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  1. #1
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    Problems with RPM Hybrid Transmission Case

    I installed this trans case a while ago, and every time I take the truck out, I strip the idler, diff, or top drive gear. It's getting really freaking annoying!! I have installed everything correctly, following the exploded transmission view. I NEVER had any problems with the stock trans case. Is anyone else having this problem??

    Nick
    Last edited by Dadx2mj; 09-12-2013 at 08:55 PM. Reason: Language

  2. #2
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    That sucks, mine has been working great.
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  3. #3
    RC Turnbuckle Jr. Greatscott's Avatar
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    Have you made sure your bearings are still good?
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  4. #4
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    All were replaced with new Traxxas bearings the last time I had the top gear and idler blow out. Happened again today within 10 minutes of use. I may have found a problem... I don't know if this is it, but I took apart my "waterproof" velineon motor to find it literally full of dirt and the bearings were shot... A ton of shaft play. The rotor has dirt caked on the ends that's so hard from the heat that it's impossible to dig out. So I had to buy a new rotor. I'm thinking maybe the imbalance from the caked on dirt is causing a huge vibration and maybe causing everything to go whacky, killing my gears. I'll let you all know once it's all back together next week.



    Nick
    Last edited by Stang8URMPRT; 09-12-2013 at 09:02 PM.

  5. #5
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    motor shouldent do it

    if you havent cleaned out the transcase after every gear blow out. then the fragments could be cuaseing the continuios problem
    summit /mustang /stampede-2s spc lipo

  6. #6
    RC Turnbuckle Jr. DiggerPede's Avatar
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    Quote Originally Posted by reod12x2 View Post
    motor shouldent do it

    if you havent cleaned out the transcase after every gear blow out. then the fragments could be cuaseing the continuios problem
    +1 to that!!

    Also did you put the teflon spacers back in place? Those little suckers get lost quickly if you arent paying attention, could have been missed when you swapped to the RPM case. How does the case look bolted up? Any openings on any of the corners?

    I'm using the RPM case on my Slash and i've beat the snot out of it for countless hours with no issues.
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  7. #7
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    Case was cleaned spotless every time. All Teflon spacers are in place per the transmission exploded view. I'm stumped.

  8. #8
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    There are no spaces or openings either. Bolts together just fine and looks great.

  9. #9
    RC Turnbuckle Jr. DiggerPede's Avatar
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    Are you taking lots of jumps or bashing hard (really hard)? Just curious, i bash my Slash to the max, well not skate park extreme, but it ramps up a whole lot during normal running.
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  10. #10
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    The three times I've broken it I've just been going back and forth in parking lots. Not really bashing at all.

  11. #11
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    Steel or Nylon gears ?

    Does your slipper slip or is it locked down ??
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  12. #12
    RC Turnbuckle Jr. DiggerPede's Avatar
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    Man I don't know. Like said above after the first breakage you cleaned everything out of the tranny case and slapped new thin later of grease on the gears? How's the slipper, tight/ loose?
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  13. #13
    RC Turnbuckle Jr. rag6's Avatar
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    could be a defective gearbox, and it could be out of line inside somewhere. Have to ask... are you replacing the idler with the steel or alum one? The alum one is not as strong as steel and can fail with brushless power...
    Wanna bash at Greenwood Bashplex in Pittsburgh ???

  14. #14
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    Always metal (steel) gears. Slipper is adjusted about 1/8 off tight. It slips for just a split second before full engagement. Never had the gear box open before I replaced the case with the rpm one. Always been reliable until now. I will contact rpm and see what they say. And yes, liberal use of grease.

