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  1. #1
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    I've about had it... (broken driveshafts)

    Got my new aluminum shock assemblies installed last night and was looking forward to a nice long drive. Went out...broke a drive shaft. Came in replaced it with another, broken...and again broken... That's right 3 broken drive shafts in about thirty minutes. All three were from the rear two assemblies. I am running the Revo drive shaft as recommended on this forum, but I have been through about 10-15 broken shafts... Not the full assembly, but one half or the other. Honestly I'm really tired of wasting my time and money. I love my Summit, but I can't afford to keep buying and repairing the same item over and over.

    I'm reaching out to you guys to see what I can do in order to remedy the situation. I am already using the Revo shafts, and I know that the Rustler parts can be retrofited in order to keep the U joints from popping out. I'm looking for a more permanent solution. I have already upgraded to the MERV RPM arms front and back. If I replace my rockers (LT) with the MERV rockers will the MERV shafts last longer? Also I understand that with the MERV RPM arms and MERV rockers, I should be able to run the steel CVDs correct? What do I sacrifice by replacing my LT rockers with MERV rockers such as these?

    http://www.amazon.com/Atomik-RC-Allo...+1%2F16+rocker

    I read the threads about broken driveshafts and people talked about using the P2 rockers...what's the difference between LT/P2/MERV rockers?

    Thanks!

  2. #2
    RC Turnbuckle Jr. JimmyNeutron's Avatar
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    You do know that the shafts pop back in...
    or are the ears getting ripped off?

    The difference between the rockers is ride height... and progressiveness of suspension pressure.
    P2 is the Merv rockers... and I would just go with stock.
    Whatever it is I just typed... could be wrong.

  3. #3
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    Yeah, Jimmy that's not including the times I've popped the U-Joints back in. The metal u-joint is ripping through the plastic. Do you recommend trying a Traxxas P2 rocker at all 4 corners with stock MERV drive shafts first? Or should I just jump to the CVDs with P2 rockers?

  4. #4
    RC Turnbuckle Jr. JimmyNeutron's Avatar
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    P2's with stock MERV axles.

    That is what I am running with buggy rear Dirt Hawgs on 2S and 3S... not a single issue.
    Whatever it is I just typed... could be wrong.

  5. #5
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    I had major issues with my stock Summit shafts and stock Merv shafts untill I put Merv arms, rockers, and Traxxas CVD's. I haven't looked back since and driveshaft issues are now the least of my Sumervs problems.

  6. #6
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    Alright, thanks fellas. I think for now I'll just replace my rockers with the P2 Traxxas ones. Then get new MERV drive shafts for the time being. If I can get a whole battery pack or two out of them I'll hold off on the CVDs. Good to know they are an option in the future though. Thanks!

  7. #7
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    I can understand the summit shafts as they don't take all that much abuse, but what the heck are you doing to break the stock plastic mini revo shafts?

  8. #8
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    Just driving...not jumping, not going and doing crazy stunts...kind of weird huh?

  9. #9
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    Quote Originally Posted by AggieFCO View Post
    Just driving...not jumping, not going and doing crazy stunts...kind of weird huh?
    Driving how? Into concrete walls? There is no way they are breaking from just driving. My 4 year is doing backflips off the trees in front of my house over and over and over again and the shafts aren't breaking. There has to be something else that is going on.

  10. #10
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    I wish I could tell you. Honestly I am just driving through the grass, sand, dirt roads, streets... Nothing that would be considered abuse by any stretch of the imagination. I'd love to have the shafts last longer than one to two battery packs, believe me. So far, I've shimmed the diffs, adjusted the slipper clutch, added RPM arms front and rear, added aluminum shock bodies, and replaced a ton of drive shafts. All have the U-Joints sheering out of the plastic shaft.

  11. #11
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    Impossible with what you are describing you are doing. Are you running 3s? You really can only break them by having the truck not moving and applying power or huge amounts of torque. At any rate, we need to figure out the problem.

  12. #12
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    No, I am running 2S in parallel. Anyone else find this so incredibly hard to believe? Seems to be pretty commonplace from what I've read on the rest of the forum. Summit LT rockers and arms = broken drive shafts no matter if they are Summit or MERV. Am I wrong?

