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Discussion Starter #1
Ok, so I am not a rocket scientist when it comes to diffs/gearing.

I have never run Detroits before now. Put a detroit in the rear and a tru-trac in the front. This truck has ALWAYS had a whine, No matter what the tolerances in either or any of the 3 diffs (center included).

Now I know about the clanking of a detroit, (experienced that when I first put it in, now quiet) but now after about 1200 miles of highway and trails I am getting a whine like a pinion noise off throttle that appears to be coming from the rear. The pinion was NOT touched during set up. (drop in diff style for you non rover guys)

I know that detroits inherently have some slop, but that shouldn't affect the pinion right?

TIA

j
 

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your gears were set up wrong rangie. Sounds like you also reused your old 3.54's as well, thats probably not good, as the old gears were probably pretty worn. As for the detroit in a rover making noise, It should not make any noise except a barely audible ratchet around corners, but most of the time you will not hear it. Mine is dead quiet, and I run a tru trac up front as well. who set up your gears, and what method did they use.
 

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Discussion Starter #3
I did, and they were done almost exactly to the method you and I commented to on the topic on the rover board.

Running at 6thou with the original gearing. However, the whine does not SOUND like a true bearing or side gear whine. The gears where clean with NO discoloration or pitting at all, and about 7 thou when I took out the other.

The ratcheting sound has gone completely away. It was big a couple of times, (at least to me) but that was right after install. Went away quickly.

I am beginning to think that the gears were more worn than I thought. Would the detroit diff actentuate the pinion tolerance? I was thinking the opposite.

j
 

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If it's just gear whine I wouldn't worry about it RR. Now if it's a carrier or pinion bearing then you've got troubles...How much pre-load did you put on the pinion?
 

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Discussion Starter #5
I didn't touch the pinion shaft, since the pinion didn't move (theoretically). Should I have? (dumb question, but I didn't think I would need to.)


j
 

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you did not have to touch the pinion, so that shoudl be fine, but you might open up your backlash a bit, and that might reduce your noise, but that is only if it is the gears, and not bearings. 6 thou is a little tight, even tho rover calls for it. try 7-8 thou. All it takes is a little to make gears noisy especially if they are used. Also, you might check the run out on the ring gear. You may have warped the gear. Always check backlash at 2 or three spots, and they should be the same, and you might pattern the gears as well, to see where they are.
 

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Discussion Starter #7
Well, I think I found it. I didn't even have to pull it yet. I don't drive this thing much, but I have been lately to try and play in the snow with the new diffs.

While on hell's revenge I laid it on the rear drive shaft pretty hard, (still straight, but took a little material off). I have still got the stock one there. I know, I have too much lift for it, but well, I am a poor guy. Anyway, I think the vibration and the hit were too much for the pinion bearing. I have almost 3/32's slop at the shaft! I mean it clunks when you move it vertically by hand!

The noise is definitely sounding like pinion lash.

Whaddya think?

j
 

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If the pinion moves that much it will self destruct in no time.If you cant afford a new set of gears and bearings, i guess you will have to work with what you have.Is the pinion depth set correct? If so, then you need to set the pinion preload...If it uses a crush sleeve you need to get a new one and a new pinion nut.The pinion should have no play.When reusing old pinion bearings the preload should be set a little looser comparred to using new parts.When you set the backlash make sure the carrier has a little bit a preload.Check the pattern with gear marking compound.
 
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