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  1. #1
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    Question Brand new Hoss. Signficant cogging and noisy drive train?

    Hey, first post, new member, new to Traxxass RC and RC in general

    Bought a Hoss for my boy to learn to drive but noticed something that I feel is a bit unusual. It has what i would consider a significant amount of cogging throughout the throttle range. There are times when I apply full throttle and the car will just shudder. Other times it launches fine at full throttle Other times still it will have very light throttle applied and will cog, sometimes it wont.

    On top of this the drivetrain is very noisy at low speeds. I believe the sound I am hearing is the slop in the metal driveshaft against the center drive unit gears and front wheel drive unit gears. I dont mean longitudinal slop, but rather twisting slack of the driveshaft contacting the gears. It makes the noise if i push the car by hand while powered off and also if i drive the car slowly with low throttle(With one caveat ill mention below)

    With the TQi controller I rebound it to the car and reset it to default settings and this seemed to have a small affect on the cogging effect but i noticed something else too. Sometimes the the throttle will allow the car to inch forward very slowly, other times the car wont move until a certain amount of throttle is depressed ie 10% or so. This means the car will drive faster and there will be less drivetrain noise mentioned above. I heard about an ESC dead band and assumed this might be what is happening here, except it happens sometimes and not others.

    I have checked the spur and pinion meshing and it seems fine, im no expert though. Im still using the guide piece though to set it.

    Probably the biggest issue is the cogging effect and why it sometimes does it and other times is fine, followed by the noisy drivetrain which is only noisy at very low throttle or when pushed by hand. Are these issues normal? Can someone say whether their Hoss makes a metal clink clink clink sound when pushed by hand and at very low throttle? Is there anything else I can try to reduce/eliminate the cogging effect? Could it be a bad esc? should I try adjusting the throttle trim via the transmitter?

    Ill get a video up later showing the noise im talking about

    Thank you for time

  2. #2
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    First, remove the pinion and just roll the car by hand. It should be smooth and quiet. You can tell if it is drive train or just the motor acting up.

    If you have the Bluetooth module you can see if there are any updates for the receiver and ESC.

    Definitely give Traxxas a call they have pretty good tech support.


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  3. #3
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    Quote Originally Posted by Dmarzke View Post
    First, remove the pinion and just roll the car by hand. It should be smooth and quiet. You can tell if it is drive train or just the motor acting up.

    If you have the Bluetooth module you can see if there are any updates for the receiver and ESC.

    Definitely give Traxxas a call they have pretty good tech support.


    Sent from my iPhone using Tapatalk

    Here is the sound with pinion meshed to spur
    https://youtu.be/KfQo7_t9-Qk

    sound without
    https://youtu.be/cVDDVSzrSwM

    Without the pinion meshed it is quieter and easier to move by hand but still makes the noise. Being my first RC i have no idea if this is normal or not

    Any other way to update ESC besides using the bluetooth module?

    Thanks

  4. #4
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    I have a FrankenHoss. Started life as a 4Pede and I added the Hoss Chassis and associated parts. But pretty much the same drive train.

    Here is my truck with the motor still connected. It makes some noise but rolls smooth.

    https://youtu.be/6O3Q3GHmdNo

    Here it is without the motor. Butter smooth and silent.

    https://youtu.be/PjCqYuUBTwo

    I would start by pulling the back end off as that is only 4 screws. See if the back end or from end make noise on their own. Make sure the center shaft and center diff are mounted properly.

    Definitely give Traxxas Support a call.


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  5. #5
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    Any other way to update ESC besides using the bluetooth module?

    Thanks[/QUOTE]

    I could never get the hang of the Traxxas controller so I always bought the BT. I have since switched to Futaba radios and other speed controls.

    Anyone else know about alternative update paths?


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  6. #6
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    Quote Originally Posted by Dmarzke View Post
    I have a FrankenHoss. Started life as a 4Pede and I added the Hoss Chassis and associated parts. But pretty much the same drive train.

    Here is my truck with the motor still connected. It makes some noise but rolls smooth.

    https://youtu.be/6O3Q3GHmdNo

    Here it is without the motor. Butter smooth and silent.

    https://youtu.be/PjCqYuUBTwo

    I would start by pulling the back end off as that is only 4 screws. See if the back end or from end make noise on their own. Make sure the center shaft and center diff are mounted properly.

    Definitely give Traxxas Support a call.


