Kraton Pinion slid around after being lubed up from leaky diff!

[RecklessRC Bashing]

Well, after cleaning up my leaky diff and tightening the screws that go into the spur gear and diff case, I took the kraton for a test run to see if it still leaks, it didn’t really leak but I think the leftover diff fluid (from when it was leaking) Got all over the pinion gear and lubed the pinion up so when I took it out for a lite bash, and upon inspection I noticed the pinion slid in towards the motor causing a light metal grinding sound towards the end of my run and some scraping against the motor mount. Geuss I should have pulled the motor out and cleaned it up but wasn’t trying to deal with the mesh and now I’m left with little to no choice, lol.

 

[SrC]

I don't think the diff fluid loosened the spur. That would be a neat trick. The set screw wasn't secure enough. Use Blue TL.
A properly secured set screw does not come apart because of any fluids contacting it. There's no short cuts when rebuilding the center diff. And when you are there, you always make sure mesh and gears are correct. Its all related components. You are in there already. If you cut corners, you usually have to do work twice. But we all live and learn. It probably wont happen again.

 

[NewSensei]

SrC isn't wrong, it is highly unlikely the diff fluid caused that to happen, not that corrosive. I replaced the center diff oil with silicone ear plugs (what swimmers use) to even the power distribution between the front and back and now leaking won't happen, even if there's a hole in the diff

Always use locktite on the pinion. I even put a tiny amount on the shaft itself, just don't use the red stuff or you'll be torching your motor every time you need to take the gear off.

 

[RecklessRC Bashing]

I don't think the diff fluid loosened the spur. That would be a neat trick. The set screw wasn't secure enough. Use Blue TL.
A properly secured set screw does not come apart because of any fluids contacting it. There's no short cuts when rebuilding the center diff. And when you are there, you always make sure mesh and gears are correct. Its all related components. You are in there already. If you cut corners, you usually have to do work twice. But we all live and learn. It probably wont happen again.

Well I never removed the pinion at all, nor have I rebuilt the diff yet. The diff started leaking after about 6 runs out of the box and fluid got all over the pinion and spur and basically everywhere. I removed the center diff and cleaned it all up and tightened the screws on the spur/ diff case and re installed. After 1 short lite run after cleaning, the pinion came loose. Never touched the pinion from the way it came from the factory. I am currently waiting on new hex drivers to remove set screw and add thread lock as I have recently stripped out my only other hex drivers on my other rig due to poor quality. The hex drivers I have coming are dynamite brand so hopefully they’ll work good for at least a little while. They were $26 for 1.5, 2.0, & 2.5mm where MIP are about $45$-50 so ill see how long these dynamite ones last and if they don’t then I’ll know to go with MIP on my next replacement.

 

[nino]

When your hex drivers start rounding out, you can give them a new life by shaving off a bit off the end. Just grind off a mm or so and bam, new sharp edges.

 

[RecklessRC Bashing]

When your hex drivers start rounding out, you can give them a new life by shaving off a bit off the end. Just grind off a mm or so and bam, new sharp edges.

Thanks, I’ve already done that twice with this set, it works in a pinch but it’s definitely time for a new one. The set I have is a very cheap set I had lying around before getting into the hobby and just decided to use that as much as possible before investing in some more expensive tools.

 

[SrC]

Well I never removed the pinion at all, nor have I rebuilt the diff yet. The diff started leaking after about 6 runs out of the box and fluid got all over the pinion and spur and basically everywhere. I removed the center diff and cleaned it all up and tightened the screws on the spur/ diff case and re installed. After 1 short lite run after cleaning, the pinion came loose. Never touched the pinion from the way it came from the factory. I am currently waiting on new hex drivers to remove set screw and add thread lock as I have recently stripped out my only other hex drivers on my other rig due to poor quality. The hex drivers I have coming are dynamite brand so hopefully they’ll work good for at least a little while. They were $26 for 1.5, 2.0, & 2.5mm where MIP are about $45$-50 so ill see how long these dynamite ones last and if they don’t then I’ll know to go with MIP on my next replacement.

