Just rebuilt my rear, backlash came out to .005", pinion depth checks out along with pinion preload and gear meshing between the pinion and ring is good. Everything is new except for the actual housing. It's not terribly loud but enough to notice, is this normal or do I have to take it all apart again? I should add it isn't a howl, sounds kinda like a stuka dive siren if you know what that sounds like. The ratio of the r/p is 4:10

 

I feel like these cars tend to have more gear noise w aftermarket gears. I'm sure setup is a component to it but aftermarket gears are often louder. I've had numerous trucks regeared but you can't her the gear over everything else. My current car has a moser 9 w 4.11s. You can absolutely hear them more than stock rear/gears. The stock 3rd gen rear I had rebuild years ago w 3.73s was louder than stock. (Same w some friends) I forgot the RnP brand I used but they said they would be slightly louder than stock.

 

Ahh ok, I got everything from napa (balkcamp and Richmond makes/ supplies everything for napa gear and axle basically). So I'm not on the actual brand of the carrier and r/p. To be fair I have many holes in my floor and no interior / sound insulation (patching floors). So basically it's nothing to worry about?

 

"Torsen" as such doesn't really have anything at all to do with it.

First, that backlash is too tight. Remember, you're setting it when everything is cold, and it all expands when it gets hot. That means the backlash goes away in operation. An extra .001" or 2 will never even be noticed, let alone cause any problems; butt even .001" too little risks causing the gears to attempt to occupy the same volume when heavily loaded, which we all know what happens when 2 moving parts do that. Needs to be in the .008" - .012" kind of range to assure long-term success; toward the lower end of that range for just yerbasic street driving, more for when it's gonna get pushed harder.

Howl is most usually caused by bearings. In a rear axle, the pinion is pushed forward in the housing in "drive" mode, which loads the larger bearing right behind the gear part, and unloads the smaller "tail" bearing; and is pulled into the housing in "coast" mode or in reverse. Most of the time, the noise comes from insufficient preload on those bearings. New bearings should be tightened to get around 24 in-lb on the pinion with no seal installed. The seal can add anywhere from maybe 8 to maybe 15 in-lbs; trying to set up the preload with it installed will always leave it way too loose. A crush sleeve eliminator makes this MUCH easier to get consistently right.

Meanwhile the driver's side carrier bearing is loaded at all times that power is being transferred in either direction, as the gears try to push themselves apart. Carrier bearings can also make noise from inadequate preload. Preloading them is a bit harder since the only way to do it is to add too much shim to actually fit; consequently it's almost impossible to ever get too much. I like to shoot for .010" of extra shim on each side, after setting the backlash; butt often I can't get that much in there. I'd say though, .005" each side is about the bare minimum.

And of course some gears are just ... noisy. The higher the ratio, the more they tend that way. So to some extent, even if they're set up perfectly, it might just be something you'll have to live with.

Not sure about this "checks out" stuff. What gears are they, exactly? What pinion shim thickness did you end up with? How much preload was on the pinion bearings before the last time you took it back apart and put in the seal and tightened back to the same spot? How much preload is there on the carrier bearings?

 

I found that the spec for the 7.6 10 bolt is 3-6 thousandths, that's not right?
The pinion preload is 20 in-lbs
The measuring distance between the new and old pinion was insignificant, under .0003 of an inch difference so the old 29 thou shim was reused I even used the ratech 10003 pinion depth tool to double check my numbers
The the carrier shims started with 235 on driver and 246 on passenger and I wiggled the shims around a few thou to get the backlash of .005"
There's no bearing noise of any kind and I can provide part #'s for the carrier and r/p if that'll help
The carrier is definitely preloaded, it was a massive pain in the **** to get the carrier with the shims in

 

I did do the pinion preload with the seal installed, would that cause the issues

 

I thought you said it howls? Which is usually bearings?

That's almost always true. Gears are VERY precise, almost as precise as bearings. The thing you're ACTUALLY shimming, with good quality stock-type gears like you have (NOT special purpose ones like the Richmond drag-race-only ones), is the housing. That's where all the variability is. If you imagine all the moving parts just hanging out in free space somewhere all in perfect alignment, then you add shims when draping a housing around them all, to fit that to the moving parts. The shims may be installed onto the moving parts, butt they're taking up tolerances in the housing.

Yes it could. As said, the seal adds however much drag; meaning, if not taken into account, there won't be enough preload on the bearings. You could try just tightening it a bit, maybe add 10 more in-lb or something to it as it now sits (carrier and all) without tearing it all back down, it can't hurt.

.235" & .246" sounds pretty normal for carrier shims. I don't see any problem with that.

When I do backlash, I don't preload the carrier at all while setting it up; then when I get the shim packs right for the backlash I want (I shoot for .008" - .010" usually, for the reason I gave you), I add an equal amount to each side, and use 2 big C-clamps to compress the bearings onto the carrier, while I try to drop it in. I shoot for .010" extra per side, butt sometimes I can't that much to go in. They make "case spreaders" to open up the housing, which then theoretically it should return to its original shape, butt considering that that's the way that the housing distorts when power is applied, I really don't like the idea of doing that to my housings.

 

It does make a noise it genuinely sounds like a stuka siren. Forgive my ignorance this is my first rear end, it could be a bearing noise it just isn't one I've heard yet. I'm gonna tighten down the pinion nut slightly more ~10/12 in-lbs more.
Should I care and reset backlash to more than the 5 thou? I have the shims to bring it to 11 thou

 

Obviously everything sofa is saying is correct. Then you add in the holes in the floor and not having carpet/insulation, ooof it's gonna be loud!

it's interesting, I had a friend have his 84 get the rear rebuilt around 2000. It was loud after. Like louder than I thought is should be. That car had a large exhaust/headers and a full interior and inside you really could hear that rear. I expected it to self destruct. It didn't, it was amazing. He put tons of miles on it. Like up and down the east cost numerous times. He probably put 70- 80k on that noisy rear and sold the car w it still working. I have no idea how that happens. If it was my car making that noise it would have blown up in 1 mile.

 

I went on a 6 mile light drive and it was fine, just the noise on deceleration. I'm gonna tighten down the pinion nut by about 10 in-lbs more than whatever it is now with the carrier and axles in. Would it be irrational to ignore the backlash until 500 miles from now to finish the break in then see if the issue needs addressing? I mean I have driven this car maybe 2k miles in 3 years so if the rear end is gonna blow up in 10k miles that's like 15 years from now

 

Try the nut thing first, then if that doesn't help, you can try this.

Any idea how much preload you got onto the carrier bearings?

Keep in mind incidentally, the factory's specs are optimized for gas mileage as much as anything else. Less preload might have given them .05 mpg or something on average, which to us individually isn't noticeable, butt when they were working up their CAFE tax, could possibly have amounted to MILLIONS of $$$. I can't possibly know that of course, butt remembering how things were at the time, it seems quite probable. Especially if you can look it up for different years and the "spec" is different; even though they all had the EXACT SAME parts. "Specs" serve many masters, and it can't always be assumed that deviating from them is not an option, if you understand why they are what they are, and what the effect of each is. Much like main & rod bearing clearances for example. Just because the factory said [whatever] doesn't mean that hitting those numbers perfectly is The Best Way for every single build. Not that they're necessarily "wrong"; just, there's more to it sometimes than looking up in "book" and not thinking any farther.

 

For the carrier preload, I have no idea all I know of that I barely got it in the housing. I do know much about the nonsense OEMs tend to put in and around their parts to fit regulation. I just wanna make sure I'm not horribly messing something up and it's gonna be a waste of money lol