    Sent from my iPhone using Tapatalk
    Thanks, yours without the motor sounds very quiet. Ill ring support see what they say about it

  7. #7
    RC Champion RazorRC22's Avatar
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    Quote Originally Posted by helis4life View Post
    Here is the sound with pinion meshed to spur
    https://youtu.be/KfQo7_t9-Qk
    That sound is pretty normal. The pinion and diff are both metal and the stock mesh has a bit of gap, so yeah you'll hear them slap against each other as the motor clicks through its poles.
    youtube.com/c/RazorRCvideos

  8. #8
    RC Champion RazorRC22's Avatar
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    Quote Originally Posted by helis4life View Post
    OK, that is NOT normal. The motor is not turning at all here and you slid it over so the gears are not engaged? You're going to have to take apart the car and find the source of the clicking. I'd start my pulling the center driveshaft and/or center diff and see if you can isolate if it's front or rear.

    You can also disconnect each corner's driveshaft and try spinning the axles one by one to see if it's a bearing in one of the wheel carriers.
    youtube.com/c/RazorRCvideos

  9. #9
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    Quote Originally Posted by RazorRC22 View Post
    OK, that is NOT normal. The motor is not turning at all here and you slid it over so the gears are not engaged? You're going to have to take apart the car and find the source of the clicking. I'd start my pulling the center driveshaft and/or center diff and see if you can isolate if it's front or rear.

    You can also disconnect each corner's driveshaft and try spinning the axles one by one to see if it's a bearing in one of the wheel carriers.
    Yeah thats right, the pinion and spur arnt contacting each other. The center drive is still spinning along with the diffs and driveshaft

    Ok thanks Ill have a look later tonight and see if I can determine where its coming from. This being my first RC i have no experience in what these parts should sound or feel like. Do you know of any reference videos showing a 4x4 conversion or something similar that goes in to detail about how the parts are installed and sound/feel like? Ive searched but havent really come across anything in depth

  10. #10
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    The back comes off pretty easy.




    These 4 screws and the back end comes off.

    You can then access the center diff and spur.

    Be careful the driveshaft doesnít fall out. There is also a bearing for the center diff in the motor mount behind the diff.

    Front end is a bit more involved because of the steering but not too bad.

    Get a decent set of metric hex drivers 1.5, 2, 2.5, and 3. A set of ball end Allen wrenches help too.

    On the Traxxas web site under support you can find PDFs of the parts breakdown. Helps you get things back together with the proper screws in the proper position.

    If you ainít breaking it you arenít trying hard enough.

    Fixing them is some of the fun. Certainly not half.


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  11. #11
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    the front differential turned out to be less smooth than the rear. After dismantling it the only thing I could notice was that if two screws holding the cover in place are too tight it seems to either compress the casing or slightly deform it to the point where it is noticeably harder to turn and far less smooth than i think it should be. All bearings and gears looked fine. After reassembling and keeping those two screws tight but not too tight the car is much smoother when pushed by hand.

    The cogging issue is still present intermittently. I checked the motor and ESC/receiver connections are all looks fine. There are two distinct behaviors Ive noticed -

    Cogging not present, car has a higher minimum speed, transmitter throttle has a noticeable dead range at the very beginning

    Cogging present, car has a lower minimum speed, transmitter throttle has no apparent dead range at very beginning.

    When the cogging is present it can happen no matter the throttle level, for instance yesterday it was doing it with very minimal throttle and also from a stop with full throttle( the car was just making metallic noises and moving nowhere).

  12. #12
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    Is there a local hobby shop nearby? If so, I recommend going there and asking for help. They can start swapping out the electronics until they figure out what part is faulty. It could be the ESC, motor, radio, transmitter, battery, etc.

  13. #13
    RC Turnbuckle Jr. olds97_lss's Avatar
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    What lipo are you using in it?

    Do you have a soldering iron?

    You might have a cold solder joint either on your lipo, esc or either side of the motor bullet connectors. Cogging is usually a result of either not enough current can pass through the system, your over geared or the motor got too hot and magnets are dead/dying.
    https://www.youtube.com/c/olds97lss

  14. #14
    RC Champion grizzly03's Avatar
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    Quote Originally Posted by helis4life View Post
    the front differential turned out to be less smooth than the rear. After dismantling it the only thing I could notice was that if two screws holding the cover in place are too tight it seems to either compress the casing or slightly deform it to the point where it is noticeably harder to turn and far less smooth than i think it should be. All bearings and gears looked fine. After reassembling and keeping those two screws tight but not too tight the car is much smoother when pushed by hand.
    I would check here or in this location. The way all the parts fit together (gear cases,transmissions) is they all fit tightly together. Meaning you should strip a screw or the plastic the screw is in before deforming any of the cases. A bearing or something might not be seated correctly could also cause this issue.

    What two screws are you talking about?

    I highly doubt it's your ESC or Motor. Because when you disconnected the pinion from the spur the cogging was still there. If it was your motor the cogging would have disappeared.

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