Outcast Diff cups hitting a arms

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Infractiondk

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Arrma RC's
  1. Infraction
Hey
I noticed something today

my front diff cups have digged into the plastic of the front a arms ?? And the dog bones have made their own room in the cups ? How the fiddlestick ?? When i push the suspension all the Way Down it Isent even close to Do this ?? Is it normal for it to Do this
 
This seems more like the cups grinding directly in the arms not dirt and Stones. I Will take pictures
 
I think the question would be how many times have the dogbones come out of the cups? If a pillow ball comes loose and it pops a bone they will chew the arm at the face of the cup, and they will chew in good...

Pictures would help, but I'm going with this reasoning after your description..
 
I think the question would be how many times have the dogbones come out of the cups? If a pillow ball comes loose and it pops a bone they will chew the arm at the face of the cup, and they will chew in good...

Pictures would help, but I'm going with this reasoning after your description..
None it hasent happend at all
 
When you bash the a arms flex, when they flex enough the diff cups will dig in the a arms. All of mine have gouges from the diff cups.

If the bones never popped, this is your answer... (y)
 
If the bones never popped, this is your answer... (y)
I've only ever popped a front axle once, but it was a pretty good hit, sorta surprised nothing broke.
 
My rpm arms are so whooped the balls unscrew, or maybe better yet, pull..lol.. I have to keep an eye on them or it pops a bone..
 
Here are pictures.

50D7A1A3-0F0D-4C9D-9741-534D2AAA233D.jpeg
D23FA7A3-DFD2-46A6-AE61-23F8810669C5.jpeg
04FB3E6D-01DF-4965-ACCB-E260922161D1.jpeg
057A35F4-1A9D-406E-9F4C-5DA8C740D1A3.jpeg
77257060-0874-4B49-882B-8594FCBB629E.jpeg
7A8B6EE0-B1A1-4BF2-9E35-E7AAA376F3C8.jpeg
 
Arm flexing may be the obvious cause. But a diff with worn gears will cause the drive cups to oscillate and hit the flexing arm also. A combination of two negatives. If the drive cups are scratched and grooved, then it is pebbles and debris causing the arm gauging between both. On the front, I would recommend you take out all spacers(top and bottom) at the PB's. Getting the dog bones inboard closer inside the diff's drive cups.
 
This happend on the first run ever so don't Think that it is wear.
I have head about the Spacer remove on the arms But i thought it May only was something you did on rpm arms
 
Probably not due to diff wear in your case. I removed the spacers/shims on my 6S from the beginning with stock arms. I have RPMs F/R and still don't use the PB shims. And it also helps keep the PB's screwed into the upper/lower Front arms better. IMO.
One thing to not overlook is your DROOP. Too much will over extend your arms, flexing them and cause what you see. The amount of force exerted on these parts is extreme and more than one thinks. The arms flex violently with 6S running hard. The wheels are unsprung rotating mass and weight and weigh almost a pound for some of them. I have some slo-mo vids showing that. But flex is your friend.(up to some point)
 
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Arm flexing may be the obvious cause. But a diff with worn gears will cause the drive cups to oscillate and hit the flexing arm also. A combination of two negatives. If the drive cups are scratched and grooved, then it is pebbles and debris causing the arm gauging between both. On the front, I would recommend you take out all spacers(top and bottom) at the PB's. Getting the dog bones inboard closer inside the diff's drive cups.


Yep looks like every outcast and notorious arm I've seen lol...
 
I recently got some diffs from a friend to build another ride, and one was super fragged. His cups were worse than this... My theory is that under big a arm flex the dog bone starts to come out, hits the a arm and sometimes hits the right groove in the cup. But other times I think it rides in these other low spots and not always directly in the long grooves, where it belongs. So at that point the dog bone turns until it hits the right groove and goes back home...
 
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