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  1. #1
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    E-Revo not going good

    Hi,

    Today after trying to go on a high slope , my E-Revo VXL started not going good as seen in this video:

    https://youtu.be/TP-vfE1zntg

    I opened it up to check the gears. The motor gear seems normal to me. And here is a video:

    https://youtu.be/E2bGErheW2k

    But when I try to increase power I get a burnt plastic smell. And it does not go if the motor gear is connected to the wheels.

    What might be the problem ?
    Do I have a problematic gear ?
    How can I check ?

    Please also see these photos:
    https://ibb.co/TcTcZZv
    https://ibb.co/6HW0tDK
    https://ibb.co/px82Bzx
    Last edited by mrmrmrmr; 07-12-2020 at 05:34 AM.

  2. #2
    RC Champion grizzly03's Avatar
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    Sounds like the slipper clutch is loose. Try tightening the nut on the spring to tighten the slipper clutch.

  3. #3
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    can you show me on a photo ? what part should I tighten ?

    thanks

  4. #4
    RC Champion grizzly03's Avatar
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    Here you go:

    I just watched the vids again. I think you might have something else going on also. Maybe a pin behind the spur gear?
    Last edited by grizzly03; 07-12-2020 at 11:27 AM.

  5. #5
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    which one is the spur gear ? and how can I see what's behind it ?
    Before it broke I was driving it in a dirty road with a high slope upwards.

  6. #6
    RC Champion grizzly03's Avatar
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    The nut circled is what controls the tension on the spring which controls the slipper clutch. The spur gear is the gear your finger is pointing to.

    Did you try tightening up the nut? Try that first. If that doesn't help take that nut off and then the slipper clutch and spur gear will slide off.

  7. #7
    RC Champion Acidic01's Avatar
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    Quote Originally Posted by grizzly03 View Post
    Here you go:

    I just watched the vids again. I think you might have something else going on also. Maybe a pin behind the spur gear?
    When watching vids something is still spinning when letting off throttle.

    This doesn't sound right.


    But issue is slipper needs tighten. You do some some play but not that much. Try with 1/4 turn on nut till you get it to where you want it.

    I block car with my foot and pull throttle and make it to where I get some slippage but still enough tourge that the car wants to climb up my leg.


    Sent from my Pixel 3 XL using Tapatalk

  8. #8
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    ok thanks. I am not at home now. tomorrow I will try what you recommend.
    I guess I need a small pliers to tighten or loose that nut.

    first I will try tightening it but I guess it is already tightened.
    if it was loose would I get that burnt smell ?

    if it is tightened already, I will remove the nut and then the sprint and gear.
    then shall I be able to see the problem ?

  9. #9
    RC Champion Acidic01's Avatar
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    Small plyers and or a 7mmnsocket or end wrench. There is also a hole in spur gear shaft on the back side. See pic with where I put tool

    Also circled all the items that are on that shaft.

    I hold the slipper nut with plyers and then stick a allen wrench or something else into hole and use that to turn the slipper to tighten The nut. As very hard to tighten nut when assembly is mounted to car.

    Since there is a spring behind the nut. It will be tight but can be tighten more. The more it's tight. The more pressure and then friction is applied to the slipper clutch assembly.

    The smell was just the slipper pads getting hot. I've had my assembly emit smoke they got so hot. This is bad....

    Sent from my Pixel 3 XL using Tapatalk

  10. #10
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    tanks. I hope it is really that simple. I'm just worried that something might be broken or worn out...

  11. #11
    RC Champion Acidic01's Avatar
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    Quote Originally Posted by mrmrmrmr View Post
    tanks. I hope it is really that simple. I'm just worried that something might be broken or worn out...
    The slipper pads may be work. Or a broken pin. Tighten it up some and see. If still won't work then take off spur gear and look at things.

    Sent from my Pixel 3 XL using Tapatalk

  12. #12
    RC Champion grizzly03's Avatar
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    I agree with Acidic01. Try tightening the nut up first. If you do need to pull it apart, it's a fairly easy task.

