Hawk Rear Sprocket Failures - reason why.

[Megadan]

Originally Posted by old kid

did you happen to look at the studs and see if there was any play in them?

I replaced mine because I had one that was stripped when i got the bike, it looked like it was cross threaded and cranked on with an air gun.
I got 4 new ones from a local Honda dealer, the new ones were much tighter fitting in the hub, I had to grease them up and tap them in with a mallet.

Im not sure what the tolerance is for them but the ones that came with the bike would go in and out without any resistance at all.

The cush drive studs had a bit of play in them on their own. When I seated the studs on the sprocket and then put it on the hub they were nice and tight, oddly.

I am all for upgrading them. What model Honda did the studs you bought come from? Or what Part Number?

I got lucky with the cross threading as far as the wheel goes, but 2 of the bolts that hold down the rear tray to the bike were both cross threaded, and a couple of others were partially stripped. I spent a lot of time with my tap set chasing threads. I have a couple of holes I am going to try Loctite's new Form A Thread on.

Originally Posted by pistolclass

I got a slight wiggle with the chain on so I'm sure it is worse with the chain off. I'm not riding until it is fixed. If only there were more time in a day.

Probably a good idea, and yea, there never does seem to be enough time in the day. Always pesky "responsibilities" that seem to eat it up lol.

[old kid]

the bag they gave them to me in dosent have a model # just has a hand written number on it 90128-312-000

i brought one out of the Hawk with me and had them match it up.

[Megadan]

That is a Honda part number. Thank you!

[pistolclass]

OK I think I need a reset and education. I have worked on plenty of cars and replaced many wheel studs. What the heck is a cush drive and why wouldn't this just have studs like a car. I think I need a "Hawk Talk" Lesson.

I googled it and I see a rubber thingy that absorbs the shock of the acceleration and deceleration??????

Someone please educate my sorry butt.

[Megadan]

Originally Posted by pistolclass

OK I think I need a reset and education. I have worked on plenty of cars and replaced many wheel studs. What the heck is a cush drive and why wouldn't this just have studs like a car. I think I need a "Hawk Talk" Lesson.

I googled it and I see a rubber thingy that absorbs the shock of the acceleration and deceleration??????

Someone please educate my sorry butt.

Cush drives are found on most bikes as a means of reducing not only driveline shock, but smooths the transition of power to the rear wheel to aid control and driveability. In a big way it aids with traction by giving a slightly more progressive feed of power to the rear tire. It has the same effect on deceleration as well. That is the laymans way to explain it at least.

[pistolclass]

so why is my sprocket loose when the nuts are tight?

[Megadan]

Because those studs arent really meant to hold the sprocket on fully. They are there primarily for power transfer from the sprocket to the rear wheel. That said, they should serve a small function to retention, but the primary retainer is that snap ring. The end of the stud that goes into the bushings on the wheel should not have much play in them. Mine do, but I managed to get it to seat correctly. I finger tightened the studs to the sprocket to ensure the studs flats were fully in the channel on the back of the sprocket. Then I installed the sprocket on the wheel, put the snap ring back on, removed the nuts one at a time to loctite them and reinstalled each one before doing the next, and then tightened them down. This method took all of the play out of the sprocket. I plan to go back and check it after a couple of rides to see if it loosened up again, and probably install the honda studs as a matter of course aince they are likely much higher quality anyway.

[pistolclass]

OK I think I'm slowly getting this.

[RustyShackleford15]

So I got thinking last night and took a look at mine last night, with it fully assembled and chain tight, I could still move my rear sprocket side to side about 1-2mm.
I looked at ordering the same JT sprockets that you did to gear up (17/45). But at check out I realized amazon said "typically ships out within 1 or 2 MONTHS!"
Anyway they also had no chains in stock like MotoCheez recommends.


Can the stock sprocket be tightened down in anyway without the use of new sprockets like you recommend? I read that you said the center bore may be the culprit, so I guess not.

[JerryHawk250]

[QUOTE=RustyShackleford15;258572]
I looked at ordering the same JT sprockets that you did to gear up (17/45). But at check out I realized amazon said "typically ships out within 1 or 2 MONTHS!"QUOTE]
I went with the 15/40 combo because the 45's where out of stock. very close to the 17/45 gear ratio. I later got the 17 for the front which I like more for the highway.

[Megadan]

Originally Posted by RustyShackleford15

Can the stock sprocket be tightened down in anyway without the use of new sprockets like you recommend? I read that you said the center bore may be the culprit, so I guess not.

