Kraton Pinion gear completely stripped

[calabiyau]

And not sure why it happened so I don't do it again
Ran my K on 6s for first time yesterday. Started pretty slow then after a few minutes ran it up to full throttle out about 100 yards and then turned around and headed back. Hit a bump on the way back and did a few cartwheels before landing uptight ( all on grass btw)
Hit the throttle to keep on going and no power to the wheels. Opened it up and could see the pinion was turning but not hitting the spur, then saw how stripped it was.
Will be replacing it obviously but trying to understand why it happened in the first place since this is all stil pretty new to me
Any help or suggestins are welcomed!
Thanks

 

[Brian schmidt]

It very well could be caused from impact while still on throttle. Second my stock pinion lasted two runs on 6s not running hard or with any crashes! I think it's just weak there are plenty of companies that make 5mm mod1 pinion gears that are much better! I'll be heading to my local hobby shop tomorrow to get a couple myself I've been running the optional 14 tooth only on 4s till I get a few replacements and it's seems to be a better ratio then the 12 tooth at least on 4s

 

[dpricenator]

WOW, I can't believe the Main gear is not all chewed up too. That pinion can be tough to get off. Be sure to heat p the grub screw with a soldering iron. Lots of guys have stripped that out trying to get the red Loctite to break free.

 

[calabiyau]

Not pulling anyone's leg here but I was prepared for a long ordeal to get my stripped pinion gear off in anticipation of receiving my replacement one tomorrow and it literally took less than 10 minutes...........and I went slow. This Kraton must have been assembled on the day the factory ran out of red loctite. Everything was tight plus some, but with a little leverage and strongish pressure (and I ain't no weightlifter), the screws, set screw and pinion came off pretty smoothly. Guess I caught a lucky break compared to a lot of others.

Since I have the motor out, any other maintenance I should do other than a little cleaning? I have Fast Eddy bearings so could upgrade that part while I'm doing the pinion change.

 

[crankestein]

Stripped gear for me as well on 5S.

Metal quality on the RTR pinion must be cheap grade.

 

[dpricenator]

Not pulling anyone's leg here but I was prepared for a long ordeal to get my stripped pinion gear off in anticipation of receiving my replacement one tomorrow and it literally took less than 10 minutes...........and I went slow. This Kraton must have been assembled on the day the factory ran out of red loctite. Everything was tight plus some, but with a little leverage and strongish pressure (and I ain't no weightlifter), the screws, set screw and pinion came off pretty smoothly. Guess I caught a lucky break compared to a lot of others.

Since I have the motor out, any other maintenance I should do other than a little cleaning? I have Fast Eddy bearings so could upgrade that part while I'm doing the pinion change.

Funny you say this, I have not had an issue wth any of the Loctite either. I have not tried the pinion yet though.

As far as other upgrades, the bearings in the center are going to be easiest while the diff and motor are out. When I did mine, I was also swapping the center diff mount, for the cut up motor mount mod. About 10 minutes into my next run, the car was acting funnt and I took a look at it, and the center diff bearing had exploded. Brand new FAST EDDIE's. It was not the bearings fault, My guess is that I did not have it fully seated, so while sitting at a slight (<1* off) angle, the heat produced caused a catastrophic failure. Anyway, my point here is to be sure those bearings are fully seated.
Also, if you fancy another mod you could order the Hot Racing Center Differential mount. I had swapped the cut motor mount, for this one, and it is working great. I swear some of these mods have made my car last longer between breakages. Lasting long, like I have yet to shred a differential of pinion gear. Between the hot Racing Diff Mount, Hot Racing Chassis braces, home made tower to tower brace, and shimmed differentials, the drive train keeps is shape better than it would stock. So the drive train is not experiencing the push and pull of the car flexing and keep the mesh and other tolerances closer to zero. Probably not necessary for basic RC usage, but the Kraton is not meant for basic Usage. It's meant for fierce bashing.

 

[Trickelitrick]

Have the same experience with the hr diff mount...blew the rear diff bearing three timesso i said screw this for now and threw hr in a box and its still there....regretting its sins

 

[dpricenator]

My HR Center Diff mount is fine, bummer yours isn't. It was the Home made Diff mount, made from a cut down motor mount, that gave me issues. It probably would have worked, but I didn't seat the bearing.

 

[Trickelitrick]

well actually im gonna give it another look since its a bit disassembled while waiting for replacement esc

You know what i got it to fit....but so embarrassing.....all i can say is i now know where i put the so called mystery spacer...haha wow that was long time ago....

 

[crankestein]

***Above; NO SHIMMING, thats the rear diff after more than 20 packs, 5S and a few runs on 6S.

All people need to do is threadlock everything before bashing, and bashing does not mean pushing the truck to its limit borderline to destruction.

Its not indestructible, but many watch way too many Youtube videos.

Not throwing anyone under or bashing their thread. I will be completely honest, I received mine and went at least through 10 packs, re glued the tires, tweaked the suspension and done. After about 25 packs redid all the diffs, all spankin new w factory diff oil.

All I can say there has to be multiple factories or depending on the shift and production line.

I will post mine as soon as I have the time and maybe we can track a trend of issues w certain serial number RTRs.

Mine has no center diff mod, no cnc center motor aftermarket mount, no cnc diff housing, its running strong like a champ from day one. There were minor issues w the motor pinion and some of the wheels which Hobbico corrected (although after some hassle) under warranty.

Mine lands plenty of time hitting the rear plate, on some jumps again and again. IMO it is one of the most reliable RTR out of the box. Its not perfect, but with some minor tlc it is really a true basher. Be adviced, the manual has RECOMMENDED diff service intervals and I am pretty sure most do only when they explode.

 

[Trickelitrick]

Actually my center broke in one of my first movies i ever did lol. My kraton was still very new and i hadn't even changed tires and yes the diff had enough grease inside.

 

[crankestein]

How did you drive it?
Where is the movie?

 

[Trickelitrick]

around 8.42

 

[crankestein]

Ja ja, yeah immediate loss of power after it gave up.

Yo should provide this video to Hobbico and claim that diff under warranty.

Mine is run on 15T and on grass, gravel, never on the road, but thats just me. And most of the time is on 5S.

Yours is a heavier truck, add driving on a track and field, plus a 12T, but it seems after all a bad batch diff gears was still around from factory. Gotta knock knock on wood on mine, sorry to say it, but its pristine w no broken parts.

Definitely not user error the center diff premature failure.

 

[calabiyau]

So not problem installing the new pinion gear. Ran great on 4s. Will try the 6s this weekend.
One small problem though
I stripped the pinion set screw when I attempted to give it a little snudge at the end to make sure it was tight. Now I have to learn how to removed stripped set screws when that need arises in the future

 

[calabiyau]

Problem solved! Ran it on 6s tonight just up and down the street about a dozen times. Holy crap is it fast on 6s. Didn't break anything. Yeah! But.....

Last run as it finished the run down the street slowed, turned to head for home, nothing happened. I could hear the gear turning but no power to the wheels. Figured I stripped the pinion gear again. Upon further review, the pinion gear was completely gone! Spur gear looks fine. Now I don't have to remove a stripped pinion gear, just make sure the set screw is in good and tight, and not stripped the next time