M500 sprocket nut

[rwirtzfeld]

I have a question about the final drive sprocket nut and retaining washer. I bought a dead M500 and during my repower project, I noticed one of the rear inner wheel bearing hubs was cracked in two places. So, I opened up the chain case on that side, to find the sprocket nut had backed out to the inside hub, cracking the inner hub and bearing race. So, that brings me to the retaining washer, how is it suppose to keep the drive sprocket nut tight? If you bend it over(the retaining washer) onto the nut, what keeps them both from backing away from the sprocket together, other than the torque initially when installed (450 ftlbs, book says)? My thought was to bend one side of the washer over the nut, then bend the other side of the washer over the flat spot on the sprocket, that would truely lock it, but the service manual specifically says just to bend it over the nut? Of course this method would not work on the front drive sprocket, because they use smaller diameter washers, that do not hang over enough to bend it towards both pieces.

 

[Fishfiles]

I have never done a M500,I have never seen one , maybe they are foreign models of something else ? but can visualize that maybe the tang that goes into the keyway shaft to keep the retaining washer from turning has sheered off clean --------the other way I see it is a tab bends in and one out to lock the nut , you could locktite the threads and then use a center punch to peen the nut right where the threads contact the nut , leave a small slice of nut in bewtween thw peen mark and the threads and not right over the line between the threads and the nut , this methods seems to hold pretty good as a lot of cylinders are done that way -----fishfiles

 

[jerry]

I have never done a M500,I have never seen one , maybe they are foreign models of something else ? but can visualize that maybe the tang that goes into the keyway shaft to keep the retaining washer from turning has sheered off clean --------the other way I see it is a tab bends in and one out to lock the nut , you could locktite the threads and then use a center punch to peen the nut right where the threads contact the nut , leave a small slice of nut in bewtween thw peen mark and the threads and not right over the line between the threads and the nut , this methods seems to hold pretty good as a lot of cylinders are done that way -----fishfiles

I think that is exactly right, the tab is gone on the bearing lock washer. If there is a keyway in the shaft there was a tab on the lock washer, there is a number on the washer and any bearing supply or auto parts dealer should have it.

 

[rwirtzfeld]

I have never done a M500,I have never seen one , maybe they are foreign models of something else ? but can visualize that maybe the tang that goes into the keyway shaft to keep the retaining washer from turning has sheered off clean --------the other way I see it is a tab bends in and one out to lock the nut , you could locktite the threads and then use a center punch to peen the nut right where the threads contact the nut , leave a small slice of nut in bewtween thw peen mark and the threads and not right over the line between the threads and the nut , this methods seems to hold pretty good as a lot of cylinders are done that way -----fishfiles

The M500 is a Melroe 500, its not a foreign model, built and designed in good old North Dakota, my homeland. On that subject, I actually have come to the conclusion, I may have Melroe 600, but for conversation purposes this do not matter. I hear what you are saying about a tab on the lock washer either being on a keyway or spline, that's also the way I have seen them in other applications. However, even my shop manual shows the washer with no tab. The washer would have to have a tab on the id, that is where the shaft is splined. On the back wheels of the Melroe, the lock washers are larger(shop manual also makes a point of this), so it is possible to fold the washer over both pieces its in between. Bend one side of the washer towards the sprocket, the other half towards the nut. But the front washer being of smaller diameter, don't allow you to fold over both sides. I was just trying to figure out what Melroe had in mind with the stock design setup, thought maybe someone had been down this road. I have also used some of your alternative methods described. I like the blue locitite idea. However the red wouldn't suit me to well, since to heat it for removal you would have to expose a oil lubricated chain case to a torch. I also don't like to "fold a thread" just because the area is so limited in size, to fight the nut past the folded thread would not be fun, if you had to remove it. Thanks for the reply.

