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  1. #1
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    Transmission/Diff issue

    Hey all, I'm having some issues with my Xl-5 Rustler. I've had it for almost a year, and done a ton of work on it to accommodate the terrain and conditions I run it in. I started having some issues this afternoon with it. I had been running all afternoon, but when I swapped in a fresh battery and took it out again, I wasn't getting near the power I'm used to on the back wheels, and after running it for a few minutes, my motor was super hot. I tinkered with it a bit, and bench tested it. While it was off the ground, I ran it full throttle for a few minutes, and wasn't getting the same amount of motor heat. I out it back together, but when I took it outside to run it, I had the same problem. I noticed that if I park on a steep slope, the Rustler doesn't roll backwards, leading me to think it may be something wrong in the diff. I really hate messing with the differential; it's probably the most labor intensive part in the whole car. Does anyone have any advice or ideas on what exactly might be going on? It feels like the diff is locking up, and thus making my motor work harder to turn the wheels, which is making it overheat. Y'all have any ideas or opinions?

  2. #2
    RC Champion grizzly03's Avatar
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    I think you probably have a bad bearing or something else. Could also be the bushings in the motor itself. A bad diff would just lock up and both tires would turn together and would be harder to steer the car. It wouldn't cause a drastic loss of power.
    Last edited by grizzly03; 11-01-2020 at 08:40 PM.

  3. #3
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    Ok, I took the motor out and ran it by itself, and it seemed to be ok. I'll check my bearings again, but I didn't notice any of the wheel bearings were damaged or blown out. It was also making a loud ticking sound when I tried to run it, but only for a few seconds. The car feels really stiff and it's only running at maybe 2/3 the speed it usually does.

  4. #4
    RC Champion grizzly03's Avatar
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    How does the motor feel when you turn it by hand? Should spin smoothly. Does it smell burnt?

  5. #5
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    It feels fairly smooth; I've only had it in the Rustler for a couple of weeks. When I first noticed the problem, it had a faint burnt smell, but it wasn't smoking nd it didn't have the heavy "yep this motor is toast" smell, or at least not quite.

  6. #6
    RC Champion RCWilly's Avatar
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    The differential is used more in turning the car. When turning, the outside wheel needs to turn more than the inside wheel, and the differential slips to make the turning action smoother. It seems like some kind of gear issue... Does the clicking remain constant when the motor is spinning at the same speed? Does the clicking go faster when the motor spins faster? If both are yes, then it is likely a damaged gear (maybe the idler gear - the gear in the middle of the two other gears in the transmission).

    As for the motor, it should be fine. The first time I swapped the motor from my Slash 2wd to my Slash 4x4, it overheated a bit, and it had a bit of the burning smell, but the motor works fine after it cooled down (it's was a bit more than a year-old at the time, so yours should be fine).
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  7. #7
    RC Champion grizzly03's Avatar
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    If it's not the motor it's inside the tranny. Time to break out the tools,LoL.

  8. #8
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    I'll be able to do some more digging into it tomorrow. When I had the motor disconnected from the transmission, it seemed like it was running pretty well. I have diff gears that I pulled out of my cannibalized part car, so if I have to swap some gears out it can be done... Just a pain to do it, lol. I'll let y'all know if I find anything

  9. #9
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    Quote Originally Posted by KennethMiller19 View Post
    I'll be able to do some more digging into it tomorrow. When I had the motor disconnected from the transmission, it seemed like it was running pretty well. I have diff gears that I pulled out of my cannibalized part car, so if I have to swap some gears out it can be done... Just a pain to do it, lol. I'll let y'all know if I find anything
    You may want to have an idler gear and a few bearings on hand when you open it up.
    If the rolling resistance is good, you may have a bad internal bearing.
    You may also have a plastic idler gear in there.
    Also check the roll pin on the top shaft isnít part way out causing resistance.

  10. #10
    RC Qualifier ElectricPropils's Avatar
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    Quote Originally Posted by KennethMiller19 View Post
    Hey all, I'm having some issues with my Xl-5 Rustler. I've had it for almost a year, and done a ton of work on it to accommodate the terrain and conditions I run it in. I started having some issues this afternoon with it. I had been running all afternoon, but when I swapped in a fresh battery and took it out again, I wasn't getting near the power I'm used to on the back wheels, and after running it for a few minutes, my motor was super hot. I tinkered with it a bit, and bench tested it. While it was off the ground, I ran it full throttle for a few minutes, and wasn't getting the same amount of motor heat. I out it back together, but when I took it outside to run it, I had the same problem. I noticed that if I park on a steep slope, the Rustler doesn't roll backwards, leading me to think it may be something wrong in the diff. I really hate messing with the differential; it's probably the most labor intensive part in the whole car. Does anyone have any advice or ideas on what exactly might be going on? It feels like the diff is locking up, and thus making my motor work harder to turn the wheels, which is making it overheat. Y'all have any ideas or opinions?
    Before you do any of the things above I would just spray some WD-40 or dry lubricant into every visible bearing/bushing. Since the brushed rustler uses bushings instead of bearings I think the problem is that one or more of your bushings seized up (it's happened to me on several occasions). Try to spray it on any bushing that you can find or basically any place that the axle goes into the transmission. Also try spraying it on the motor bushings and behind the spur gear.

