Xmaxx ultimate cogging problem, please help

[Greywolf74]

I don't have a running X-Maxx, so I have no idea if 1.75 works or not with his setup. When I was working on ours, I watched vids of ones running pretty damn good, and recorded the gearset they used for reference later and popped them into that spreadsheet. Whether they are too steep or not, I have no idea. But the OP's ratio is right in that range I found others to be using. The stock motor and ESC are underpowered according to what I found (and from JT). Swapping to the HW setups allows for taller gearing. JT's was overheating before he swapped to the Max5. Or was his a 6 also? But he did have a few mods on it before he swapped electronics

I sorta remember that. I want to say he went with the MAX 5 because at that time I believe others were reporting issues running the MAX6 on the XMAXX. I really don't remember for sure though, that's probably been 3 years ago now. lol

 

[WickedFog]

I sorta remember that. I want to say he went with the MAX 5 because at that time I believe others were reporting issues running the MAX6 on the XMAXX. I really don't remember for sure though, that's probably been 3 years ago now. lol

I think you're right. There were a lot of people having issues with the Max6, and I think JT was hopping his up as Tunedfrog and I were buying parts. And that's when I was seeing folks complaining.

 

[KnowAir]

Got any pics of a the mangled pinions? Any number of these measurements being off on that spur could cause premature pinion wear. The pinion has less surface area, so it's gonna wear first if there is a problem with the machining.
View attachment 211881

I don't have any pics unfortunately, but have noted that I'm getting less than ideal mesh with the "pin" system that TRX uses on the X. Just the other day I was running it after I recently replaced the rear ring/pinion gears. Lost a couple teeth off the rear input pinion, not bad considering it's nearly 3 years old. I replaced the rear upper and lower bulkheads, along with the rear diff cover. All stock pieces since the factory stock lasted me nearly 3 years I figured why mess with a good thing. So while running the truck the other day, it took a nasty end over end tumble, 3 or 4 flips in 30F. After that I was hearing a strange noise from the gears, still running, but not sounding happy. I found that my pinion/spur mesh is waay loose, pinion has a few chipped teeth as well. Motor mount screws are tight, motor "seems" tight in the mounts.
I added the GPM alloy upper cover w/extra bearing at the spur gear/shaft in hopes of eliminating some of the flex that the spur shaft has in stock form. I bet anything the "crazy racer" spur is out of round. Like you said, the pinion rotates 2.5 RPM for every turn on the spur, so the pinion experiences the wear more quickly.

 

[KnowAir]

I think you're right. There were a lot of people having issues with the Max6, and I think JT was hopping his up as Tunedfrog and I were buying parts. And that's when I was seeing folks complaining.

Yeah, I'm still content with the G1 Max 6 and now have actually "upgraded" to a Firma 160 in my X, LOL. The Firma 160 gives me 8.4v BEC vs G1 Max6 at 7.4v. So that gives you some indication of where my performance bar is set to. Also why my X has made it 3 years without blowing diffs I believe. Trust me, it's got alot of miles on it. I know I'd have double the money in it by now if I were running a big block system in it.

 

[WickedFog]

I don't have any pics unfortunately, but have noted that I'm getting less than ideal mesh with the "pin" system that TRX uses on the X. Just the other day I was running it after I recently replaced the rear ring/pinion gears. Lost a couple teeth off the rear input pinion, not bad considering it's nearly 3 years old. I replaced the rear upper and lower bulkheads, along with the rear diff cover. All stock pieces since the factory stock lasted me nearly 3 years I figured why mess with a good thing. So while running the truck the other day, it took a nasty end over end tumble, 3 or 4 flips in 30F. After that I was hearing a strange noise from the gears, still running, but not sounding happy. I found that my pinion/spur mesh is waay loose, pinion has a few chipped teeth as well. Motor mount screws are tight, motor "seems" tight in the mounts.
I added the GPM alloy upper cover w/extra bearing at the spur gear/shaft in hopes of eliminating some of the flex that the spur shaft has in stock form. I bet anything the "crazy racer" spur is out of round. Like you said, the pinion rotates 2.5 RPM for every turn on the spur, so the pinion experiences the wear more quickly.

That gear SHOULD have been made in a Swiss machine, so all final machining should have been done simultaneously. So everything should be concentric. But not everyone can afford a good Swiss machine, and will handle the part over various operations, leaving room for problems.

