I have a 2004.5 Polaris 500 HO. When I was changing the oil in the front diff I noticed aluminum in the treads of the drain plug. I cleaned the aluminum out of the threads. When I tried to tighten the drain plug back in I striped the threads off the Diff. I would like to put a helicoil in but I am not sure the exact size of the drain bolt or how many threads per inch it is. Would anyone know what size the drain plug is on the front diff and how many threads per inch? I believe it is a 3/8" bolt. Has anyone had this problem and used a helicoil to repair it? I believe I nailed a rock with the drain plug because the threads on the drain plug were not evenly spaced. I have bought a new drain plug but would like to put a helicoil in as well because I don't think there is much meat left on the diff for threads to grab.

 

I don't have the foggiest idea as to what size or pitch the diff plug is. You need a thread pitch gauge plus the diameter of the plug itself.Helicoils come in all sizes,I've just never tried one that large! A good hardware/automotive store is your best bet on at least finding out what size it is. Don't know if this chart helps that much. Helicoil tap chart , helicoil tapping chart , helicoil tap size, helicoil tapping size, helicoil tapping data , helicoil tap data , helicoil , heli-coil , helicoils , helicoil tapping depth

 

Thanks OPT. I measured it with a thread gage and came up with 16 threads per inch. It is a 3/8" bolt. I will have to get a helicoil to match the bolt and then drill and tap out the diff to match the helicoil. I was just thought maybe someone else new the size of the bolt and thread patern to double check my measurements.
Do you have any ideas to fix my problem without using a helicoil or buying a new casting?

 

Could you tap it to use a slightly larger bolt?

 

ONLY other thing is by using the threads of the new plug to see if it starts in correctly and can "make it's own" threads by cleaning up the case threads is the only thing I can think of if it's only like a burr on the case,BUT I DON'T know how much damage you have on the threads! Plus you take a good chance of messing the threads of the new plug up?? Would help if you had some close up pics...

 

The threads on the diff are almost completely gone. It might be a good idea to put in a 7/16 bolt instead or go metric to limit the size of the bolt. I am in Canada so I might be able to get something between 3/8" and 7/16" in metric. There is not much meat on the diff to go up many sizes so thats why I thought a helicoil would work better. Thanks Jumbofrank and OPT.
I think I will think about this for a couple of days first.
Thanks again for all of your suggestions. Keep them comming if you have any more thoughts on how to fix my problem.

 

torque is 8-10 ft lbs

 

Very good point Mongrol. But it wasn't that I over tightened it. I nailed a rock and it actually bent the threads on the bolt and pinched the alluminum on the casting.Causing it to strip when I took it out.