Cogging noise at faster speeds?

[BBQAlta]

I have a 2017 MX love the bike. I've had it for about 3 months and put 1000 miles on it! It has 2225 miles on it total. Recently I noticed the cogging noise at faster speeds when coasting and more rolling resistance and a vibration you can feel through the foot pegs. The sound seems to go away on acceleration. I took the gear reduction cover off and everything looks fine and still on the paint marks. I also checked the chain, sprockets and wheel bearings. Just wondering if anyone else has had this issue?

 

[Fog 25]

Check your cradle bolts.

 

[BBQAlta]

Checked the cradle bolts and there tight.

 

[Oded]

Can you post a video (with sound) of the problem?

 

[BBQAlta]

I changed the rear tire today to eliminate any possible issues. Then I took it for a ride and it sounds normal. If it's something as simple as a tire I feel stupid I'll update if the noise comes back. Thanks for the replies!

 

[leeo45]

Because these bikes are so quiet compared to a typical ICE dirt bike you will hear all sorts of 'strange and worrying noises'. Most of them existed on your ICE bikes, you just couldn't hear them. On the plus side, you can even hear the tires slide on dirt which can be a riding aid if you tune it in.

 

[Mark911]

My 17 was making the same noise. I pulled both covers to feel the motor and countershaft bearings. The right side motor bearing is definitely loose. I'm not surprised, those bearings are pretty tiny for the loads they see. I also know there was an engineering change to that right side bearing as I've seen at least two variations; one where the bearing is totally sealed and one where it's splash lubricated from the drive gear oil. I'm not sure of the incorporation disposition(s), however, as I've only seen this in spare (trace unknown) motors. When I get my motor out to replace that bearing I'll know more.

 

[Mark911]

Update. I pulled the pinion gear and can see that my early 17 used the open/splash lubricated right side roller bearing. I must therefore conclude that the sealed bearing is the preferred "should be" configuration. I believe this change order also revised the bearing type from a roller to ball bearing. The replacement part number I've used successfully before with my gas to electric conversions (Alta Grom, Alta CRG Shifter, etc) is 6202-2RSR C3. I've never replaced this particular bearing before due to failure but because I needed a totaled sealed bearing for my conversion applications. But it should work.

 

[C5tor]

Update. I pulled the pinion gear and can see that my early 17 used the open/splash lubricated right side roller bearing. I must therefore conclude that the sealed bearing is the preferred "should be" configuration. I believe this change order also revised the bearing type from a roller to ball bearing. The replacement part number I've used successfully before with my gas to electric conversions (Alta Grom, Alta CRG Shifter, etc) is 6202-2RSR C3. I've never replaced this particular bearing before due to failure but because I needed a totaled sealed bearing for my conversion applications. But it should work.

Got any pics or video of the replacement process? This seems like a good thing to document.

 

[Mark911]

I'll do that.

 

[Motophyllic]

When you pulled the covers, were you able to reuse the gasket? Mine is making noise and I wanna check it.

 

[Mark911]

yes.

 

[Rashid510]

Update. I pulled the pinion gear and can see that my early 17 used the open/splash lubricated right side roller bearing. I must therefore conclude that the sealed bearing is the preferred "should be" configuration. I believe this change order also revised the bearing type from a roller to ball bearing.

-02 Motors (which are in the majority of all later Alta models) use these bearings:

(Inside the motor; on the spline: NU202-E-TVP2-C3 - FAG Cylindrical Roller Bearing - 15x35x11mm) - NU202-E-TVP2-C3
In the motor plate: Also a NU202-E-TVP2-C

https://www.motionindustries.com/products/sku/00048145 = Bearing that lives on the spline.

When you pulled the covers, were you able to reuse the gasket? Mine is making noise and I wanna check it.

If there is seepage in the gasket, may not be wise to re-use the gasket. When I did my oil drain bolt inspection my gasket did tear up.

 

[Mark911]

Rashid,
Can you check to see if there's an EO existing on that bearing? The one you described is an open (well, sealed on one side only) bearing like my early 17. From the half dozen or so motors I've looked at most are of the totally sealed type and not a roller but ball bearing. Also, I'm not certain but suspect having two rollers on the same shaft results in a design with very little axial loading capability. Typically, at least one bearing is a ball to accommodate those side loads. The sensor side bearing needs some lubrication and since there's no source of oil (like the gear side) it's typically a seal bearing as well.

 

[Rashid510]

Rashid, Can you check to see if there's an EO existing on that bearing?

I do not see that in any descriptions.

The ball bearing lives inside the stator assembly on the sensor side. (Accommodation of those side loads) which is what you indicated for a part number. I have yet to see or hear of a bike which had those parts fail.


The Alta motor from -00 till -02 had roller bearings on the outer and inner sides of the bearing plate. It survived quite a lot of shock testing so I strongly think its been validated to handle axial loads.

 

[Mark911]

So there's a design with two bearings on the one bearing plate (the gear side of the motor), an inner and outer? Maybe I'm getting the part description wrong, but this is what I'm callling the bearing plate.

 

[Rashid510]

Yes. Remember that bearing plate also goes down: 20 is the inner bearing and 19 is the outer bearing.

 

[Mark911]

Ok, got it. Two bearings but not on the same shaft. Now I understand what you were saying. I thought maybe there was a revision that had two bearings on one side of the rotor shaft.

Could the motor vender have changed that bearing without telling you guys? Was there any testing or other developmental work being done which involved changing that bearing? I'm just trying to figure out an explanation for how sealed ball bearings got into some of the motors I've seen.

 

[Rashid510]

Ok, got it. Two bearings but not on the same shaft. Now I understand what you were saying. I thought maybe there was a revision that had two bearings on one side of the rotor shaft.

Could the motor vender have changed that bearing without telling you guys? Was there any testing or other developmental work being done which involved changing that bearing? I'm just trying to figure out an explanation for how sealed ball bearings got into some of the motors I've seen.

Close. On this side of the bearing plate there is a bearing on each side. The bearing set which is on the drive spline shaft is on the bottom is a ball bearing set. The picture below shows the bearings on the top part of the plate.




Unless the vendor was working on something with engineering, the production motors have whats shown in the posts above. If those motors had spec differences or part number differences ,they would have also been set aside/reviewed. Early Alta production did have alot of.....flexibility for a lack of a better word. Once serial production of the bikes was more constant, parts came more standardized.

Also I do not know what motors you have (other than the one I sold you). -01 motors were updates done to the stator and manufacturing refinements. -02 motors were spec updates to the motor wires. There may have been developmental motors that were being created to help out with future projects...

 

[Mark911]

Yea, a couple of the motors I've seen were obtained in the "snatch and grab" of the office areas in those final days. Who knows what/who were messing with them, lol.

BTW, the "inner" bearing (item 20) is actually the inner race for the one roller bearing (item 19). I guess because with a roller of this type the inner race is actually a loose part you guys decided to give it a separate part number. In fact, the outer bearing stays with the bearing plate when removed and the inner race stays on the motor shaft as its a press fit. A bastard to remove as well, lol.