Track racing - set up and riding style

This week I got new wheels to try out. Stooge race wheels - 120mm x 63mm 50a/45a. Supposedly made specific for racing, and I bought them specifically for my track racing. They were an easy mount and ready to race without any struggle.

They were quite a different experience than the six-shooters and it took me a good 45 minuts to be comfortable enough to start give full effort.

Coasting: This was perhaps the biggest difference. They coast more than the shooters and that makes approaching corners different. With the shooters I didn’t need the brakes at all. I could time letting go of the throttle with the corners, and I didn’t need to let go of the throttle early. With the race wheels letting go off the throttle and use coasting as brakes had to be done long before the corner. It didn’t really make sense to coast that long.

Grib: Grib was one of the things I had high expectations about. When mounting the wheels they attracted a lot of dust and stuff and they felt sticky to the touch. When I rolled the first meters the first thing I noticed was the sound they made. It sounded sort of slimy and sticky to the ground - a good sound.

They felt very secure and for the first time I had a couple of corners where I threw everything in to the corner with out worrying that the wheels would slip. This is great and I can’t wait to work more with that. Now my backside cornering are just as I like it to be. The front side (where I grab) changed a little with these wheels, and I need to get comfortable throwing everything in to that corner side again.

Gearing: It was geared 16/60. I need to change to 42 in the wheel. With 60 I reached top speed on the straight stretch and I felt I could handle significantly more speed there. So I need higher top speed. Will see if I can get it by changing wheel gear.

Sensitivity: One of the things that I love the most about pneumatics are the way the suck up all unevenness. The race wheel are more sensitive, and even though this is a pretty smooth race track there are some unevenness where the asphalt are connected.

Especially there are one tight corner where there are a small bump. This corner require a full lean forcing a very tight turn. Two times the bump started a slight slip which was not a good feeling hanging there. I need to find out what to do in that particular corner because after the slip I did not give everything in that corner.

Peeling: When looking at the wheels of the gokarts I see that the rubber is peeling off the tire, and there are small rubber peels everywhere. These race wheels also peels. Take a look at the picture to see how the wheel looked after the session. Cant figure out how much is the wheels own peel, and how much these sticky wheels have sucked up peel and shit from the track. It will be interesting to see how long they will last.

Overall these wheels definitely are race wheels and they thrive on the track. Can’t wait to get more time on the track with these. I did cut time again. From 37,67 last week to 37,49 this week. This lap was my last lap of the day, with a drained battery and a “slow” gearing. The race wheels gave me better cornering and I look forward to see what I can get with the 42 gearing and higher top speed on the straight stretch.

To be continued….

Bump in the track: IMG_8421

Peel on wheel IMG_8425

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Great write up David!! Wait til you try those with 42t gearing!!!

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What you see is dead rubber picked up from the track. When you start out on a cold tire make sure not to hard charge the first two turns. It allows time for the dead rubber to clear off and the grip to maximize as heat is built. I’m still on my origional set.

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Yeah I thought so. Couldn’t believe if the wheels where shredding that much rubber. Do you know what kind of temperature the wheels are getting and if that equals the temp the rubber is the most sticky? I have the feeling that the wheel could benefit from getting a little warmer.

Wheels seem to fire off around 80f/ 26c. Ive recorded tire temps 135f/ 57c. Never became greasy in high temps. Just stuck down grip.

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mmm…. first session without a new best lap.

I made some small changes from last week. 2 degree more in the front truck. Wheel pulley from 60t to 42t. And the back truck got a little riser so the deck was level.

So todays set up looked like this: Front truck 57 degrees. Rear 35 degrees. Gearing 16/42. Motor max 70. Battery max 25. Stooge race wheels.

It actually felt pretty good. The turning was good both frontside and backside. I did not reach max speed as last time, so this wasn’t a limit. The acceleration was a little slower but it didn’t feel slow compared to last week where I got the fastes lap in my last lap with a drained battery.

I am a little puzzled why I did not cut time today. Last week it felt like I had a lot more in me if only the top speed had been higher.

Either I just wasn’t fast today or this setup just is a bit slower than the setup from last week, or I am slowly reaching the limit where I am close to how fast I can be on this track.

I think I will keep this setup next week and maybe change the VESC a little for more acceleration and see what happens. If I am still not fast there I will change back and see if the fastness returns.

The wheels still feels good on the track and I can lean good in corners. Feels secure.

IMG_8426

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Maybe lower the teeth on the motor pulley The speed should have gone up cause the motors are able to spin the wheels quicker with the smaller gears. But could have been something small like you were not as aerodynamic as last time

I have thought of playing with the motor pulley as well. The speed did go up today and I didn’t reach the max the setup could deliver. So the max speed wasn’t the limit today.

