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  1. #1
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    Keep stripping spur gears, any suggestions?

    I know there are a ton of similar threads on this subject and I have read through all the ones I can find that are relevant.

    I'm running 17/38 and 17/36 mod1 gears in my slash 4x4 and in the past couple of months have gone through a spur on every other run.

    I've upgraded the slipper to the revo type, tried various slipper settings but struggling to overcome the problem. The last time it happened i noticed there was a lot of back and forth play on the spur so i added a bearing and some washers between the slipper and rear diff. I did manage to run a couple of packs through it but turned too sharply at about 45mph and it flipped about 15 times.

    It may be that sorting out the back and forth play was the problem but that i just got unlucky by flipping it?

    I'm running on short grass (football field), with badlands style tyres, so traction is quite high.

    Any thoughts or advice??

    I've been reading about steel spurs but opinion seems to be about 50/50, some people saying you are just transfering the issue further down the drivetrain and some saying they run them with good results, with the amount I'm spending on plastic one i could've bought a steel one!
    Last edited by garethalanjames; 03-26-2017 at 11:34 AM.

  2. #2
    RC Qualifier MaxxBash's Avatar
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    Is there any binds when you take out the slipper assembly to cause any tension?


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  3. #3
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    No, not that i can find, I've checked over all the bearings. One mistake I did make a while back was using a screw that was too long that fixed the front bulkhead to the chassis and goes into the front diff, it was causing binding when landing.

    I've had a few spurs go where there has been no obvious reason for it, the transmission just gets louder where i think the teeth are breaking away, then they just strip.

  4. #4
    RC Champion RazorRC22's Avatar
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    Assuming your motor mount screw is not loosening on its own and your mesh is right, then your slipper is probably too tight.
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  5. #5
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    Quote Originally Posted by RazorRC22 View Post
    Assuming your motor mount screw is not loosening on its own and your mesh is right, then your slipper is probably too tight.
    I guess that is what it points to, just frustrating that I never used to have this problem and note getting it all the time. I have one more plastic spur which I'll replace and if is still have problems i was thinking about trying a steel spur.

    I've seen lots of people talk about how steel spurs can cause other drive train failures such as diffs, but not many examples of that actually happening. What are the opinions on running a steel spur?

  6. #6
    RC Turnbuckle Jr. El Sob's Avatar
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    In my experience there are a few reasons to strip gears. The motor plate can be warped, the screw on the bottom of the motor mount which the motor plate attaches to is either loose or not there. The motor is not attached to the motor plate securely. The bearing adapter that goes into the motor mount bearing is worn or the pinion gear has a lot of wear on it.
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  7. #7
    RC Champion Dcuda69's Avatar
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    I'm with ElSob on this one. I have a 2 yr old Slash that has run the 3500, a 2400, a 2700 and a 2150kv motor on 2s,3s and 4s. I JUST took the 54t(still in good shape) original plastic spur out and replaced it with a 50t Traxxas plastic gear. Either I'm a lucky guy or there's something wrong with the OPs truck. I'm not a lucky guy...lol. Mount,mount bearing,mount plate,slipper adjustment...something's not right. Good luck!
    Slash 4x4 Ult.SC8 2150kv MIP KH
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  8. #8
    RC Champion RazorRC22's Avatar
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    Quote Originally Posted by garethalanjames View Post
    I guess that is what it points to, just frustrating that I never used to have this problem and note getting it all the time. I have one more plastic spur which I'll replace and if is still have problems i was thinking about trying a steel spur.

    I've seen lots of people talk about how steel spurs can cause other drive train failures such as diffs, but not many examples of that actually happening. What are the opinions on running a steel spur?
    Do you know how to set your slipper properly?
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  9. #9
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    Thanks all for the replies. I do know how to set the slipper, but in honesty I have found getting difficult finding the right balance between too loose and too tight, which i wonder whether it has anything to do with the fact it's a 2000kv motor on 6s which I hadn't mentioned in my original post (though I've had it for a couple of years and only had this problem recently).

    As for the mount, aluminium bearing adapter etc, all parts have been replaced in the past 6 months.

    As El Sob and Dcuda69 recommend I think I need to take it all apart and inspect for loose screws and warped mounts to make sure.

    The only other thing I can think is that due to the high gearing, the motor is very close to the chassis, perhaps a hard landing might cause the motor to move?

  10. #10
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    Quick update on this, seems i should've checked the truck over a bit better before posting!

    So far I've gone through everything except the front diff.
    I found part of the steering linkage was fouling the input shaft when steering on full lock (tekno dogbone centre shaft). This was down to the threaded pin being too long, so i shortened and replaced.
    I also corrected some play on the rear yokes as they are tmaxx shafts and a little big.
    Replaced the slipper and set a little looser than before may need to tweak.

    Now, the biggest thing i have discovered after opening the rear diff housing, is that the edge of the bevel gear has disintegrated and there are are shards of metal everywhere.
    I've cleaned up, replaced the bevel with a new spare, greased and reassembled and it's a lot smoother.

    I'm going to check the front tomorrow before putting it all back together and test running.

    Will post the results!

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