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Discussion Starter #1
I have searched the forums and cant find my specific issue.

I recently noticed grinding, like gears grinding, coming from the front end of my 09 850XP browning. I have 7000 miles on the bike and have used the ADC only once or twice. This all happens whether the bike is in AWD or in 2WD. I have not tried it in ADC mode, I don't use ADC.

The grinding only occurs when hitting the gas from a dead stop or when applying strong throttle while in deep mud. It sounds like gears grinding in a manual transmission.

I pulled the front end and found nothing but dark sludge for fluid. I cleaned all the parts and the main gears look fine, no missing or broken teeth, and the clutch packs all looked good (no metal on metal). I replaced all the bearings and seals and replaced the plastic cage with an all aluminum cage.

I also noticed the ADC fluid was dark and flushed the system. I followed the shop manual and bleed the ADC fluid until clear fluid with no bubbles was seen.

I replaced both front axles to make sure it was not a CV joint issue.

Put the front end back in the bike and the problem seems to have lessened. The bike does not grind when in mud but still grinds when hitting the gas hard, from a dead stop.

This all happens whether the bike is in AWD or in 2WD. I have not tried it in ADC mode, I don't use ADC.

Any and ALL suggestions will be greatly appreciated.
 

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run it a bit and try changing the fluid again....I know you cleaned it out...but cant hurt doing again...
 

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run it a bit and try changing the fluid again....I know you cleaned it out...but cant hurt doing again...
That would be my suggestion as well. One or two good flushings can work wonders. However, I haven't ever heard anything out of mine if it wasn't in the ADC mode. I have disabled mine because I can't stand ADC. A costly, worthless crutch IMHO. Other than that, no idea.
 

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Check front wheel bearings. I would also check the u joints as well
 

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Discussion Starter #5
I have changed the fluid 3 times now and bleed the adc each time. This weekend I have now picked up a popping sound when driving slow. I can feel the pop through the handle bars and can hear it.

I fairly sure I have a front wheel bearing that is bad and may explain the new popping noise.

However, the front grind is not getting any better. it does not grind if I am moving and nail the throttle but if I am sitting still and hit the throttle hard the grind is awful. It almost sounds like the grind that occurs if you try to put a Polaris in gear when the RPM's are too high.

I am going to pull the front drive shaft out of the bike this week and see if I still get the grinding noise. maybe I can isolate the noise and ensure it is, in fact, coming from the front end. I rebuilt the transmission last year and cant imagine it is the transmission, but with this 850XP nothing would surprise me. if it is the front ADC giving me the problems, I am going to cut the ADC power wire and remove the ADC system and CAM.

Any other suggestions will be GREATLY appreciated.
 

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Just curious after reading your first post again. Is this the first time in 7,000 miles that you have changed the oil in the front differential?
 

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Discussion Starter #7
I have changed the fluid in front end, rear end, and transmission with every other oil change. I change the oil every 50 hours. therefore the front end, rear end, and transmission get changed every 100-hours.
 

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I have changed the fluid in front end, rear end, and transmission with every other oil change. I change the oil every 50 hours. therefore the front end, rear end, and transmission get changed every 100-hours.
Curious where did the sludge for fluid you mentioned in the first post come from...fluid changed every 100hrs surely would not be sludge?
 

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Discussion Starter #9
the sludge came from bad fluid that appeared to have been contaminated with water. I have since changed my vent hose and ran it into the light pod on the handle bars. also replaced all seals, bearings, and o-rings. I believe the sludge came from contaminated fluid and freezing tempetures. that is my best guess about the sludge.
 
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