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  1. #1
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    Angry clutch bearings wear out faster than the clutch

    I have messed with nitro rc vehicles for 10+ years. I'm on my 2nd 3.3 motor in my revo and the clutch bearings just aren't holding up long at all. Both motors exsct same thing. Before I can wear out a factory clutch the bearings have torn apart. Anybody know anything to stop chewing up bearings??? It's getting frustrating now..I've had to replace the motor mount because I wore it out taking the motor off replacing bearings...I am running aluminum 2 piece shoes with factory spring around them right now cause I've seen them last a long time m.but its the bearings..sorry for long post..please any advice greatly appreciated

  2. #2
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    I had the same issue. Could be a couple of things...heat, what does your engine run at temp wise. Second, mesh. A wrong mesh will chew up the bearings pretty fast. Make sure the tranny is tight and you mesh is solid

    Hope this helps

  3. #3
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    Quote Originally Posted by stroker3.3 View Post
    I had the same issue. Could be a couple of things...heat, what does your engine run at temp wise. Second, mesh. A wrong mesh will chew up the bearings pretty fast. Make sure the tranny is tight and you mesh is solid

    Hope this helps
    The motor normally runs 230-240 degrees ...I have to assuming the mesh is right I'm running the same spur gear that came on it new.. and it still looks good..I've been doin this quiet a while and this is the only one ever did this to me. I'm trying aluminum shoes now but hadnt had time to tell if that helps any..any more ideas please???
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  4. #4
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    I have been doing this quite a while too, and have had multiple vehicle platforms over the years. Shoes will always outlast the bearings. Bearings are cheap, and there is no reason not to replace them regularly, as a standard maintenance practice. I buy CB bearings in a 10 pack, for each vehicle that I own. I check them all the time, and replace them before they become a problem. I may change them within one raceday, even though I started out with a new set at the beginning of the day.

    The only 2 things that will break down the bearing quicker than normal, are what stroker pointed out, heat or mesh. If your mesh is too tight, it will create more heat. Just because your spur looks good, doesnt mean that you have not been setting your mesh too tight. Also, if some other aspect of your drivetrain is presenting too much load on the system, the clutch is going to take the brunt, and lead to more heat. If your chassis was bent, the CB/Spur mesh will not be parallel, and the bearings will take the brunt of this load.

    Aluminum shoes will not increase the life of the bearings, relative to a stock clutch.
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  5. #5
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    one more thing that will wear out clutch bell bearings is if you have them shim to tight and not enough play for teh clutch bell to move back and forth...
    you know.. i never had a sig.. but i do now...

  6. #6
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    Quote Originally Posted by kgombe1 View Post
    one more thing that will wear out clutch bell bearings is if you have them shim to tight and not enough play for teh clutch bell to move back and forth...
    How much play should the clutch bell have? Or movement ..I take all things said into consideration ..for example oomp days frame maybe tweaked..never crashed or hit anything to cause this. Remember it happened from brand new..now on 2nd motor..I have to think I've set the gear mesh every way possible from extremely loose to extremely tight. I buy bearings from rev-tech 50 at a time ceramic speed bearings with shield..it is easy to replace the bearingsbyes but I have friends who I work on there trucks..put cheap factory bearing and clutch in and they go through 3 or 4 clutches on the same bearings. I thought maybe I had a problem in my crank or something like that..but now on motor 2 same problem..but what I hear it isn't a problem..if you change 2 times a day I would have fun watvhing my revo burn before I did that. Obviously this wad a bad question ..didn't want to get flamed out at over a "opinion"...so ill worry with my bearings or a fire lol. Thanks for any positive input..no thanks on the harsh for no reason .
    Have a blessed day .
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  7. #7
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    1mm is safe but the most i will go..... i race now and i go through more bearings than i do clutches... through my experience ceramic clutch bell bearings offer nothing in performance or longevity .. rem that bearing is only in action at idle once vehicle is moving everything spins at same speed... so 1 dollar bearings are the way to go.. or you can get those tko special bearings... man those things last for ever.. don't think they have them in revo size though.


    good luck.. Oomp is an awesome guy... but asking for help and when someone offers their help and in yor response you have "i have been doing this for a while" well clearly you need help and you ran into something you can't fix so your experience is not helping you.. so don't be mad when you get responses that mirrors your comments..


    hope you fix you problem... peace out
    you know.. i never had a sig.. but i do now...

  8. #8
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    Quote Originally Posted by kgombe1 View Post
    1mm is safe but the most i will go..... i race now and i go through more bearings than i do clutches... through my experience ceramic clutch bell bearings offer nothing in performance or longevity .. rem that bearing is only in action at idle once vehicle is moving everything spins at same speed... so 1 dollar bearings are the way to go.. or you can get those tko special bearings... man those things last for ever.. don't think they have them in revo size though.



    good luck.. Oomp is an awesome guy... but asking for help and when someone offers their help and in yor response you have "i have been doing this for a while" well clearly you need help and you ran into something you can't fix so your experience is not helping you.. so don't be mad when you get responses that mirrors your comments..


    hope you fix you problem... peace out
    I'm sure he is..I'm not mad at all I ask for advice..there's two ways to do that ..I appreciatevthe advice from anybody because the more I hear the more I rule out...both you give me good advice..and I said I been doin thid a while just to let folks know I'm not new to nitro that's all..didn't mean anything else..I've had easily 30-40 rc cars just never this problem..and I said about ceramic bearings because seams I get about twice ad long with them..I have machine shop with c&c mills and I get those bearings for same price of cheaper bearings because my machines use ceramic.bearings..but thank you and oomp for your help I have other things to look for now..ill Mic out my cb clearance in the morning something I've never did..do learned something new there...
    Have a good one.n
    Last edited by Double G; 05-21-2013 at 11:39 PM.
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  9. #9
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    Quote Originally Posted by kgombe1 View Post
    one more thing that will wear out clutch bell bearings is if you have them shim to tight and not enough play for teh clutch bell to move back and forth...









