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Went for a ride in some snow Wednesday, and I was cutting through a big bank in 4wd and suddenly heard some nasty grinding and popping noises, and lost 4wd. My girlfriend winched me out of the snowbank, and I limped home in 2wd thinking that either my actuator had gone out, or the block and pin had finally worn down enough that it wasn't moving the slider anymore. But when looked into it today, I was surprised to see the actuator working fine, and the block and pin looked great.
The bad news is that the front shaft looks shot, and the bearing and coupler in the front diff have more movement than I like to see!
So, what am I looking at here? How can I fix this? Is it worth buying another shaft coupler and hope that it won't spin around the teeth on the propellor shaft coming out of the engine? How much work is it to replace that shaft? How hard is it to replace that coupler bearing in the front diff? 26,000 miles and I've never had to do anything with the diff before...

 

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front diff bearing at 26,000 miles

youtube.com

 

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You...are the first person I have ever heard about that has warn out that front bevel shaft's spline..wow..so it takes 26K miles to do that..now we know. Not a terrible project but yours will be a little extra as it comes out the rear so the swing arm has to come off. Then you will see the tail piece with 4-bolts I believe. Buy the shaft, (I think you can reuse the old gear), the seals front and back and the cover gasket. May not need shims...but don't be disappointed if you do. Then the front coupler is cake. Inside the center you will see a 10mm nut. That comes off and it slides out. Get it complete with a new slide..the part the actuator moves. Why? Because it's due and it just slides in after you pull the coupler out. Get a new seal too. There's two. one big one you see and one small one on the pinion shaft that in that coupler. Maybe the new one has one. Be sure it get one. And yes...you will need a new drive line. And pop it out and grease it once in a while...lol.

I'll bet that the splines would've gone forever if the stupid boot on the propellor shaft hadn't torn and let dirt and mud in there!😡 Guess I should've been watching it better. I took it out and greased it a little while ago, but didn't notice the top half of the boot was not attached to the shaft anymore.

Got a trip planned for next weekend and would like to take this quad. Do you think I could just get a new prop shaft coupler and put some red lok-tite in it and see if it holds?
I've heard of guys doing that or welding on new splines?

Also, why does the coupler on the back of the diff wobble? Isn't it because the bearing is going bad?

 

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You will notice the splines are slightly curved not straight. This compensates for the alignment changes between the front diff and the engine through frame twisting so..can't be solid and no loc-tite will hold. A new prop shaft coupler will take 50% of the warn parts out and probably hold for a while but may waste it if you use 4wd a lot...so try not to. The front piece has movement because the bushing between it and the pinion is warn out. But even brand new one have a little movement. When you pull it you will see it...and the little seal.

That makes sense. I thought I noticed the splines had a curve to them, but wasn't sure if that was due to the grinding or not.

So on the front diff, shouldn't I replace the bushing around the pinion instead of the front piece? The front piece has good splines and wobbles as much as it did 3000 miles ago when I greased the prop shaft and checked it.....

 

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I ended up buying a prop shaft coupler and bevel output shaft off ebay for $55 combined. I threw the coupler on first just to see if it was going to be good enough to let me use 4wd a little bit, and it seems to be working fine. I'll put the shaft in later when I have more time.