Pinned my own flywheel (spinning ring gear). Will it be balanced enough?

[Jcary85]

This is the 3rd 760 flywheel I’ve spun the ring gear on. Never had hydro lock issues, so idk why this keeps happening. Anyway, I figured I’d fix this one once and for all. I drilled and roll pinned the flywheel in two places 180 degrees apart then filed the roll pin flush. Do you think this will be enough to throw off the balance of the flywheel at all?

 

[2lick]

I always thought a balanced FW was really important.

Then in this Zeeltronics world people are taking stock 760 FWs and knocking off a magnet lump on one side and bolting them on. This missing magnet FW has to be way out of balance and I haven't heard of issues yet.

So through observations and deductive reasoning, I'm guessing your roll pin job isn't going to be of a significance to hurt.

 

[2lick]

@speedysprocket any thoughts?

 

[Jcary85]

I always thought a balanced FW was really important.

Then in this Zeeltronics world people are taking stock 760 FWs and knocking off a magnet lump on one side and bolting them on. This missing magnet FW has to be way out of balance and I haven't heard of issues yet.

So through observations and deductive reasoning, I'm guessing your roll pin job isn't going to be of a significance to hurt.

That’s a really good point. Hadn’t thought about that! I guess I’m just slightly hesitant, you know, with the $1600 crank and all lol

 

[Wetbuffalo]

Who lightened that one? And did you take the magnets out?

 

[Jcary85]

I think this one was Alex (not sure the x username). The quality and everything is top notch. This didn't happen because of any incorrect lightening or anything. The magnets are gone, but I bought it that way. I'm thinking theres just a lot more load on these things with higher compression big motors. IDK.... I'm fairly confident it won't fail now that its pinned.

 

[speedysprocket]

I did those drilled ones for PHP, even though I didn’t really want to...
If there were balancing holes drilled in the ring gear and you matched them up where they were originally, no problem. If there weren’t any, means it was balanced well as is and you may be good.
I don’t know why, but I’ve had a few of the TL versions spin (as do the “other guy’s” versions), so I now put a couple tack welds on all the TL ones I do.

 

[Jcary85]

I did those drilled ones for PHP, even though I didn’t really want to...
If there were balancing holes drilled in the ring gear and you matched them up where they were originally, no problem. If there weren’t any, means it was balanced well as is and you may be good.
I don’t know why, but I’ve had a few of the TL versions spin (as do the “other guy’s” versions), so I now put a couple tack welds on all the TL ones I do.

Cool thanks man! No balancing holes in the ring gear (just the flywheel) so I’m thinking I’m good. Love this flywheel btw. Very light!

 

[Wetbuffalo]

I did those drilled ones for PHP, even though I didn’t really want to...
If there were balancing holes drilled in the ring gear and you matched them up where they were originally, no problem. If there weren’t any, means it was balanced well as is and you may be good.
I don’t know why, but I’ve had a few of the TL versions spin (as do the “other guy’s” versions), so I now put a couple tack welds on all the TL ones I do.

I am thinking that taking the magnets out and then lightening let’s the flywheel flex more causing the gear to spin.

 

[Jcary85]

I think newer msd TL flywheels come pinned like this FYI. That’s where I stole the idea from ‍♂️

 

[Roseand]

I think newer msd TL flywheels come pinned like this FYI. That’s where I stole the idea from ‍♂️

I know the msd flywheels that zero lightens come pinned. He also fills the pin with metal reinforced epoxy like devcon or jb weld

 

[TheBuzzard]

I always thought a balanced FW was really important..

its not. back when I rode the sxr, I took a 750 flywheel, busted the magnets out, then hillbilly connected it to my drill press to spin it , took my 4" hang grinder and ground off the outer edge down to the trigger bumps.
it worked perfect and it had no vibration or ill effects.

 

[Jcary85]

It failed. 6-8 starts and it failed. Autopsy report coming in an hour or two....

 

[Jcary85]

Pins simply came out. Found them totally intact. Realigned the ring gear, popped pins in, then tacked them in and filed down for Bendix clearance. Should be good now. Lesson learned. Epoxy in the roll pins could have worked as well.

 

[2lick]

It failed. 6-8 starts and it failed. Autopsy report coming in an hour or two....

Too much powa!!!

 

[JetManiac]

Spun ring gears seem to be fairly common with stock 760 flywheels on stock 760 motors with stock compression. On many 760 skis we have parted out over the years, the ring gear was welded to flywheel already, so they had obviously failed and been previously repaired.

 

[Jcary85]

Just to report back - this is holding up well. No vibrations or anything and its starting just fine now!

 

[Jcary85]

Can’t believe I’m saying this, but it broke again tonight. I tried to make the welds very small but I guess didn’t get any penetration. They broke off and the pieces of weld got in between the flywheel and pickup and bent the pickup back causing the motor to die (which was a good thing I’d argue). Cleaned it all up, bent pickup back, more heavily welded on the other side (so no grinding was necessary) and she’s running again. Fingers crossed this is strong enough. Someone needs to make an aftermarket flywheel for the zeel setup. Hell, I might buy a lathe and do it myself at this point.

 

[2lick]

Can’t believe I’m saying this, but it broke again tonight. I tried to make the welds very small but I guess didn’t get any penetration. They broke off and the pieces of weld got in between the flywheel and pickup and bent the pickup back causing the motor to die (which was a good thing I’d argue). Cleaned it all up, bent pickup back, more heavily welded on the other side (so no grinding was necessary) and she’s running again. Fingers crossed this is strong enough. Someone needs to make an aftermarket flywheel for the zeel setup. Hell, I might buy a lathe and do it myself at this point.

Damn you got lucky! Maybe your FW is just cursed... toss it in the river and buy another man!