Kraton Gear Mesh Problem - Help Replacing Pinion

[upTheIrons453]

Independently, the pinion & the spur spin smoothly, but seemingly no matter how I position them together, I get some very nasty noises. I actually had the LHS swap out the pinion when I had it there for help with a transmitter-pairing issue. They goofed something up, and definitely didn't test it, because the 1st time I drove it, it sounded like the gears were being ripped apart. I took the motor out have been tinkering with it for a while now and just can't seem to get it right. I know there's probably not enough info here... but I really want to avoid disassembling this beast any further. Any theories?

Video here

 

[KevinC]

It sounds fine to me, however; I saw your pinion move toward the Eclip on the second throttle pull. Your pinion needs locktite.
The mesh didnt sound out of whack to me.....it sounded normal.

cheers,
kev

 

[Hammer Down]

Doesn’t sound terrible to me.. your pinon is definitely loose tho, I can see it move in your vid.

Edit: Kev beat me to it

 

[upTheIrons453]

revised post

 

[marucci87]

As stated above It sounds fine, but your pinion is loose. Check to make sure your center diff caps hardware is tight…some ppl including me have had the hardware back out on the case caps where the out drives come out. I went to eat plug mine and found one starting to back out and one more that was finger tight. I caught it just in time before it started skipping. Maybe that’s happening to you? I think it’s worth checking and re tread locking it regardless. It seems to be a common problem.

 

[SrC]

^^^+1
Mesh sounds fine. Use blue TL'er and a decent handled hex driver. Pinion is loose.
If not for the Circlip, you would have been SOL.

 

[upTheIrons453]

Apologies! And thank you... I submitted that last post like 3 seconds before I got some extra light (and my glasses) and realized the pinion was indeed loose... I tightened that all up with thread-lock, and haven't done another test yet...but they sure don't make that adjustment easy - having to use that groove in the metal for the driver, etc. My new glasses will be ready tomorrow lol... another big change from when I was 14 & in my "R/C prime". Of course back then I had instructions to follow, and this little Kyosho dude pointing his oversized finger at the potential trouble spot - tho I'm still uneasy about this...feels like thread-lock should be an insurance policy here & not required for a quick bench-test, but I'll find out soon enough...I just hope it's not after I load up & haul this beast out to the park.

I say it all the time, but it just still annoys me that a proper assembly manual isn't included with every kit, RTR or not. Squinting at exploded views & hunting around for the right segment of a YouTube video has made this part of the hobby a lot less fun for me, and I think is part of what causes me to procrastinate & make 2 hour jobs take 2 weeks. Thanks again y'all... I'll post an update when I get it all back together & go for a drive.

 

[KevinC]

Exploded views can be found on the Arrma site as well…….and they can be expanded with a click of the mouse for those of us who’s eyes aren’t what they used to be.

 

[upTheIrons453]

Exploded views can be found on the Arrma site as well…….and they can be expanded with a click of the mouse for those of us who’s eyes aren’t what they used to be.

Yeah, if I had a decent iPad, I'd probably have an easier time, but I think I'm also just cranky because I can't get comfortable at my workbench. The giant size of the Kraton is part of it, but mostly I just need better ergonomics & lighting. That's enough complaining about how I'm too old to play with my R/C cars!

The tranny still doesn't sound great, but things did get a little better when I moved the pinion just a few mm further from the motor. I am still trying to figure out how to make the thing coast a little without stopping so abruptly. I thought that was the "punch" setting, and it's what the throttle trim might help with back in the olden days, but neither of those are helping.

I'll take some video of the test run & circle back I am grateful for so many folks willing to take the time to chime in.

 

[SrC]

^^^Heck I'm too old to even lug around a 30 pound 8s rig.
Why I don't own one or any large scale rig for that matter.
It would end up being a shelf queen. I would need to build a suspension bridge for a shelf.

 

[upTheIrons453]

In the end I don't think it turned out to be anything. There were definitely some metal shavings coming out of there & must have been from the pinion being positioned too close to the motor & rubbing that motor mount. I moved that out a little, put it all back together, and had a very smooth test run...solid 35 minutes around the neighborhood - jumping speed-bumps, tormenting backyard dogs, etc., and it ran like a top. I think it's ready for this weekend's big basher event. I probably just jinxed it, but all appears well. Thanks again for indulging my paranoia

 

[upTheIrons453]

So I took the Kraton out to the park for a more serious bash session, and discovered as soon as I put it down that the pinion had been knocked loose again (on the previous run that was 95% neighborhood streets). I reapplied some threadlock (blue) and was on my way, but even though I was impressed with myself in that I managed to handle the repair track-side (after which the truck performed very well), it's not something I want to have to worry about. Any other tips or tricks to keep that pinion planted?

