I hate my XMaxx - Spur/Pinion Help

[MiamiRC]

Hey guys, lots of smart people here so I'm hoping someone has figured this out. I cannot get through a single pack of batteries in my XMaxx without the pinion coming loose, typically then destroying the spur gear. I have searched around the internet, watched the Youtubes, etc. and tried all of the following:

1. Hot Racing steel spur and Tekno pinion,. mod 1 with the 2.5mm grub screw. Blue then red loctite and I'm cranking the poop out of that screw with a MIP driver.
2. GPM steel spur and Arrma D pinion. This requires filing off a bit of the motor shaft so it slides on. The good thing about this approach is the pinion can't spin even if the grub screw comes loose because of the d hole in the pinion, but it still manages to just loosen and then vibrate until it falls off the end of the motor shaft. I'm red loctite all day at this point but makes no difference.
3. Replaced plastic motor mount with HR metal mount to increase rigidity.

I'm basically at the point I'm going to JB weld this motherf*fiddlesticker on and when the pinion fails just throw it out with the motor and get a HW combo, but hoping there might be something else worth trying before I go there. Anyone else have this issue that has it figured out? Thanks for your input.

 

[BigBrownEye]

My XRT was doing the same thing. LHS dropped my pinion size way down and problem went away. Not ideal solution if you're a speed freak, but it keeps me running so I'm good with that.

 

[lipo-joe]

I had a similar problem w/ the stock gearing in my XRT.
Switched to the speed gears and no issues - Have 10-12 packs thru and still running strong.
Did you check to make sure the pins are properly set ?

 

[razorrc]

Make sure you clean off the grub screw with some motor spray and also let the loctite dry overnight.

 

[cazrack]

Gear up by buying bigger tires...

 

[KnowAir]

I wish I could give ya some solid remedy.. I struggled with my Xmaxx too, as has my brother with his. Along with what @razorrc said, I think it helps to run the grub screw into the pinion well past where it hits the motor shaft. Obviously you have to do this with the pinion off of the motor. I believe the thread locker forms a lip where it stops when it grabs the motor shaft. Chasing the grub deeper into the gear will clean that buildup out. A new grub screw may help too. It's frustrating as heck I know!! Good luck!!

 

[Xjeepguy]

One thing I’ve done in the past is to mark the spot where the grub screw touches the shaft, and using a small drill bit, drill a shallow divot into the shaft. Then, a drop of red loctite into the divot, and tighten down the grub screw. Works great, but can be an absolute bear to get the pinion off if you need to lol.

 

[gotnitro]

One thing I’ve done in the past is to mark the spot where the grub screw touches the shaft, and using a small drill bit, drill a shallow divot into the shaft. Then, a drop of red loctite into the divot, and tighten down the grub screw. Works great, but can be an absolute bear to get the pinion off if you need to lol.

Whoap nope you just unbalanced that motor by removing material, RC police checking in, it’s trash, throw it away.

 

[GNT1]

Same problem at one time. I switched to vitavon 1.5 gears. Made damn sure the pinion threads and grub screw were clean. Added loctite and let it cure 24 hours. Ive been good so far with lots of runtime.

 

[Bustedaw11]

One thing I’ve done in the past is to mark the spot where the grub screw touches the shaft, and using a small drill bit, drill a shallow divot into the shaft. Then, a drop of red loctite into the divot, and tighten down the grub screw. Works great, but can be an absolute bear to get the pinion off if you need to lol.

Red lock tight the grub. Let it dry.. then put that sucker in..
Once in put more red lock tight behind the grub on any exposed threads that are left to "jam" the threads and jeep the grub from being able to back out. I've staked the threads before (aka f them up with a punch) to keep something from being able to back out..

Also you can heat the pinion THEN tighten the crap out of it... when it cools it will be even tighter then what you could ever get it cold...

Thinking outside the box

 

[Littlemotor]

What kind of Loctite are you using-liquid or the paste? Seems like it wouldn’t matter to a lot of folks, but with “problem childs” I’ve had much better luck with the chapstick style paste. You could always use a drop of Loctite “bearing retainer” green… You’ll have to use a mini torch to remove it again for sure though…

 

[Xjeepguy]

Whoap nope you just unbalanced that motor by removing material, RC police checking in, it’s trash, throw it away.

Didn’t seem to cause an issue, but I’ll keep that in mind.

