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Thread: Repair Advice

  1. #1
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    Repair Advice

    Today I took my Erevo 2.0 out bashing at a BMX track. Took some heavy pounding and I didnt think anything had broken , until I got home. I was running it around the backyard to finish off the batteries before charging and I noticed an issue that I can not seem to track down the culprit of. When I fully turn right the drivetrain and or engine seems to seize up. It can stop me dead in my tracks , but if I go straight or turn left I have no issues at all. I put the car on the repair stand and cant see any bent rods or drive shafts. I even pulled off the bottom skid plated to check the center shaft. Nothing stuck or ledged in any wheels or drive shafts. While also on the repair stand I turned it on and accelerated a bit , again turning left or straight I had no issue but when I turned right it got pretty shaky and started making some noises.

    Where would I start to look to find my issue? I apologize for the noob question but I am really new to the hobby.

  2. #2
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    I would suggest putting it on a box, turning the steering incrementally to the right, and rotating the front wheels by hand. Presumably there should be a point where you start feeling binding of clicking. That might narrow it down if you notice that it binds repeatedly at certain points. Is also look very carefully at the spot where the drive shaft meets the wheel assembly.

  3. #3
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    Thanks for the input. So I did just notice that when turning one of the front wheels by hand , with it steered dead center , all 4 tires spin and the center drive shaft spins. However when I turn in either direction about 50% , the rear tires and center drive shaft stop spinning. Does the mean front Diff? Is it normal for steering to effect the front diff?

    Edit - I should say that is when only spinning one tire. So I guess its working fine(The diff). When I spin both tires it seems operate all 4 just fine even at full steering.
    Last edited by Fugitivelama; 11-19-2020 at 07:45 PM.

  4. #4
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    It seems like you might have a couple unidentified issues. Normally turning a wheel by hand will result in the matching wheel on the other side (left/right matched) turning in the opposite direction and that's it. If you get all three other wheels spinning, then you might have a serious center diff issue. That wouldn't really explain why the steering impacts the issue though.

  5. #5
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    Quote Originally Posted by omen View Post
    It seems like you might have a couple unidentified issues. Normally turning a wheel by hand will result in the matching wheel on the other side (left/right matched) turning in the opposite direction and that's it. If you get all three other wheels spinning, then you might have a serious center diff issue. That wouldn't really explain why the steering impacts the issue though.
    My bad. I didn't mean center diff. I meant front diff.

  6. #6
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    OK thanks. I think maybe both my diffs are shot , maybe even the center? When its up on the stand and I turn a wheel by hand , all the other wheels spin as well , with like 90% certainty. Every once and again it seems to work as it should but only briefly.

    Should I start with the center , front , or rear? It doesn't seem to be limited to the front tires so that makes me think center diff? But again I am incredibly new to this. I enjoy doing the work and upgrades but my knowledge is very low still.

    I really appreciate you taking the time to reply to me.

  7. #7
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    So you have 3 diffs in your vehicle. The center diff is filled with 20 million weight oil, which can basically hold it's shape like jello or silly putty. As a result, transfer of rotation in the same direction through that diff is expected. The front and rear diffs have much thinner oils. Thus the expectation that turning one front wheel will cause the other front wheel to rotate in the opposite direction. If rotating a single wheel causes all the others to rotate in the same direction, that sounds like the corresponding front/rear diff is jammed.

  8. #8
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    Thanks again omen for you help and knowledge , I really appreciate it.

    I took apart the rear diff didn't find any issues with it. All the teeth still look really fresh no chips or wear at all. I should probably add that this whole car is only about 1 month old , 6 weeks at the very most. I hope I find something wrong with the front otherwise IDK whats up.