    Since I've never went down that road let me ask this...is a lighter cb ot a heavier cb the best way to go..the light one obviously had a lot of opening to slow sir inn..the heavier one does not..what'd your take on that or everybody ot anybody I'm all ears...may have started on wrong foot and I hope my appologies are accepted across the board..this is a forum and again I'm all ears.
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  10. #10
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    personally the difference in clutch bells should be vented or not.. and i would go vented which is lighter, but i go for the ability to keep the clutch cooler, but as you say depends on the conditions it could do more harm than good, when playing with weight around the clutch area the flywheel is where the weight would make a difference in performance, but then you get into racing aspect of it, those options aren't made for the revo...
    you know.. i never had a sig.. but i do now...

  11. #11
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    Hey, it's all good. There are no bad questions. Sometimes, the conversations go a little sour though, LOL.

    The bearings we are talking about are only meant to handle a radial load. Doesnt really matter the composition of the bearings, because in this size, they don't make bearings that can effectively handle axial runout. Being a machinist, as I am also (23 years), you understand how critical some assemblies are. You understand circular runout, etc..

    I am less concerned of the CB bearings in my sons buggy, because of it's flat chassis, than I am of the CB bearings in my Revo. That is along one of the points I was trying to make. The revo chassis, in the motor mount area, is flexing all the time. The gear mesh is moving right along with it. I see this forced circular runout of the CB bearings, as a contributing factor to the bearings needing servicing more frequently. It flexes when you nail the throttle, land a jump, etc.. It may return to a neutral position at rest, but believe me, it was moving while you were driving.

    It still all comes down to the same things, heat or runout. The engine temp is not really a factor, because you would have to keep overheating it for that heat transfer to affect the CB bearings. These things are either caused by something out of your control, or operator error. Just as Kgombe pointed out, it could be something as simple as you trying to shim the clutch bell just right (being a machinist, this would seem the right thing to do), but it may need to be a little sloppy to spin smoothly while the load is fluctuating. Kgombe is a much more seasoned racer than me, and I am pretty sure has owned a Revo since they came out, so I respect his points of view.

    I would like to add one thing that is irrelevent to the topic. Ever since this forum changed it's format, I HATE TYPING. It cannot keep up with me, and I have to correct half of every sentence that I type. It's like the spacebar is disfunctional. Example like this; It' slike the spaceba ri s disfunctional. Like the screen is refreshing while Ia m typing.
    Believe 1/2 of what you see,and 0 of what you hear

  12. #12
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    I'm gonna check all this very thoroughly hoping to find a problem a answer..thanks for all thevinput..
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  13. #13
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    seems like you space bar is dysfunctional t :-)
    you know.. i never had a sig.. but i do now...

  14. #14
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    Quote Originally Posted by kgombe1 View Post
    seems like you space bar is dysfunctional t :-)

    I think I hit the v or the b Thinking I hit the space bar ..lot of times my mind is three sentences ahead of my typing lol ; )
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  15. #15
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    Something to ponder ...I measured the amount the clutch bell can travel..first conversion of mm to in. 1mm is .039 in. Mine was .030...then specked the mesh between the spur and clutch bell... It was .021 ... With that it seems that should work fine. I rigged up a small jig to hold the chassis and use movement of a machine head and table to make the chassis flex up..now I know there's no way to tell how much it actually flex's on take off at wot ot landing a descent jump. But I flexed it .491 with .500 being 1/2 in. And at .491 there was still movement between spur and clutch bell..flexing in the other direction had hardly no difference in the travel distance...still testing and looking hoping to find a problem...any ideas are appreciated.
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  16. #16
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    You flexed the engine mount flange .491"? I must not be grasping what you are laying out here. The flex I was refering to, was only in regard to the engine mount flange. It is the weakest part of the chassis, the reasoning for Traxxas adding a brace below the engine mount on the 3.3 version, and some of us use the M2C brace because it is machined from billet. And also, some use a Qoncepts brace on top of the engine mount flange. Anything to keep the engine mount flange from flexing. It is, and always will be, a major flaw in the chassis design.

    If you flexed the engine mount flange upward .491", the CB would be smashed into the spur gear, and rip the tranny right out of the chassis. There would be no .021 mesh anywhere, it would be .0000. Flexing that engine mount flange that much would shear it off, or at the very least distort it to the point of it not being able to be fixed or straightened. If you flexed the flange downward, you would shear it right off, or at the very least distort it to the point that proper mesh would never be possible.

    I must admit, I am now confused at to what we are talking about. Kgombe and I were only trying to make simple points. The same logic that we are laying out, applies to all RC chassis types. If the gear mesh is tight, the bearings are going to go bad quicker. If the gear mesh is crooked, the bearings are going to go bad quicker. If there is no front to rear play in the CB assembly, the bearings are going to go bad quicker. The first two examples will occur at the same time when the Revo chassis flexes.
    Believe 1/2 of what you see,and 0 of what you hear

  17. #17
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    Thanks for all of both of you guys help. I can see how I have you lost but bottom line is the last few sentences you said period ..if its not right gonna go bad lots faster that simple...
    Again thanks for the help I'm just checking every thing possible at this point. I'm sure to fun across more crazy stuff lol...seeya later
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