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Discussion Starter #1 (Edited)
I just replaced the 3rd member of my rear differential with a "new one" (not new, but front the FRONT of another Zuk that was so unused the gears showed no use at all) in order to stop what to ME sounded like differential whine.

The car still makes what sounds like about the same level of whine with the "new" gears (maybe slightly less, and starting at a slightly faster speed, but it could be my imagination) as with the old.

I posted here ( http://www.suzuki-forums.com/suzuki-jimny-sierra-samurai-forum/119273-best-way-source-cause-whine.html#post728937 ) and another thought it was the transfer case making the noise, but then someone else rode w/ me in my Zuk and said that to HIS ears, it's STILL differential whine.

He said setting up the ring and pinon is VERY, VERY picky, and even 0.001" can make a world of difference, so maybe I screwed it up.

When disassembling the "new" differential I didn't disturb one side of the threaded adjustment ring at all (I left it in position in the housing threads where it was from the factory), and after swapping the side gears (to match the rear axle spline pattern), set the other side adjustment ring for 0.004" of ring-gear backlash, and maybe 0.002" side-play or less. Naturally, I didn't touch the pinion shaft adjustment (crush ring), and left the pinion nut in-place. (My "old" differential w/ 160k miles on it had almost 0.008" gear backlash, and corrosion/pitting on the ring gear, BTW.)

It would seem that what I did hopefully put the gear relationship almost exactly back where it was in the differential before I swapped side gears.

Does this sound like a flawed way to replacing and adjusting the differential gears after removal that could cause as much whine as I described in the other post?

BTW, on a "lark" I just bought a used transfer case the seller swears was dead quiet, so I figured if it makes the SAME noise, it HAS to be the transmission, but then the passenger who now weighed-in is re-blaming the differential, so I am experiencing doubts.

I have no experience with the difs and gear boxes in these vehicles to know how "silent" they were from the factory, or how prone to wear and noise they were after a lot of miles.

Mine is the ONLY Zuk I ever rode in or drove, and it came to me whining already.

Opinions, suggestions?

Bob
 

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I wouldn't say .001" can make "a world of difference". But maybe his "world of difference" is different than mine.
I think .004" is a little tight, from what I recall, without looking up the actual backlash specs.
What is this .002" of side play you speak of? The carrier and ring gear should have no side play at all. If it does, then your backlash will change, based on how much torque is being sent to your pinion gear. And that can cause all sorts of issues...from noise to actually breaking the teeth off the gears.

When you are doing a simple sidegear swap, you should have just marked where the carrier bearing adjusters were, spun them out...counting the turns of each, removed your carrier and swapped your sidegears, then spun each bearing adjuster in exactly the same number of turns it took to remove them and ended up in the same location as original. Then it would have been set back exactly to the previous specs and there would have been no guess work or precise setup measurements necessary.
 

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Discussion Starter #3
I received and installed the used transfer case, and the noise is GONE, so it WAS the T-Case after all making the noise. (Phew!) It sure SOUNDED like differential whine, but it wasn't.

As far as the differential, I was concerned that if I set the side-play of the bevel gear (ring gear) to zero, perhaps with temperature changes, it could be too tight and cause a problem.

The 0.002" side play I set (measured by placing the dial gauge on one side, and using a screwdriver to gently pry the gear either way) is very little at half the thickness of a human hair, so I doubt it would change the backlash noticeably, or lead to gear breakage.

I got a hold of the manual and the backlash specs are 0.004-0.006 so I should be OK w/ my 0.004 setting.

It says to adjust the side-play to essentially "zero" by running the adjustments in until they just contact the bearing races, so perhaps I could have gone a tiny bit tighter, though the difference between "zero" and 0.002" is not much, and since it's quiet, I am happy.

BTW, I DID mark one side adjuster and made sure it stayed the same, then ran the other side down to the 0.002", which gave me the 0.004" gear backlash. The tiny bit of sideplay didn't appear to measurably affect backlash, though obviously under load driving forward, the ring gear (bevel gear) is forced against one side fully, leaving the 0.004".

Thanks...
Bob
 

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Discussion Starter #5
For future reference: Always replace ring and pinion at the same time. They are cut in sets.
For future reference (and thanks for the lecture tone), no rings, pinions, or wing-nuts were replaced in this procedure.

Only the front axle side-gears were swapped out for the pair of rear axle side gears I took from my old differential since the splines are different (but you already know that I am sure). The remainder of the 3rd member components were discarded (since the ring gear had some pitting and corrosion on some of the teeth).

But when installing the side gears, one must remove the differential, and remove the ring gear from it, in order to access them. This still means one must reset the side adjusters (and backlash) to more-or-less to restore original backlash.

I didn't disturb the pinion at all.

Bob
 

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Discussion Starter #7
Not trying to lecture you here.
Don't take offence.
No offense really taken.

No worries.

I probably should have been more specific in my first posting saying nothing but the side-gears were changed.

I obtained a third member from the front axle of a vehicle that had never been used in 4wd, so I just basically plugged it into my rear housing thinking my whine was differential whine, but it turned out to be T-Case related despite the wear and corrosion damage found on the one I removed from my vehicle..
 
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