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  1. #1
    RC Racer
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    New engine bearings

    Hey guys had a quick question for yall. I am looking online at the various engine bearings for a trx 3.3 engine that I believe the front bearing may have a leak. Anyway I have looked a few different places and notice that the front bearing is a 7x17x5 and the rear bearing is a 12x21x5. I understand the sizing and the differences between a normal and ceramic bearing as well as the different shield types on bearings. What I don't understand is why is there a regular rubber sealed 7x17x5 and then an engine specific 7x17x5 that costs $5 instead of $1 like the regular bearing? The same thing with the 12x21x5 bearing. The regular one is $1 and the engine specific one is $8.

    Could the shields be pulled off that bearing and used inside the engine? I do not mind paying the $13 dollars for the new bearings if needed, but if I can buy sets for 5 engines for $10 total I would rather do it. What gives here?
    Last edited by wvaughn7; 05-04-2013 at 06:29 PM.

  2. #2
    RC Champion
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    Traxxas is good, but so are other Manus

  3. #3
    RC Racer
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    Thanks that was exactly what I was looking for. I assumed a bearing was a bearing to an extent as long as they were from a quality manufacturer. I knew pulling the seals off the inside bearing wouldn't be a problem just didn't know if it would hurt anything, but now I know. Any other opinions on the subject feel free to chime in.

  4. #4
    RC Turnbuckle Jr. Nitronaught's Avatar
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    You can get the bearings without having to remove anything...
    If you are going to just do the seal removal on some other bearings avoid the bearing retainer, it's plastic and often can be damaged by trying to remove the seal....

    I use these front http://www.avidrc.com/product/1/bear...-bearings.html

    These rear http://www.avidrc.com/product/1/bear...-bearings.html

    Yeah they are double the steel bearings but hey if I'm going to the trouble of a full rebuild, might as well.
    Robin Williams
    He will be greatly missed...

  5. #5
    RC Racer
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    How about Boca Bearings? I'm afraid that if I was to do an engine rebuild and install a new piston and sleeve and also went ahead and installed a nice set of Boca Bearings, I'm afraid I will have spent just as much if not more if I just bought a new 3.3 on eBay. I hear so much hype about Boca Bearings and I'm tempted to buy a set but how are they so much superior to stock bearings?

    Also, I just installed a brand new 3.3 on my 4910 TMAXX and its sitting at just 6 tanks ran through it. I'm still unsure if I will do it or not but, would it be ok open it up and install Boca Bearings or would that not be advisable?
    Last edited by Monte_1977; 05-10-2013 at 11:29 PM.
    Traxxas Nitro Sport w/ TRX 3.3 Racing Engine

  6. #6
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    its really all up to the person on this issue, some like using expensive bearings, me personally i have my engines apart for cleaning and dinkering, often enough i could prolly use $1 bearings and be fine, i dont but i could, personally i dont see spending a lot on bearings, but some people do...

    its all up to your wallet in the end...

    as i said i rip my engines down the the last screw constantly, so yes you can open up your engine at anytime and do anything you like, such as bearing upgrades...
    Traxxas is good, but so are other Manus

  7. #7
    RC Racer
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    yeah...I dont see any point really on forking out a lot of money on aftermarket bearings either. Who's to say they're any better than stock bearings. I have never had any issues with the stock bearings but have seen some of the horrifying pics that other people have posted when they heard a strange noise coming from the engine and turned out to be the rear bearing which also left pitted marks on the top of the piston and cooling head. Then again...How many gallons of fuel and how much stress has the engine gone through. I think that if that happened to me, I'd just throw in the towel and buy a new engine.
    Traxxas Nitro Sport w/ TRX 3.3 Racing Engine

  8. #8
    RC Champion
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    Quote Originally Posted by Monte_1977 View Post
    yeah...I dont see any point really on forking out a lot of money on aftermarket bearings either. Who's to say they're any better than stock bearings. I have never had any issues with the stock bearings but have seen some of the horrifying pics that other people have posted when they heard a strange noise coming from the engine and turned out to be the rear bearing which also left pitted marks on the top of the piston and cooling head. Then again...How many gallons of fuel and how much stress has the engine gone through. I think that if that happened to me, I'd just throw in the towel and buy a new engine.
    look at the link i posted in post #2, that did happen to me, and i still saved the engine and it is perfectly fine now... happened at around the 10 gallon mark....
    Traxxas is good, but so are other Manus

  9. #9
    RC Racer
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    Yup... those are the pics. I have yet to experience that. Actually I hope I don't...haha. I have considered myself lucky so far and only have had to replace just the piston and sleeve. The only thing that I have happen to me considerably close to that was the runaway I had a the track. I was running my Losi XXX-NT with the stock Dynamite Mach .15 and also had the stock TX/Rx. I'm not exactly sure whether it was someone running on the same frequency, a near by CB radio or just some kind of interference. Either way... my car just took off by itself and hit the concrete wall at wide open throttle. Amazingly enough, nothing broke... that is except for the engine. Which of course seized up. There was a "corner/turn marshal" as they call them but he was some older dude that didn't know to grab the car quickly and plug the exhaust and shut the engine off in an attempt to avoid further damage. I tried to run down off the drivers stand and run across the track to get my car but the damage had already been done. It was still running at wide open throttle when I got to the car and the dude had it in his hand and he was like... "I don't know how to turn it off". He also didn't know that I had experienced a runaway. I wasn't racing, this was all just a practice/play day. Racing nitro here in my parts is a thing of the past anymore, it's all about electric... unfortunately. Also... sadly enough, I have heard that they're considering not even letting nitros run at all. I guess as the saying goes... "if ya cant beat em,join em" I wont get rid of my nitros but I'm considering buying a slash or something. I'm all about nitro and dont know anything about electric. All I cared to know was nitro. I like and prefer the looks,sounds and realism of a nitro powered engine.

    As for my Losi... The top of the piston had bits of piston and sleeve sitting on it and the con rod was toast as well. Bits and pieces of it were sitting in the bottom of the engine. I still have the engine as a conversation piece..lol. It now has an OS. 18 CV-RX, upgraded to the Traxxas 2.4 GHz Tx/Rx and also has Traxxas 2056 and 2075 waterproof digital servos.
    Last edited by Monte_1977; 05-12-2013 at 01:28 AM.
    Traxxas Nitro Sport w/ TRX 3.3 Racing Engine

  10. #10
    RC Qualifier
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    not sure if you guys know but you can buy a new case with bearings in it for cheap.
    $11.87 http://www.dollarhobbyz.com/servlet/...3.3/Categories

  11. #11
    RC Turnbuckle Jr. Nitronaught's Avatar
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    I've seen what happens with some "CHEAP" bearings... It's basically a roll of the dice...

    The bearings I used are $30.00 for both. Those are ceramics and you do get a little more efficiency from them (less resistance) so I can squeeze just a little more out of a tank of fuel and get up to high rpms a tiny bit quicker... When racing every little thing can add up...

    But also if you go to the same site you can get their chrome molly steel version of the same bearings for $15.00...

    Oh, and if you ever seen a rear bearing let go,,, You just bought another total rebuild or engine... I'd pay $15.00 for decent bearings. Ceramics are more expensive and not necessary for your average basher.

    Is it cheaper to buy a new engine? You can get them for $105.00 on Ebay new. My rebuild costs me $60.00 for piston, sleeve, conrod, and then $30.00 for the ceramic bearing upgrade. So $90.00 and I save a huge $15.00 loll... But I have the satisfaction of a nice rebuild cause I port and polish my internals as well.
    Robin Williams
    He will be greatly missed...

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