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  1. #1
    RC Qualifier nebulous.cow's Avatar
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    Latest development with my 3.3, blown bearings.

    Hey nitro folks,

    Title says it all. My new 3.3 in the Revo I purchased new about a month ago with less than a gallon on it has had one (maybe both) bearings go out. What the heck.

    The insides look great. Never ran too lean, there's zero burnt or pitted spots on the piston, sleeve, or head, no rust, no corrosion, all of the friction zones are mirror polished from running. Of course when i opened the motor up, it had a nice coat of oil on it from the fuel.

    It was making a metallic rattling sound, I'm familiar with the sound of bad bearings in nitro motors, from my nitro helicopter days. Heard the sound, drained the fuel and ran it dry, and dropped the engine out to inspect.

    What gives? I've literally never had a nitro car bearing go bad ever. I tune well, I clean the motors quite often, inside and out, no leaks, yet it blows a bearing so soon.

    What gives? I've seen other posts online over the years of people just having the worst time with 3.3 bearings, and I am getting very tempted to have it warranty repaired and then just flipping the motor. Worried my Jato with the 3.3 is going to follow suit with the revo in a short matter of time as well.

    Sorry for the rant, just real bummed this happened so fast. Any engine bearing kits you guys recommend? Grizzly told me some, any more ideas appreciated. To me, bearings should last at least as long as a piston/sleeve does, this wasn't even close. I can see the metal ball bearing parts all stuck up in the piston top, and the metal pieces nuked my glow plug too. Luckily the sleeve walls and piston skirt are unharmed though, so looks good that the bearing didn't take out the rest of the motor too.

    Anyone else have this experience with TRX motors?
    Thanks in advance.

    -Mike

  2. #2
    Marshal Double G's Avatar
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    Never had issues with my 3.3 engines. I replaced the bearings every gallon and a half or two with either Boca or Avid RC bearings. Now that I have a .21 I replace them about every gallon.
    The Super Derecho

  3. #3
    RC Qualifier nebulous.cow's Avatar
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    Good to know, just seemed like such a short life span. All my other engines got multiple gallons in before something else went wrong or I parted ways with the motor.

    I saw Boca has a cheap hybrid ceramic kit for the TRX motors, might pick that up for my Jato 3.3 motor.

    I just bought the OS 21tm engine for the revo, found a nice discount code so I figured why not, I just keep staring at it. If I love it, might have to squeeze one in the Jato as well. Looking forward to that.

    Hoping Traxxas will warranty it, I have not heard back from them yet....

    -Mike

  4. #4
    RC Champion grizzly03's Avatar
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    Quote Originally Posted by nebulous.cow View Post
    I saw Boca has a cheap hybrid ceramic kit for the TRX motors, might pick that up for my Jato 3.3 motor.
    For high precision bearings, Boca Bearings are my go to.

    I just bought the OS 21tm engine for the revo...
    You should be much happier. Mine lived up to their reputation.

  5. #5
    RC Qualifier nebulous.cow's Avatar
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    Hyped. Hey, liking the new avatar Grizzly!

    Yeah I found the Boca kits for the 3.3, they have a bunch of options.

    I used the "ceramic hybrid" set in my heli engines, and I didn't keep it long enough to see what happens when they wear out.
    Any particular kit either of you guys recommend from them? I was thinking the ceramic hybrid ones for $24, since I had good luck with them in my last application. But any other suggestions, please.

    Thanks guys
    -Mike

  6. #6
    RC Champion grizzly03's Avatar
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    Quote Originally Posted by nebulous.cow View Post
    Hyped. Hey, liking the new avatar Grizzly!
    Thanks! First brand new Big Boy ATV. I still have it. Strong runner like an O.S. LOL
    Like yours too! Keeping my R6, one day i'll get back on it.
    Yeah I found the Boca kits for the 3.3, they have a bunch of options.
    I would say personal preference. I probably would try them. It would be those $24 hybrids or the $29 kit.
    Last edited by grizzly03; 05-13-2020 at 03:39 PM.

  7. #7
    RC Racer
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    I am actually looking to get new bearings for the ol Pro 15. I took them out yesterday and they were a little shabby. Are Boca by best bet there? I also saw Fast Eddy but those looked a little cheap.
    I'm not afraid of my fellow man.

