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redcat rampage front diff help please

Discussion in 'General Large Scale RC' started by JBloom33, Aug 18, 2015.

  1. JBloom33

    JBloom33 Member

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    I bought a used rampage Mt and it runs and drives good but feels like it has drag on the drive train cuz it slows it's self down a lot when I let off the gas and the brake is not dragging.. I took off all 4 wheels and noticed the back hubs spin freely by hand on both sides but the front hubs get maybe a 1/4 turn either way and stop on both sides.. I can not turn the front axles at all by hand? Is this a diff issue? And no the pins are not sticking out and dragging.. shouldn't it spin just as freely as the rear? Any help would be greatly appreciated as I am new to 1/5 scales
     
  2. looker2756

    looker2756 Well-Known Member

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    Yes the front & rear should feel the exact same.
     
  3. JBloom33

    JBloom33 Member

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    So I have something binding in the diff?
     
  4. looker2756

    looker2756 Well-Known Member

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    Or some bearing problem. Remove both side dog bone drive shafts, and attempt to spin everything sperately, and see where the binding is at.
    It is possible that you will have to go inside the differential housing, but maybe not.
     
  5. JBloom33

    JBloom33 Member

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    OK remove each drive shaft and try to spin the diff cups separately? When I spin the drive gears the center drive shafts spins so I will check the cups.. it drives fine u can just tell there is drag on it and I can't spin it by hand so something is definitely wrong.. am I supposed to use grease and diff lube in the diff? I searched it but everyone says something different.. if I'm gonna open it just wanna make sure I have the right stuff.. thanks
     
  6. looker2756

    looker2756 Well-Known Member

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    Some people use VERY thick oil in the differentials to make them harder to turn, causing a limited slip / Semi Posi traction action.
    This is also possible.
    Would be worth taking a look at though, as drag in most cases causes slower speeds, and possible future failures.
     
  7. JBloom33

    JBloom33 Member

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    Thanks for the replies.. I took the diff all apart cleaned all the old sticky caked up factory grease and am ready to put it back together but gotta decide what grease/lube to put in there so any help at this point would be greatly appreciated
     
  8. looker2756

    looker2756 Well-Known Member

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  9. JBloom33

    JBloom33 Member

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    Thanks.. I took apart front diff cleaned it all up add 7k diff fluid and it spins freely and smooth in my hand.. put it back in the truck and front diff doesn't turn by hand.. I can roll the truck no problem but as soon as I stop pushing it stops rolling instantly.. like if u tried to roll it down ur driveway on a slope it would just stop on its own instead off rolling forward..
     
  10. JBloom33

    JBloom33 Member

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    If I pick the rear of the truck up I can free spin the wheels but if I lift the front of the truck and try to spin the wheels it starts to drive the truck.. it turns center diff and all 4 wheels when I try to turn 1 front wheel
     
  11. looker2756

    looker2756 Well-Known Member

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    Difinitely someting wrong inside the differential it's self sounds like to me.
    If it seems free in your hand, but not on the truck.
    I would be looking into the differential case, and the mounting area of the vehicle.
    A warped case, or a bent chassis, causing the case to flex is a possability of a problem.
    A video, and possibly some pictures could be helpful, as solving an issue like this by typed conversation only is quite difficult.

     
    #11 looker2756, Aug 20, 2015
    Last edited by a moderator: Jan 20, 2016
  12. JBloom33

    JBloom33 Member

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    It was definitely really hard to get it back into the outer case where the bearings ride for the diff cups for each wheel.. the inner part where all the spider gears are r smooth by hand.. when I install it into the case where the pinion gear is I can't turn it.. the mesh is good and pinion and spur gear spin freely by themselves but really hard to press the bearings into the half of the housing where they ride
     
  13. looker2756

    looker2756 Well-Known Member

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    It should not be a struggle to fit the actual differential into the frame mounted enclosure case.
    Something is wrong in that area, I would possibly get a new case first, and see if that helps the initial issue of installing the diff. into it.
    If so ... You are headed in the correct direction.
    An accident could have caused the warpage, or possobly a heat related thing.
    If you get the new case, and all seems good in your hand, Then it is definitely time to look at the mounting to the chassis, and a possible bent chassis, causing the Diff. case to be distorted, and cause your binding issue.
    Being as this is the front, it is WAY more likely to have this issue, as in any accident the front end in the most likely to get damaged.
     
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