just a few pieces in there it will drive you nuts as they rattle around in there.

That sucks though. Sometimes glass breaks on its own from a defect. Sometimes a small stone or pebble strike is all it takes. If the cars passing by picked up something it could bounce up there.

Usually you need to nose the front portion in first then line it up once it’s all in there. You got this dude!

We have Pinewood Derby coming up too. I wish Uncle @SpaceEVDriver could come help. Past few years our cars haven’t performed too well, but the kids still love it so and that’s the point, right? Lol

In mountain biking, we call this the "flow state". Its definitely a thing. So much going on, that you have to pay attention and react to, but it has to be instinctual, without second guessing yourself (hesitation is dangerous on some of the big features).

https://www.flowresearchcollective.com/blog/what-is-flow-state

On topic for the thread here, I had my Tucsons driver side window explode on me the other day. I have no idea what caused it. Driving down the road at ~40mph, and BOOM, window shattered. The Heat/AC wasn't on (no HVAC at all was on, it was like 55f, and I had the heated seats on low). A vehicle or two had passed a moment ago.

All I can think is maybe I got hit by a random BB gun?

View attachment 10040

I've never done a window repair before, but after finding some videos, and a service manual, I've now got the door apart, and have gotten to the stage where I'm cleaning out the door. Just wanted to make sure I could get into the door before I ordered the glass. But I think I'm at that point now.

View attachment 10042

Also, working on some pinewood derby cars with the kids.

Was it cars that passed or trucks. Any chance it was a 3-lane and trucks on either side? Could have been a sudden drop in pressure and higher pressure inside car that caused a pressure issue to blow out the window

 

[Logan]

Was it cars that passed or trucks. Any chance it was a 3-lane and trucks on either side? Could have been a sudden drop in pressure and higher pressure inside car that caused a pressure issue to blow out the window

It was two trucks that passed, but its on a 2 lane road (1 lane each direction). A tacoma, and something full sized behind them. But neither were muddy/hauling anything. Plus, if anything did break off/fall out of/get thrown by the trucks, it would have to have taken quite the lateral burst of acceleration to bust a window like that.

I first thought it was a rock strike... but I'm pretty certain it was more likely a BB gun or something similar. But, it was loud (similar to rock strike on a windshield, but... like 8in from my head, and the whole thing turned white/frosty looking for a second).

I also thought maybe temperature differential. But, no HVAC was on, it was like 55f, and the vehicle was parked outside that night, so its not like it had a sudden temp change happening either.

The worst part is the falling glass also scratched up the door when it fell. Alas.

As Jerryrigeverything says “Glass is glass, and glass breaks.”

Glad you are okay man.


The shopvac will be the real MVP here. If you leave just a few pieces in there it will drive you nuts as they rattle around in there.

That sucks though. Sometimes glass breaks on its own from a defect. Sometimes a small stone or pebble strike is all it takes. If the cars passing by picked up something it could bounce up there.

Usually you need to nose the front portion in first then line it up once it’s all in there. You got this dude!

We have Pinewood Derby coming up too. I wish Uncle @SpaceEVDriver could come help. Past few years our cars haven’t performed too well, but the kids still love it so and that’s the point, right? Lol

Yeah, the first check was "wait, am I bleeding anywhere???"

And yes, I did check for an exit mark on the other side of the vehicle (haven't found anything yet).

And thanks for the tips.

I haven't been able to get the Regulator out quite all the way yet, but I did manage to get it out enough to get the shop vac in there. And I've been using a spare target arrow to help reach in there and scrape out any of those last pieces of glass. I've also seriously wondered about hosing it out, just to make sure I get it all (not sure if thats a good idea though???).

I will likely order the glass today. I just really wanted to make sure I could get it all apart the way I thought I could, BEFORE I got the glass. That way I didn't end up buying glass, and then having to have someone come out and replace it .

I'm familiar with auto repair stuff. I just haven't ever done windows before. And its weird how sometimes despite being similar to something you know, certain things can feel more daunting. So thats sort of how I was approaching this at first.

