loose sprocket damaged new hub

[RMZ450FIRST4T]

Hi guys. I bought a new complete back wheel for my rmz. I did not have the original bolts for the sprocket so used normal stainless countersink screws. The screws came loose while riding and damaged the hub (rad man.), I cannot afford to buy a new hub and would like to know if anyone else has experienced the same problem and what you have done to fix it. any ideas would be apreciated.

 

[Ol'89r]

Sounds like you have learned a very expensive lesson. :( It is important to use OEM hardware on your bike. If it only pulled out the threads, you may be able to replace the threads with Heli-coils. If it broke out the threaded area, you will have to have someone tig-weld it back up, machine it and re-thread it. Good luck.

 

[RMZ450FIRST4T]

The holes for the sprocket is not threaded, the screws go thru and tightens with a nut. The holes are now enlarged and the screws keeps on coming loose. I have tried locknuts, spring washers and locktite. I thougt of re drilling the holes to a larger size but dont know if the hub wil handel the forces with less material. I think using heli coils is a good idea but there might be a reason why the hub is not threaded in the first place?

 

[Ol'89r]

If there is enough material around the holes, you may be able to drill out the elongated holes and make sleeves to press into the holes. The sleeves would have to press tightly into the holes and be tight around the bolts. Then go back to the OEM hardware. If there is not enough material to drill them out, check on the Service Honda link on the left side of the page for a discount price on a new hub.

 

[MikeT]

I'd actually try filling in the holes with JBweld and then redrill them back to the correct size. First I'd roll up a piece of 100 grit sandpaper and slightly roughen the inside of the existing holes then clean it out with brake cleaner. Then you can fill and redrill with JBweld. Use the stock hardware and torque the nuts down to the correct specification. Hopefully that will work. I would not drill out the holes any larger because that would be removing metal and therefore make the whole thing weaker.

 

[RM_guy]

Unless you weld the holes and re-drill them the trick is going to be maintaining the clamp load of the bolted joint. The thing that keeps the sprocket from spinning on the hub is the friction between the hub and sprocket that is developed by the clamping load from the bolts. Once the bolts become loose, the clamp load is lost and the sprocket spins. The bolts do not act like pins that keep the sprocket from spinning.

If you use JB Weld or press sleeves in you will need a washer on the nut side of the joint to spread the load to the hub to get the right clamp load. Chances are the hole that is now elongated in the hub is such that the nut might either pull through it or start to pull through. In either case it won’t give you the clamp load you need and will easily pull through JB Weld or push a spacer right out. The washer will allow the nut to clamp against solid material that won’t move and will give you a solid joint. You may not have enough room to put a washer in there since it’s usually a pretty tight space. Also, it will need to be thick enough so it doesn’t bend into the JB Weld. If you go the spacer route the washer needs to be large enough to be outside the diameter of the spacer and thick enough to transfer the load to the solid hub material.

My recommendation is to have the hub welded or buy a new one with buying a new one as my preference.