 

[DLK83]

Are you using the oval shaped aluminum washers between the motor mount screws and chassis?

 

[gotnitro]

Didn’t seem to cause an issue, but I’ll keep that in mind.

It was a joke brotha, hence the

 

[Bustedaw11]

Didn’t seem to cause an issue, but I’ll keep that in mind.

In comparison to the weight of the rotor I don't think that tiny bit off the shaft would ever make a difference. I doubt highly they are balanced all that well stock anyway.
Back in the days of the 540 brushed I know you remember having to balance your own armature. Doubt much has actually changed. Just an over looked thing today

 

[MiamiRC]

My XRT was doing the same thing. LHS dropped my pinion size way down and problem went away. Not ideal solution if you're a speed freak, but it keeps me running so I'm good with that.

I’m running 18\50 which certainly isn’t crazy. What are you running?

I had a similar problem w/ the stock gearing in my XRT.
Switched to the speed gears and no issues - Have 10-12 packs thru and still running strong.
Did you check to make sure the pins are properly set ?

Well, I was using the pins with the stock motor mount but the mesh wasn't right with the Hot Racing one so now I'm just setting it manually. Basically I've done it both ways and doesn't seem to matter.

Gear up by buying bigger tires...

Running the PL Mashers which probably isn't helping but I just can't with the stock tires which are absolute crap and just blow up constantly.

Red lock tight the grub. Let it dry.. then put that sucker in..
Once in put more red lock tight behind the grub on any exposed threads that are left to "jam" the threads and jeep the grub from being able to back out. I've staked the threads before (aka f them up with a punch) to keep something from being able to back out..

Also you can heat the pinion THEN tighten the crap out of it... when it cools it will be even tighter then what you could ever get it cold...

Thinking outside the box

This is diabolical. I love it. I'm going to superheat that MoFo before I crank it down. Definitely worth a try.

Are you using the oval shaped aluminum washers between the motor mount screws and chassis?

I'm using the stock washers but with the HR motor mount I'm blue loctiting those in. I haven't reallly had an issue with them coming loose but I had that same thought.

Whoap nope you just unbalanced that motor by removing material, RC police checking in, it’s trash, throw it away.

Haha, that kind of answer is exactly why I didn't post in the Traxxas forums! Bunch of cotton headed ninny muggins over there.

What kind of Loctite are you using-liquid or the paste? Seems like it wouldn’t matter to a lot of folks, but with “problem childs” I’ve had much better luck with the chapstick style paste. You could always use a drop of Loctite “bearing retainer” green… You’ll have to use a mini torch to remove it again for sure though…

Red 271 liquid

Same problem at one time. I switched to vitavon 1.5 gears. Made damn sure the pinion threads and grub screw were clean. Added loctite and let it cure 24 hours. Ive been good so far with lots of runtime.

Been trying to avoid that expense but If I go to a new HW setup I'm definitely going Mod 1.5. Thanks

 

[KnowAir]

I'm doubtful that the brand or tooth count has much to do with the pinion not holding. I mean, we know TRX gears are less than the best..and they do stay on. It is possible to get a defective gear for sure, but I think you'd see and or hear that. Plus the OP is using a Tekno pinion, which are definitely quality. Just gotta get it cleaned up proper, torqued and loctite cured. I have put loctite on the shaft before installing the pinion before as well. Be prepared to use heat when removing the pinion next time round.. I never used red loctite on an rc myself.

 

[Bustedaw11]

This is diabolical. I love it. I'm going to superheat that MoFo before I crank it down. Definitely worth a try.

Back when I built barge boats that was the method we had to do on quite a few things in order to get them tight enough. I cannot see for a second why it wouldn't work to help get the grub extra tight.

Does the grub sit down in the pinion where you can see some threads still on the pinion? Or does the grub sit flush to above the pinion? If it sits below the pinion level and you can get thread locker behind it to lock some threads that'd be great. Or super glue. Just something to act as a lock. Maybe look for a shorter grub so you can do that for a thread or too on top of heating it first.

Ps. I also recommend using an L wrenches with a long handle. You'll get more torque on the grub vs a simple twist of a hand driver.

 

[Xjeepguy]

It was a joke brotha, hence the

I’m in the middle of a game and just glanced it over .

 

[Xjeepguy]

This is how I ultimately fixed the issue.