8-3/4 rear running very hot and whining at 35mph

the 8-3/4 in my charger has new richmond 3.55`s, new bearings throughout, the correct fluid and posi additive. THe pinion is set to the correct depth at 2.767 in. The axle bearings are properly greased and the backlash is a .009. The whine comes in at about 35 mph and goes away around 50 mph. It is very noticable. The noise is not really effected by throttle position and is present under acceleration and coast. When jacking up the car to check it out, it had been sitting for 2hrs after a 30 mile ride, and the housing was hot enough that I could not hold my hand on it for more than a few seconds. And that was after 2hrs of sitting! I pulled out the axles and center section to inspect. I removed the carrier and spun the pinion. It does not feel too tight or loose. The preload feels ok. The carrier bearings look ok and the wear pattern on the ring gear looks decent. Anyone ever run into this. I am most concerned about the heat issue. It should not have been that hot after sitting for 2hrs from a 30 mile ride. It is a 489 casting.

thanks

The fact that it is happening under coast and accell makes me think something is way wrong on the contact. Something will give with that amt of heat even if it's just the noise getting worse & it sounds bad as it is. My rear end guy tells me Richmond gears are hard to set up (compared to other brands). I would wait for Doc or someone as knowledgeable to chime in

How was the final contact pattern? Pinion bearing preload can be checked with a beam type torque wrench. Richmond says 15 to 20 miles under normal operating temperatures without creating a shock or towing. Allow to cool completely and repeat 2 to 3 times. I know break creates a lot of heat but 2 hours later and can't keep your hand on the differential?
http://www.richmondgear.com/07pdfs/BodyEXCEL.pdf

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The backlash you have is set on the high side of the spec , you should try to get as close to the low side as possible because backlash will grow over time.

There seems to be something about richmond gears that they whine , I've seen it posted many times over the years .

As far as the heat , not sure how typical that is , it's new and things are wearing in ???

Heat is normal. I had a bearing making noise once and in my troubleshooting, I started touching other known good rears, and even after a 25-30 minute drive, they were HOT. after an hour drive, I could toss water on one and it would flash into steam. But I didn't check to see how long they would take to cool down.

I'd try to get a temp reading as soon as you park.

Heat at least initially during the break in is normal. If it's too hot to put you hand on and you havent been drag racing or road racing it's getting too hot.
Noise is an indicator of poor contact. You set the stuff to spec - but did you run a pattern? the trick is a good pattern within spec. not just "within spec". Also - new gears require a break in period. You jack the car up, run it in drive between 30-50mph for 15 minutes. Then let it cool completely (over night). Then drive it a short distance, no hard accel or decel, drive for about 15 minutes, then let cool (overnight is best). After that it's good to go. After the initial break in on the jacks, it should not get that hot and if it's noisey at all during either, something's wrong.

The pattern looks good to me, but I am not an expert. I just checked the pinion depth and it is .005 below the spec, (shallow). Both pinion bearings and the carrier bearings look great. Unfortunately I did not follow the break in procedure. On the first drive after a few miles, I stood on it in low gear, could not resist. Not sure at this point if I should sink the pinion .005, check the pattern and tighten up the back lash from .008 to .006 and see what happens, or replace the gears and start over? A little nervous about buying another set of Richmonds. Heard a lot of complaints about noise.

thanks

I am not an expert, and don't claim to be...BUT, I have had personal experience with this exact same issue. Although it may look good, the pinion bearing is probably bad. The rear in my car was doing the same thing, I replaced everything in it except the pinion bearing. Everyone told me that the pinion bearing was OK. They replaced every bearing in it, BUT the pinion bearing, don't ask me why, I dunno. They told me it looked OK, but it howled just like you described until it was replaced.

Which case are you using and did you get the recommended pinion bearing preload set up correctly on it?

It is the "489" Case with the 1-7/8 pinion. The pinion bearing preload was correct. I have decided to remove the Richmond gears and go with a different brand including replacing the pinion bearings. I don`t want to go through this again. I don`t think since there is already a wear pattern that this noise will go away with a change in pinion depth and I don`t want to waste the time and money to find out Im going to have to replace the gears anyway to have a quiet Diff.
I have not made a decision on which brand as of yet. I have heard noise complaints on U.S. Gear as well, which now are made in China. Possibly going to go with Motive gear, but now sure yet. I am trying to find a set of factory gears but have not as of yet.

Thanks for your assistance.

Did you use a solid spacer to replace the crush sleeve ? If not do it .

Do yourself a favor and do not buy a used gear set unless it is a completely assembled and ready to go chuck that you know will be quiet , if you don't get the pattern back to the way it was it's going to make noise.

richmonds are noisy...every set I have ever set up is...nature of the beast unfortunately. as for the heat, the improper break in doomed that rear end, without the proper heat cycle it will wear quickly. you say your specs are good, what was the preload on the pinion bearings? did you check it with a rotational torque wrench? im assuming the carrier was out when you did so? what did your contact pattern look like? just because its in "spec" doesnt mean its right. they get the pinion depth and thats a place to start. Sometimes it looks good other times not so much. if your taking it apart again get new pinion bearings. id stay away from usa gear or value gear...ive had a lot of good luck with yukon gear. post some pics of what you got.

Anywhere to get a decent price on Yukon Gears in the southeast?? Randys ring and pinion seems high at 412.00 for a set of 3.55`s for a 489 case.

Don't know how far out you want to go...

Drive Train Specialists(Mich)

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Anywhere to get a decent price on Yukon Gears in the southeast?? Randys ring and pinion seems high at 412.00 for a set of 3.55`s for a 489 case.

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Mosher shows them on their site for $255. bucks. Motive Gear...web page