Any problem using plain old 90W GL4 with the traction loc additive for break in?

I used this for break in and after  a few miles had a howl from the rear end on deceleration. A few more miles and a rattling sound from the right rear. Pulled the axles and the right rear wheel bearing seemed to be shot.  When I pulled the axles they were almost too hot to touch on the center section end. Pretty sure the wheel bearing was shot but not the real problem. I am in the process of getting new bearings installed. Will see what happens with new bearings. I am pretty sure that the problem is in the center section. I don't think it was the grease but thats why I am asking. Rear end was a total rebuild with all new parts assembled by a friend who is a retired mechanic who I know and trust. He says if bearings don't fix it pull it and he will figure out what is going on. I'm thinking faulty parts or assembly error. Didn't notice it till after 40 or 50 miles.

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

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.

GL4 shouldn't be any problem

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.

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

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

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.

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.