Kraton Kraton 6s front diff clicking

[ollie6s]

Hi all, first post here. Bought a brand new k6 did the usual diff inspection and ran a few packs through it. Shimmed they diff and all still working fine, recently under braking or full throttle from a standstill the front diff is making a loud clicking sound for a second or two then goes. Checked i hadn’t assembled it wrong or missed anything out and I can’t seem to find the problem?! Any help or similar issues?! Thanks

 

[KnowAir]

Visually make sure the diff cover is fully seated to the gearbox, easy to think it's all the way on when it's actually not. It's a tight fit, if the cover isn't fully seated, the diff gets pushed away from the pinion gear causing it to skip and click under acceleration and braking.

 

[SrC]

Great that you did in fact give it a once over. Kudos.
Are you sure it is at the front diff??
Sometimes it's hard to tell if it is front or Rear. And the rear will usually wear out first. But I don't think wear is your issue since your rig is fairly new?
When braking hard from a high speed, do you hear the click????? Try holding the rig with one end up one end on its wheels and pull "some" throttle, you might be abe to see which diff is really clicking. Lift from both ends to listen for the clicking.
Sounds like the fr or rr Main/Input gears are not shimmed properly. I know you said you did check shimming....but you never know. I been in this scenario before, after a rebuild. If your gut feeling is at the front dff, take it out. If not 100% sure, I would start at the rear diff first. Just me.
Either way, you won't know till you remove one first to check. Look over the gears well, for chipped teeth also.
Landing hard just one time under hard throttle can even brick a Main/Input gear quick. Hopefully you just need another shim.
Need to unload power when landing at that moment. I don't know how you are driving your rig though.
Good luck.

>>Follow what @KnowAir stated above.

 

[KnowAir]

Also, when you say you shimmed, are you referring to externally? Shims outside the diff between the housing and bearings or inside the diff cup itself?
I agree with what @SrC said. Try holding the rig with just the front on the ground while lightly applying throttle, then the rear. Usually the rear diff takes the most abuse. Unless of course you nose landed on full throttle or something.
FWIW I ran my mojave for nearly 2 years without even opening a diff or diff cases..
Not saying it's a bad idea to check things out, but rather that these things are pretty forgiving with regard to tolerances and if someone doesn't know how to properly shim they might do more harm than good. With regards to diff fluids, if it's got "some", it's enough..over filling is more harmful than under filled.
Just my opinions..

 

[SrC]

+1
Checking shims placed at the main gear side BB of the diff and the diff case ( bulkhead)......
Adding one more shim may be needed?? IDK.
Should be no endplay. I rather have mine on the tighter side than loose. The shims compress with use/break in. But absolutely check the gears for broken teeth first. Removing the grease to look closely. Ignoring this and a chipped tooth floating around, can brick the whole gear set subsequently, with use.
Try a set of the Tekno diff shims, which are thinner, adding as needed. (not for EXB diffs, only for the RTR 6s diffs, as in your case)

 

[ollie6s]

Great that you did in fact give it a once over. Kudos.
Are you sure it is at the front diff??
Sometimes it's hard to tell if it is front or Rear. And the rear will usually wear out first. But I don't think wear is your issue since your rig is fairly new?
When braking hard from a high speed, do you hear the click????? Try holding the rig with one end up one end on its wheels and pull "some" throttle, you might be abe to see which diff is really clicking. Lift from both ends to listen for the clicking.
Sounds like the fr or rr Main/Input gears are not shimmed properly. I know you said you did check shimming....but you never know. I been in this scenario before, after a rebuild. If your gut feeling is at the front dff, take it out. If not 100% sure, I would start at the rear diff first. Just me.
Either way, you won't know till you remove one first to check. Look over the gears well, for chipped teeth also.
Landing hard just one time under hard throttle can even brick a Main/Input gear quick. Hopefully you just need another shim.
Need to unload power when landing at that moment. I don't know how you are driving your rig though.
Good luck.

>>Follow what @KnowAir stated above.

Thank you, been super helpful in what to look for. Tried the holding one set of wheels on nye ground and definitely the front diff clicking. Saw someone say that a bent chassis could be the issue too checked with a new steel rule and it’s pretty bang on there, shimming I though the same thing and used the ones that come in the box to pack out both with one. Then I put 2 on the front thinking it would sort it. And yes definitely on the outside of the little lip inside the housing! Still doing it and I will try to get a video too!!