Buy cheap buy twice and more. Have the Dynamites and several other AMZ China crap as backups and field tools. But MIP's at $45. have outlasted all. Now 7 years old MIP's never ruined any of my fasteners. Built up many kits with them. Cant say that about any of the others. It only takes one time to mangle a set screw in all of 2 seconds. Then you rethink your decision. Heating any TL fasteners is a good idea, especially the first time when removing a Red TL'ed screw. Only my opinion. Yes there are other quality Hex drivers and tips out there. Priced like MIP and even more.
Included allen wrenches should never be used for Metal on metal TL fasteners. I think most will agree.
I don't work for MIP.

 

[RecklessRC Bashing]

I here you there! If you saw this kit o had laying around (I never bought it just found it and figured it might work for a little while until I need to buy some better hex drivers) you would laugh. I recently stripped a set screw in all of 2 seconds on one of my other rigs, then ended up trying to drill it out with my dremel, but it was not happening. I tried cutting it and with the cutting discs that came with my dremel I went through 3 discs and had dent made it very far through the pinion. Then I said to myself, “I wonder if this liberty oil will get in there enough to break the pinion loose from the shaft, and to my delightful suprise it worked! Slid that pinion right off! That is what led me to believe the diff fluid might have worked it’s way into the pinion on the motor shaft enough to make it loose and that is what appears happened. I’m not saying anything’s impossible and I can definitely see a quality lube getting into that pinion enough to break it free from the set screws hold enough to move around on the shaft. Remember I never listened it before it came loose on its own even with threadlock from the factory. I can’t see any other reason that pinion would have came loose so suddenly. Looking into buying a set of mips now so I don’t have to worry, It seems mips the best as far as hex drivers go, I’ve seen it at least a hundred times. Thank you for the reassurance, and letting me know. I shall attempt to fix this pinion up with the dynamites then move them to backups as soon as I have some mips arrive. ?

 

[SrC]

I share my experiences so others wont make the mistakes I made 30 years ago. Saving money and frustration in the end. I have used PB blaster before to get a setscrew to "Slide" off the motor shaft before by using a puller of sorts. But not necessarily to loosen that set screw. Set screws will rust and even a quality known Driver means crap... the setscrew just rounds out . Been there.
Set screws are consumables IMHO. Spares should be on hand. They become rusty, worn out and don't stay secure over time with removing and reinstalling even with TL. They can cause the pinion to slide out of alignment to the spur gear. But a fresh set setscrew properly Thread Locked very firm and tight never moves regardless of fluid getting in that area. Using poor quality hex drivers to install a set screw tends to round out the setscrew as you tighten it. Then, its when you go to remove that setscrew that you discover the set screw is rounded out and becomes mangled. Even if you use a quality Driver for its removal.

 

[RecklessRC Bashing]

I share my experiences so others wont make the mistakes I made 30 years ago. Saving money and frustration in the end. I have used PB blaster before to get a setscrew to "Slide" off the motor shaft before by using a puller of sorts. But not necessarily to loosen that set screw. Set screws will rust and even a quality known Driver means crap... the setscrew just rounds out . Been there.
Set screws are consumables IMHO. Spares should be on hand. They become rusty, worn out and don't stay secure over time with removing and reinstalling even with TL. They can cause the pinion to slide out of alignment to the spur gear. But a fresh set setscrew properly Thread Locked very firm and tight never moves regardless of fluid getting in that area. Using poor quality hex drivers to install a set screw tends to round out the setscrew as you tighten it. Then, its when you go to remove that setscrew that you discover the set screw is rounded out and becomes mangled. Even if you use a quality Driver for its removal.

Do you know if the 6s kraton uses 2 set screws? There is only 1 set screw mine and I noticed there are 2 set screw holes on the pinion. If it doesn’t come with 2 screws, would it be a good idea to use a second one?

