RPM axle carrier bearings bad after an hr?

[stealth2669]

So I replaced my axle carriers with RPM's about a week ago and got about an hour of runtime on them in a dirt pit and when I came in to shut it down it sounded like their was tons of sand stuck between the axle and the carrier well I took it apart and it wasn't all that dirty so I removed the bearings and the smaller one wouldn't spin and the large one felt like their was tons of grit in it?!?!? Any ideas? Could a hard lateral load have caused this? I landed about a 7ft jump on one of the front tires and expected damage but nothing broke could that Destroy the bearings?

 

[olds97_lss]

Not usually... what kind of wheel hex's do you have? Alloy or plastic? I'm talking about the little hubs on the axle that has a pin behind them.

 

[stealth2669]

Stock 14mm plastic

 

[Metalhead Matt]

I'd say either a bad pair of bearings(very rare) or a bad install(pretty rare). I think you had bad luck was all.

 

[olds97_lss]

Tightening the wheel nuts too much with stock plastic hex's will cause the back of the hex to smash into the bearing which will ruin the seal on it and cause it to bind/overheat.

I wish RC companies would just buck up the extra $10 and put alloy ones on all rigs. I mean really, this day in age with the kind of power they jam into these rigs and still using plastic hex's... just plain stupid IMHO.

 

[stealth2669]

Tightening the wheel nuts too much with stock plastic hex's will cause the back of the hex to smash into the bearing which will ruin the seal on it and cause it to bind/overheat.

I wish RC companies would just buck up the extra $10 and put alloy ones on all rigs. I mean really, this day in age with the kind of power they jam into these rigs and still using plastic hex's... just plain stupid IMHO.

I think you nailed it. Thanks for the input you'll probably save me from more bearing failures, didn't want to lose a wheel.

 

[stealth2669]

I've been looking at replacement aluminum hex's and call me crazy but the hex should only press against the inner race correct? Most all of them appear to be machined flush?? I imagine the axle should be pressing against the other side of the inner race like in automotive applications?

 

[olds97_lss]

Actually, it shouldn't press against the bearing at all, it should press against the pin that goes through the axle. Most hex's have a very faint collar on the back that would rest against the bearing, but it really should have a very small air gap or you run into the problem your having now.

Traxxas makes some that work just fine. May want to stick with factory on something so crucial to fitment. They cost a bit more, but fit well:
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXSP60&P=7


You can see that barely raised portion on the back of the stock hex's:

 

[stealth2669]

Excellent info, thank you very much. I'm going to get the traxxas to ensure proper fit.