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Discussion Starter · #1 ·
Hi All,

New to the forum and could use some help with my JD 990 4WD. When I shift into 4 WD it will engage and move in 4 Wheel but there is a clunking noise. Two wheel drive works fine. I visually inspected and see no problems. I am attempting to examine the front drive shaft but am not sure how to remove it. I have the shields back and have removed the bolts holding the shaft to the front differential. No mention of removal in my technical manual. Here's a picture. Any ideas welcomed.
 

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Why are a bunch of the bolts missing on the differential..??

Never seen that spring loaded affair before on the driveline.

Go to jdparts.com look up that model then the front axle assembly.

Should see some good exploded veiws that may give a clue as to how its held on.

Is this a new to you tractor?
Looks like someone has been in that differential already to inspect/diagnose?
 

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Discussion Starter · #3 ·
I removed the bolts-sorry to throw you for a loop! I'm looking at the parts diagram as we speak. I am trying to figure out how to get the clearance needed to pull the drive shaft out of the front differential. I've had the tractor about 11 years.
 

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Maybe the back end of driveline is the place to start.......then push it forwards and drop the rear first.

possibly

That spring loaded dealio is different than any other set up I've seen.
 

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Yes as the Duke noted - the parts breakout can be very useful on deereparts.com
I have a similar situation on my 4710 tractor, it likes to clunk on its way OUT of 4-wheel mode. Been reversing off a few feet before disengaging and its seems to have gotten better.
I am surprised that the tech manual does not cover removing the 4x4 shaft - seems like a requisite topic to cover in there!
Keep us updated
 
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Discussion Starter · #7 ·
I looked at the parts diagram but it doesn't really show you how to remove the shaft. (and it doesn't simply slide back). I am trying to slide the shaft back on the splines but it won't budge. It seems like the spring loaded mechanism should slide back and I believe there are ball bearings inside. I am wondering if maybe the ball bearings are worn and won't let it slide.

I have an operators manual which is the simple maintenance stuff and have a technical manual which gives detailed information about almost everything else including engine overhaul and transmission repair. But one scant paragraph about the front drive axle and it is a very general overview with nothing about the disassembly/reassembly process. Wonder what they use at John Deere to work on them??
 

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Sometimes when I crack open these tech manuals I cant find much detail I end up stumbling upon what I needed in some other portion of the manual that didn't seem like the most intuitive place for it to be located. Are you looking at a paper manual? I believe the e-versions have search functions that could ease the shake out a bit.
 

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Discussion Starter · #9 ·
Found out that the rear end of the
Sometimes when I crack open these tech manuals I cant find much detail I end up stumbling upon what I needed in some other portion of the manual that didn't seem like the most intuitive place for it to be located. Are you looking at a paper manual? I believe the e-versions have search functions that could ease the shake out a bit.
You are correct. I am looking at a paper manual. Thanks for the tip on the e-versions.
 

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Discussion Starter · #10 ·
So, with some advice from another site, I jacked up the front end of the tractor and it took the pressure off of the shaft, which then easily slid out. Of course, out rolled the 6 ball bearings from each end of the shaft but I found them easily. It looks like the rear end of the shaft coupler had excessive wear, causing the coupler to "hop" over the ball bearings under load which made the clunking sound. I'll post some pictures in a minute. Interestingly, the ball bearings in the front coupler are bigger than those in the rear (wear?)
 

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I was gonna mention ...jack it up.

Why did you remove differential bolts?

Not sure you want to open that can of worms.......I'd read up on that if its a thought..
 

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I was gonna mention ...jack it up.

Why did you remove differential bolts?

Not sure you want to open that can of worms.......I'd read up on that if its a thought..
i'm guessing he was probably thinking the clunking was inside the diff and was going to investigate?...
but it appears the problem is elsewhere - so hopefully he's not opening up that can....
 
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