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Surprised at how well it was driving given this issue...

tetsuo

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I've been driving around with a bent drive shaft for some time - it wasn't a huge bend and nothing was binding (at least as far as I could tell) so I thought it was OK to keep driving with it. I wouldn't have even known about this new/recent damage (see below) if I hadn't been doing a visual once-over on the car just in case. The pin on the drive shaft must have been slowly backing out over time, gradually chewing away more and more at the rear arm and outdrive, because it was driving beautifully shortly before this pictures were taken and never would have known anything was wrong if I hadn't see this. Sheesh!
IMG_20200521_132335.jpg

IMG_20200521_132354.jpg

IMG_20200521_142523.jpg

So do you think that continuing to drive with a slightly bent driveshaft was the cause, or is it more likely that whatever caused the bent shaft in the first place is also what loosened the pin and started the process? Am I being too abusive or expecting to much durability? I guess maybe I need to back off the standing backflips and other antics, as I really didn't expect to be breaking parts so often on a vehicle renowned for its durability. I Just don't FEEL like I've been all that abusive w/ this thing: 4s only, and no crazy-high jumps or skate parks a this point.
 

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Nicochau

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Interesting issue! 🤔 A friend of mine was telling me today that he had the same problem happen.

1/ i bend shafts back once in a while to make sure they are as straight as possible. You can easily bend them back couple of times before the axle needs a replacement
2/ the bent axles could have created the pin issue. I would just hammer it back in.
3/ I also rotate the outdrives once in a while for wear
4/ pins can be replaced using this tool: https://www.amainhobbies.com/mugen-seiki-driveshaft-pin-replacement-tool-mugb0541/p221425
And pins are cheap on ebay, i use M3 x 13mm pin.
https://www.ebay.com/itm/183907080693

RC do require very regular maintenance. I personally love my Tekno because I get to be able to drive it a lot before and after it breaks. My previous RCs would all spend 2 to 3 x more time on the bench.
 
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Sludog

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I would check your chassis to make sure its straight. I know the Arrma Kraton 8s had bent chassis problems early on resulting in bent drive shafts soon afterwards.
 

tetsuo

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Interesting issue! 🤔 A friend of mine was telling me today that he had the same problem happen.

1/ i bend shafts back once in a while to make sure they are as straight as possible. You can easily bend them back couple of times before the axle needs a replacement
2/ the bent axles could have created the pin issue. I would just hammer it back in.
3/ I also rotate the outdrives once in a while for wear
4/ pins can be replaced using this tool: https://www.amainhobbies.com/mugen-seiki-driveshaft-pin-replacement-tool-mugb0541/p221425
And pins are cheap on ebay, i use M3 x 13mm pin.
https://www.ebay.com/itm/183907080693

RC do require very regular maintenance. I personally love my Tekno because I get to be able to drive it a lot before and after it breaks. My previous RCs would all spend 2 to 3 x more time on the bench.
1 - I know to look more closely at the pins now and will certainly straighten any shafts or recenter any pins in the future rather than running one that looks wobbly.

2- In this case, it's too far gone. The head of the drive shaft is completely chewed up now (kind of peanut shaped rather than spherical) along with the outdrive having a worn notch in it as you can see in the first and last pictures

3 - when you say rotate the outdrives, do you mean rotate left to right? front to back? or do you just mean replace periodically?

4 - Hmm.. mixed feedback on the tool. I might just stick with replacing the driveshafts from time to time. I guess it would depend on how often I find them bent or, worse, run into this issue.

Thanks for the advice! Also, @Sludog, good call checking for bends in the chassis, but I imagine that would be more of an issue for the main driveshaft running from the center diff to front rather than these side shafts. Thanks again, all!
 

Nicochau

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1 - I know to look more closely at the pins now and will certainly straighten any shafts or recenter any pins in the future rather than running one that looks wobbly.

2- In this case, it's too far gone. The head of the drive shaft is completely chewed up now (kind of peanut shaped rather than spherical) along with the outdrive having a worn notch in it as you can see in the first and last pictures

3 - when you say rotate the outdrives, do you mean rotate left to right? front to back? or do you just mean replace periodically?

4 - Hmm.. mixed feedback on the tool. I might just stick with replacing the driveshafts from time to time. I guess it would depend on how often I find them bent or, worse, run into this issue.

Thanks for the advice! Also, @Sludog, good call checking for bends in the chassis, but I imagine that would be more of an issue for the main driveshaft running from the center diff to front rather than these side shafts. Thanks again, all!
Hey @tetsuo,

Yes, I rotate one side to another when rebuilding the diffs.

Do not hesitate to use the Tekno warranty if you change parts. Send them one bent shaft and you get a 50% discount on the couple.

I never had issues with the pins but am interested in all feedback. I do put a lot of attention when replacing the pins and make sure they are well centered. My buddy was questioning this maintenance item too since he had the same problem.
 

TBuggy

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Thats a first I have seen about pins working themselves loose. I replace my pins regularly and add a touch of thread lock when I install new pins. I never never had this happen personally.

Was this a new vehicle? Maybe send Tekno the pics and see if they will do anything? The pin shouldn't have worked itself loose on a brand new drive shaft..or even a slightly bent one.
 

tetsuo

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Yeah... it wasn't even something I was keeping an eye on. I'll send the photos to tekno and see what they have to say.

I didn't have any tools that seemed like they could re-center the pin as @Nicochau suggested, but i ended up straightening out the shaft (at least a little) and then placing it on a 2x4 and driving the pin back through with a hammer! :D (essentially driving the other side into the soft pine of the 2x4). Seemed to work - I ran a couple packs through it and it's all working fine. I really thought there'd be some binding w/ the ourdrive being as misshapen as it is, but there was none.

I figure if I have to replace the drive shaft and outdrive anyway, I might as well see how long I can run on the already-busted parts first... so far so good, and now I have spares ready to go.
 

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