  13. #13
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    My son drives 2s lipo. 2 packs a weekend and we have broken two stock Summit shafts and neither merv shaft I replaced them with. He backflips off the Tree in front of my house, hits things Like its his job and when he gets tired of driving, daddy plays with it. We aren't breaking drive shafts every run.

  14. #14
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    well...good to hear. want to swap Summits?

  15. #15
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    Have u checked to make sure one of the u joints is not binding especially at angles? Broke a shaft in my summit the other day it was pretty stiff even after some oil. Pulled it back off turned it 180 degrees and it was fine.

  16. #16
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    The shafts only fit 1 or two ways or they don't slide right. Certainly a possibility.

  17. #17
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    U mean rotate right? I'm talking the unjointed on the end of each shaft not where the join together and slide. Also if you have slid them apart u should make sure each end is lined up.

  18. #18
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    Quote Originally Posted by Crock View Post
    U mean rotate right? I'm talking the unjointed on the end of each shaft not where the join together and slide. Also if you have slid them apart u should make sure each end is lined up.
    I'm saying they only slide well Like one way, if they aren't sliding, that could do it.

  19. #19
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    I just ordered 4 new drive shafts, and the P2 Traxxas rockers. Will pay extra close attention to ensure they slide freely. Did you mention some type of lube on the inner shaft? I'm assuming something dry like graphite lube, white lithium, etc.
    Last edited by ksb51rl; 03-31-2013 at 10:12 PM.

  20. #20
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    I'm not talking the sliding part of the shaft. The u joints in both ends if they don't rotate smooth they will bind and break things. The sliding part really will not have any effect

  21. #21
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    Quote Originally Posted by Crock View Post
    I'm not talking the sliding part of the shaft. The u joints in both ends if they don't rotate smooth they will bind and break things. The sliding part really will not have any effect
    if they don't slide correctly, the whole system will bind. Not really sure which part your talking about.

  22. #22
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    Unless these are different from my summit shafts each end has a rotating joint one connects to the diff one connects to the wheel. If these do not rotate smoothly through out their whole range they will bind causing the axle to snap. The slid portion of the shaft has no real effect on the rotation. If it does not slide it will just bind up suspension travel. Like I said earlier I had one that was bound up on a new shaft. If I would have run it I would have snapped a shaft easy

  23. #23
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    There is no way that all aren't turning correctly with how many he says snapped. I went out yesterday And ran a couple packs through the kids summit. I most of the time flipping it Off trees, banging into things at top speed, flipping it over, etc. Nothing broke. Then the kid went at it. Nothing brine I am running 2 summit shafts and 2 merv shafts. I could understand a fluke where one didn't rotate correctly, but not all of them

  24. #24
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    Ya it could be a possibility. Only takes 1 stone or something to get flipped up to bind it and it falls out after. And if I had a brand new one binding then it is quite possible and a easy check and fix if they are. If they are not binding then he knows that's not the issue. Simple and easy to cross off the list

  25. #25
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    Stone coudl do it, but I doubt it. once or twice I could see, but 15 times no way, something has to be binding or something for it to keep snapping drive shafts.

  26. #26
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    Quick update. I installed the P2 rockers and 4 new MERV driveshafts. I checked for freedom of movement in the suspension and drive train. Everything seems fine. Only time will tell. Only thing I noticed that was non standard was a little bit of grease on the front diff outputs.

  27. #27
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    You can also take the merv shafts, and use the u-joints from the nitro rustler. They are the same size, only the pins are longer. You should also check your bearings, and make sure all is free there.
    T-maxx 3.3
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  28. #28
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    I don't think the u joints are too short. I'm having a plastic shearing issue not a problem with the u joints popping out. Thanks.

  29. #29
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    I think the rockers are a waste, you are limiting travel for no reason.