The center bore is just a speculation. I never measured it. Try my method I used on the JT Sprocket to see if your stock sprocket can be installed without any play.

Method. 1. Remove Snap Ring (with a proper pair of snap ring pliers), remove sprocket and studs from wheel.
2. Install studs on the sprocket finger tight - ensure the flats sit in the groove on the back of the channel.
3. Install sprocket and stud assembly to wheel, and reinstall snap ring - ensuring the snap ring is FULLY seated in the channel on the hub.
4. Removing and reinstalling one at a time, take off the nuts on the sprocket, add loctite to the stud threads, and spin the nuts back on finger tight.
5. Once all studs/nuts have loctite, tighten down in a cross pattern.

If that doesn't take the slop out of the sprocket, then it is most likely the sprocket that is the problem. Definitely report back if that is the case and add to the cause. I think with enough evidence gathered, we may be able to petition RPS of a known safety hazard due to a production/manufacturing flaw. I can sure promise you they will start honoring warranties if they get threatened with legal action backed by evidence of multiple failures.

As far as the 17 and 45 being out of stock, that happens a lot (Thousands of Hawks have been sold recently). As Jerry stated, you can simply get a 40 tooth rear, or you can go with a 16 front/43 rear. Those two combinations have more or less the same gear ratio as a 17/45. The 16/43 may require removing a link or two from a 130 link chain, the 15/40 combo will definitely require removing some links from a 130 link chain. Personally, I like the 16/43 combination, and kind of wish I went that route. It starts with around a 2.70 (2.69 exactly) ratio just like the 17/45, and with a simple +1 or -1 on the front sprocket, you can choose between slightly better highway with a 17 (2.53 ratio), or slightly better off-road with a 15 (2.87 ratio). Not a huge difference, but it definitely gives some flexibility.

Whatever you choose, realize that it is just a starting point, and you will want to adjust the ratio to your preference and how the bike is used a majority of the time. Since I plan on mainly riding around on the road, but still occasionally want to run a mild trail from time to time, I tried to find a good compromise. Either way, the stock 15/50 gearing is just way too short for this bike and transmission gearing.

[nortelpilot]

The factory sprockets from the factory are junk.
I have a 16 front and notice a big difference.
I have a new 44 rear(45 was out of stock) that I am going to try and hopefully I won't have to remove any links.

On a side note I learned the hard way that you can't go by the adjustment marks when tightening the chain.I just line up the center of the tire with the center of the frame when replacing or removing wheel.

[Megadan]

Originally Posted by nortelpilot

The factory sprockets from the factory are junk.
I have a 16 front and notice a big difference.
I have a new 44 rear(45 was out of stock) that I am going to try and hopefully I won't have to remove any links.

On a side note I learned the hard way that you can't go by the adjustment marks when tightening the chain.I just line up the center of the tire with the center of the frame when replacing or removing wheel.

Yeah, those 45's sell out quick! A 16/43 combination would give you more or less the same ratio as the 17/45, so a 16/44 is going to fall right between them. Most likely you will need to remove at least 1 link, possibly 2.

Also, yes, the alignment marks are garbage. I lined mine up the same way you did, and then used a tape measure to fine tune my alignment.

[Megadan]

I went ahead and ordered 4 of the 90128-312-000 Honda sprocket studs. These come up under a 1971 Honda SL350. Being so old, these are a discontinued part from Honda, so they may take a little bit of work to track down, and supplies are going to be limited. Paying $30 for 4 studs... Oh well, better than crashing.

[Megadan]

Ok, just to revise this, any Honda SL stud is a no go. The pin side that goes into the hub bushing is way too big. I can only assume the part number on the bag, 90128-312-000, just happened to be a handy bag to throw other studs into. That said, I do have 90128-361-000 on order and they hould be here Monday or Tuesday next week. These are visually and dimensionally very similar to the OE Hawk studs, but the pin side is a tiny bit larger. These are for an MT125 and XL175

On the note of the stock sprocket, as mentioned in my build/project/bike thread, even my initial fix to tighten down the studs that did firm up the sprocket did not prevent it from getting a little loose again. It was still worlds tighter than the OE Sprocket was, but loose none the less. That narrows this problem down to the studs just being too small on the pin side. They allow up and down as well as angular movement within their respective holes, which allow the sprocket to rock. Once proper fitting studs are in place, this problem should disappear. Once I get these new ones in, and assuming they are all I need to solve this, I will make a video on this subject to bring it to an end.