 

[Hammer Down]

Thread lock takes 24hrs to fully cure. (No playing until then..) Also clean the threads good with alcohol to ensure all the oil and contamination is gone.

 

[upTheIrons453]

Thread lock takes 24hrs to fully cure. (No playing until then..) Also clean the threads good with alcohol to ensure all the oil and contamination is gone.

The last application definitely had enough time to cure...though your comment does remind me that the trackside re-do wasn't done under optimal conditions & I couldn't really clean it up properly. Next time it comes loose I'll be able to polish that motor shaft first, and maybe I'll go with the "Red" compound, but at a certain point you want to be able to swap out the pinion.... If it comes undone after that, I'd suspect something else could be wrong.

 

[SrC]

I say replace the grub screw if you have a loosening problem.. They are consumables at some point. Cheap to have on hand. I also wont used Red TL on any Pinion gear. Even though Arrma does out the box. I warranteed a motor, and pinion, because I checked one out the box and just could not remove it without stripping the hex. Again using heat and all with a quality MIP driver. A new one. I let HH know it was never run, sent a pict. Told them to stop using Red TL. They know its a problem. And just replaced the related parts. Drilling out the grub screw can even damage the motor's armature shaft. Careful with that.
Technically Red is for much larger fasteners. (1/2"+ size) It needs 500F heat for removal. Not willing to destroy my Motor and it's BB's with high heat like that. You may never get that grub off without stripping it. Even with heat. Been there.
Blue TL is all thats needed for this size grub.. And left to cure.
Red 271 is for heaving machinery and Automotive applications. Just not for most small RC fastners IMHO. Some large scale nitro and gas engined rigs maybe.
If Blue TL 242 or 243( what I use) is not working for you, you are doing something wrong.

 

[upTheIrons453]

I say replace the grub scre if you have a loosen problem.. They are consumables at some point. Cheap to have on hand. I also wont used Red TL on any Pinion gear. Even tough Arrma does out the box. I warranteed a motor, and pinion, because I checked one out the box and just could not remove it without stripping the hex. Again het and all. I let HH know it was never run, sent a pict. Told them to stop using Red TL. They know its a problem. And just replaced the related parts. Drilling out the grub screw can even damage the motor's armature shaft. Careful with that.
Technically Red is for much larger fasteners. You may never get that grub off without stripping it. Even with heat. Been there.
Blue TL is all thats needed for this size grub.. And left to cure.

Thanks for sharing that experience... the idea of using thread lock at all on a pinion is still a little weird to me, but I'm glad you saved me from the "red experiment" - I'll definitely NOT be trying that route.

 

[SrC]

Yeah, at the track I never used any TL. changing out Pinions trying to dial it in and all. But my rig was examined well between Heats in the pit.
Never lost a pinion without TL. But with bashing these days and all, Many bashers are never checked meticulously enough. Blue TL has become a thing.
Red
Might as well just use Epoxy if using Red.

 

[marucci87]

I had issues all the time until I realized my method for instalIng the pinions was all wrong, I’ll tell you Exactly what I do now. First never use red thread locker, if the pinion is used or new doesn’t matter I take the grub screw out I clean it with brake clean and a metal brush and make sure there is no oil, dirt, or old thread locker And it is perfectly clean, I do the same with the whole pinion, I run the clean grub screw through the threads of the pinion with brake clean running it in and out, you want it to be pristine on the threads of the pinion and grub then when you are sure it’s perfect you also clean both the grub and pinion again with brake cleaner and make sure it drys, then clean the motor shaft to perfection too. I start by sliding my pinion on the shaft with no grub screw, then I positioning in the area of the spur gear, I face the flat part of the motor up and the pinion grub screw hole up too, I drop 2-3 drops of blue thread locker in there I spin the pinion around the shaft making sure the shaft isn’t spinning, I move the pinion forward and back a few millimeters to coat the are of the shaft that will be touching the pinion, making sure there is a thin film between the pinion and shaft, then I line up my pinion best I can next to the spurt and put a nice drop on the grub screw and insert it until it gets tight, then back it off very slightly to make sure my pinion and spur is centered to each other then lock the grub down, not crazy tight but pretty tight you don’t want to strip the tool hole, then I set my mesh and let it sit for 24-48 hours. I absolutely never have a problem since I have been doing it this way, I have pinions that have been on my cars for months without any issues. To take it off you will need to heat it up but it’s a lot better then welding it on with red, red is horrible. I even have a car that I didn’t even tighten the grub all the way as a experiment and it’s still hiding, using that method and just spinning the grub till it touched the shaft. But that’s a 3s car.