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  1. #1
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    Question about differential!

    My 1st experience dismantling my rear diff, very cool but ends up all my gears are ok.
    I heard a few crunches while summit playing, the lock lever was not engaging properly so I decided to take the plunge.
    It appears I have pinion end play. When I push in on the pinion shaft towards the ring gear it feels crunchy yet when I pull on the pinion its very smooth to turn. I have approxmently 3/16ths play.

    I am not sure if thats normal. If I were to install shims it would have the same effect as pushing the pinion gear towards the ring gear which again feels crunchy. My diff itself is very smooth with no end play. I also noticed the lock lever gets hooked up every once in a while yet inspecting the operation I see no fault.

    Any advice much appreciated!

    Thanks
    Joe

  2. #2
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    Check the bearings on the pinion. Just had mine fail with less than 20 runs. Their really should be no in out movement on pinion.

  3. #3
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    Has anyone just started replacing parts until the problem was solved because they physically don't see a defect?

    I am thinking of buying the 5678 kit (gear lock) and 5681 diff carrier though it physically seems OK,
    the lever that operates the lock operation for the rear diff gets stuck in the open position.
    Has anyone experience the diff housing twisted?

  4. #4
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    If you shim you will have to shim side to side as well.

  5. #5
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    I would shim either way but maybe try cleaning it out really good first (the crunchy sound must be dirt if the gears and bearings are good)
    What's a coffee if it aint Irish

  6. #6
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    I don't have any side play in the axle output shaft but there are stock shims, I am thinking by relocating the shims or adding will re position the ring gear against the pinion which may affect pinion end play and the crunchy feeling I am getting. Rest assure all components were thoroughly cleaned.
    I am going to pick up the ring\pinion gear kit today to see if that makes a difference too, if not nothing else, I will add it to my tool box for future repairs.
    Thanks in advance too all the responses, much appreciated!

  7. #7
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    Never heard of stock shims in any Traxxas RCs, you sure that isn't a piece of the bearings better double check man
    What's a coffee if it aint Irish

  8. #8
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    Ya I second that never seen stock shims in a traxxas.

  9. #9
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    The shim I am referring to is part 5631, but I could be wrong. It’s on the output side where the locking mechanism is!

  10. #10
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    Sorry that's 5681

  11. #11
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    This is the Diagram, 5681 Not sure if this will work, 1st time posting a pic, (select,copy,paste) http://traxxas.com/explodedviews/560...Qi-24GHz-radio

  12. #12
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    Oh I see, I guess that's a type of spacer but you should get some actual shims to help durability
    What's a coffee if it aint Irish

  13. #13
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    I replaced the pinion and ring gear tonight, made no difference off to my parts compartment.
    I also bought 2 shim sizes for the 3 different locations (pinion and 2 output shaft bearings) and after many different configurations I have it almost perfect, "that pinion end play, crunchy feeling is solved"
    2nd problem is not so easy.
    The differential fork gets hung up because the locking hub does not go into the carrier yet I can manually move it in and out, no burs on the output shaft nor cross pin. I cannot see a fault with the carrier but it still gets hung up in the open diff position. The easy way out is to replace the carrier, locking hub and output shaft but no one has the parts errr.
    Can anyone recommend and ideas without replacing the parts or is that the only solution?

  14. #14
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    Quote Originally Posted by 79Broncojoe View Post
    This is the Diagram, 5681 Not sure if this will work, 1st time posting a pic, (select,copy,paste) http://traxxas.com/explodedviews/560...Qi-24GHz-radio
    That is not a shim but a bushing that should be next to the bearing
    Endeavoring to persevere !

  15. #15
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    Try on the locking to shave the sharp edges just a hair. Their might just be a edge catching

  16. #16
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    My guess is the output shaft is not perfectly centered because of the shimming it has slightly changed the alignment.does it do it when in half the case and the bearings in place.to much grease can also cause it. May need a shim adjustment.i got some on the way as well.


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  17. #17
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    I hit the locking hub on the wire wheel thinking that would hopefully fix it, noop. But then again I could try it again!
    I have no grease in that area just light oil, this was happening prior to installing any shims, its 1 of 2 reasons why I dismantled the diff, ok maybe 3 as I was curious.
    The locking hub gets stuck in the open position when I try to turn the lever so the fork can slide the locking hub into the carrier. The pin seems perfectly smooth and free to move in the hole. The locking hub is a little sloppy on the output shaft but I have no experience to compare it too. Could it be the output shaft slightly bent or the diff housing slightly warped?

  18. #18
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    OK, conclusion to my post:

    Overly Picky would best describe my answer. Yes the shims are the answer to run a smooth differential and yes when manually operating the diff it does appear the lock shift fork gets stuck but in reality when it is in motion in the truck it has a different effect in other words it works!

    I am not impressed how loose the rear diff fits in the housing after 3 months running the summit, that will be a whole new topic to research as 1 solution I found is hot clue or finding my own way to keep the diff still. Simply replacing the bulkhead would work too. This was a great exercise for me with that note I would say the summit is a great truck that has many features but certainly leaves room for improvements, it is what it is!

    Thanks for all the replies.

    Joe

  19. #19
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    Ya I'm not impressed eather on how lose the diff fits. I'm going to try the hot glue as well going to install some alum skids to help take some of the movement out of the frame

  20. #20
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    http://www.youtube.com/watch?v=IhVuc6RNyaw

    Great for everything!!!!!!!!

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