Rear-end roar - can I fix it myself?

[mcintyrederek]

1986 C10 with 350, TH400 and 10 bolt 8.5" rear end, 2.73 gears, open carrier peg leg.

I replaced a bent axle and both wheel bearings a while back, and the pinion seal.  I've noticed a roar that's been there for about a week now but doesn't seem to be getting worse..  but I don't drive that much, or that fast.

The roar resonates at certain speeds, some worse than others.  It disappears when I let off the gas but also does a funky growl about 2 MPH before stopping.  Most people tell me that's the pinion bearing.  I'd like to get your opinion first.

Second, IF IT IS a pinion bearing, is this something that I can change myself?  I have a press and most other shop tools you'd need but I'm nervous about setting it up correctly.  I've read and heard that the backlash and gear meshing is very critical and the shims need to be installed just perfectly.  I have a pretty good "feel" for mechanical stuff but apparently that's not good enough.

I don't do any heavy pulling, I'm not racing or burning tires.  This is a my daily driver, 25 miles/day and rarely get over 55.  I'd also like to change the 2.73 to a 3.42.  There are plenty of Richmond kits available with a total rebuild package on Ebay and other places.

Not trying to be funny, but just how particular is the backlash and setup of the gears?  Is it like honing and decking a block, and then balancing an engine?  Nice, but not necessary for a daily driver?  Or do I really need to take this to a machine shop or someone who knows what they're doing?

Or go to the junk yard and pull a complete rear axle?  Ha..

Thanks in advance,
Mack.

[zieg85]

There is an art and precision is critical.  When you changed the pinion seal did you mark the nut and tighten exactly where it was?  There is a crush sleeve that sets the pinion depth and if you tightened it further than it was originally the gear meshing was disturbed.  There are special tools involved and plenty of video's on youtube to see if it is something you want to tackle.  If you are wanting to change the guts and gearing make sure you flush out any shavings that may have floated around the differential.

[VileZambonie]

Improperly setting the torque on the pinion nut will result in incorrect pinion bearing preload and ultimately it will fail. Your best bet is to find a used unit with the desired ratio you seek.

[mcintyrederek]

Yes, the pinion nut was marked and put back very close to the original position.  I am still afraid that somehow even though it was loosened and then re-tightened that it may have caused a problem..  still not sure about that but it's funny how the noise is there now just a few months after I changed the seal.

I'll probably seek out the junkyards now and see what I can find.  Removing the whole rear end and replacing seems like it might be easier than learning how to rebuild it properly.

[mcintyrederek]

I found a 3.42 complete rear end with everything intact from an '87 with just over 100K for $275 within 50 miles of me.  Is this a good deal?

[AZ87V10]

That's a lot cheaper than rebuilding and regearing the axle you currently have! Your truck is 2WD so make sure the donor axle is also from a 2WD so all the components are the same, like axle shafts and such. The spring perches and shock mounts are slightly different too I believe. It's a lot of work to swap an axle, but much less than working on gears and such and not knowing if they're set up correctly. Just obviously inspect the donor closely to make sure you're getting a good axle that doesn't then need to be rebuilt!

[mcintyrederek]

Great, thanks.  The source I'm getting this from is someone I trust, so if he says just over 100K and the pinion nut has never been touched, I believe it.

I'll give it a good look over.  It's been suggested that I run it warm, then drain the oil, jack the left side up and then right to get all the oil out of the axles and then replace with 75W/90 synthetic Mobil 1.. 

[Irish_Alley]

i can speak for your area but that price seam way too high. cant remember if it was 200 or 300 i paid for a matching set for a ¾ ton 4x4. i wouldnt pay no more than 100 for a single axle. theres no difference in a 4x4 axle vs 4x2 IF its the same style meaning a 10 bolt and 12 bolt wont be the same but a 10 bolt off a 4x4 will be the same as a 4x2. i would go to a junkyard and see what they have

[mcintyrederek]

I'm getting mixed opinions.  Some say that's high and some say that's OK..  The guy sent me the photos.  It comes complete with E-brake cables, drums, yoke has never been touched..  I'm in eastern NC..  These trucks are all over the place down here so maybe that's why the price is up..

[Irish_Alley]

if theyre all over the place the price should be even lower. supply and demand

[mcintyrederek]

Well, yes...  I guess what I mean is everyone is hitting the junkyards hard for parts for these trucks and it seems like parts are getting harder and harder to find....  supply & demand...