 

[SpaceEVDriver]

We have Pinewood Derby coming up too. I wish Uncle @SpaceEVDriver could come help. Past few years our cars haven’t performed too well, but the kids still love it so and that’s the point, right? Lol

I let my spawn do their own. They were grumpy about it when they didn’t win, but years later they thanked me for not being the parent who built their car for them.

Tips:

Weight and its distribution matters most. The car should be as heavy as allowed. But you should control where the weight is by reducing the water content in the wood (bake it at low temperature for a couple of hours) and then shaping (see below) the vehicle. You want to bring it back up to max weight by adding weight to just forward of the rear axle. The only motive force is gravity. The potential energy is the mass of the car times its height above the end of the track times gravity. The only control you have seems to be the mass of the car. But really, what you control is the height above the end of the track. If everyone has the same maximum mass, then that’s not really a variable. But the car has a length, which means the front is lower and thus closer the the end of the track and the rear is higher. So m*g*h is greater if you have more of the mass toward the rear of the car. But don’t put it at the very back—you want it so the center of mass is between the axles, as close to the rear axle as possible. And as low on the vehicle as practicable and reasonable.

Axle friction is next. High-grit sandpaper used to smooth the axles will reduce their friction. You can use dry graphite or dry silicon on the axles to reduce the friction, if that’s allowed in your area. Less friction means more of the potential energy (m*g*h) can be converted to kinetic energy (1/2 m * v^2). This is pretty self-explanatory.

Depending on the rules, you might be able to modify the tires. But be careful because any imperfections in the wheels shapes, roughness, or camber could lead to steering against the walls and a reduction in performance. And reducing the size of the tires doesn’t really change friction since the frictive force is dependent on mass, not surface area.

Shape kind of matters, but honestly it’s not all that important—the speeds are just too low for air resistance to matter. Do something fun and interesting. The reason to shape it is: 1) so whomever is placing the vehicle on the track knows which is the front and which is the rear; 2) so you can control the mass distribution. Slim down the front, leave extra mass in the back. Add enough mass to the underside of the vehicle near the rear axle (as described above) to meet the maximum allowed.

If there are multiple races, protect the axles so they don’t get bent if the car leaves the track.

 

[Logan]

Right (but it’s so fun when they get that plastic trophy)

My 7 yr old literally hoards my old trophies like this.

I kept some of them from when I was a kid (the "slightly more impressive" ones). They are mostly sports related (I played competitive soccer for 15 years, like 3-4 seasons a year), there are a few from other things. Including winning the pinewood derby my first year running.

And this year as we've been working on his pinewood derby car, he has asked me a lot about my old cars. Turns out, I'd also kept my old cars.

So I plan to bring my old cars with me, to race with the kiddos "after" the races, when its more or less a "free play" while the everyone else mingles, and the kids go nuts with the track .

Also, my favorite part about Pinewood Derby cars, is how the weight always seems hacked together. My sons car currently has an old motor mount bolt for my Mazda as its sole piece of weight (its like a 7/8in bolt... the COG is like 1/4 in front of the rear axle ). Strangely that random connection has made it more interesting to him "Hey MOM, my car has a PIECE OF OUR OLD CAR IN IT".

Kids .

 

[cyure]

My 7 yr old literally hoards my old trophies like this.

I kept some of them from when I was a kid (the "slightly more impressive" ones). They are mostly sports related (I played competitive soccer for 15 years, like 3-4 seasons a year), there are a few from other things. Including winning the pinewood derby my first year running.

And this year as we've been working on his pinewood derby car, he has asked me a lot about my old cars. Turns out, I'd also kept my old cars.

So I plan to bring my old cars with me, to race with the kiddos "after" the races, when its more or less a "free play" while the everyone else mingles, and the kids go nuts with the track .

Also, my favorite part about Pinewood Derby cars, is how the weight always seems hacked together. My sons car currently has an old motor mount bolt for my Mazda as its sole piece of weight (its like a 7/8in bolt... the COG is like 1/4 in front of the rear axle ). Strangely that random connection has made it more interesting to him "Hey MOM, my car has a PIECE OF OUR OLD CAR IN IT".

Kids .

So cute!

 

[Chavannigans]

It was two trucks that passed, but its on a 2 lane road (1 lane each direction). A tacoma, and something full sized behind them. But neither were muddy/hauling anything. Plus, if anything did break off/fall out of/get thrown by the trucks, it would have to have taken quite the lateral burst of acceleration to bust a window like that.

