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  1. #1
    RC Qualifier
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    Jul 2010
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    Rpm a arms must flex a fair bit

    Took car out today for first time in a month and finally it's running good again

    But twice I popped a losi axle out of the losi diff cup
    Strange thing is I can't bend the rpm a arms enough to pop axle back in
    So I have to remove wheel unscrew top pivot screw out all the way
    Refit axle and refit screw and wheel

    So they must flex a fair bit for them to pop out when it takes so much to pop them back in

    I can't run longer diff cups cause once the wheels are on full droop the axles touch the edge of the cup
    Maybe that's what's making them pop out when the suspension droops and axle locks on one of the two
    Side grooves on the diff cups
    Might have to stop suspension dropping so much when in the air or when doing cartwheels
    Hehehe

  2. #2
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    Try thicker oil to slow down the movements of the shocks...far as the a arms much rather be bothered by flex than breaking rpm arms are sooo nice
    ERBE,Losi 8ight,Slash 4X4

  3. #3
    RC Turnbuckle Jr. MITCH316's Avatar
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    May 2012
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    Get some summit shafts...you wont have that problem mate ; just the occasional one breaking.
    Rock n Rolla !

  4. #4
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    i have variable damping thingy in the shocks and also 70 weight oil in shocks
    i think the axles pop out when the car does cartwheels hehehe
    maybe i need a boot to go over the cup and lock onto the axle
    like a front wheel drive car axle which has cv shaft boots
    but in minature size hehehe
    anyway im happy i got it out after the haslses i had with tqi rx
    its all sorted now

  5. #5
    RC Champion
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    Quote Originally Posted by craig.mitch316 View Post
    Get some summit shafts...you wont have that problem mate ; just the occasional one breaking.
    But The summit shafts are a down grade vs the losi cvds. I would much rather spend 5 minutes unscrewing my pillow ball screw with an electric screw driver than purchasing and replacing parts.

    Sideshow, ive had this same issue when attempting backflips on concrete. Lol The only way i fixed mine was to actually screw the pillow ball screws a mm or two deeper. Even a little deeper than MC suggested. I also set the distance visually by where the dogbone sat in the cup. I am running P3 rockers and P3 pushrods, blue/purple even when bashing.
    Its All relative to your perspective.

  6. #6
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    its hard to go in to far as the axle then binds on cup when suspension is on full droop
    anyway i dont mind unscrewing it
    if i had rims with holes in them i would not have to remove the wheel heheheh

  7. #7
    RC Turnbuckle Jr. rjm2519's Avatar
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    Feb 2008
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    Yes rpm does tend to flex, on the rustler over time it causes the arms to bend at the shock mounting point, so at high speed it wouldn't track straight. I haven't had a revo long enough to see if this is a problem with the rpm arms on it. But it is something to keep an eye out for if you try do high speed runs.
    Donít handicap children by making life easy

  8. #8
    RC Qualifier
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    luckily when i first bought some rpm a arms on ebay
    it said how many do u want so i put 4
    well i then realise it was 4 of one side hehehe
    so i bought 4 of the other 3 sides
    now i have 3 spare sets hehehe

  9. #9
    RC Champion
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    Lol^ Good stuff.

    I suppose your only other option is RCM cups on cut traxxas stub axles. They do look like they have more length to work with, which is what you are after.

    The HPI chrome cups ive been running for center shafts have worn in pretty bad. So RCM is the way to go.
    Its All relative to your perspective.

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