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  1. #1
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    My car tip off, what can I do?

    Hi,

    I post before about my car. It is a traxxas slash 4x4 platinum edition, but I added a computer and sensors to make it autonomous. You can find some pix here and here

    I am part of the DIY robocars group in SF bay area and we race our autonomous cars with each other quaterly in meetups. Basically, we push a button, the car will race by itself. After a lot of modifications, programming, and the help from this forum, I improved my car a lot and became one of the top racers in the group.

    During our last meetup, my car lost in the final because it tipped off when it tried to run at a faster speed. You can find the video here (I am the black car)

    https://photos.google.com/share/AF1Q...5nVjRLS3E0LS1B

    The autonomous driving part has no problem, but the car itself becomes the bottle neck to run faster. I need your help. How can I modify the car so it can run faster without tipping off? A few directions I am thinking:

    1. Reduce weight. The car is 10 pounds. The battery (4S 6000 mah) alone is 1.4 pounds. Can I remove the rear bumper? Can I replace the plastic part with other lighter materials?
    2. Can I use different tires? But I am already using the Proline carpet tires? What else can I do?
    3. ???

    Thanks a lot
    Last edited by gecong; 12-11-2019 at 11:31 PM.

  2. #2
    RC Champion
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    Lower it as much as you can. Place the shocks on the outer most holes on the a-arms and the under most holes on the shock towers. Maybe try some different spring rates and also some different weight shock oil. It will take some tuning by you to get the best result in the end. I do know that placing the shocks on as described above helps a lot. You may need to get some heavier shock oil and heavier spring rate to compensate for the truck being heavy to accomplish your needs. Good luck and have fun!

  3. #3
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    It’s all about (1) lowering the COG and (2) reduce lean and (3) find the balance between traction and tire catching to much of it and the whole car flips over.

    (1) is tough with the large amount of weight on top. you can, in addition to what 222 said, reduce the shock eye to eye lengths by putting spacers under the piston inside the shock body. For (2) stiffer springs, heavier oils and thicker sway bars will help. For (3) though, you may actually want to find something with a little bit LESS traction on carpet so the tires don’t just “dig in” and flip

    Removing the rear bumper requires you to get something like the rustler 4x4 rear hinge pin holders since on the Sl4sh that piece is built into the bumper. Of course nothing is stopping you from cutting off the extra parts aside from the bits needed to hold in the pins and attach to the bulkhead, but then you lose the option of putting it back on. Remember that if you remove too much weight from the lower parts of the car without reducing weight from higher areas, it will make the car easier to flip.

    Have you looked into maybe just start with the 4-tec platform?

    Good luck.
    Last edited by TwoBelugas; 12-12-2019 at 05:58 AM.

  4. #4
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    Scott
    Slash 2wd
    Slash Ultimate 4wd
    Stampede 4wd

  5. #5
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    @Scott91370 Yes or no. My car speed is much faster now compared to last time I posted because I followed the youtube video: put tubes inside shocks to made it as short and as tight as possible. So the weight is much lower now. (and the car looks much cooler). I used to have to keep my speed under 11 mph. But now I can run 14 mph. However, to win the race, I always need more. So it comes back to the same problem, how to run at 15 mph without tipping off.

    1. My car bottom now is 10mm from the ground. Maybe I can reduce it to 5mm by playing with shocks?
    2. Reduce weight. I use a 4S 6000mAh 50C lipo battery which is 1.4 pound. I am trying a 4S 3300mAh 60C which is 0.7 pound. (I need peak current 200A)
    3. I am not sure about my tire. As you can see from the video, the winning car drift a lot. Should I do that too?

    Also, the last race of every meetup is a human-vs-robo. The winning robocar will race with a human who controls the car with remote. The robocar now can finish the 40m track in 6 seconds and the car who beat me also beat the human driver. But I think human can drive much faster than that. If you guys live in bay area and are interested, you are more than welcome to come, race with us, have fun, BBQ and beer...

  6. #6
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    Have you considered using hex extenders to widen the width?

  7. #7
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    You are definitely at a disadvantage because of the height & weight of the vehicle. I was going to mention tires but the set you run in the video are not the same as in the picture.
    A little drifting might not be a bad idea since you seem to have a lot of traction and that is causing you to roll.
    I am by no means an expert, I wouldn't even be able to drive around that track in 20 seconds with a properly set up vehicle.

    I do wish this was something closer, it would be pretty cool to see these things live!

    Good luck and keep posting up the videos!
    Scott
    Slash 2wd
    Slash Ultimate 4wd
    Stampede 4wd

  8. #8
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    How fast do you go? You might consider a smaller battery with higher gearing. You could also use multiple batteries instead of just one. Just swap them when they run low.

    Those do not like like carpet tires.


    Sent from my iPhone using Tapatalk

  9. #9
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    Quote Originally Posted by TwoBelugas View Post
    Have you considered using hex extenders to widen the width?
    Could you please let me know how?

  10. #10
    RC Champion olds97_lss's Avatar
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    What do you mean by "tipping off"? Rolling over?
    Expert rigging at it's best!

  11. #11
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    Quote Originally Posted by gecong View Post
    Could you please let me know how?
    Just search for “slash hex extender”, that will get you choices for 12mm hex extensions to widen the track and make it harder to flip

    Or you can get 17mm hex conversions from say hot racing or any number of manufacturers that have choices of offset to widen the width

  12. #12
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    Quote Originally Posted by TwoBelugas View Post
    Just search for “slash hex extender”, that will get you choices for 12mm hex extensions to widen the track and make it harder to flip

    Or you can get 17mm hex conversions from say hot racing or any number of manufacturers that have choices of offset to widen the width
    I ordered this, hopefully it will solve my problem.

    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

  13. #13
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    Can I just extend my left side and keep my right side untouched? Our race is always clock-wise and turns are mostly right turns.

  14. #14
    RC Turnbuckle Jr.
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    You can do whatever you want, but just doing one side is going to be weird... I get the idea like a nascar, but those use different sized tires too...

    Those spacers will work, but wear out bearings faster, and are sloppy

  15. #15
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    It worked. I added the wheel hex extension to left side. (I wanted to add the right side too, but seemed my car right-rear axis was defective. I could not insert the tiny pole through the extension and axis). The car now run faster without tipping off.


    More here https://twitter.com/SmallpixelCar/st...03116217667584

  16. #16
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    This project is all kinds of COOL!

  17. #17
    RC Champion olds97_lss's Avatar
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    This whole automated rc thing is far beyond my head, but still curious what you mean by "tipping off". Do you mean rolling over? Or leaning and dragging? Or steering weird when the weight transfers in the corner?
    Expert rigging at it's best!

  18. #18
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    Quote Originally Posted by olds97_lss View Post
    This whole automated rc thing is far beyond my head, but still curious what you mean by "tipping off". Do you mean rolling over? Or leaning and dragging? Or steering weird when the weight transfers in the corner?
    I gathered from the original post that they meant tipping over . Rolling in a turn

  19. #19
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    Quote Originally Posted by olds97_lss View Post
    This whole automated rc thing is far beyond my head, but still curious what you mean by "tipping off". Do you mean rolling over? Or leaning and dragging? Or steering weird when the weight transfers in the corner?
    Yes, I meant roll over

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