I first thought it was a rock strike... but I'm pretty certain it was more likely a BB gun or something similar. But, it was loud (similar to rock strike on a windshield, but... like 8in from my head, and the whole thing turned white/frosty looking for a second).

I also thought maybe temperature differential. But, no HVAC was on, it was like 55f, and the vehicle was parked outside that night, so its not like it had a sudden temp change happening either.

The worst part is the falling glass also scratched up the door when it fell. Alas.



Yeah, the first check was "wait, am I bleeding anywhere???"

And yes, I did check for an exit mark on the other side of the vehicle (haven't found anything yet).

And thanks for the tips.

I haven't been able to get the Regulator out quite all the way yet, but I did manage to get it out enough to get the shop vac in there. And I've been using a spare target arrow to help reach in there and scrape out any of those last pieces of glass. I've also seriously wondered about hosing it out, just to make sure I get it all (not sure if thats a good idea though???).

I will likely order the glass today. I just really wanted to make sure I could get it all apart the way I thought I could, BEFORE I got the glass. That way I didn't end up buying glass, and then having to have someone come out and replace it .

I'm familiar with auto repair stuff. I just haven't ever done windows before. And its weird how sometimes despite being similar to something you know, certain things can feel more daunting. So thats sort of how I was approaching this at first.

You’re on the right track, and the window will be soon too.

Love seeing people handle their own problems like this.

You can try wrapping an arrow or dowel rod in some duct tape and jamming it around in there to pick up any remains ceramic giblets. Not sure if water will flush them all out, but that can certainly be a step in the process.

Sometimes the regulator can stay in place and you just need to remove the nuts or clips where the window slots into the “trench” of the regulator. Then you can move it up or down as needed as you slide the new one down. But you’ve got the manual so you know more about replacing that one than I do.

You’ve got this bro!

I let my spawn do their own. They were grumpy about it when they didn’t win, but years later they thanked me for not being the parent who built their car for them.

Tips:

Weight and its distribution matters most. The car should be as heavy as allowed. But you should control where the weight is by reducing the water content in the wood (bake it at low temperature for a couple of hours) and then shaping (see below) the vehicle. You want to bring it back up to max weight by adding weight to just forward of the rear axle. The only motive force is gravity. The potential energy is the mass of the car times its height above the end of the track times gravity. The only control you have seems to be the mass of the car. But really, what you control is the height above the end of the track. If everyone has the same maximum mass, then that’s not really a variable. But the car has a length, which means the front is lower and thus closer the the end of the track and the rear is higher. So m*g*h is greater if you have more of the mass toward the rear of the car. But don’t put it at the very back—you want it so the center of mass is between the axles, as close to the rear axle as possible. And as low on the vehicle as practicable and reasonable.

Axle friction is next. High-grit sandpaper used to smooth the axles will reduce their friction. You can use dry graphite or dry silicon on the axles to reduce the friction, if that’s allowed in your area. Less friction means more of the potential energy (m*g*h) can be converted to kinetic energy (1/2 m * v^2). This is pretty self-explanatory.

Depending on the rules, you might be able to modify the tires. But be careful because any imperfections in the wheels shapes, roughness, or camber could lead to steering against the walls and a reduction in performance. And reducing the size of the tires doesn’t really change friction since the frictive force is dependent on mass, not surface area.

Shape kind of matters, but honestly it’s not all that important—the speeds are just too low for air resistance to matter. Do something fun and interesting. The reason to shape it is: 1) so whomever is placing the vehicle on the track knows which is the front and which is the rear; 2) so you can control the mass distribution. Slim down the front, leave extra mass in the back. Add enough mass to the underside of the vehicle near the rear axle (as described above) to meet the maximum allowed.

If there are multiple races, protect the axles so they don’t get bent if the car leaves the track.

No no, you misunderstood.

The way this works is, you are here in my garage explaining all the magic and doing it while I drink a beer and nod my head.

Then at the end I say “Damn dude that is a badass little car.” I give you a backslap as I admire your craftsmanship, then tell you there are two more to go