  15. #15
    RC Turnbuckle Jr. DiggerPede's Avatar
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    For a plastic gearbox, having owned an RPM one (not that all impressed), the stock one is actually nice. I do prefer alluminum ones for stiffness and cooling reasons. Something like the REM, or FLM one.
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  16. #16
    RC Turnbuckle Jr. rag6's Avatar
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    After re-reading all your responses(your doing everything right), it has to be the gearbox. You stripped the top gear. I dont think I have ever seen a broken top gear. The pin that holds it can fail, and should fail first, but the top gear is the keystone of the tranny. Ask rpm to send you a replacement. I have a feeling the gearbox is a defect. Now I could be wrong, but it seems to me that you have every other variable covered. Just my opinion tho...
    Wanna bash at Greenwood Bashplex in Pittsburgh ???

  17. #17
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    I would agree with you. I have contacted RPM about the problem and haven't received a response yet from them. The only variable that's changed from not stripping gears, to stripping gears is the case itself. I'll keep everyone informed of the progress!

  18. #18
    RC Turnbuckle Jr. DiggerPede's Avatar
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    I've contacted RPM myself also with no luck in receiving a replacement part. I ended up buying a new one or something else I felt was better. They make exceptional parts in some places and others are a total flop.

    I agree with rag I don't believe I've seen a top gear fail before. The spring pin goes first which is there to protect the transmission and a more costly fail. Who knows there can always be a first.

    Do you like the RPM one that you'd buy another?

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  19. #19
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    I mean, it's nice. But I only purchased it for the heat sink. The price was lower than a full metal case, too. I'm thinking of just buying another trans from a chopped truck and sticking it in for now.

  20. #20
    RC Turnbuckle Jr. DiggerPede's Avatar
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    Yep understand that. On my slash I swapped this RPM one for a GH all aluminum one to save weight and balance the truck back out.

    I haven't seen much of a temp drop from stock. If you feel it's worth trying again and see if that's the problem. Let us know.

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  21. #21
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    Problems with RPM Hybrid Transmission Case

    Quote Originally Posted by DiggerPede View Post
    Yep understand that. On my slash I swapped this RPM one for a GH all aluminum one to save weight and balance the truck back out.

    I haven't seen much of a temp drop from stock. If you feel it's worth trying again and see if that's the problem. Let us know.

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    And what are your thoughts on the GH case? Fitment wise anyways. you say not much difference in temp from stock. Ive contemplated getting one for my p2de but im not sure if it is worth it.


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  22. #22
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    I had a GH case and the gears didn't spin freely. I ended up sending it back. That's when I replaced it with the RPM case.
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  23. #23
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    Really wanted to like the RPM case. So close, so far away. I replaced it after maybe 15 runs with a Hot Racing all-aluminum one, which fits better, runs smoother, and looks like a million bucks. The worst single thing about the RPM box was the shock tower screws pulling out. Not backing out, pulling out. RPM plastic just won't hold a thread. I'll buy bumpers and other little bits, and the rod ends are very, very good, but other than that, no more RPM for me.

  24. #24
    RC Turnbuckle Jr. DiggerPede's Avatar
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    Quote Originally Posted by Blaster75 View Post
    Really wanted to like the RPM case. So close, so far away. I replaced it after maybe 15 runs with a Hot Racing all-aluminum one, which fits better, runs smoother, and looks like a million bucks. The worst single thing about the RPM box was the shock tower screws pulling out. Not backing out, pulling out. RPM plastic just won't hold a thread. I'll buy bumpers and other little bits, and the rod ends are very, very good, but other than that, no more RPM for me.
    Yeah my thoughts exactly. While I still have the one case installed on my Slash, it has been ok and I bash that truck pretty hard. I didnt like the fitment or the gap it had.

    Quote Originally Posted by theant View Post
    And what are your thoughts on the GH case? Fitment wise anyways. you say not much difference in temp from stock. Ive contemplated getting one for my p2de but im not sure if it is worth it.


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    I had this installed on my Slash for a few years right before the RPM one that is on there now. I didnt have any issues with mine. A few have had really good luck then all of a sudden it seemed like their QA/QC went to the pits or something and everyone was having problems with them. For the money and USA companys i'd go with REM and FLM, they have really good warranties to. I also like the HR ones.