  13. #13
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    Tightened the nut as advised. It now goes well. However, speed telemetry is broken now.
    Then I removed the spring and spur gear to see what's happening.

    it seems that the part inside the spur gear is worn out (seen in the following photos)
    https://ibb.co/hZkDDkC
    https://ibb.co/3RHzWpr
    https://ibb.co/rsDDcJk
    https://ibb.co/B35rxQF

    because it is worn out , the magnetic telemetry is not working (because it is now a little away from the magnet inside spur gear)
    how can I fix this ?
    is there a quick workaround ?
    if not, which part should I get ?

    is this worn out part available with the spur gear ?
    what is the part number ?

    if I need to order a new spur gear, which one should I buy ?
    on local stores I can find 55 tooth spur gear but not 50 tooth. does it matter ?

  14. #14
    RC Champion grizzly03's Avatar
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    Exploded view for reference: 1-16-E-Revo-VXL-Transmission-Assembly

    I would order Part #7152 slipper clutch and a spur gear. Those two parts will fix you up. If you get the 55T instead of the current 50T the gearing ratio will be slightly lower, with slightly more power. Depending on if you drive on pavement(top speed) or off road you might not notice. If you drive more off road give the 55T a try.

    You melted the spur gear, because of the excess slipping which creates heat. A minor amount on hard acceleration is ok but more than that you seen what happens.

  15. #15
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    so actually I don'T need the whole 7152 set, just the slipper pad. But it is not sold separately I understand. is that correct ?

    what is the material of it ? maybe if I find it, I can cut the same part.

    also, do I really need the spur gear ? it seems it is not worn out.

    does a standard spur gear support the magnet for rpm telemetry ?
    Last edited by mrmrmrmr; 07-15-2020 at 09:52 AM.

  16. #16
    RC Champion grizzly03's Avatar
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    Quote Originally Posted by mrmrmrmr View Post
    so actually I don'T need the whole 7152 set, just the slipper pad. But it is not sold separately I understand. is that correct ? Yes

    what is the material of it ? maybe if I find it, I can cut the same part.

    also, do I really need the spur gear ? it seems it is not worn out. Yes it's melted

    does a standard spur gear support the magnet for rpm telemetry ?Yes
    The spur gear is the biggest problem. It is melted. The slipper pad fits into a groove. The slipper pad could be ok, but for the price of the rebuild kit, you would have new parts and know it's not worn. This is what the spur gear is suppose to look like.


  17. #17
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    ok. I've ordered a 50T spur gear and a 7152 kit with slipper pad.
    hopefully , when I receive them, my problem will be solved.
    thanks.

  18. #18
    RC Champion grizzly03's Avatar
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    Yup. You'll be back in business in no time.

    When you put it back together test that the slipper clutch is working. It shouldn't slip during normal driving, only slightly on hard take offs. You can adjust it looser (more slipping) or tighter (less slipping) if you want. Just make sure it doesn't slip too much.

    Tighten the locknut down till it stops (don't overtighten) and turn it back off around 3/4 of a turn. That's where I would start for a slipper setting.

  19. #19
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    ok. why do we want slipping ?
    why not tighten so that it doesn't slip ?
    (I really don't know the physics required here, so forgive my dumb question)

  20. #20
    RC Champion grizzly03's Avatar
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    No worries. It's there to help protect the driveline, it offers a "cushion" against shock loads. If it didn't slip at all the power would instantly be transferred to the gears (transmission,diffs). Helps protect things like the axles and diffs (ring and pinion).

    I run mine on the tight side. It only slips for a moment on hard acceleration with high traction similiar to how Acidic01 describes:
    Quote Originally Posted by Acidic01 View Post
    I block car with my foot and pull throttle and make it to where I get some slippage but still enough torque that the car wants to climb up my leg.

    You can adjust yours how you want, it all preference. There is no right or wrong.
    Try to imagine what would break if the tires were stuck and couldn't turn, then you gave full throttle to the motor. Something has to give. I'd rather have the clutch slip than to break parts.
    Last edited by grizzly03; 07-15-2020 at 03:26 PM.

  21. #21
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    Hi,

    replacement parts arrived today. But the 55 tooth spur gear I received (part 7047) does not have the hole required for the magnet for rpm measurement.
    is that another part ? Where can I find it ?
    Can I open a hole for the magnet myself ?

    or should I use the old spur gear ?

  22. #22
    RC Champion grizzly03's Avatar
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    The spur gears that have the spot for the magnet have an "R" at the end of the part number (example part# 7047R). The spur gears without the "R" designation are Old Stock (discontinued) and doesn't have the spot for the magnet. They were made before the Traxxas Telemetry came out. Maybe return or exchange it for the current part# needed?

    Does your old one look like this? If not it has damage and should be replaced.