  30. #30
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    So is maybe your sllipper tightened all the way down. I run 2 2s parallel, and once I switched to merv shafts in the rear, no breaks. I am also still running summit shafts in the front until they break. There has to be a reason, either throttle control, a binding, too tight slipper, 3s, or 2s series. If you change out to heavier drive lines the carnage will just move to another spot, like the diffs or tranny. What gearing are you running? Are you in lipo mode? What wheels, and tires are you running? And how are you driving it?
    T-maxx 3.3
    Rusty 2.5r
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    Nitro 4-tec

  31. #31
    RC Turnbuckle Jr. pavmentsurfer's Avatar
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    Ive run a number of different 1/16 vehcles with all different sizes of tires on 2 and 3S and have never had trouble like that with shafts.

    The LT rockers and summit arms allow for more wheel travel. This means the wheels drop out farther than on a MERV with MERV arms and rockers. When the arms drop out this far, the CV joints are flexing at too extreme an angle and they end up failing. This is why using MERV arms and rockers helps. The dont allow the wheels to drop out as far so the joints aren't flexing at an extreme angle.
    Pede, Summit,
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  32. #32
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    Sure, that might help the occasional break, but giving up the extra travel is not going to help breaking shaft after shaft.

    Quote Originally Posted by pavmentsurfer View Post
    Ive run a number of different 1/16 vehcles with all different sizes of tires on 2 and 3S and have never had trouble like that with shafts.

    The LT rockers and summit arms allow for more wheel travel. This means the wheels drop out farther than on a MERV with MERV arms and rockers. When the arms drop out this far, the CV joints are flexing at too extreme an angle and they end up failing. This is why using MERV arms and rockers helps. The dont allow the wheels to drop out as far so the joints aren't flexing at an extreme angle.

  33. #33
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    As an added measure of security I took my Summit to my LHS and asked them to look at my slipper clutch. I adjusted it according to a video posted on YouTube, which matched Traxxas' directions. However I never had a chance to compare my tension spring against another vehicle. For some unknown reason my slipper clutch was tightened all the way down. As most everyone said on the forum. I got it adjusted now so that when I give full throttle from a dead stop my front tires lift slightly, but it won't do a wheelie. It was a good learning point for me, because the references I was using to adjust my slipper clutch didn't give me a clear enough picture of what the spring should look like or how much thread should be showing on the slipper clutch shaft.

    What I did like, whether perceived or not, was the lower stance that the P2 rockers gave me. I wasn't flipping over as much in the turns, which was nice, and for the first time ever I made it through a while battery pack (in parallel of course) without breaking anything. You should have seen the smile on my face. I did have to do some slipper clutch adjustments at the park, but I think I have it dialed in.

    New suspension parts worked well too. I think my stock Traxxas shock tubes were leaking oil because they don't have as consistent feel as the new HR bodies I have installed. Maybe in time I might switch back to the LT rockers, but for now I'm really happy where I am.

  34. #34
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    On 2S lipo, I can easily flip the truck on its lid, are you saying you can't wheelie now if you nail the trigger?

  35. #35
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    Yeah, and I realize that I may have the slipper clutch too loose, but after all the repairs I've made I'm not in a hurry to crank that sucker back down. I'm happy where it is.

  36. #36
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    Quote Originally Posted by AggieFCO View Post
    Yeah, and I realize that I may have the slipper clutch too loose, but after all the repairs I've made I'm not in a hurry to crank that sucker back down. I'm happy where it is.
    Problem is thats a double edged sword, two tight and you can break drivetrain parts, too loose and you burn up the slipper.

  37. #37
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    Thanks to your good Karma, my kid is busting rear diffs weekly now if it makes you feel any better

  38. #38
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    Ha, doesn't make me feel better. I know how much it sucks to have to fix stuff. But I am sure "back-flipping" off trees doesn't help. You seem knowledgeable enough to solve the problem. Best of luck!

  39. #39
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    No it doesn't help, but he's barely four and he thinks it's cool, so what's daddy to do? I don't really know what to do as I posted on another thread. Probably just keep fixing it until I buy him a truck that won't rip up diffs so easily. Center diff might be next to help the drive train.

  40. #40
    RC Turnbuckle Jr. JimmyNeutron's Avatar
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    My center diff in the MERV helped a lot... be sure to top it off with 50K before installing. Mine was empty upon arrival.
    Whatever it is I just typed... could be wrong.

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