Why is my spur gear / shaft wobbling?

[Damnir]

My spur gear appears to wobble and not spin "true". I only noticed when I took the cover off the transmission and had the wheels moving back and forth. I assumed it was the slipper drive gear shaft (AX31063), so I went ahead and ordered it. Installed it today, didn't fix a thing... Thought maybe it was the spur that was bent, sits flat on a table.

I decided to just stack slipper clutch parts and see how they spun compared to the housing, they also wobble.

When I built the kit, I put a bearing instead of the plastic spacer on the shaft for the spur to sit on. Also found nothing wrong, ie; shavings, bad bearings, etc, when I had it completely disassembled.

Never had an RC wobble this much, I thought for sure it'd start shearing teeth.

Keep running it as is? Anyone else having similar issue so I shouldn't be concerned?

Thanks guys!

Forgot to mention, truck seems to be running fine, just dumb luck I noticed it.

[BarHarborBasher]

roll the shaft & spur on a thick pice of glass then check the bearings.... I have had both happen to me ...

[Damnir]

You think the shaft might still be the problem? Even though it's brand new/not even run? The bearing was still buttery smooth so I didn't even consider that to be a problem.. Hmm.
Like I said before, slid the slipper clutch pieces on the shaft and spun them while watching the case, and they were also wobbling. At that point I was already about 2hrs into farting around I just slapped it back together. Which part was specifically YOUR issue?

[MaxxPain]

I think most of the wobble comes from the spring, especially when you tighten it down a lot. You can try loosing everything up and rotate all the parts then re-tighten it down sometime helps or makes it worse. I later changed the gear out to a hot racing gear and it went together with a lot less wobble. Plus the stock gear is very heavy too compared to the HR one.

[84yoda]

I already went through this exact problem, its just the shitty slipper setup. Went to robinson racing slipper and no more problems. I went through 2 slipper shafts, new spring, HR 68t spur, axial machined slipper plates too, nothing fixed it except RR slipper. Dont know how or why but it was my fix and still problem free.

[Damnir]

Just to clarify.. wobble is there with the spring uninstalled. I'm talking about literally just spinning it without hardware, or putting a slipper piece or spur on the shaft and spinning it by hand. I've taken some pictures of the components.. Both the old shaft (about 12 battery packs) and the new (not ran yet) are not straight. Spur looks good, the other shaft looks good, but it's hard to tell.

Anyways, not trying to beat a dead horse, I'm just scratching my head and also wondering if it's always been like that since day one (and I never noticed). The slipper components are not the problem, it's visible without it installed. Everything in the case is good, bearings, gears, grease.. Spins nice and free. I'll share the pics I took anyways so you can see for yourselves. I'll just slap it back together and deal with it when it grenades.

Used shaft:


New shaft:


Spur gear:


Lower shaft view # 1


Lower shaft view #2

[Damnir]

Originally Posted by 84yoda

I already went through this exact problem, its just the shitty slipper setup. Went to robinson racing slipper and no more problems. I went through 2 slipper shafts, new spring, HR 68t spur, axial machined slipper plates too, nothing fixed it except RR slipper. Dont know how or why but it was my fix and still problem free.

Are these the specific items you recommend:

Hot Racing Axial Yeti XL RC Car upgrades and Hop-ups

and

Hot Racing Axial Yeti XL RC Car upgrades and Hop-ups

Thanks!

[cmbscx10]

Originally Posted by Damnir

Are these the specific items you recommend:

Hot Racing Axial Yeti XL RC Car upgrades and Hop-ups

and

Hot Racing Axial Yeti XL RC Car upgrades and Hop-ups

Thanks!

1st= Awesome pictures. Very detailed and really shows what's going on.

2nd= I would run the stock shaft before the bent "new" shaft. Wholly milk producer is that bent.

3rd= I think it is this setup Robinson Racing Axial Yeti Gen 3 Slipper Unit w/Blackened Steel Spur Gear (64) [RRP1564] | Parts - AMain Performance Hobbies - AMain Performance Hobbies with a pinion change if you want the same gearing.

[Damnir]

Well, out of frustration, I slapped it back together with the new shaft. I replaced the two Axial bearings on the lower shaft because they are the non-rubber cased ones (I've seen that style grenaded on this forum a few times). If I am staring at the space between the spur gear and the back case, there's approximately 1/8th of an inch of wobble as compared to the bottom seated position.

I thought people were complaining about the Robinson racing 1/10th Yeti slipper? ie; not worth the money, nothing to gain.

Starting to think 84yoda is right about the spring... Like it's cocking everything sideways a bit. I thought maybe it was the angled back side of the slipper plate not sitting in the grooved section of the back plate. Was debating on putting something between the rear slipper and case to give it a flat surface to mate to, not sure if that'd help either. LOL.