 

[jerry]

The M500 is a Melroe 500, its not a foreign model, built and designed in good old North Dakota, my homeland. On that subject, I actually have come to the conclusion, I may have Melroe 600, but for conversation purposes this do not matter. I hear what you are saying about a tab on the lock washer either being on a keyway or spline, that's also the way I have seen them in other applications. However, even my shop manual shows the washer with no tab. The washer would have to have a tab on the id, that is where the shaft is splined. On the back wheels of the Melroe, the lock washers are larger(shop manual also makes a point of this), so it is possible to fold the washer over both pieces its in between. Bend one side of the washer towards the sprocket, the other half towards the nut. But the front washer being of smaller diameter, don't allow you to fold over both sides. I was just trying to figure out what Melroe had in mind with the stock design setup, thought maybe someone had been down this road. I have also used some of your alternative methods described. I like the blue locitite idea. However the red wouldn't suit me to well, since to heat it for removal you would have to expose a oil lubricated chain case to a torch. I also don't like to "fold a thread" just because the area is so limited in size, to fight the nut past the folded thread would not be fun, if you had to remove it. Thanks for the reply.

Are the splines fine or are they like 6-8 spline so you could file a tab down and fit it in the tabs are on the i.d. Can you use a nylon locking nut and loctite ? If all else fails go to the dealer and see what they come up with.

 

[gymsbyjo]

The M500 is a Melroe 500, its not a foreign model, built and designed in good old North Dakota, my homeland. On that subject, I actually have come to the conclusion, I may have Melroe 600, but for conversation purposes this do not matter. I hear what you are saying about a tab on the lock washer either being on a keyway or spline, that's also the way I have seen them in other applications. However, even my shop manual shows the washer with no tab. The washer would have to have a tab on the id, that is where the shaft is splined. On the back wheels of the Melroe, the lock washers are larger(shop manual also makes a point of this), so it is possible to fold the washer over both pieces its in between. Bend one side of the washer towards the sprocket, the other half towards the nut. But the front washer being of smaller diameter, don't allow you to fold over both sides. I was just trying to figure out what Melroe had in mind with the stock design setup, thought maybe someone had been down this road. I have also used some of your alternative methods described. I like the blue locitite idea. However the red wouldn't suit me to well, since to heat it for removal you would have to expose a oil lubricated chain case to a torch. I also don't like to "fold a thread" just because the area is so limited in size, to fight the nut past the folded thread would not be fun, if you had to remove it. Thanks for the reply.

Randy, are you talking about that big long nut inside the side cover? The one I took off to get that sprocket off? If so, I didn't have to unbend any washers to get that nut off. I couldn't see in there because it was dark and still full of fluid(which I dropped my little Maglite in and still have not gotten it out....lol), but all I did was put a wrench on it and turn the outside hub that the wheel was bolted to. Not sure why they stay tight. That one was though and nothing special was there to hold it tight. Joe

 

[rwirtzfeld]

Randy, are you talking about that big long nut inside the side cover? The one I took off to get that sprocket off? If so, I didn't have to unbend any washers to get that nut off. I couldn't see in there because it was dark and still full of fluid(which I dropped my little Maglite in and still have not gotten it out....lol), but all I did was put a wrench on it and turn the outside hub that the wheel was bolted to. Not sure why they stay tight. That one was though and nothing special was there to hold it tight. Joe

Yep, thats the nut, its like a 1 3/8 thread size. I think Melroe's intention is the torque of the fastener to retain it(manual says 450 ft/lbs). There is suppose to be a flat lock washer that you bend over one of the nut "flats", it is in the service manual. My machine has them in place. However, as mentioned above even with the washer bent over the nut, it still backed out and busted my innner wheel hub, hence why I had to get one from you.

 

[gymsbyjo]

Yep, thats the nut, its like a 1 3/8 thread size. I think Melroe's intention is the torque of the fastener to retain it(manual says 450 ft/lbs). There is suppose to be a flat lock washer that you bend over one of the nut "flats", it is in the service manual. My machine has them in place. However, as mentioned above even with the washer bent over the nut, it still backed out and busted my innner wheel hub, hence why I had to get one from you.

Must be it brakes or flattens back down rael easy. I must have flattened it back out when I was taking taking the nut off and didn't even know it was there. Must have fallen in the fluid when I pulled the axle assembly out.