 

[SrC]

Some Arrma pinions came with 2 holes, some not. The primary set screw should always make contact with the "flat" section of the motor's shaft. That second setscrew hole will be 180 degrees opposed and will not touch any "flat". In theory, there is nothing wrong with using a secondary setscrew, but remember that it will not bottom out like the primary, and this may cause the setscrew to hit the motor mount during rotation. A bad thing for sure. If you trial fit a slightly shorter setscrew, it can work. Some guys do this. I generally don't. I rarely have issues with loosening pinions. At least that I can recall.
But 2 setscrews can work to your favor, in theory if your pinions can accommodate 2.
You have to think about why those 2 holed pinions only come with one setscrew......

 

[RecklessRC Bashing]

Some Arrma pinions came with 2 holes, some not. The primary set screw should always make contact with the "flat" section of the motor's shaft. That second setscrew hole will be 180 degrees opposed and will not touch any "flat". In theory, there is nothing wrong with using a secondary setscrew, but remember that it will not bottom out like the primary, and this may cause the setscrew to hit the motor mount during rotation. A bad thing for sure. If you trial fit a slightly shorter setscrew, it can work. Some guys do this. I generally don't. I rarely have issues with loosening pinions. At least that I can recall.
But 2 setscrews can work to your favor, in theory if your pinions can accommodate 2.
You have to think about why those 2 holed pinions only come with one setscrew......

Good point, I’ll probably just stick with 1 set screw at a time, I just started to wonder if it did come with 2 and one fell out although that seems unlikely. I took your advice on having spare set screws and just purchased 10 of them. Not a bad deal for only $5 shipping included. It would definitely be a bummer to need something so minuscule and not have any extras on hand causing the rig to be unusable until a new one comes in the mail! Kinda like right now, waiting on tools ?

 

[SrC]

A cheap inexpensive consumable part that you don't have on hand can ruin a whole weekend for sure. Been there.

 

[RecklessRC Bashing]

A cheap inexpensive consumable part that you don't have on hand can ruin a whole weekend for sure. Been there.

Facts!

 

[RecklessRC Bashing]

A cheap inexpensive consumable part that you don't have on hand can ruin a whole weekend for sure. Been there.

Got my MIP hex drivers today! I’m so excited to have these it’s not even funny ?

 

[jscholler]

A cheap inexpensive consumable part that you don't have on hand can ruin a whole weekend for sure. Been there.

My pinion slipped into the motor mount yesterday. When I tried to remove the mount one of my mount screws was stuck in with lots of loctite. Had to drill it out. Now I sit and wait for new motor mount screws from A-main since no LHS's have them in stock...

 

[RecklessRC Bashing]

My pinion slipped into the motor mount yesterday. When I tried to remove the mount one of my mount screws was stuck in with lots of loctite. Had to drill it out. Now I sit and wait for new motor mount screws from A-main since no LHS's have them in stock...

That’s no fun! I don’t enjoy waiting for things lol. I have noticed that it is not necessary to remove the mount just to re-tighten the pinion gear.

 

[jscholler]

Yeah, saw some guys do that on video- lesson learned(all part of the RC experience right?). As soon as I knew I wasn't getting the screw out I should have just re-positioned the pinion and tightened it as is.

 

[NewSensei]

Number one rule with ALL Arrma vehicles: heat up the metal around where screws are that are screwed into metal.

Rule two for ALL RC: use locktite on pinion grubs. I also add a a small amount of locktite to the motors shaft and if there is space for a second grub I'll add that too. Did that on my kraton, two grubs and a bit of locktite on the shaft. Let it cure 24 hours before use, this is one of the most important steps people often forgo due to i NM patience...I get it, this is why I have more than one RC

 

[jscholler]

I'm learning that about Arrma (this is my first and I'm a noob to boot). There was a good bit of loctite on the grub that let loose already from the factory- on about the 5th pack of the car.
@NewSensei any other wisdom you care to share with me? I know I should be looking in the diffs for oil and any needed shims, but to be honest I have minimal experience with them and they intimidate me a bit- don't want to do more harm than good if all is well...