    I do this about every 3 runs to ensure smooth running as bushings can get seized up pretty easily when running dry for too long.
    This is what I use (WD-40 special formula dry lubricant), it keeps dirt from sticking to bearings/bushings so that they last longer.

    https://www.wd40.com/products/dry-lube/

    I hope I was able to help you!
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  11. #11
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    Quote Originally Posted by ElectricPropils View Post
    Before you do any of the things above I would just spray some WD-40 or dry lubricant into every visible bearing/bushing. Since the brushed rustler uses bushings instead of bearings I think the problem is that one or more of your bushings seized up (it's happened to me on several occasions). Try to spray it on any bushing that you can find or basically any place that the axle goes into the transmission. Also try spraying it on the motor bushings and behind the spur gear.

    I do this about every 3 runs to ensure smooth running as bushings can get seized up pretty easily when running dry for too long.
    This is what I use (WD-40 special formula dry lubricant), it keeps dirt from sticking to bearings/bushings so that they last longer.

    https://www.wd40.com/products/dry-lube/

    I hope I was able to help you!
    I switched over to bearings a long time ago, and took the bushings out. I'll check out that dry lube WD-40, though, for sure. I use regular WD on it, but it would be ideal if the dirt didn't stick to it. Thanks for the suggestion!

  12. #12
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    Okay, so I opened up the diff case, and didn't see anything glaringly obvious wrong. I went ahead and swapped out the two smaller gears with some spares I had laying around, and dropped the gears I took out into another diff case. When I tried spinning the shaft to turn the removed gears in the new case, I could feel that they seemed to have a little bit of resistance, but nothing major. All the bearings were intact and looked like they were in good shape. I'll get it all out back together tonight or tomorrow when I get off work, and see what happens when I rest run it. I have an extra (used) motor that I may go ahead and drop in it just in case my motor is fried. I hope this will fix my problem; if not, I don't know where to go from here. Thanks for y'all's help and suggestions, and I'll update when I get to test run it.

  13. #13
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    Hiya
    Usually its the case melted where the input shaft from slipper comes in on slipper side.
    Bearing fails and causes case to melt.

  14. #14
    RC Qualifier ElectricPropils's Avatar
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    Quote Originally Posted by KennethMiller19 View Post
    I switched over to bearings a long time ago, and took the bushings out. I'll check out that dry lube WD-40, though, for sure. I use regular WD on it, but it would be ideal if the dirt didn't stick to it. Thanks for the suggestion!
    No problem! I recently (yesterday) had something in my E-revo transmission blow so now I am going to have to take that mess of screws apart, I was just hoping that you were luckier than I and were just having bushing problems. The E-revo sucks to work on, at least for the transmission that is.
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  15. #15
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    I would not recommend using Water Displacement 40 as a lubricant, because it often removes original lubricant without replacing it. I would instead recommend using something like lithium grease, molybdenum grease, or a gear lubricant like Lucas Red 'n' Tacky for your gears. 3-in-One oil, marine grease, or bearing-specific greases work well for bearings. WD-40 is a great cleaner, but not a very good lubricant.
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  16. #16
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    Just took the old rusty out for a test run, and everything seems to be running well. Thanks to everyone for your advice and comments; I really appreciate it!

  17. #17
    RC Qualifier ElectricPropils's Avatar
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    Quote Originally Posted by Is_It_Broken? View Post
    I would not recommend using Water Displacement 40 as a lubricant, because it often removes original lubricant without replacing it. I would instead recommend using something like lithium grease, molybdenum grease, or a gear lubricant like Lucas Red 'n' Tacky for your gears. 3-in-One oil, marine grease, or bearing-specific greases work well for bearings. WD-40 is a great cleaner, but not a very good lubricant.
    Yeh, that's why I told him that WD-40 dry lubricant would work better, it seems to leave a film for a good amount of time if you get good coverage.
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  18. #18
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    Quote Originally Posted by ElectricPropils View Post
    Yeh, that's why I told him that WD-40 dry lubricant would work better, it seems to leave a film for a good amount of time if you get good coverage.
    Ah. I missed that somehow. Thank you for clarifying.!
    LONG LIVE THE PROFESSOR! Rest in peace, Mr. Peart.

  19. #19
    RC Qualifier ElectricPropils's Avatar
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    Quote Originally Posted by Is_It_Broken? View Post
    Ah. I missed that somehow. Thank you for clarifying.!
    No problem, I miss stuff all of the time when responding to people.
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