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  1. #1
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    Guess who else has diff problems in their slash 4x4

    Background story on the truck: It's a Rally converted to a Slash (SC tires, SC body, SC bumpers), It has an LCG chassis but otherwise stock.

    About a week ago I was at the track getting a few practice laps in when as I went down the straightaway I heard an incredibly loud clicking noise from my car. I pulled my car into the pits to find the center driveshaft bent. I'm not sure how that's possible because I had a chassis brace installed at the time. I immediately started tearing down the car looking for other potential problems.

    So far I've found 2 bad bearings, some grease (I'm not even sure it counts as grease anymore), and a potentially bent center shaft (the one that spur gear sits on, not the long blue center shaft). This was all from the rear diff. I am yet to take apart the front diff but I'm hoping to do that today.

    Any ideas what else the noise may be?
    Last edited by Sprinkletron; 02-05-2018 at 11:05 AM.

  2. #2
    RC Turnbuckle Jr.
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    That chassis brace is most likely what caused the bend.

  3. #3
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    Quote Originally Posted by jimbo74 View Post
    That chassis brace is most likely what caused the bend.
    Thanks! Once I have finished putting new bearing in the diffs I will run without the brace.

  4. #4
    RC Qualifier spunkybob's Avatar
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    Quote Originally Posted by jimbo74 View Post
    That chassis brace is most likely what caused the bend.
    How? Geniunely, I don't understand the physics on how something that stops it from flexing causes a drive shaft to bend.

    I understand it would break the chassis or whatnot but not the drive shaft?

    Sent from my SM-G935F using Tapatalk

  5. #5
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    (How? Geniunely, I don't understand the physics on how something that stops it from flexing causes a drive shaft to bend.

    I understand it would break the chassis or whatnot but not the drive shaft?

    Sent from my SM-G935F using Tapatalk) - quote

    Personally I don't understand it either. This is the brace I'm using: https://www.vgracing.com/product/Sla...sis_Brace.html

    I understand why a brace might break the chassis or suspension but the center shaft really. It's the common advice on these forums that braces break center shafts. I'll try it

  6. #6
    RC Racer Sneetches's Avatar
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    Seems like it would be pretty weird for the brace to bend a slipper shaft, which is solid steel, before the hollow aluminum center driveshaft bent.

  7. #7
    RC Champion RazorRC22's Avatar
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    I've broken 3-4 VG chassis braces in crashes, never bent/broken any of the parts in the center drivetrain.
    youtube.com/c/RazorRCvideos

  8. #8
    RC Qualifier spunkybob's Avatar
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    Quote Originally Posted by Sneetches View Post
    Seems like it would be pretty weird for the brace to bend a slipper shaft, which is solid steel, before the hollow aluminum center driveshaft bent.
    Still.. the drive shaft and slipper shaft are between the ends of the chassis brace so I don't see how it would be possible to bend a drive shaft because of it.

    I twisted my drive shaft on 2200kv, 3s power when a rock got stuck between it and the chassis (no idea how it didn't just break the chassis) so I upgraded to the tekno big bone and it's been amazing.

    Edit: PS, always have your slipper set correctly.

    Sent from my SM-G935F using Tapatalk
    Last edited by spunkybob; 02-06-2018 at 06:10 AM.

  9. #9
    RC Qualifier spunkybob's Avatar
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    Hang on... I completely miss read his initial post.. I read it as the blue shaft bent... A slipper shaft bending still boggles my mind.

    I snaped mine once after a really bad landing and I could not get me head around HOW???!!!

    How did THAT break but not any of the other parts around it.

    Sent from my SM-G935F using Tapatalk

  10. #10
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    Quote Originally Posted by spunkybob View Post
    Hang on... I completely miss read his initial post.. I read it as the blue shaft bent... A slipper shaft bending still boggles my mind.

    I snaped mine once after a really bad landing and I could not get me head around HOW???!!!

    How did THAT break but not any of the other parts around it.

    Sent from my SM-G935F using Tapatalk
    I think both shafts are bent. Definitely the blue shaft and possibly the slipper shaft. The spur was also worn down on one side alot.
    Last edited by Sprinkletron; 02-06-2018 at 10:54 AM. Reason: I poorly wrote the first post

  11. #11
    RC Qualifier Trentbaby65's Avatar
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    Quote Originally Posted by Sprinkletron View Post
    I think both shafts are bent. Definitely the blue shaft and possibly the slipper shaft. The spur was also worn down on one side alot.
    Bearing failure maybe. The spur worn on one side might be the clue here.

  12. #12
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    Yeah maybe. That's the one bearing on the back that I haven't checked yet.

  13. #13
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    Usually a bent drive shaftshaft is caused by the same thing as axle shaft breakage.

    Bent/broken shafts are normally caused by sudden resistance when under load/rpm.
    Example. Jump with motor driving all tires and one tire stops on impact = bent/broken axle.
    Say both front tires stop when under load = bent main driveshaft/broken slipper clutch shaft.
    The chassis brace only stops chassis flex, not changes in tire inertia through the driveline.
    2x 'Pede VXL 4x4, 3x Slash VXL 4x4 HCG & LCG, ERBE

  14. #14
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    Quote Originally Posted by spunkybob View Post
    Hang on... I completely miss read his initial post.. I read it as the blue shaft bent... A slipper shaft bending still boggles my mind.

    I snaped mine once after a really bad landing and I could not get me head around HOW???!!!

    How did THAT break but not any of the other parts around it.

    Sent from my SM-G935F using Tapatalk
    That is from high speed drive shaft rpm and sudden stop of the front wheels. Plus the typical spring stress from the slipper clutch spring.
    Basically, your slipper clutch did not disengage fast enough, which overloaded the shaft and 'SNAP'!
    2x 'Pede VXL 4x4, 3x Slash VXL 4x4 HCG & LCG, ERBE

  15. #15
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    Quote Originally Posted by Jarlath View Post
    That is from high speed drive shaft rpm and sudden stop of the front wheels. Plus the typical spring stress from the slipper clutch spring.
    Basically, your slipper clutch did not disengage fast enough, which overloaded the shaft and 'SNAP'!
    I did get bumped in mid-air at the track, resulting in a cartwheel. No problems directly after the crash though, everything looked fine, so I kept running. I probably bent the blue shaft more and more as I accelerated out of the corners
    Guess who's back.
    Back again.

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