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  1. #1
    RC Competitor
    Join Date
    Jan 2015
    Posts
    50

    Troubleshooting Transmission

    So I just spent all this time recording the problem on video before disconnecting my batteries & putting them into 'storage' mode. Then I discovered the video I shot was unusable. I'll do my best to describe what's happening anyway... When I run the truck with the wheels in the air, all seems fine. When I put it on the ground, it seems OK until I accelerate at just the right RPM, at which time it'll sound like there's a rock stuck in my spur gear. That awful grinding sound follows, sounding like all of my gears are being stripped. The pinion & spur are steel Robinson Racing sort, and are worn but far from stripped. There's no rocks and the sound I'm describing while the steps to reproduce it point me to the main pinion/spur, the sound is one that you hear with plastic gears. It's absolutely un-drivable, and when I take it for a test drive, it will quickly get to a stage where the gears are spinning but the truck's not moving, and all you'll hear is that awful grinding if you stick on the throttle.

    I actually had my LHS do an overhaul of the tranny after there was an issue with the center shaft (recently replaced with Traxxas HD version; all others are Hot Racing). I've had struggles with this transmission since I brought the truck home, but prior to this issue, I had a pretty gnarly bash session on an off road track where there was lots of mud. This noise is what ended the run, and I figured through the course of the cleanup that it'd be apparent what had broken. Unfortunately it's not.

    Any hope someone else dealt with a similar problem & can grasp what's happening here without the video?

    I had to try... If not, I guess I'll have to get some help shooting the video.

  2. #2
    RC Enthusiast
    Join Date
    Nov 2019
    Posts
    23
    So I annihilated my erevo transmission a while back. If you look at the transmission in my photo you will see a hairline crack between the upper section and the lower housing for the center diff. That separated on the run AFTER a big crash when I floored the accelerator. When that happened, it made a horrible crunching noise and the transmission seized. The gears basically exploded. But before that, the car seemed to roll fine so I didn't notice it. Inspect your housing carefully. Otherwise look for rocks in the space for the center driveshafts.

    Sent from my SM-G950U1 using Tapatalk

  3. #3
    RC Qualifier
    Join Date
    Jul 2018
    Posts
    453
    A video would be super helpful... Upload to YouTube or something.

    trouble shooting noises can be hard via text.

    Does the truck roll smoothly by hand or is it binding?

    If you disengage the motor from spur gear and then run the motor does sound still exists?

    ( My motor would make a horrible sound at about 75% throttle, only is a small rpm range. My motor bearings were toast. They can be replaced but they are glued in. So a pita, trx says not replaceable)

    For me, to trouble shoot. I would start by isolating the area, and then going on from there...

    Remove tires. Put car on bench stand and run car and see if you can tell where it's from. Look over car for obvious issues

    Disengage motor from spur gear and run.
    This checks motor.

    Reengage motor, remove front drive shaft and run. This checks rear driveline and diff

    Remove rear drive shaft and put back in front. And run. This check the front end.

    Have both drive shafts off and run. This check center diff and transmission.

    Can be bad bearings,. Something broken, or just dirt where it should not be...

    Once you have isolated what area it is in, you can then start taking that area apart. Normally if something broken it will be mostly obvious.

    There are vids on how to tear down and replace about everything on the car

    Sent from my Pixel 3 XL using Tapatalk

  4. #4
    RC Competitor
    Join Date
    Jan 2015
    Posts
    50
    Thanks for the quick replies.... I can say for sure there's no issue until it's connected with the spur... I think Omen more than likely hit it right on the head in that there's something that's either shaken loose or a foreign object lodged inside the transmission itself..which is what I was afraid of. There's just something about this truck....there's always seems to be such a tremendous amount of disassembly necessary to get at the problem, and without a traditional step-by-step instruction manual, it just seems to take longer than it should to get it all back together. I'm just a grumpy old man now too... with so much less free time than I had when I was into R/C at 14, I have much less affection for the workbench time & just want to drive the sucker. Ah well. I'd better get crackin if I want to have it back in the dirt before the summer heat! I'll post back in the thread if I find it....

  5. #5
    RC Qualifier
    Join Date
    Dec 2014
    Location
    Adirondacks
    Posts
    601
    Which version E-Revo to you have? Each have different transmission assemblies. If you have an E-revo 1.0 it could be the slipper clutch.

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