Thats my thoughts. I am tending to think defective ring and gear rather than assembly error because of how well I know the mechanic, however everyone messes up sometimes.

I'd say the type of lube was unlikely to be the problem in that short a period of operation. Clearance problem(s) somewhere most likely if this all happened in 50 miles or so total in three separate trips. Something wasn't right. Plain motor oil would have lasted longer if things were right. Much longer.

You have been running GL4 with no problems? I was thinking that the GL4 may have been the problem?
For initial break in I took a 10-12 mile drive under 45-50 mph and acclerated up and down. a few days late took maybe a 5 mile drive at low speeds.  Next trip was maybe 25-30 miles up to 65-70 mph. Thats when it got noisey. When pulled the axels right after that the axels were almost too hot to hold on to on the center section end. Gear oil has a terrible odor. I pulled the center section today and left it with the guy who built it to see what he could fine.

When I had my new gears, bearings etc set up by the rear end shop that I have used for years I asked if I could use some synthetic oil I had and they said there was no problem using it, the only issue would possibly be if I had old axle seals could leak. They also recommend running for 20-30 minutes normal driving then let it cool down.  I normally run GL4 and this was the first time I used synthetic, 7000 miles now and no problem.

Moser told me that aftermarket gears can be louder than stock gears.  They also recommended changing the oil, if possible after that break in but that is not in their instructions.



Lawrenceville, GA

I have had a couple of new Ford Moser 9" and they have this break in procedure for street listed on the web.
A new ring & pinion installed with new bearings will initially generate higher than normal operating temperatures. It is advisable to use whiscruber of the following break-inProcedures matches your application.STREET:
1. With car still on jack stands and rear end filled with proper amount ofNON-Synthetic gear lube, run in forward and reverse for approximately 2-3 minutes.
2. Drive vehicle approximately 10 miles at normal operating speed. Accelerate anddecelerate several times conservatively; let cool down for one hour.

  Vic Correnti

I don't think so either. Pretty sure it is either a parts failure or assembly failure. Took it easy driving. No hard launches. Did run it up to 65-70 on the highway after maybe 20-30 miles at lower speeds and driving around town. Guys put brand new ones in race cars and go flat out immediately without normally having problems.

GL4 shouldn't be any problem

All new parts except for the case. New gears, rebuild kit with bearings, shims etc. New Traction Loc. Professonally set up. As stated if the bearings don't fix it I pull the center section and take it back to the guy who built it to figure it out. Thats what he has already told me to do. Just trying to confirm that the GL4 should have not caused the problem. I had discussed the GL 4 here recently and never had any negative feed back on it.

If you have the axles out I would pull the center section and check the back lash. Noise on deceleration is usually too much backlash. I think it should be around .010. Is the ring and pinion new?

  Vic Correnti