Noisy, new 9" center section questions.

[cleandan]

The item in question:
All new Moser, 9" center section.
28 spline axles.
Detroit Truetrac differential.
3.70:1 gears (US Gear)
Iron N-Case.
Iron Dayton pinion carrier.
1350 yolk.
Fully set up by Moser and shipped to me.

After install I followed the break in instructions to the letter....likely being a bit too cautious.

I used the supplied Lucas brand 85W-90 gear lube.
Lucas products have treated me well over the years.

So far there is about 300-400 miles on the new gears, and everything seemed just fine.

Today I drove for about an hour at higher rpm on the highway (2800-3200) varying the speeds per the instructions.
When close to home I stopped at the grocery store to pick up a few things, about a ten minute stop, then the mile to home to finish the trip.

On that short trip after the store the rear end sounded like something had broken.
It was clunky like some pinion or spider gear teeth had broken off and were now rambling around in the case.

When I got home I checked the fluid for pieces....nothing but a normal silvery mix you get from break in.

I used a magnet to fish around in the case to see if I could find anything troubling....nothing.

I used my bore scope to look around....looking for physical damage to gear teeth and bearings as well as discoloration and signs of overheating of any metals....nothing.

I drained the fluid and refilled with 85W-140 just to see what would happen and things are quiet again.

I drove around town a little bit making sure to take sharp corners, power on, power off, and so on, but nothing hard, just trying to hear anything troubling....nothing.

I also pulled the driveshaft off the yolk so I could turn the yolk by hand to feel the bearings, gears and lash and all feels very good.

I'm wondering if the 85W-90 just got too hot to do its job properly?
If this is the case, did I do any harm in my relatively short highway driving?

I have driven on many Detroit Lockers so I know their noises and quirks very well, but this is my first Detroit Truetrac (Torsen) differential. I thought they were supposed to be essentially silent and drive without any noticeable issues.

Any ideas or insights are welcome, but for now things seem in good order despite the odd noises after the highway drive.

Thanks and have a great day.

[galaxiex]

Rear brakes ok?

[cleandan]

The rear brakes work well and are giving no issues.

[pbf777]

      Probably not possible to accurately diagnose here but be sure both rear tires present the same rolling diameter, as otherwise your "working" the True-Trac even if driving strait ahead and this can lead to excessive heat build-up of the gear-sets and then they can tend to want to "lock-up" unexpectedly; but then with a little cool-down period everything can return to normal.   

      How's that for a wild guess?   

      Scott.

[cleandan]

Great guess pdf777, but both tires are the same diameter, same pressure.

[e philpott]

Maybe the spiral gears and being new/tight caused a momentary binding situation that is now fine after more miles ? I've only built one with the Tru Tracs and it was a carry in type deal and new parts but I do see the customer frequently and never get complaints of noise

[cleandan]

After changing the fluid the issue has not happened again.
I have taken a couple trips to try and replicate the first situation, but seeing as it rains every day here in Minnesota, this year, taking the car on a longer, hotter, run has not yet presented itself.

But for now I have not heard any further odd noises.

[cleandan]

The differential seems to be working well, but it is a howler on deceleration......I may have warranty claims in my future.

[shady]

something isn't right. shouldn't be hearing any whine.

[pbf777]

The differential seems to be working well, but it is a howler on deceleration......I may have warranty claims in my future.

     Note that the clashing of the ring & pinion attempting to present a force upon the vehicles' motion will produce a certain sum of noise, this is inevitable, but is the sum you are hearing "excessive?     If you're familiar with what actually should be expected and that which you are experiencing is something different, then I would recommend that you stop operating the vehicle, and if there is some sort of "warranty" value you need to contact the supplier A.S.A.P.! 

     These gear sets, will rarely "quiet" significantly with break-in, as generally the truly auditable noises will only increase with time in service, and if there is an improper set-up leading to the cause, there is a relatively limited operational period that will permit rectification before that gear-set "takes a set", and then "it is, what it is"; and if one should chose to delay, this may lead to discrepancies in what each side might think should be warrantable.   

     Scott.

[e philpott]

Pinion yoke still tight ? I've seen a few that were loose brought into the shop and they make a ton of noise on deacceleration and quiet under load

[cleandan]

UPDATE:
Things are fairly broken in now, with about 1,000 miles on the new differential.
Everything seems pretty quiet and the traction is very good.

There is still a rather noisy coasting whine, which is bothersome, but other than that things have settled in nicely.

I have gone in with a magnet searching for any debris and there is none.
I have gone in with a bore scope just to see what I can and things look good, including the mesh pattern.

If there was no coasting whine I think things would be very good.

[TurboChris]

Have you called and spoke to Moser yet? I did have a regear / rebuild once done by Currie, it was noisy as well and they had to redo it. It happens I guess.

[6667fan]

Is the pinion angle reasonable? Had a third member where the pinion was pointed too high and it would make noise upon deceleration.

[pbf777]

It happens I guess.

      More and more these days, if only due to the fact that most (if not all at this point) of these gear sets are made "off-shore", and with no requirement to be of the quality requirement of the original O.E.M. product.   

      The original, back in the day, FORD MOTOR COMPANY new product and even the old used O.E.M. stuff, unless damaged or just plain wore-out, nearly always set-up nicely, patterned nicely, rarely made any excessive noise; whereas today's stuff, rarely sets-up as nicely, and even if the pattern, made as good as it's going to be in setting-up but still suffers, will too often leave something to be desired from the gear whine department!     

      It's just how it is!   

      Scott.