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Discussion Starter #1
When I put it in gear, 2WD, the rear drive shaft spins but gives no power to the final drive. Could both rear drive axles be stripped in the housing? Or would it be inside the housing? I did hear a "clunk" when changing from Drive to Reverse but that went away after a few gear shifts.

In 4WD I get power to the front tires.

02 Grizzly 660
 
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Lift the rear and spin each wheel while in neutral; see that both rears are locked and spin together.That will tell you if your rear axles are stripped or not. Does the drive shaft spins at all when you do that? If not it may be a stripped shaft/coupler .
Worst case if not any of the two above you'll have to split the final drive and take a look inside. Good luck!
 

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It's more than likely you stripped the splines on the rear driveshaft, whether on the front or rear coupler.
Not real common to happen, but it does happen.

When your back there checking things out, inspect the rear diff for movement in the frame. That's a common issue with the 660. This puts extra strain and loads on the rear driveshaft and rear axles.
 

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In gear, hold the rear brake to see if this prevents the engine from gaining r.p.m. normally. If so the problem is behind the brake disc.
 

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Discussion Starter #5
In gear, hold the rear brake to see if this prevents the engine from gaining r.p.m. normally. If so the problem is behind the brake disc.
In 2WD it doesn't move at all. I just hear a soft grinding noise, not very loud.
 

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@Scorpyon, that sucks. Hope you get it squared away without too much pain in the pocketbook!
 

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Discussion Starter #7 (Edited)
I jacked up the rear end and the wheels both want to turn together but then it's like it skips a tooth and blocks. I also hear grinding.

This doesn't sound good but it does sound expensive.

I'll be trying to fix this myself so I'll surely be needing some of Grizzly Central's valuable knowledge.
 

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I jacked up the rear end and the wheels both want to turn together but then it's like it skips a tooth and blocks. I also hear grinding.

This doesn't sound good but it does sound expensive.

I'll be trying to fix this myself so I'll surely be needing some of Grizzly Central's valuable knowledge.

I just went through a tear down of mine on the rear end. Both rear axles and removed the final drive. If you get stuck let me know !




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Because your bike move in 4wd means your middle drive gear is good.

Because both axles are moving together means your axles and diff should be good.

The problem is within your rear driveshaft, and is the most likely area of failure. You have a stripped spline. Now you just need to find out if it's the front or rear splines stripped. And that's easy.
In 2wd and in gear, hold the brake and press the throttle while looking at the rear driveshaft. It is does NOT spin, the front splines are stripped. If it does spin, then the rear splines are stripped.
 
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It's more than likely you stripped the splines on the rear driveshaft, whether on the front or rear coupler.
Not real common to happen, but it does happen........
X2

I jacked up the rear end and the wheels both want to turn together but then it's like it skips a tooth and blocks. I also hear grinding.

This doesn't sound good but it does sound expensive.

I'll be trying to fix this myself so I'll surely be needing some of Grizzly Central's valuable knowledge.
Easiest and most logical place to start is to pull out the driveshaft check out the splines on both ends and both couplers.
 
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Discussion Starter #11
In 2wd and in gear, hold the brake and press the throttle while looking at the rear driveshaft. It is does NOT spin, the front splines are stripped. If it does spin, then the rear splines are stripped.
Well, with the brake held, it DOES spin. So that means the splines just forward of the brake are stripped? Am I understanding that right?

I also noticed some damage after removing the plastic skids. Should I be worried? (That's under the motor)
 

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Well, with the brake held, it DOES spin. So that means the splines just forward of the brake are stripped? Am I understanding that right?

What spins? with the rear brake held tight. The output shaft from the transmission?
If the rear diff is good, with the rear tires off the ground and the rear brake held tight with a good rear shaft splin, the axles should not turn.
 

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Discussion Starter #13
What spins? with the rear brake held tight. The output shaft from the transmission?
Just the driveshaft spins. The brake and the axles don't spin.
 

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Well, with the brake held, it DOES spin. So that means the splines just forward of the brake are stripped? Am I understanding that right?

I also noticed some damage after removing the plastic skids. Should I be worried? (That's under the motor)
Not hard to check out and repair.

Must have been a nice size rock?

I would at least weld up that broke brace and try to straighten and reinforce that front one that is flattened.
 

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Well, with the brake held, it DOES spin. So that means the splines just forward of the brake are stripped? Am I understanding that right?
Yes you have that correct. Pull the rear driveshaft.
 
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Discussion Starter #16 (Edited)
Must have been a nice size rock?
Must have been. I bought it just over a month ago and finally got it into a warm place to be able to do a complete inspection without freezing my fingers off.

So far I've adjusted the valves and changed the primary sheave. It's now on jack stands waiting for me to take it apart.
 

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Discussion Starter #17
Once I get the final drive out what should I use to clean it up?



I've used parts cleaner and engine cleaner with no results. It only seems to come off with some scraping. This stuff is really crusty.
 

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Discussion Starter #18
Looks like someone decided to weld instead of replace. I think I need to replace more than just the shaft.


I also had to get rid of my sway bar (for now). The inside 14mm was stripped. Apparently quite a few people ride without it and like it.


The final drive breather vent just slipped right off and it's pretty dirty down there. Will I need to open it up to clean it?
 

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You definitely found the problem with the splines. You need a new shaft and coupler for the rear.

That differential vent should not of came off that easily. That is supposed to be a pressed fit. Definitely split the diff and have a look inside. If any bearings look like they have corrosion or play, Replace them all. You can rebuild rear diffs for about $100. This includes bearings and seals.

The sway bar end link is common. It's the exact same setup as automotive. The nut seizes on the threads and the area for the wrench just strips over. Burn the nut off, cut it off using a grinder or use a pair of vise grips. Keep jamming in between the joint and bracket (Keep tightening as required to get them deep enough to grab the shaft), then remove the nut.

I still haven't removed my sway bar....but I think that's next on my list.
 

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Once you got the diff inspected, to install that vent again just use some cold weld compound like JB Weld. Make sure it's perfectly clean....and I mean clean clean clean...then JB Weld it back in place.
 
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