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  1. #1
    RC Racer
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    Rear arms sticking

    I've just stripped he shocks off our trucks and my sons rear arms both seem stiff. I can push them up (as if suspension compressed) and they stay there, where as mine move freely up and down. Any thoughts on what the issue is and how to remedy it?

    Thanks!


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  2. #2
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    Your son's truck have a suspension binding issue. Check the pins that hold the arms to the transmission, the pins could be bent since it was driven at the skate park you mentioned in your previous threads earlier.
    Did you say Traxxas?

    Yes with or without lipos.

  3. #3
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    I'll take a look at them. I noticed the other day that on one side the screw had come out a few turns. Will see what I can find on the next inspection. Thinking about it, his truck has looked more squatted at the back recently, and I thought it was a more sag in the shock, but having binding arms would explain it if they're not moving freely enough to return to a neutral position.

  4. #4
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    Backing out suspension screw pins can be annoying and with backed out pins, that increases the chance of them bending. That issue can be easily fix however. Some people simply put them on the opposite side of the arms while others use a dab of tire glue on the threads then screw them in.

    I have to re-straighten a bent front pin for one of my 2nd cousin's P2de last year. I got another one to fix now, but this time I'm going to try these:

    http://www.teamstrc.com/index.php?ro...product_id=345

    I heard they are pretty good.
    Last edited by SouperkNight; 06-04-2017 at 06:34 PM.
    Did you say Traxxas?

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  5. #5
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    Yeah I think a few bits on these could do with a proper nut on the end of the screw. Something I'll defo look into.


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  6. #6
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    I took a look at one of these this morning and the screw was straight. Even with the screw removed it was pretty stiff, it almost seemed like the arm was binding to the chassis, or the drive shaft was not sliding cleanly.

  7. #7
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    Could be a very dirty or heavily worn drive shaft. Take it apart to see and then feel the motion of the arm.

  8. #8
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    It has been driven on some dusty and wet areas so may well be the cause. I'll have a look at how they come off. Do they need any sort of lubrication?

  9. #9
    RC Qualifier chops1sc's Avatar
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    When I get new arms I always sand down the "ears" if you know what I mean so they don't bind against the transmission housing. I also check the movement without the shocks installed. Make sure the shocks aren't tightened so much that they cant pivot.
    Revo .18TM BL Rustler Stampede MERV HPI Sprint 2

  10. #10
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    Quote Originally Posted by onionsa View Post
    It has been driven on some dusty and wet areas so may well be the cause. I'll have a look at how they come off. Do they need any sort of lubrication?
    They don't "need" it, but I like to put on some kind of dry lube and or graphite.

  11. #11
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    Quote Originally Posted by chops1sc View Post
    When I get new arms I always sand down the "ears" if you know what I mean so they don't bind against the transmission housing. I also check the movement without the shocks installed. Make sure the shocks aren't tightened so much that they cant pivot.
    Yes I know what you mean, I will give them a light going over to see if that also helps to free them up.

    Quote Originally Posted by Blown94 View Post
    They don't "need" it, but I like to put on some kind of dry lube and or graphite.
    Is that the same sort of "dry lube" that you'd use on a bike chain?

  12. #12
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    I do Jeng's method of cleaning the driveshafts. In the video he cleans a driveshaft from a Sl4sh, but still will work for the P2de.

    https://www.youtube.com/watch?v=yzqmKoj2yc8

    When you have the driveshafts off, test the rear arms again. If they still won't move freely, then the holes where the pins goes in needs to be clean as well.

    I'm remember a video, but I don't remember which one it is. All it is you take a 1/8 drill bit and gently slide it through back and forth for each hole to remove any tiny debris trapped in there without ruining the holes. I also sometimes spray some electric motor in the holes, let it sit for a few seconds, and spray compressed air to blow out any dust or dirt out if its really bad.
    Did you say Traxxas?

    Yes with or without lipos.

  13. #13
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    Quote Originally Posted by onionsa View Post


    Is that the same sort of "dry lube" that you'd use on a bike chain?
    That would work.

  14. #14
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    Cool thanks for the info guys, I'll get the drive shafts stripped down, give the ears a rub down too.

  15. #15
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    Quote Originally Posted by SouperkNight View Post
    I do Jeng's method of cleaning the driveshafts. In the video he cleans a driveshaft from a Sl4sh, but still will work for the P2de.

    https://www.youtube.com/watch?v=yzqmKoj2yc8

    When you have the driveshafts off, test the rear arms again. If they still won't move freely, then the holes where the pins goes in needs to be clean as well.

