Need Help Front Sprocket nut thread size?

[FrankiePoops]

Does anyone know the thread size for the front sprocket retaining nut on an 08 FZ6? It would be the threads on #16 / #35 on this parts diagram. The nut on mine decided to abandon ship (and luckily the sprocket didn't walk off until after I crossed the bridge from Manhattan and not while I was in a corner). I managed to pop the sprocket back on and limp home but the threads are boogered up pretty good on the drive axle so I want to buy a die to clean them up.

Side note, I typically wouldn't use locktite on this, but is it a good idea on this bike? Seems like a fairly common issue.

 

[TownsendsFJR1300]

The S2's don't generally have an issue with that sprocket nut coming loose..

The S1's-common...

A new nut, locked down properly with red loctite won't hurt anything..

As for the thread pitch, no idea...

*Instead of a die, you might try finding a metric thread file. You'd be cleaning up the threads,
literally filing, along with the threads.. Less likely to fail..


The thin, outer edge, gets "tapped inward" into the transmission output shaft:

 

[FrankiePoops]

Thread file is a good idea. I'll have to see if I can find one somewhere. Thanks.

You'd use red locktite instead of blue? I'd worry about getting red back off if I need to change the sprocket in the future.

 

[Motogiro]

If there is usable thread I would use a small "V' file to walk the the end of the threads out to accept the new nut you will install. There were 2 different locking procedures for the sprocket nuts . One was a washer that had a tab that keyed to a slot on the output shaft and once the nut was tightened the washer edge was peened against a flat on the nut. If all was torqued and done properly, there was no problem. The other was the nut had an area where you use a punch to dent the nut collar into the a keyway on the shaft.
Even though there have been failures on these I think the failures are more due to people not having experience in servicing. Or possibly lots of wheelies etc. If bikes are used more severely they will require more scrutiny for service.

Trying to use a die may result in more damage to the shaft threads because if the starting point of the die does not follow perpendicular to the shaft or in time with the existing thread the shaft will have further damage. This is not an area to treat lightly with respect to repair/recovery because failure here results is costly repair as well as a critical safety issue that can result in a rear wheel lockup at speed

 

[Motogiro]

Riffling file....

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

Also:

Crescent Nicholson 6-1/2" 2 Cut Style 7 Die Sinker's File - T36054 - Hand Files - Amazon.com

Crescent Nicholson 6-1/2" 2 Cut Style 7 Die Sinker's File - T36054 - Hand Files - Amazon.com

www.amazon.com

 

[Gary in NJ]

Can we get a photo of the condition of your output shaft?

 

[FrankiePoops]

Here's a picture of the output shaft. Looks like I'll need a new sprocket pretty soon as well judging by the gaps in the internal splines. Hopefully most of that missing material is from the sprocket and not the shaft.

 

[TownsendsFJR1300]

Ouch.... Me thinks a proper thread file would be worth the investment..

That sprockets been loose for awhile looking at the "rust dust"...

 

[FrankiePoops]

Yep. I got suspicious initially because someone left an ad for a motorcycle tow / transport company on the bike the same day...

Hopefully I can clean up the threads to get the replacement nut on there (whenever it gets to me). I ordered one from Partszilla since my local Yamaha dealer said they're backordered for 2 weeks.

 

[Gary in NJ]

I think that shaft is toast. There’s pitting under the threads.

 

[FrankiePoops]

We'll see how much I can clean it up. That would suck if I needed a new shaft. I'm gonna clean it up with a wirebrush. Where the pitting is luckily isn't where the nut bites.

 

[TownsendsFJR1300]

I suspect you have enough "meat" there.

That sprockets been loose for a LONG time with little pressure from the nut..

It's not like it's keeping the sprocket from spinning, it's simply holding it to the splined shaft..

Plz post back how it goes..

 

[Motogiro]

Ever hear of a product called Ospho? If I remember correctly, I heard it was originally developed by Dupont for the US Navy. I guess it's mother company is now Skyco. It converts iron oxide (rust) into Iron phosphate. I swear by this stuff! I've used it in so many applications where there was rust. It's converts the rust and it turns a black color. I've used this on metal screen doors the got really bad rust and where you had to repaint them every year I'm going on 6 years and the door looks fantastic. The secret is get the loose rust of before treating and then prime/paint.
Check it out. the site also has material handling data sheet. http://ospho.com/
It is phosphoric acid so watch your eyes and breathing because it's a strong product.

 

[bigborer]

A few small dabs of weld would be more than enough to fill the missing material, and it's unlikely that it'll melt the rubber gasket. Then file or die the threads.

I wouldn't open up the engine just to replace the shaft. Even with too little thread left and no means of repairing the threads you could still force tighten the nut and then apply 1-2 spots of weld at the end on the nut to secure it.

The main reason nuts fall off is people cutting corners by not buying new parts (S1 tabs and S2 nuts are to be replaced after each dissasembly) and/or not folding the tabs and/or not torquing to spec.

 

[TownsendsFJR1300]

I wouldn't open up the engine just to replace the shaft. Even with too little thread left and no means of repairing the threads you could still force tighten the nut and then apply 1-2 spots of weld at the end on the nut to secure it.

That, ^^, is exactly what I would do if the threads don't clean up..

 

[TownsendsFJR1300]

Ever hear of a product called Ospho? If I remember correctly, I heard it was originally developed by Dupont for the US Navy. I guess it's mother company is now Skyco. It converts iron oxide (rust) into Iron phosphate. I swear by this stuff! I've used it in so many applications where there was rust. It's converts the rust and it turns a black color. I've used this on metal screen doors the got really bad rust and where you had to repaint them every year I'm going on 6 years and the door looks fantastic. The secret is get the loose rust of before treating and then prime/paint.
Check it out. the site also has material handling data sheet. http://ospho.com/
It is phosphoric acid so watch your eyes and breathing because it's a strong product.

Just used a similar product on the cutting(inside) deck of a Toro Zero turn mower (15 years old)I just basically rebuilt. Before and after:





Off track a bit, but the results of an exhaust valve seat coming loose, the exhaust valve snapping off a running 16 HP Briggs. You can see part of the valve seat embedded in the head itself:



Nothin a new head/ piston and rings can't fix!

 

[FrankiePoops]

Definitely will post back. I think I will become a regular here. Speaking of which, is there an app that you guys use to view?

I wish I did my due diligence when I bought it and went over everything, but it was February in NY and then I didn't think to check it later.

 

[Motogiro]

Definitely will post back. I think I will become a regular here. Speaking of which, is there an app that you guys use to view?

I wish I did my due diligence when I bought it and went over everything, but it was February in NY and then I didn't think to check it later.

I used to use Tapalk for the forum but there were issues with it and the forum stopped supporting it. Dennis (Admin) then set us up with new forum software that is super phone friendly with your phone browser so I like it better with my phone than using the other apps of the past...

 

[TownsendsFJR1300]

Definitely will post back. I think I will become a regular here. Speaking of which, is there an app that you guys use to view?

Rabbit ears..

 

[Gary in NJ]

Safari.