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just a welding fool.
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Discussion Starter #1
This probably pertains more to guys with DRW, and even more with the 450/550 crowd.

I've noticed on the highway, at certain speeds I'll get a harmonic whine coming from the driveline somewhere. seems to be in the45mph, 65mph range and 70+mph range. especially when coasting downhill.

sometimes the noise is louder than the truck and radio, at least inside the cab.

It almost seems as if it's a bad carrier bearing, but i pulled the driveshaft and checked it, spins free with no issues. I also checked the gears, nothing is chipped, and the wear pattern is as good as when we put them in (went from 4.88 to 4.11) all the tires are inflated too.

I can't seem to figure out where its coming from. anyone else with the issue?
 

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PSN Pretender
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My guess would be ring and pinion, especially if it only occurs during coasting.

When you checked the pattern did you "paint" the gears?

Pay very close attention the the coast side pattern, and checking back lash will show if there has been any wear since the gears were installed.
 

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just a welding fool.
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1,097 Posts
Discussion Starter #3
yeah, we painted the gears when we installed them. the coast pattern was dead on, and the backlash was within the tolerance.

If it is a gear issue, is there an oil or an additive beyond the 80 weight that will help it?
 

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just a welding fool.
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1,097 Posts
Discussion Starter #5
haven't really had the time to tear into it again since. unless a bearing went bad, would it change after breaking in that much?
 

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PSN Pretender
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Shouldn't change much, but if the setup was marginal (not saying your was) then when it wears in a bit it will be "out of spec".
 

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my 2000 F-450 always had that same whine since new, I changed the 4.88 to a 4.10 gear. I checked the patern on the 4.88 before switching them, it was within spec's, a little tight on the backlash about .005/.006 . when I set up the new gear I set it at .008 no more whine. your problem could be bearing related but it sounds more like gear noise if it is only on decel
 

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just a welding fool.
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1,097 Posts
Discussion Starter #8
i went from 4.88's to 4.10's as well (Yukon gears). I don't think i wrote down the backlash numbers in my notes, but it was a pita to match up the shims and get the preload all set.

i wish i knew that about the backlash before installing them...
 

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just a welding fool.
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1,097 Posts
Discussion Starter #9
the problem was, the pinion nut required something rediculous, like 300 ft/lbs of torque, and besides a torque multiplier, no one makes a torque wrench to go that high, and if they did, it was more expensive than the entire gear set. even the ford tech at the dealership told me they snug it up with the impact gun, so consistency was quite a gamble. to say the least.
 

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Harbor Freight 3/4" torque wrench... Goes to 300ft/lbs. Had a buddy check it, it was fine. DON'T DROP IT! lol
 

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PSN Pretender
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No need for that, with the crush spacer all you need is enough torque to set the turning torque.

An impact gun will have no problems with that.
 

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just a welding fool.
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1,097 Posts
Discussion Starter #12
it's not a crush sleeve, it's shimmed.
 

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just a welding fool.
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1,097 Posts
Discussion Starter #13
well... I found the whining noise. and the grinding as i'd come to a stop noise. turns out one of the cups on the u-joint at the rear wasn't getting grease and it cooked it. and by cooked it i mean the needle bearings exited the cup as powder as i pulled it apart. the race for the needles was nice and purplish-blue, beneath the rust, so it had to have been gone for a while. just glad i caught it now, rather than picking up pieces on the highway somewhere.
 

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Nice. Make sure you get the right U-Joints! I'd recommend a genuine Dana-Spicer parts supply house... Not Autozone or the others. I had to get a new yoke and driveshaft because what looked very much right was just enough off to wallow out the cup lands...
 
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