You can check the runnout with calipers. Measure around between the teeth across the gear in a few places. That should be accurate enough to spot a problem. Maybe after you burn through 20 or so more pinions that spur will be worn into a good one

 

[CertifiedMike]

I don't have any pics unfortunately, but have noted that I'm getting less than ideal mesh with the "pin" system that TRX uses on the X. Just the other day I was running it after I recently replaced the rear ring/pinion gears. Lost a couple teeth off the rear input pinion, not bad considering it's nearly 3 years old. I replaced the rear upper and lower bulkheads, along with the rear diff cover. All stock pieces since the factory stock lasted me nearly 3 years I figured why mess with a good thing. So while running the truck the other day, it took a nasty end over end tumble, 3 or 4 flips in 30F. After that I was hearing a strange noise from the gears, still running, but not sounding happy. I found that my pinion/spur mesh is waay loose, pinion has a few chipped teeth as well. Motor mount screws are tight, motor "seems" tight in the mounts.
I added the GPM alloy upper cover w/extra bearing at the spur gear/shaft in hopes of eliminating some of the flex that the spur shaft has in stock form. I bet anything the "crazy racer" spur is out of round. Like you said, the pinion rotates 2.5 RPM for every turn on the spur, so the pinion experiences the wear more quickly.

Is your motor able to be "supported" by sliding a piece of plastic under it or something?
Arrma chassis flex at the motor mounts and cause chaos too.
A shim between motor and chassis seems like a popular "help" more than "fix". Just enough to fill the space.

I love watching these threads unfold to a solution!!!
If Sherlock Holmes could get any more dorky... here I am!

 

[KnowAir]

That gear SHOULD have been made in a Swiss machine, so all final machining should have been done simultaneously. So everything should be concentric. But not everyone can afford a good Swiss machine, and will handle the part over various operations, leaving room for problems.

You can check the runnout with calipers. Measure around between the teeth across the gear in a few places. That should be accurate enough to spot a problem. Maybe after you burn through 20 or so more pinions that spur will be worn into a good one

I need to get to the bottom of this. Guess I will have to pull the spur and check it out. Thanks!

 

[WickedFog]

I need to get to the bottom of this. Guess I will have to pull the spur and check it out. Thanks!

Check from the pinion bore to the root diameter too. They may not be concentric.

 

[KnowAir]

Is your motor able to be "supported" by sliding a piece of plastic under it or something?
Arrma chassis flex at the motor mounts and cause chaos too.
A shim between motor and chassis seems like a popular "help" more than "fix". Just enough to fill the space.

I love watching these threads unfold to a solution!!!
If Sherlock Holmes could get any more dorky... here I am!

I actually pulled the pins and added some strips of excercise bands under the motor mount at one point, IIRC, I put the pins in the holes for a different gear ratio. Been a while since I did that. Ended up going back to stock sometime after that. I have heard of the plastic mounts loosening from the motor itself too and causing issues on the TRX 8s rigs. I’ve been half arsing it, time to dig inI guess and see wtf is going on.

 

[KnowAir]

Check from the pinion bore to the root diameter too. They may not be concentric.
View attachment 211887

I suppose a bent spur shaft ispossible, but honestly it sounded and ran great before that last little somersault..

 

[WickedFog]

I actually pulled the pins and added some strips of excercise bands under the motor mount at one point, IIRC, I put the pins in the holes for a different gear ratio. Been a while since I did that. Ended up going back to stock sometime after that. I have heard of the plastic mounts loosening from the motor itself too and causing issues on the TRX 8s rigs. I’ve been half arsing it, time to dig inI guess and see wtf is going on.

Measure the green and red dimensions in at least 4 points around the gear. That should be plenty good enough to find any problem there. Kinda hard if your spur has an odd number of teeth, but you're just looking for reference numbers to compare. Just try to measure each spot the same way to get consistant values.

And I hate those pin locating motor mounts, but they are supposed to keep your motor from moving. Our Hammer Rey has a motor mount like that, but fortunately, the holes put the mesh as perfect as I could hope for after holding the motor towards the spur as I snugged the screws. Just slapping them in in free state had the mesh just slightly loose for me because you're dealing with using a threaded screw to locate on a cast hole. I was actually surprised how close it was, but there is a tiny bit of play there to tweak it. They should use precision ground shoulder bolts and reamed holes there

If yours won't get you there, I would do some light file work with a rat tail file on those holes in the direction you need to go.

 

[WickedFog]

I suppose a bent spur shaft ispossible, but honestly it sounded and ran great before that last little somersault..

Oh yeah, that is definitely possible. You need a dial indicator on the spur while you rotate it to check that. The X-Maxx is actually bad about that now that I remember. But you upgraded your bearing retainers in there you said right? I've seen a few mods that address that crappy Traxxas design.

 

[KnowAir]

Oh yeah, that is definitely possible. You need a dial indicator on the spur while you rotate it to check that. The X-Maxx is actually bad about that now that I remember. But you upgraded your bearing retainers in there you said right? I've seen a few mods that address that crappy Traxxas design.