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  25. #25
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    Problems with RPM Hybrid Transmission Case

    Quote Originally Posted by DiggerPede View Post
    Yeah my thoughts exactly. While I still have the one case installed on my Slash, it has been ok and I bash that truck pretty hard. I didnt like the fitment or the gap it had.



    I had this installed on my Slash for a few years right before the RPM one that is on there now. I didnt have any issues with mine. A few have had really good luck then all of a sudden it seemed like their QA/QC went to the pits or something and everyone was having problems with them. For the money and USA companys i'd go with REM and FLM, they have really good warranties to. I also like the HR ones.

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    The more i read the more i think i will just stick with the stock trans case. WAY cheaper than aluminum and marginally cheaper than rpm. Other than bringing temps down slightly it doesnt seem as though the value is really there in this particular upgrade. Plus the stock plastic trans case is plenty strong enough. I really like rpm parts so it is too bad to hear some people having issues. I have never had problems with any GH parts that i have ever used but have heard of others having fitment issues and pieces just snapping on them so seems to be hit and miss.


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  26. #26
    RC Turnbuckle Jr. DiggerPede's Avatar
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    Yep the stock gearbox works really well. If you were worried about temps you can add a heatsink and fan if need be. They help drop temps 5-10 typically. The only other thing is to gear accordingly.

    The alloy cases still come in handy for speed passes where you dont bash a whole bunch.

    I do have an REM black anodized gearbox on my Digger and I love it. It's been on there for over 2 years. I wouldnt trade it for anything else other than going back to the stock one. LOL
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  27. #27
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    This is the response I got from RPM.


    Usually when we hear of problems stripping anything in the gearbox, it is because the slipper clutch nut is set way too tight. Essentially, you're transferring 100% of the power from the motor through the gears or, the opposite is the problem where any sudden changes in the speed of the tires is directly transferred through the gears. Simply set your slipper clutch nut to the proper specifications and the problems should disappear. Please refer to your Traxxas owners manual for proper slipper clutch settings. We also recommend Traxxas metal idler gears for the best performance of the transmission.
    Take care and thank you for your interest and support of RPM products. If you have any other questions or comments, please feel free to send us another e-mail.

    I figured they'd do nothing to help.

  28. #28
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    I sent this in response..

    I would agree with you, but the input shaft into the trans has a pin designed to sheer before is takes out the top gear. After three sets of internal gears with your case, and zero problems with the stock case, the only thing that could be a problem is the alignment of the gears, specified by the location set forth from your case. My slipper clutch is set to slip for a split second at full throttle off the line, like it was with the stock case. What I'm asking for is another case. There is obviously a problem with the one I purchased.


    And promptly got this response...

    The pin on the top shaft is not a sheer pin, it is a roll pin (and in some vehicles, it is a straight dowel pin). It's sole purpose is designed to drive the gear. If it were a sheer pin, it would have failed before the gears failed in each one of the problems you've encountered.
    There is nothing wrong with the RPM Gearbox Housing. Again, your slipper clutch is set too tight. If it slips for a "split second", that is simply too tight and not adjusted according to Traxxas recommendations. RPM gearbox housings are molded so any replacements we were to send to you would be exactly like what you currently have. Take a look at any message board where damaging internal gears is a problem and you'll see the exact same answer we sent you. The slipper needs to be loosened. That IS the problem. Try our fix (which also happens to be stock recommendations) and you'll see that the problem will immediately go away. For reference, here's the manufacturer's recommendations - http://traxxas.com/node/89088 and as you can see, a "split second" is much too tight.
    Take care and please let me know if there is anything more I can do for you.

    And responded with this

    This is the type of response me and everyone on every forum I post on said I would get. Push the blame. It is not set too tight. I've never had this problem until I installed your gear box housing. Thanks for all your help and stand up customer service!

  29. #29
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    After reading your description of the slipper action, I am left wondering how close your "split second" is to the recommended "two feet."
    Additionally, the one thing you did not mention trying (or I missed it) was taking their advice. I am wondering what it would have hurt to do so. If you backed off the slipper to the point of slipping for - wait for it - three feet! and the gears stripped, don't you think you would have performed your due diligence and been able to give the CS tech some more complete information?