 

[SrC]

Seems you know what you are doing there.
Let us know how it goes.
Will be helpful for others

 

[ollie6s]

+1
Checking shims placed at the main gear side BB of the diff and the diff case ( bulkhead)......
Adding one more shim may be needed?? IDK.
Should be no endplay. I rather have mine on the tighter side than loose. The shims compress with use/break in. But absolutely check the gears for broken teeth first. Removing the grease to look closely. Ignoring this and a chipped tooth floating around, can brick the whole gear set subsequently, with use.
Try a set of the Tekno diff shims, which are thinner, adding as needed. (not for EXB diffs, only for the RTR 6s diffs, as in your case)

Had a good look over the teeth, similar to the motorcycle stuff I work on, no shiny grease or metal shavings and no shark teeth or missing. It’s baffling me

Visually make sure the diff cover is fully seated to the gearbox, easy to think it's all the way on when it's actually not. It's a tight fit, if the cover isn't fully seated, the diff gets pushed away from the pinion gear causing it to skip and click under acceleration and braking

Visually make sure the diff cover is fully seated to the gearbox, easy to think it's all the way on when it's actually not. It's a tight fit, if the cover isn't fully seated, the diff gets pushed away from the pinion gear causing it to skip and click under acceleration and braking.

Had a good look over the housings and it’s well seated, it’s a proper squeeze to get it in but fully seated down

 

[Hector_Fisher]

Did you check spider gears inside the diff case? i've had "clicking" type issues from when the diff internals weren't fully assembled correctly (my fault). But if you haven't touched the center diff internals, it would be bad to assume that Horizon hobby assembles everything 100% correctly every time

Also, I know it's tedious, but if you've inspected the gears on the front and found nothing, you may want to consider disconnecting front and rear diffs separately to see if the clicking can be isolated. Since the center diff connects both front and rear, even if you held one of the front or rear tires down, you could still be working the center diff. I know i've heard of people having issue with the center diff right out of the box.

 

[Senton_Prime]

A bench video would help a lot

 

[KnowAir]

You can try holding the front driveshaft with one hand, then get a couple fingers on one of the front outdrives and see if there's any play.. if the ring and pinion are slacked, you should be able to feel it?

 

[carckton driver]

sooo you didnt check all the shims/gaps. theres 3 areas of the diff that could need shimming. the ring gear which is sounds like the one you checked, the pinion (the one where the input shaft goes to), and internally in the diff (the spider gears and other 2 gears). check everything for any damage and start with the pinion since you already did the ring gear.

 

[ollie6s]

Thanks for the help guys, still can’t find a thing that is sloppy / sheared / loose. I’ve taken the great idea of allowing it to break then seeing what it was, informing all on here and then upgrading the part to something better. Scorched M2c vivaton whatever seems the best. But thanks all for the help, keep an eye out on here ))

 

[SrC]

Upgrading doesn't always solve the problem, by throwing more $$ at it.
99% of time it is the Main gear shimming that is "off" a bit.
I never shimmed the Input gear. Should not have to if you have known good Main and Input gears and shim the main gear side properly. On occasion a new bulkhead will solve the problem. Inexpensive enough to replace as a part. Even loose Bulkhead screws on the bottom of the chassis may be too loose, causing this. The front chassis Kick up in the front can even get tweaked/twisted/bent from nose impacts, and will distort the front main/input gear alignment/ mesh.
Sometimes I will continue driving it until whatever fails, does. Sometimes you beat yourself up chasing a ghost. Need the failure to present itself more clearly to learn it better. Keep driving it if you can't figure it out. Keep bashing as long as the rig still performs.
I prefer stocker plastic bulkheads. How I fly. Overall, I like my rigs on the light side. Heavy alloys can work against you also. One by one, they all add up in weight. I even prefer light, lower capacity Lipos.

 

[KnowAir]

Thanks for the help guys, still can’t find a thing that is sloppy / sheared / loose. I’ve taken the great idea of allowing it to break then seeing what it was, informing all on here and then upgrading the part to something better. Scorched M2c vivaton whatever seems the best. But thanks all for the help, keep an eye out on here ))

I would run it till it manifests itself as @SrC Suggested. It's frustrating for sure, but since you've already put eyes on everything,,just send it and enjoy. Who knows, maybe it'll clear up on it's own..stranger things have happened..

 

[SrC]

So true.
Might clear up.
I had a situation where I said screw it. Had enough ghost chasing, Maybe a breakin will resolve it. And it did.
Sometimes I fight the anal habit voices inside me. Just drive the dam thing. If it fails, won't be the first or last time anyway.

 

[KnowAir]

I just finished converting my Mojave lsd rear diff to open..what a $hit show.. I really should have started with new gears and cup at least seeing how it is 2 years old and no maintenance..
My bad.
It's back together and working, but not until I disassembled and reassembled 20 times..worn gears can wreak havoc trying to shim..
Next time,JRC all the way!!!

 

[SrC]

Feel ya 100%
Hours and hours of frustration rebuilding over and over, trying to find where the issue is. Fit being off a bit, etc. At some point good enough is just good enough. So maybe the diff lasts only 10 packs instead of 15 or 20. So be it. Working with what you got.
Just drive as is. Let a hard failure present itself.
Then address it with new parts.
Break fix, repeat. Part of the RC hobby. Don't resist that.
These are far from precision models.

 

[KnowAir]

Yeah, if I weren't so stubborn, I would've just bought a complete diff from Jenny's, a quick once over and done..
Hell, even my WIFE told me to just buy a new one!! THAT'S how stubborn I can be bout fixin things!