Wabash-RT creaking due to chainring play (?)

[Grueso]

My Wabash-RT started creaking on heavier pedal strokes a few weeks ago. It has 1700 miles on it. I traced the creaking back to play in the chainring: when I push & pull the chainring at 10 and 4 o'clock, I can feel some movement.
Is this a known issue? Is it sufficient to reseat the chainring ('drive sprocket', as Yamaha calls it), or does one have to dig deeper into the drive unit? I ordered a crank puller and a 36mm socket for the drive sprocket lock nut. Are there any other tools needed for this?

I did check and retorque the pedal bolts, crank bolts, motor mounts and the bolts holding the motor covers before tracing the noise to the chainring movement.

 

[Base]

depending on the type of lockring you would need a left torque wrench, a 36mm (thinwall) socket and set the torque at 25Nm for the Alu and 35Nm for the steel locknut.

 

[Grueso]

Thanks, Base! Are the two locknut types (steel vs aluminum) interchangeable? I hope the wobble is not a problem with the drive shaft or its bearings, and just due to the chainring seating. Is the chainring itself threaded on, or does it sit on a square or spline? I do not have the service manual.

 

[Base]

The chainring can either be one piece or on a spider like above, like with other brands this assembly is over a splined shaft and the locknut is a left threaded nut, for Yamaha just a regular nut where oither brands prefer to use their own nut for which you would need a special tool.

Did you check if the chainring is on a spider or is a one-piece design? Could also be the chainring-bolts.

 

[Base]

Btw, did you check if the creaking is indeed coming from the drive train? Like in another thread, did you check for the creaking sounds when you are out of the saddle with force on the pedals and what happens when you just barely touch the handlebar? Could also coming from a lot of other places than the drive-train/DU

 

[Grueso]

Thanks again! I have a spider, and the chainring bolts to the spider are tight. I can see and feel the chainring and spider move when I pull on it sideways. (I had checked the handlebar and fork and saddle (including post) before.)
I watched a PW motor disassembly video. From the parts diagram, the PW-ST should be very similar. If that is true, the chainring spline mounts on the drive gear, which is supported at that end inside the motor housing with what the video calls the 'crankshaft bearing'. If the splines are loose, one might have to replace both parts, the drive gear assembly and the spider? But (less likely, since the pedal axle does not seem to be moving, and it must be supported indirectly via the same bearing on the right side) it could also be excessive play of the whole drive gear against the motor housing, which would point at the large bearing there. All in all not good prospects.
I'm not very hopeful that just tightening the lock nut will do the job.

The tools arrived early. Unfortunately I was right: No traces of corrosion or dirt or wear on the seating surfaces on both sides of the chainring spider, the splines on both parts look unworn, but after reassembly and retightening the locknut (steel) the slight wobble and the creaking are still there. I am not able to feel play in the splined hollow shaft when trying to move it by hand without the chainring mounted, but that's probably due to a lack of lever arm.

So I guess I'll drop the bike off at the dealership, hopefully this is covered under warranty (bike was bought in October 2024).

 

[Base]

This is what the chain ring carrier looks like

 

[Rexlion]

So I guess I'll drop the bike off at the dealership, hopefully this is covered under warranty (bike was bought in October 2024).

Let us know if they cover it. My local Yamaha dealer wouldn't touch mine when I brought it in for a loose headset (which needed spacers added) and they said they no longer even had a way to select warranty repair (for reimbursement) in their Yamaha dealership software.

 

[Grueso]

Update: I got rid of the creaking by letting a mix of WD40 and Ballistol soak into the right side bottom bracket area (both inside and outside of the splined hollow drive shaft, see Base's pictures above). The play is of course still there.

Is some amount of play maybe normal? I'd say I see about one mm of chainring back and forth movement at the teeth.
Correction: 0.3mm play (difference between maximum and minimum distance from chainring teeth to frame) at about 85 mm radius.

 

[Base]

just checked 9 bikes with this DU, they all have the same amount of free play of +/- 1mm sideways.

 

[Grueso]

Base, thanks a lot for checking. Just to be clear, by 'sideways' you mean you can move the chainring circumference back and forth in the axial direction, but outwards on one side of the chainring and towards the frame on the other side, when applying force at the teeth (also in the axial direction, perpendicular to the bike)?

I can't feel any axial play in the chainring, meaning when I pull outwards or push towards the frame on both sides of the chainring, I do not feel the chainring as a whole move. But there definitely is free tilting motion with an audible stop when pushing and pulling simultaneously in opposite directions on opposite sides, of about 0.3 mm (see corrected previous post).

 

[Base]

Both, the most play is oure axial, when pulling the chainring crosswise also some play but nto as much as pure axiale.

 

[Grueso]

Ok, that's different from mine, with no detectable axial play (obviously there must be a very tiny amount, just none I can detect by hand) and clearly detectable crosswise play. This was super helpful, Base. Thanks for taking the time to check.

I'll keep watching the situation on my bike, maybe measuring each time I swap/rewax the chain.

I also added a question mark in the thread title, because the relationship between the creaking sound and the observed tilting play might still be accidental.

 

[stompandgo]

just checked 9 bikes with this DU, they all have the same amount of free play of +/- 1mm sideways.

That would drive me insane.

 

[Grueso]

I assume if the play is mostly axial that nothing much will move or make noises when pedaling. My chainring probably still tilts slightly under heavy pedaling, but since the creaking is gone, I don't notice it (did 60 miles yesterday, the creaking did not come back).

 

[Base]

just checkt some other bikes, mix of Bosch Bes2 and Bes3, Shimano. all had a little axial play on the chain/belt ring. Yamaha has indeed a bit more free play.