Hawk Rear Sprocket Failures - reason why.

[Megadan]

Ok, so as an update now that my new, different, studs arrived.

Honda Part Number 90128-361-000 for the MT125 and XL175.
These are a viable alternative to the factory sprocket studs, in my case they are still a teeny bit loose in the bushings on the hub, but way better than the factory ones.

I whipped out my digital calipers to do a little measurin'.

OE Hawk Stud. Threads - M10. Pin side - 8.8-8.9mm diameter. Flange thickness 2.7-2.8mm. Each stud had .1mm of variance from part to part.

Honda 90128-361-000 Stud. Threads - M8 (uses the smaller set of holes on a JT sprocket). Pin diameter 9.2mm. Flange thickness 2.8mm. Consistent across the board within a few thousandths of a mm.

Wheel hub bushing sleeve the pins go into had a lot of variance to them. but overall they averaged out to 9.3mm. From the research I have done on these bushings, they should be 9.2mm, so this would explain why my factory studs were a hotdog in a hallway. .4 to .6mm of gap. Now I have about a tenth of a mm of gap with the new studs.

With the sprocket installed over the new pins and just the snap ring the sprocket with no nuts on the studs has less play than the OE studs had with the nuts torqued down and loctited. This makes me confident enough in this setup to ride the bike once they are tightened down. I think the variance in flange thickness and pin side diameter combined with the large difference in I.D. of the bushing sleeves just created a perfect scenario for play. I have total confidence in the M8 stud size to hold the torque/power of a CG250 engine, although I would prefer to retain the larger M10 sized threads. Given the quality of the metal the Hawk OE Studs are made out of, I am far more confident in the strength of the Honda studs, even if they are a bit smaller. For my own peace of mind I do plan on using Loctite retaining compound on the studs, which is the main reason I haven't fully installed them yet. I just need to figure out which one is best for the application. Either 638 or 680 are the front runners, because of their ability to fill larger gaps (up to .25mm and .38mm respectively), but this will come at the cost of high tensile strength which can make potential stud removal later a pain...

[Megadan]

To put it lightly. Tadaaaaaaaaaaaa!

Managed to get my 43 tooth installed on the back with zero play!

How you might ask? Well, as mentioned in my previous post, even with the Honda studs, there was still a teeny bit of wiggle to the sprocket, and even after tightening the nuts down on it it was still there, so I decided to eliminate one little variable, which was the miniscule gap between the sprocket and the snap ring. After pondering a few different ideas, I settled on the simplest solution. I managed to locate some M8 wave washers that were just about the right thickness to take up the space between the sprocket and the snap ring ( roughly .5mm, or .002". I put the washers on the studs, then the sprocket, then tightened them down, installed it all, and just barely managed to get the snap ring in place.

Zero wiggle, anywhere, even with the nuts just finger tight. I have a feeling the wave washers apply just enough outward force to keep it all equalized, and when tightened down the sprocket sits dead flush with the snap ring.

I did also apply a couple drops of Loctite 620 retaining compound to the pins as well, but seeing as it takes at least 12 hours to cure with the primer, at this point it is just extra security.

[Megadan]

Figured I would update this after my recent fixes. After 300 miles the sprocket is rock solid still. It took less than that after my first attempt at just tightening them up to come loose again. I think I got it.

[Rideon]

I just ordered the 45 tooth sprocket from amazon the earliest ship date is august 16th it looks like all the hawk owners have scarfed them all up lol.
I am going to run down to my local bearing distributor and pick up a blank 45 tooth 428 chain sprocket and chuck it up in the lathe and bore it out and drill out the bolt holes till the one from amazon gets here .

[o2jmpr]

Thanks so much Megadan! This was bothering me for the last few weeks. I've had this problem and I also recently noticed that my rear swingarm was crushed after torquing to "specs" and I've read tons of wheel bearing issues also so I took everything off for inspection today.

The wave washers totally eliminated ALL wiggle in the sprocket. I feel much safer now. I also found that none of my inner races (Front or rear) would spin freely. I apparently crushed the bearings inner races too tightly on the internal spacer tube. I'm replacing all my wheel bearings now and only putting the axles back on until my judgement says they're tight. I'm not using anything north of 30ft lbs for sure and probably less. I just don't think the China steel can handle it.