I think the limit was myself today. It is really demanding doing these fast laps. I have to really concentrate. I sweat like a pig, my heart is pumping and I loose my breath. I might not have been totally up to that today. You know Christmas hangover :slight_smile:

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Back in 88 I started building and racing dirt oval Stock Cars. An old timer was watching me hotlap and overdrive the turn entry. He advised me I was carrying too much entry speed and was causing the car to spend to much time in the center and that it was slowing my exit speed. It was the first time I heard the term, “back up your entry.” Pinching the entry or turning in early has much of the same effect as over driving entry speeds. Fast turns are about using the correct entry Arc and speed that maintains momentum through the apex. From my personal experience when it all comes together the corner speed feels slower and with less input effort.
Gearing: acceleration from the center off is very very important. If it was me, I would put the 60t back on and bump the pinion to a 17t. On 10s 190kv it would put you at 37-38kph vs the 16/42 which is closer to 50kph and limiting drive… A 12/42 would yeild the same results as a 17/60 for final drive. :checkered_flag::checkered_flag:

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They actually talk about what Moe is talking about on older seasons of Top Gear. A slow in to the turn to clip the apex and fast out of the turn.

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For anyone interested in rc car setup (and not only rc) do a search for “XXX main chassis setup guide”. It has invaluable information for the understanding of car dynamics. You can also register here for free for the time being and see all that info http://learnsetup.wpengine.com/

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Is it the case that the softer the wheel the better grip?
What hanger width is best for grip?

There is no singular answer to these questions. Read the link I posted. All of it. If you would like pm me your email and I will send you a copy of the book.

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Woo a book. That’s a lot of info. Interesting I’ll check the link thanks

Think you are right. I did go fast in to turns today. The staff talks about sacrificing (lower speed than you think is necessary) corner 1 and 7 in order to have throttle longer in the stretch after those corners.

What do you mean about the “center”? (“causing the car to spend to much time in the center”…“acceleration from the center off”…) is it in the apex of the turn?

I will play with the motor pulley. I think if I can get something between 16/42 and 16/60 it would work pretty good.

And I will start working more on how to do the turns. They have this map:

Edit: when I look at it I have been starting the cornering too early. Will see how it feels to go later in to the turn to be able to throttle sooner out the corner. But to be able to do that I might need to be able to turn sharper than now. We will see.

Line-Map

Green: Throttle. Red: Brake. Yellow: Coasting.

Turn 1: Pull to the right, brake late and hard. Cut the turn in a late apex, for a wide entrance to the turn.

Turn 4: Do turn 3 so you get all the way to the right for turn 4. Brake late and shortly and start the turn. Throttle again at apex.

Turn 5: Keep all the way to the left. Let go of the throttle or brake shortly. Throttle again at apex.

Turn 7: Start the turn late. Brake shortly after you reach the first apex. Turn without sliding. Keep a constant steering angle round the corners before the straight stretch.

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There are 3parts to any turn. Entry ,Apex and exit. Entry is used to setup the Apex (turn center). You should have turn speed and race line established on entry for the appex and exit. The Apex should be rolled through without drive or brake forces being applied. It allows lateral forces to be applied at maximum efficientcy without drive or brake Dynamics subtracting from lateral grip. When carrying too much speed or pinching the entry you lose kph throu the apex while trying to maintain the perfered race line. .1 second here .2 second there it adds up quickly. Setting up the entry is the key to making fast corners.

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I fund this 24 video tutorials on driver technique. I will see what I can gain from that.

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I kept the setup from last week. I now want to focus more on how I ride the track than the setup. I have begun to watch and read the tutorial I link to above. And I want to slowly work on some of the many suggestions they give. I had 3 main focus points in this weeks session:

  1. Entering the turns a little later than before and trying to do a later apex (this taken from the first tutorial).
  2. Trying to find the optimal speed entering the turns. In my case meaning I have to enter them a little slower, as Moe suggested after last week.
  3. Looking at the apex before I enter the turn. This is taken from the tutorial 3 “IMPROVING VISION ON TRACK”

And then at the end of the session I added a fourth focus and began to work on braking before the slowest turn on the track.

I find it every every difficult to get the same speed and starting turning point each time. And this affect hitting the late apex a lot. Sometimes its spot on, and next time I go through the same part of the track its way off. This track racing is difficult but I guess it’s a matter of practice. The good thing is that I really feel when its spot on. It feels so good! I didn’t have that many good laps today. I still have a tendency to approach the turns with to much speed, but I did cut time and had a couple of laps that was better than the previous best lap.

Being aware of the where i look really felt good. I got better prepare for the turns and it just felt really good to be looking ahead.

I started to work on breaking before turns. Up till now I have just been coasting. I have not felt that I was ready to work on breaking yet. To much to control and to much going on. And I am very sensitive when the board jerks with hard acceleration and when letting go of the throttle quickly or braking hard. This throws me off. But it seems that I am ready to work on that.

Gearing: As Moe suggested last week I think I will work on the gearing. This 16/42 is to slow accelerating out of the turns. Especially when the battery drains. Will go back to 60 on the wheel and see if I can find a 17 and 18 motor pulley to play with. I am just really bad in fining stuff. Does anyone know where to get them. Have to fit the Maytech motors with 8mm bore and key.

Best lap today was 37.19. Nad after I began to time my laps it have been looking like this:

41.50 sec 40.50 sec. 38.93 sec. 38.53 sec. 37.67 sec. 37.49 sec. 38.78 sec. 37.19 sec.

IMG_8560

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U ever try front drive vs rear?

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Not yet. That could be fun. With my deck being the same front and back, I could just swap bushings front - rear and swap the motor wires so the motors runs the opposite way. Right?

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