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Discussion Starter · #1 ·
Hi everybody, I am new here. I have a 2018 Can Am Outlander 650 Max Xt. I recently replaced the bearings & seals on my rear differential as well as both U Joints on the rear drive shaft and the Yoke closest to the dif. During a slow test drive I noticed a sorta humming sound coming from my rear end. I jacked it up & the humming sound gets a lot louder during acceleration, but seems to go away when off the throttle……

Any info would be much appreciated as I really don’t want to rip the rear end appart again.
 

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i replaced a rear diff 3 years ago, it hummed pretty good on acceleration for about 1500 miles, i believe it was just breaking in. as long as its phased correctly and you have all the u-joint bolts and washers in tight, i would not worry.
 

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Discussion Starter · #5 ·
Thanks for the info! I didn’t know anything about phasing. Watched a few videos, took a quick look at my drive shaft and just with my eye I can tell it is not right. Wondering now how I would have thrown it out of sync? Also will I need to remove the drive shaft to phase it properly or is there a trick? I’m thinking maybe I just have to take it out of the rear diff and leave the gear box side alone….I will likely look at it early next week.
 

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I would take it out and make sure its straight and not bent, that way you can also make sure you reassemble it in the correct center spline as well because if that spline is off it will cause the same issue as you just dealt with.
 

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Discussion Starter · #7 ·
So I took the shaft out and everything seems to be ok with it. With it out I spun the tires and the sound is clearly come from the rear differential. I had replaced the bearings and seals with a All Balls Racing kit. All the gears looked ok with no wear to speak of. I made sure all the shims went back the same way. So what could it be? Should I just drive it and worst case I blow the rear diff up?
 

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Riding until the diff blows up, is just silly.
You've narrowed it down to the diff, so I'd take it back out and reassess.
How did you remove/replace the bearings, press or hammer?
When the new bearings were fitted, were they damaged by pressing/hammering on the wrong part of the bearing. This will damage a new bearing quick smart.
Are the pinion bearings seated correctly? This will effect the gear tooth contact.
Without knowing your mechanical back ground, I might be telling you how to suck eggs.:)
 

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Discussion Starter · #9 ·
I used a press and was on the right part of the bearings. I’m not sure about the pinion bearing, I’m pretty sure I bottomed that one out up against the shims. The other 3 for the drive shaft and axles I pressed in flush with the casing.

I may have worded the sound wrong by saying Humming. It’s hard to tell but I just posted this video to you tube, I hope the link works. Weird you can’t upload straight here.

And ya I know I wouldn’t want to blow anything up! For all I know this sound is ok and everything is fine….

 

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Had to stop the video halfway through. I couldn't stand the noise. NOT NORMAL!
Sounds like the pinion to crown wheel mesh is way to deep.
Is there any chance you mixed the carrier bearing shims around? This would possibly send the crown wheel deeper into mesh.
You need to also check the backlash of the gears. There is a special tool for that. It's easy to make though.
Do you have a workshop manual?
 

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Discussion Starter · #11 ·
I may have mixed the shims up, I shouldn’t have but I do have pictures to double check once I open it back up. I will also check the backlash. I do have the full manual.

Must be something as simple as shims. Unless your replace any gears then the shims should just go back where they came from right? Or do you need to re shim with just changing bearings?
 

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I wouldn't think you'd need to re-measure shims just replacing bearings.
If you were changing gears or swapping out a cracked case, then yes I would expect to have to change shims.
Double check that all the bearings are seated the whole way home.
 

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Discussion Starter · #13 ·
So I finally got around to getting my diff back out. I’ve confirmed that the shims all went back the same way they came out from my pictures I had taken initially. All the bearings were seated the whole way home.

I think I know the culprit, taking a closer look at the pinion gear all the teeth look warn on both sides. They all look the same so I’m not sure if in fact if it is warn or is the way it should be. I snapped a few shots.
Automotive tire Bottle Motor vehicle Tableware Bicycle part
Tire Automotive tire Bumper Rim Motor vehicle
Drinkware Fluid Bicycle part Liquid Material property
 

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Discussion Starter · #14 ·
Also my 3rd last post I was mixed up when talking about bottoming out the bearings and was thinking of the seals when I said: “The other 3 for the drive shaft and axles I pressed in flush with the casing” anyhow cheers!
 

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If the cases are ok, then just change the gears, but do both.
The crown wheel teeth may look fine to the naked eye, but they will have a wear pattern in them.
If you reuse the crown wheel, you'll have trouble getting a good tooth mesh.
 

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Discussion Starter · #18 ·
Ok that makes sense! Another $150 if nothing at this point. I’ll call to order it in the am.

I’m just concerned now about re shimming. As I understand the pinion takes 1 that’s 1.67mm (or stock in my case was .556mm X 3), Stock on the crown gear had two 7 notch on the gear side and one 4 notch on other. I’m not sure what the thickness of the 4 or 7 notch are but BRP can only give me .02mm shims for the crown, it calls for one on each side. Doesn’t make much sense to me so I ordered 4 thinking what I already have should work
 

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I wouldn't assume the the new pinion will use the old shim, but it probably will. You'll need to follow the measuring procedure in the manual to determine that and start from there.
Ordering 4x .02mm shims is a good idea and will at least give you something to work with.
 

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Discussion Starter · #20 ·
Thanks sounds good. I got a new shim for the pinion which is the 1.67mm that it calls for, just weird that the crown only calls for .02mm each side.

Anyhow I’ll address that issue when the parts come in…..
 
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