    As for the pin for the top gear, I'll have to disagree with you and my learned colleagues here regarding its function. IMO it is not intended as a shear pin. If your transmission is taking hard enough jolts to break it, then a.) your slipper is set too tight; or b.) the pin was formed badly; or even c.) there is something ELSE very wrong with your transmission.

    Now I realize that you are contending that "c" is the applicable scenario, but you as yet have not made a very strong case to support your claim.
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  30. #30
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    I do agree with trying their suggestion. The problem is a "split second" equals more than two feet with 3s and a brushless setup. The slipper is set up correctly. The major issue I have with this is the gearbox never had a problem before I put the trans case in. Now every time I go out its tearing up trans gears. Nothing has changed from before the rpm case to after its install.

    I don't care about the 6-12 dollars worth of parts it destroys every time, I'm more upset about the wasted time fixing it constantly. I have installed the new gears and its reassembled, waiting on USPS for the new rotor for the motor mi will let everyone know how it turns out. I'm not expecting a different outcome.

  31. #31
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    this just isnt right......rpm gave me the cold shoulder in terms of the case fitment.....

    but i have been hammering mine on 2s with the castle 3800kv motor and with the slipper clutch set tight enought(between 1/16 and a 1/8 turn off from tight) that if it slips for about a seconed or two it smokes lol.......and still useing about 2 1/2 yr old gears.....it must be the color of the trans case....what color is yours?......mine is black other then the holes not lineing up on the stock skid plate and the outer top bearing ovaling out a hole its mostly fine
    summit /mustang /stampede-2s spc lipo

  32. #32
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    I agree, reod.... If I adjust mine any looser it destroys the clutch. I guess a "split second" is a very vague description. Mine will slip quite a bit before full engagement. If I adjust it any looser, I can literally smell the clutch burning after 2 or 3 launches.

    I also understand my responses to RPM weren't very kind, and this is no excuse, but I knew this is the response I would get from them. Their exact words... "It's NOT the case" I wish I could blow every one of my customers off, saying it isn't my (or our) fault. It was never a question in their minds that I am at fault, not their product. This is just very poor customer service. I've been playing with these RC cars for almost 10 years, and have never had a trans disintegrate the gears like this, much less 3 times!!

    I thank all you for your responses and suggestions. I really do. My rotor actually did not show up today, but it should be here tomorrow. I will go out and play with it tomorrow, starting with the clutch really loose and tightening it until it's not smoking itself. But again, I've never had this problem until I changed to the RPM case.

    Nick

  33. #33
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    Btw, mine is blue.

  34. #34
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    Here is the trans before bolting it back together and obviously putting grease in. If anyone sees anything off, please let me know...



    Obviously the gears aren't tightly meshed without the other half of the case keeping everything together.

  35. #35
    RC Turnbuckle Jr. Wolfslash16's Avatar
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    Ok, is it just me, or is the diff and the idler gear barely even touching?

    EDIT: Never mind. Can you post a picture of the two halves together to see if there is any gaps?
    Sl2sh Slayer Summit Sl4sh Teton/Rally T-Maxx Pnde

  36. #36
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    Sure, the trans is already back in the chassis... so I'll get as good of pics as I can....







    Nick

  37. #37
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    Were you running 3s with the slipper 1/8th backed off with the stock tranny? Seems like trouble to me....

  38. #38
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    Yes... Been running 3s and brushless since the truck was about a month old. So approximate 7 months.

  39. #39
    RC Turnbuckle Jr. Wolfslash16's Avatar
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    Hmmm, every thing looks ok, I'm stumped... If you feel up to it, use a micrometer to measure the specs of the stock case, the measure the RPM case and see if anything is different.
    Sl2sh Slayer Summit Sl4sh Teton/Rally T-Maxx Pnde

  40. #40
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    If/when it strips the gears again, I will do that. Thanks for the advise.

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