I grabbed this GPM cover, it adds a third bearing to support the spur shaft as well as being aluminum instead of a plastic cover.
https://nitrohobbies.com/xrt038mn-or/
There are other setups that add another bearing at the end of the spurshaft near the motor. I think I paid $25 for it, I figured it should help. On these TRX 8s trucks the spur shaft has a lot of play in it, E Revo also. I’ll tryand check the gears for trueness. I have the Kaiju on the bench now, nearly broke it in half jumping snowbanks a couple weeks ago, LOL. It’s almost back together, rear gearbox lost an ear and lower skid plate broken. Was quite comical seeing it “dog walk” down the driveway. Poor Kaiju

 

[WickedFog]

I grabbed this GPM cover, it adds a third bearing to support the spur shaft as well as being aluminum instead of a plastic cover.
https://nitrohobbies.com/xrt038mn-or/
There are other setups that add another bearing at the end of the spurshaft near the motor. I think I paid $25 for it, I figured it should help. On these TRX 8s trucks the spur shaft has a lot of play in it, E Revo also. I’ll tryand check the gears for trueness. I have the Kaiju on the bench now, nearly broke it in half jumping snowbanks a couple weeks ago, LOL. It’s almost back together, rear gearbox lost an ear and lower skid plate broken. Was quite comical seeing it “dog walk” down the driveway. Poor Kaiju

View attachment 211891

Oh, that looks much better.

 

[rc-enthusiast]

What I've read as well. For transparency, I'm a low budget basher.. a crumbsucker if you will, LOL. So I have never owned any Castle myself, never felt the need. A coworker of mine has run them, said they're garbage.. but then, he also loves Traxxas VXL! Forget that guy!!
As to Amazon returns, everyone says easy peasy.. I suspect the Max 5 combo will get ya where you wanna be. As to the Max 6 combo, would be fire in a 6s basher.. such as a K6 EXB or similar.. decisions.. LOL.

Yeah I've literally already have a fully custom built kraton 6s exb v2 completely built with m2c everything! The only thing stock in it is the motor and esc so if I drop max6 in it that will be my first true 100% rc that has every single top notch upgrade you could do. After much time and thousands of dollars later, I'll never get what I put into it back if I sell it ever it's a keeper lol.

 

[KnowAir]

Yeah I've literally already have a fully custom built kraton 6s exb v2 completely built with m2c everything! The only thing stock in it is the motor and esc so if I drop max6 in it that will be my first true 100% rc that has every single top notch upgrade you could do. After much time and thousands of dollars later, I'll never get what I put into it back if I sell it ever it's a keeper lol.

Nice! You sure can use a 5690 in a K6, though you’ll have to do some work with gear ratios to get speed out of it on 6s. Custom built rc’s are a labor of love, just like building hot rods from classic cars. The K6 is a great platform to build from though.

 

[KnowAir]

Oh, that looks much better.

It definitely eliminated most of the deflection of the spur shaft, plenty of support for stock and even mild power upgrades I feel. That’s the achilles of the TRX 8s trucks though I think, there’s just soo much flex in the trucks that gear mesh changes during operation. In more than just pinion/spur gears. What makes the plastic fantastic great is also it’s weakness if you know what I mean. Arrma 8s is almost a polar opposite. I have both, and each is great in different ways.

 

[WickedFog]

It definitely eliminated most of the deflection of the spur shaft, plenty of support for stock and even mild power upgrades I feel. That’s the achilles of the TRX 8s trucks though I think, there’s just soo much flex in the trucks that gear mesh changes during operation. In more than just pinion/spur gears. What makes the plastic fantastic great is also it’s weakness if you know what I mean. Arrma 8s is almost a polar opposite. I have both, and each is great in different ways.

That's another reason the back of the motors need support under them. So much flex everywhere.

 

[KnowAir]

That's another reason the back of the motors need support under them. So much flex everywhere.

Yes. I'm on the fence right now, stay with stock motor/mount, or take the plunge. My X has a good working stock motor, donated by my bro from his X, and I have my original motor as a spare on standby that I put new bearings in, but would love a lil mo powa, LOL. Then I have the K8, which came with the 4985, I immediately replaced that with a Firma 5687. So I also have that Firma 4985 laying around unused. IDK if it would be a legit improvement over the VXL motor and of course that would require an aftermarket MM just to try.. eh, I guess I'll just stay out here in left field and watch the butterflies, LOL.

 

[Greywolf74]

Yeah, I'm still content with the G1 Max 6 and now have actually "upgraded" to a Firma 160 in my X, LOL. The Firma 160 gives me 8.4v BEC vs G1 Max6 at 7.4v. So that gives you some indication of where my performance bar is set to. Also why my X has made it 3 years without blowing diffs I believe. Trust me, it's got alot of miles on it. I know I'd have double the money in it by now if I were running a big block system in it.

Id actually like the Firma 160 if it had a regular LVC on it. They were so close to having a solid RTR ESC! lol