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  1. #1
    RC Racer
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    Question Merv Gearing Issue :(

    Ok guys I'm new to the RC car scene, was heavily involved many years ago then it dropped out, now after joining the military I'm back, I've purchased a Merv and I'm loving it, however, recently I picked up a few 3s lipos and a venom pro charger, car ran great, to great, a tire actually flew off because of the torque (the nut holding it on, not the tire from the rim) so after many days of waiting for parts (didn't have any other nuts), I thought I got the car up and running again, took it out for a run with just the stock NiMH's and am getting a horrible grinding sound, can't exactly pinpoint where on the chassis it's coming from, but the car will run, just don't want to destroy it. Also, I'm a basher/hobby racer, don't have any tracks around me so I just drive it on base. Looking to upgrade it so it has less of a Vance of breaking, any advice on upgrades to shocks etc? Also, going to be getting rid of the 3s's, might buy 2's but doubt they will make much difference over the stock NiMH in series.

    Video of my issue, it's much more noticeable when it's outside and I can actually put power into it, also I'm not looking to replace whatever is broken with stock parts, as said before I wana upgrade it all.

    http://www.youtube.com/v/wD1RActvqzU

    Thanks.

    ~RevoRoughin
    Last edited by RevoRoughin; 07-30-2011 at 08:08 AM.

  2. #2
    RC Turnbuckle Jr.
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    your differential is stripped, it is hard to know if it is the front or the rear, you need to change the diff rin and pinion, also it might be good to shim the diffs.

  3. #3
    RC Racer
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    Thanks mate, any advice for when I shim?

  4. #4
    Marshal Dadx2mj's Avatar
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    Shims go on the output shaft so it rides between the bulkhead and the diff pushing the ring gear closer to the pinion gear on the center drive shaft. Most of use shims from Associated part #21141. You may need nothing more than to shim the diff, you will be able to tell if you hae any chipped teeth on the ring and pinion once you get it apart.
    BlindMan Racing
    Rusty - MERV - Pede 4x4-Alias
    SPC Lipo Power

  5. #5
    RC Racer
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    Ok guys, I've taken apart both the Front and the rear diff, (Not entirely, just enough to look at them), and spun around the drive shft, and each tooth seems to be making contact, don't appear to be any broken ones, what are some other issues that could be causing this sound?

  6. #6
    Marshal Dadx2mj's Avatar
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    Still think it is the diff just needing to be shimmed. Probably needs 1-3 of the Associated shims to tighten up the mesh between the ring and pinion gear. It could also be a bad bearing letting either the diff or the center shaft move around and make the mesh too loose, I have had that happen too.
    BlindMan Racing
    Rusty - MERV - Pede 4x4-Alias
    SPC Lipo Power

  7. #7
    RC Racer
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    Anyone know the parts # For the Front Diff? I believe thats the issue, its VERY hard to turn and im hearing grinding even when just turning with my hand.

    is it the 7078? Hobby shop closes soon and wana get my repair in today >.<
    Last edited by RevoRoughin; 07-30-2011 at 03:21 PM.

  8. #8
    RC Turnbuckle Jr.
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    7078 is the complete diff you can replace only the ring and pinion using traxxas 7079 works for front or rear.

  9. #9
    RC Racer
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    Ok thanks, sadly one of the screws on the Diff is rounded...thats the second rounded screw on my model that I've found, I'm going to give Traxxas a call on Monday and see If i can get replacements because this is just getting Ridiculous...

  10. #10
    RC Turnbuckle Jr.
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    donīt use traxxas provided tools, or you will end stripping screws.

  11. #11
    RC Racer
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    I've bought a completely different hobby Allen wrench set, screws came that way 

  12. #12
    RC Turnbuckle Jr. jimbo74's Avatar
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    Quote Originally Posted by RevoRoughin View Post
    I've bought a completely different hobby Allen wrench set, screws came that way 
    sure you are using the right sized tools? metric and sae usually will turn each otehr if they are close, but can easily strip it out

  13. #13
    RC Racer
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    Quote Originally Posted by jimbo74 View Post
    sure you are using the right sized tools? metric and sae usually will turn each otehr if they are close, but can easily strip it out
    yup completely sure, The first gear was the stock installed 25t (I blieve but im not sure) gear that had to be replaced with the 23t (again not sure) speed gear to run dual NiMH etc, and now the front Diff.

  14. #14
    RC Turnbuckle Jr. JimmyNeutron's Avatar
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    When you set up (or re-set up) your bulkhead, do yourself a favor: Follow Me!
    Whatever it is I just typed... could be wrong.

  15. #15
    RC Racer
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    Thanks jimmie, will do when my shims etc come in.

  16. #16
    RC Racer
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    MAN DO I FEEL LIKE AN IDIOT...Went today and purchased a new Front Diff, under the assumption that that was my issue, finally got home, installed it, and after piecing the whole car back together...the Front bulk head is lose, why may you ask? because the tabs that you screw onto the bottom chassis have broken off it, go figure thats more than likely my issue, the grinding was caused by the bulk head not being even attached to the chassis...I'm defiantly going to be calling traxxas tomorrow, considering I've had this model for under a month and have found 2 stripped screws and now the Front Bulk Head breaks? Hopefully the customer service can help me sort this out.

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