  9. #9
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    Erevo has a reputation for being really fast and really fun. It also has a reputation for breaking really badly. I had one bad wreck that took out my servos, deformed the batteries, stripped the pinion gear, destroyed the transmission gears and cracked the transmission case, cracked the front bulkhead, and deformed the metal plate that holds the front end together. Crazy thing was, some of those issues didn't really become apparent until several runs after the fact. So I'm not surprised that things are wonky after a heavy bash session, but hopefully you can track down the issues and get them fixed easily.

  10. #10
    RC Champion grizzly03's Avatar
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    Does it turn right more than it turns left?
    How's your front end alignment? Do both your front tires point straight ahead, almost parallel to each other?
    The CV style axles can bind up if turned too much. Without seeing it personally I'm guessing it could be an alignment issue. It's turning too far to the right and binding up.

    From the factory when the steering is at neutral, both front tires point straight ahead. And when turning the tires turn equally to the left and right.

  11. #11
    RC Champion Acidic01's Avatar
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    On my cars I can turn one tire by hand and I can get all other tires to turn. But I run heavy diff fluid... So if other tires turn it's not really a sign that there is a issue that is just how the diffs work. The thinner the diff fluid the less chance the other tires may turn.....

    I think grizzly is onto something. Check your drive cups and axles. If turning right causes car to lock up... Then something is binding in the front end.

    Start making detailed look at all parts in the front. And check that the car does not turn to the right more than the left.

    Sometimes things get broken that are hard to notice untill it fully breaks or create other issues that make you look the car over in detail or make other parts fail... Examples cracked bulked heads....

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    RC Champion Acidic01's Avatar
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    Worse case take the whole front end apart examine every part for damage and reassemble. Great way to get to know your car. Make sure you have parts explosion pulled up or printed off... It's also in your manual / paperwork that came with car....


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  13. #13
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    If it is notching in the diff output cups, to simulate the problem, you might want to push down on the truck to compress the suspension. Then the bones are in the cup the same depth as they would be when driving (or more close to it). Would likely be best to also use the remote to spin all the tires as you push down and turn the steering wheel.

    If the cups are notched, when spinning tires by hand, your causing the drive pins on the dogbone to touch the side it doesn't normally touch when driven by the motor. So instead of the dogbone getting pushed by the cup, it's being pulled.

    I'd look closely at the front output cups and the dogbone pins. Could be a pin is working it's way out of the bone. I haven't seen that on my ERBEv2, but I have seen it on others.
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    Quote Originally Posted by olds97_lss View Post
    If it is notching in the diff output cups, to simulate the problem, you might want to push down on the truck to compress the suspension. Then the bones are in the cup the same depth as they would be when driving (or more close to it). Would likely be best to also use the remote to spin all the tires as you push down and turn the steering wheel.

    If the cups are notched, when spinning tires by hand, your causing the drive pins on the dogbone to touch the side it doesn't normally touch when driven by the motor. So instead of the dogbone getting pushed by the cup, it's being pulled.

    I'd look closely at the front output cups and the dogbone pins. Could be a pin is working it's way out of the bone. I haven't seen that on my ERBEv2, but I have seen it on others.
    Thanks for the reply. I did notice when taking apart the rear diff that the drive cups are pretty heavily notched and/or worn but the front ones still look perfect. I suppose that could cause the hiccups but doesn't really explain the turning thing. I am going to take apart the front end tonight and If I dont find anything in the tire knuckles or steering components Ill take apart the diff.

  15. #15
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    Quote Originally Posted by grizzly03 View Post
    Does it turn right more than it turns left?
    How's your front end alignment? Do both your front tires point straight ahead, almost parallel to each other?
    The CV style axles can bind up if turned too much. Without seeing it personally I'm guessing it could be an alignment issue. It's turning too far to the right and binding up.

    From the factory when the steering is at neutral, both front tires point straight ahead. And when turning the tires turn equally to the left and right.
    Thanks for the info. I do check my alignment frequently , I am not going to say that its perfect but it is definitely something I keep an eye on. If it's out of alignment it is not by much but I will check it out after pulling apart the front end. Thanks again

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