07 Arctic Cat 250 Transmission Knock

[Sha35297]

Customer brought in this bike for no response when put in gear. After getting into the transmission I found the main shaft for the clutch had been stripped where the gears mesh up and also the shaft for the gears had been broken in half. I replaced all broken parts and reassembled the transmission. Now it makes a knocking noise in low gear and in reverse. When in neutral it tries to roll reverse while making the same knocking noise. I’ve disassembled and reassembled it several times with the same result. Any ideas??

[Mech]

Not familiar with them at all.  It's a bit like a polaris or canam though is it ? Two speeds and reverse, and belt drive ?

Could it be end float letting reverse just catch it's engagement dog ?

[Sha35297]

It is very similar to the Polaris. When I attempt to replicate the noise by manually rotating the clutch with the crank cover off. I cannot hear the noise or see anything hitting. Here is a pic of what it looks like. 

[Mech]

I see in that last photo, of the broken shaft with gears, that the old bigger gear has beveled sides to the cog, and the new one doesn't. I don't suppose that could make a difference, maybe the bevel, or just that it's different, wider perhaps.

And you say that in neutral, it's trying to creep backwards? while making a knock.. that sounds like maybe the sliding engagement dog/lugs could be rubbing together when they aren't meant to. The fact it's making a knock in low and reverse might be that the sliding dog that engages them is in backwards or not right for the new cogs/shaft or that there's some end float that needs adjusting.. They have quite a few endfloat adjustments and shims by the look of the canam manual I have.

The fact it doesn't do it when you turn it slowly might be because the angle cut gears aren't trying to wind sideways at that rev/load.

I'd be looking for signs of rubbing on those new gears someplace there shouldn't be, or that seems like too much rubbing been going on for such new parts.

[Sha35297]

Mech,

Thank you for the quick response. I will give it a good look over in the morning and update what I find. I didn’t even consider whims before this. Hopefully I can see some obvious wear and go from there. 

[Mech]

Yeah a real careful visual....   Then out with the manual and feelers and measuring stick..

[Sha35297]

Hello, Just wanted to give an update.  I found a couple broken teeth on one of the gears. Ordered a new one, had the correct part number, but was the wrong part. Found a used one on Ebay. Got it in over the weekend and installed it this morning. No more knocking sound.  Simple fix I guess.

Thanks for the help.