[Megadan]

Originally Posted by o2jmpr

Thanks so much Megadan! This was bothering me for the last few weeks. I've had this problem and I also recently noticed that my rear swingarm was crushed after torquing to "specs" and I've read tons of wheel bearing issues also so I took everything off for inspection today.

The wave washers totally eliminated ALL wiggle in the sprocket. I feel much safer now. I also found that none of my inner races (Front or rear) would spin freely. I apparently crushed the bearings inner races too tightly on the internal spacer tube. I'm replacing all my wheel bearings now and only putting the axles back on until my judgement says they're tight. I'm not using anything north of 30ft lbs for sure and probably less. I just don't think the China steel can handle it.

Glad it worked out for you. I have a feeling the snap ring groove was machined juat a bit too far out. I would recommend getting the honda studs as well. The factory studs just have too much play, at least mine did.

The wheel bearing issues are seemingly another common issue with the 2017 bikes. My rears were also locked up. Same with the swing arms. I tightened mine until the wheel spacers seated gave gave them a snug up after that. I also used loctite 242 on the axle nut just for assurance.

[Megadan]

Long-ish term update. Since doing the last fix I have logged over 700 miles on the bike, and I am happy to report that my sprocket is still rock solid. I am confident enough at this point to give my own seal of approval on the wave washer/shim method to take up the gap between the sprocket and snap ring. I still highly recommend getting NOS Honda studs to replace the factory ones, but it may not always be necessary.

[Fodarr]

Did you trim the wave washers to match the stud with a rounded section cut off or just tighten down till it squashed flat?

Originally Posted by Megadan

Long-ish term update. Since doing the last fix I have logged over 700 miles on the bike, and I am happy to report that my sprocket is still rock solid. I am confident enough at this point to give my own seal of approval on the wave washer/shim method to take up the gap between the sprocket and snap ring. I still highly recommend getting NOS Honda studs to replace the factory ones, but it may not always be necessary.

[hertz9753]

Do you have links the hardware you are using?

[Megadan]

Originally Posted by Fodarr

Did you trim the wave washers to match the stud with a rounded section cut off or just tighten down till it squashed flat?

Since I used a smaller stud size, they fit within the groove without needing any trim work, save a tiny little lip, which I just left on and they deflected around. The wave washers are so thin they don't take much force and bend relatively easy. You could trim them up if needed though.

Originally Posted by hertz9753

Do you have links the hardware you are using?

The studs were the Honda part number listed at the top of this page in my post. The rest of the hardware came from the local hardware store.

[hertz9753]

So I order the studs and go to Ace Hardware. Did you use stainless nuts?

[Megadan]

Originally Posted by hertz9753

So I order the studs and go to Ace Hardware. Did you use stainless nuts?

Sorry I didn't post more details sooner, so now that I am on my actual laptop on not my phone I should probably list it all in one spot.

As far as the studs, there are two options.
1. The studs I am using, which are an M8 thread and will use the smaller set of holes in the JT Sprockets, but will be too small for the stock sprocket which only has one pattern.
Part #: 90128-361-000

2. Alternate part number, and an M10 thread. These would be a more direct replacement to the stock studs, although I don't know if the thread pitch is the same. I may order these in the future, but I am happy with my current ones. These would use the larger holes on a JT sprocket, and would also work with the stock sprocket.
Part #: 90128-KE2-940

As far as the nuts, yes I essentially went to Ace Hardware and picked out some "serrated" flange head nuts. I did not use Stainless, but only because they didn't have any M8x1.25 flange head stainless nuts. Your other option would be normal nuts, with a lock washer and normal washer under them.

If you do the studs and nuts, tighten it all up, and still have a little wiggle in the sprocket, then 4 wave washers did the trick for me. They tend to be very thin and made a great shim to take up the gap between the sprocket and snap ring that I had.

Something I also did, but is probably not necessary, was to put 2 or 3 tiny little dabs of Loctite 620 retaining compound on the studs. This was more done for insurance, and given the forces that the studs see, has probably already released anyway. If not...I may have fun removing the studs later as even a tiny bit of that stuff can be a bear to break free. So for that reason I would say maybe skip that part.

[silva]

Magadan will these work? http://www.2wheelpros.com/oem-parts/...-940-part.html

[Megadan]

Originally Posted by silva

Magadan will these work? http://www.2wheelpros.com/oem-parts/...-940-part.html

Yes, those will be nore or less a direct replacement.

[silva]