[84yoda]

Originally Posted by cmbscx10

3rd= I think it is this setup Robinson Racing Axial Yeti Gen 3 Slipper Unit w/Blackened Steel Spur Gear (64) [RRP1564] | Parts - AMain Performance Hobbies - AMain Performance Hobbies with a pinion change if you want the same gearing.

Yes, this is the fix.

Originally Posted by Damnir

Well, out of frustration, I slapped it back together with the new shaft. I replaced the two Axial bearings on the lower shaft because they are the non-rubber cased ones (I've seen that style grenaded on this forum a few times). If I am staring at the space between the spur gear and the back case, there's approximately 1/8th of an inch of wobble as compared to the bottom seated position.

I thought people were complaining about the Robinson racing 1/10th Yeti slipper? ie; not worth the money, nothing to gain.

Starting to think 84yoda is right about the spring... Like it's cocking everything sideways a bit. I thought maybe it was the angled back side of the slipper plate not sitting in the grooved section of the back plate. Was debating on putting something between the rear slipper and case to give it a flat surface to mate to, not sure if that'd help either. LOL.

I thought it was the spring but after installing a new spring, still wobbled.

[Damnir]

84yoda, what else did you do with the Robinson Racing kit? Did you have to move down in pinions? I see its 64t vs 68t standard.

Thanks for the help!

[MaxxPain]

Assuming everything is true and straight. Another thing you can try is push on the spur gear with a strong tool like needle nose pliers or a flat head screw driver, to try and reduce the wobble.

[themacguru1]

Look for casting slag in surface of spur gear where slipper seats on it. It should be smooth. I attached a photo of mine before I cleaned it up. You can see the extra material that should not be there.


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[84yoda]

Originally Posted by Damnir

84yoda, what else did you do with the Robinson Racing kit? Did you have to move down in pinions? I see its 64t vs 68t standard.

Thanks for the help!

No you will be if fine running stock 15t pinion with the RR 64t spur. But I am running 17t pinion for a little more speed. 4s does 37mph and 6s does 51mph with 17t and 64t spur.

[84yoda]

Originally Posted by themacguru1

Look for casting slag in surface of spur gear where slipper seats on it. It should be smooth. I attached a photo of mine before I cleaned it up. You can see the extra material that should not be there.


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Ya I tried cleaning mine up with no luck, plus I tried the HR 68t spur with no luck either. I have no clue but RR 64t was my fix. Still straight to this day. Plus RR slipper is a lot better then aluminum on aluminum.

[Damnir]

OK, so I have nothing on the spur to clean, so that's not the problem for me either. I sent Axial an email on Sunday asking if there was a lot of customer complaints in regards to this problem, and if, they had a repair/solution. I sent pictures of the old vs new shaft showing how the new was in worse shape...

Got a reply today, they are sending me a new shaft, spur and pinion... I didn't ask for these items, more for help.. So, sounds like they are not really taking complaints seriously and just throwing freebies out there crossing their fingers.

Regardless, I ordered the Robinson yesterday, we'll see what happens. I'll report when it's installed in a week or so.

[84yoda]

Originally Posted by Damnir

OK, so I have nothing on the spur to clean, so that's not the problem for me either. I sent Axial an email on Sunday asking if there was a lot of customer complaints in regards to this problem, and if, they had a repair/solution. I sent pictures of the old vs new shaft showing how the new was in worse shape...

Got a reply today, they are sending me a new shaft, spur and pinion... I didn't ask for these items, more for help.. So, sounds like they are not really taking complaints seriously and just throwing freebies out there crossing their fingers.

Regardless, I ordered the Robinson yesterday, we'll see what happens. I'll report when it's installed in a week or so.

Yup, that's what axial does. I would also pick up some new fast eddy bearings for inside the tranny while your in there. Also, look up the thread about the RR slipper Fordfreak95 started, you have to bore out some plastic where the slipper shaft goes in because the RR slipper has this aluminum piece that fits between the bearing and the slipper. If it doesn't make any sense now, it will when you have it in your hands.

[Damnir]

I replaced the two large bearings (non rubber sealed ones) already in the trans w/ Fast Eddy's. The others were perfect... I've seen more issues with the completely open bearings found in the axles, etc.. I read a bit into the other guys threads on that RR slipper, which is what helped me pull the trigger. Found a great deal on it, so I'll see how she performs.

[slowe2411]

My slipper wobbles bad also. The stock gear looks to be a powdered metal forging. This process is only accurate to maybe .2mm. I think the surface for the slipper pads is not perpendicular to the axle. This would magnify the manufacturing error causing the run out. Mine has over 3mm wobble.
No noticeable run out with rr slipper.

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[redsawacs]

My input shaft was bent out of the box but I didn't think it was anything to be worried about. Still not affecting anything so I'm going to stick with the original for now - slight wobble and all.