    You can also see where the magnet goes (in the pocket on the left).

  23. #23
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    ok. I understand that. However, I live in Turkey and I couldn't find 7047R here.
    if I order from Amazon it may arrive in a month or so.
    Meanwhile maybe I could open a hole on the 7047 and glue the magnet on that hole.
    Would that work ?

  24. #24
    RC Champion grizzly03's Avatar
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    Anything is possible. Here is what the other side looks like, if it helps.

  25. #25
    RC Champion Acidic01's Avatar
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    Perhaps run the one you got for now and order up the right one.

    Do you have a add on telemetry for the car? I never even knew there was a magnet in spur gear. I know my Merv doesn't give me any speed data with just the link app.

    Sent from my Pixel 3 XL using Tapatalk

  26. #26
    RC Champion grizzly03's Avatar
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    My new Merv that i purchased in the beginning of this year still didn't include any of the Telemetry sensors from the factory. The magnet is an extra part like the other sensors needed to use the telemetry and it wasn't included either.

  27. #27
    RC Champion Acidic01's Avatar
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    Quote Originally Posted by grizzly03 View Post
    My new Merv that i purchased in the beginning of this year still didn't include any of the Telemetry sensors from the factory. The magnet is an extra part like the other sensors needed to use the telemetry and it wasn't included either.
    So if one adds a magnet. Does that then get you speed reading? Or is there other items needed?

    Sent from my Pixel 3 XL using Tapatalk

  28. #28
    RC Champion grizzly03's Avatar
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    Need the rpm sensor also. It goes in the slot on the spur gear cover. Then you get the speed based off of the settings you put into the Link App. (ex. tires,gearing,motor)

    Telemetry accessories info: https://traxxas.com/products/models/...sm?t=telemetry

  29. #29
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    yes, I have the telemetry addon.
    so I need R version of the 7047 or 7046 spur gear.
    But it will take time to order it and receive. So I am really considering to make a hole for the magnet on the 7047 I received.
    Then if I glue the magnet there, maybe it will work.

  30. #30
    RC Champion Acidic01's Avatar
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    Quote Originally Posted by mrmrmrmr View Post
    yes, I have the telemetry addon.
    so I need R version of the 7047 or 7046 spur gear.
    But it will take time to order it and receive. So I am really considering to make a hole for the magnet on the 7047 I received.
    Then if I glue the magnet there, maybe it will work.
    Should work my only concern would be how balanced the spur gear will be and if the little bit would make a difference. As don't know if on the R version they ad a bit more to other side to counterbalance it. If this is even a issue. And the. How strong it may be.

    It is always worth a shot.

    Sent from my Pixel 3 XL using Tapatalk

  31. #31
    RC Champion Acidic01's Avatar
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    Quote Originally Posted by grizzly03 View Post
    Need the rpm sensor also. It goes in the slot on the spur gear cover. Then you get the speed based off of the settings you put into the Link App. (ex. tires,gearing,motor)

    Telemetry accessories info: https://traxxas.com/products/models/...sm?t=telemetry
    Thanks for the link. Guess I got myself some more parts to order

    Sent from my Pixel 3 XL using Tapatalk

  32. #32
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    I've modified the old stock 7047 Spur gear as seen in the images (together with my old melted 7046R)
    https://ibb.co/dtpMk2z
    https://ibb.co/JmKCtfy
    https://ibb.co/FW2R66V
    https://ibb.co/F7QfcGQ
    https://ibb.co/LkVZPPC

    now the E-Revo goes fast as before.
    But RPM sensor does not read well.
    I had to press the back of the sensor with a thin cardboard.
    I guess I will try with the original 7047R when it arrives. But I really don'T see the reason why it doesn't read with my modified 7047.

    Also, since I have double battery packs and parallel connector for them , I installed the faster pinion gear.
    seen here:
    https://ibb.co/hFvp7C9

    Does it have any negative effect when used with 55 tooth spur gear ?

  33. #33
    RC Champion grizzly03's Avatar
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    The magnet needs to be a certain distance from the sensor to read correctly. If the magnet is tipped in any direction that would also affect how well it works. With a pre-made pocket in the spur gear it takes the guess work out of the magnet install.

    Installing the bigger pinion gear with the 55T spur is higher gearing than stock. If you have a way of telling the temperature of the ESC and motor, that will be the best answer for gearing. As long as neither one overheats your ok.

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