    I'm remember a video, but I don't remember which one it is. All it is you take a 1/8 drill bit and gently slide it through back and forth for each hole to remove any tiny debris trapped in there without ruining the holes. I also sometimes spray some electric motor in the holes, let it sit for a few seconds, and spray compressed air to blow out any dust or dirt out if its really bad.
    nice video thanks

  16. #16
    RC Turnbuckle Jr. jvogel's Avatar
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    The suspension pin should just fall out of the A-arm when not screwed in. If not, the inside of the A-arm could be dirty or stenotic. There are reamer tools for this, but you could just as easily use the appropriate size drill bit and very gently and slowly clean/open the holes if needed. I have had to do this a few times over the years.
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  17. #17
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    I've never had one "just fall out" even when new.....

  18. #18
    RC Turnbuckle Jr. jvogel's Avatar
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    Quote Originally Posted by Blown94 View Post
    I've never had one "just fall out" even when new.....
    Then they were too tight. This is one of two pivot points for the entire A-arm.
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  19. #19
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    Any idea what side drill bit is required for cleaning this out?

    Also, I see these STRC hardened hinge pins, but getting them in the UK seems to be a problem. Wondering what alternatives there are.

  20. #20
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    Quote Originally Posted by jvogel View Post
    Then they were too tight. This is one of two pivot points for the entire A-arm.
    I'm well aware of how the suspension works, and even brand new then never fell out. Went through easily...yes, fell out....no.

    And if anything, the part you want it to glide through is the pivot point on the gearbox more then the arms.

  21. #21
    RC Turnbuckle Jr. jvogel's Avatar
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    Quote Originally Posted by Blown94 View Post
    ...the part you want it to glide through is the pivot point on the gearbox more then the arms.
    This would be true with the stock pins that screw into the A-arms but for years now we hopeless RC addicts have been using the STRC suspension pins with nylon lock nuts — ST3640BK. The pins pivot in the arms as well as the gearbox, thus reducing friction even more and never have an A-arm pin back out ever again.
    Obstacle Magnet

  22. #22
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    ....which clearly the OP does NOT have.......

  23. #23
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    Right I just stripped down the rear corner completely. The drive shafts move freely once removed from the hub, so those are off the hook. The a-arm when disconnected from all else is almost solid at some angles of articulation. So, is this where I need to get a bit of clearance between the arms 'ears' and the chassis?

  24. #24
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    Besides a slightly tweaked pin, I've see pins get some corrosion on the pivot area going through the gearbox. Pull the pin and if it's that you can buy new, or put it in a drill with some really fine sandpaper and clean them up.

  25. #25
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    The stock pin is not a clearance fit by any means, but should it be? I get it with the STRC ones as they are secured both ends. I think I'll be getting a set of them sooner rather than later but would still like the arm to move freely without a pin in it.

  26. #26
    RC Qualifier chops1sc's Avatar
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    The stock pins screw into the a-arm so you want the fit to be smooth but not too loose with the housing. It shouldn't be so tight that the a-arm doesn't fall by itself either. It's a fine line, lol!
    Revo .18TM BL Rustler Stampede MERV HPI Sprint 2

  27. #27
    RC Turnbuckle Jr. jvogel's Avatar
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    With STRC or Pro-Line nylon locknut backed pins, you can have every part articulate as smooth as silk with minimal friction and no binding whatsoever. I very highly recommend them.

    I've had the STRC variety on my P2de, Sla2h, Rusty, P4de, Sl4sh, and Rally for years now with no complaints.
    Obstacle Magnet

  28. #28
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    ^Is blue locktight recommended for these jvogel, better safe than sorry?

    My 2nd cousin with the XL-5 is going to be the first one before me to have these.
    Did you say Traxxas?

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  29. #29
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    With a nylon it there is no need for any thread lock.

    Little update, I sanded a little off the A arms and it did free it up a little bit, but I'll leave it there till we get the STRC pins.


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  30. #30
    RC Turnbuckle Jr. jvogel's Avatar
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    Quote Originally Posted by onionsa View Post
    ...nylon...no need for any thread lock.
    onionsa is right. Only use thread lock with metal to metal. If plastic or nylon is involved, don't use it.
    Obstacle Magnet

  31. #31
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    ^I know metal to metal. However looking at the nuts in the STRC hinge pins package I got today, I see nylon or plastic inside the nuts at one end. I learned something today... I think. For all the nuts I used from good old Tony Screws, I don't recall of using lock tight on them, but I might of in rare occasions.
    Did you say Traxxas?

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  32. #32
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    Little update on this, I pulled the screws out and put them in from the front and so far they've stayed in place. Updraged hinge pins are the end goal, but for now it's doing alight. Going to swap mine over tomorrow too.

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