  8. #8
    RC Qualifier nebulous.cow's Avatar
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    I've had great luck with any products from boca over the years, for a variety of applications. You really can't go wrong man, I recommend them. Price is right, they come packaged really nicely, and I've never had any of them go bad. I might cheap out on bearings for wheels or hubs, but for engines, motors, bicycles, anything that matters a little more, boca is great imo.

    I'll be picking up the 24 dollar kit most likely.
    In other news, I got the jato to finally wheelie at my high altitude! Super fun, but the low speed needle is totally untunable. Stock needle settings completely close the fuel off, the heck lol.

    Maybe she needs a 21 next month too! Haha. And a ths system as well.

    -Mike

  9. #9
    RC Champion grizzly03's Avatar
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    I prefer the higher ABEC ratings of Boca Bearings for engine bearings. These little guys are turning 30,000+rpm's. I don't want to destroy an engine because i went cheap.

    I use the cheaper bearings where I don't mind if they go bad. If a wheel bearing goes bad, I only need to replace the bearing.

  10. #10
    RC Qualifier nebulous.cow's Avatar
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    Well dang. Turns out Traxxas does NOT warranty engines at all. Just got a message back from them, and they said they just don't do anything at all involving engine internals.

    Seriously???

    I mean at the end of the day it's only a $25 fix, but come on, they didn't even want to hear it. Even for them, it's easy to get customer satisfaction by replacing cheap parts, it's not a whole engine...

    I've had OS and HPI both send me engine parts for free when something went wrong, and I think that is because, quite frankly, those engines rarely have issues.

    How can they put no warranty on the engine at all? They said it's "guaranteed to start, that's it". So if it blows the 3rd tank, you're OL?

    Man they used to do support for their engines, what has this hobby come to... I would have been happy with even paying half for a new set of bearings, but they just turned me away.

    So I bought the 21TM and it comes tomorrow. Bummer.
    3.3 is for sale, half a gallon and internals nearly perfect, needs bearings.

    -Mike



    *Traxxas has a strict language policy which includes acronyms. Please keep it clean.
    Last edited by Double G; 05-14-2020 at 08:14 AM.

  11. #11
    RC Turnbuckle Jr. Nitronaught's Avatar
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    Avid R/C bearings, might as well go ceramic, makes a great difference. I've modified/fuel ported and crank polished many engines, I raced the TMAXX 1 year sponsored and 6 years on my own. I notice you mentioned the engine was never overheated. So did you check the pinch of the piston and sleeve?

    Also high temps are not the only thing that can cause baring failure and honestly I have never seen a TRX 3.3 or 2.5 engine bearing failure in my or any other fellow racers cars. Not having enough temps, engine under 210 degrees could also cause bearing failure. IF the engine is too cool the case is not fully expanded and this causes additional stress on the internals, usually the conrod goes before the bearings would but this scenario is applicable to your issue.

    So the bearings failed? did bearing material get into the rest of the engine? Either Way if you get new bearings Avid Bearings are FANTASTIC. I use them on my axles, transmission, engines, throttle turnbuckles, basicaly any bearing on my TMAXX or other R/C's are Avids.

    I did a complete bearing changeover at one time to see if there was a difference. I race on a track so I know how much run time I have before I need to come in for fuel in a race. When I did the total swap over I literally got 1-2 more laps before refueling. That tells me it's running more efficient, I also cut time off my laps which tells me I'm also getting up to speed a little quicker.
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  12. #12
    RC Champion grizzly03's Avatar
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    Quote Originally Posted by Nitronaught View Post
    Avid R/C bearings, might as well go ceramic, makes a great difference...
    I have never tried their ceramic engine bearings (or their engine bearings in general). Maybe I'll give them a go (I'm rebuilding two engines).

    I know I wouldn't use their normal bearings in an engine. Are their engine bearings a much better quality?

    Edit: Just looked at their engine bearings, they are ABEC 5.
    Thanks for the insight Nitronaught

  13. #13
    RC Turnbuckle Jr. Nitronaught's Avatar
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    For all applications ecept the engine bearings, I recommend their Revolutions series bearings. Steel bearings, one side has a metal shield (that faces the clean side) the other side is rubber (facing the dirty side). They run $1.00 each average and the design is extremely efficient. I raced with those bearings in all my R/C's I raced (3 of them, MT, Truggy and Buggy). Never failed me one time...
    Ceramics should go where they deal with high rpms, that would be the CB and inside the transmission.
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