New Differential break in?

[cool440]

As you guys know I recieved a new 3:55 posi diff from Mancini Racing last year and at first it made some noise but quieted down.  Yesterday at 1000miles we changed out the gear oil, putting in the best in, according to my mechanic friend. We also had a magnetic plug to catch any shavings and everything looked well.

That baby was loud yesterday, grinding especially in turns.  Today it is much better.  Is this normal?  Do I simply have to wait for the lubricant to work itself in?

When will it be broken in?

I appreciate your input.

Thanks
Michael

[Crazy440]

Did you add limited slip (posi) fluid?

Crazy

[dodge freak]

I use the GM stuff , but it might be all the same. It comes in a small little bottle and I only put half in. If a few days later I still can hear it I then put rest in.

[firefighter3931]

Crazy & Freak are right on the money....go to the dealer and pick up a bottle of friction modifier.


Ron

[Todd Wilson]

Crazy & Freak are right on the money....go to the dealer and pick up a bottle of friction modifier.


Ron

Sure Grip additive!!!!!   



Todd

[deputycrawford]

And do it soon. Don't continue to run the gear like that. One of mine blued and eventually broke badly. It wasn't pretty.

[cool440]

First of all thanks for the replies.

I put BG Ultra Gaurd 75w-90 in it.  This stuff is supposed to be incredible gear oil, it costs an arm and a leg. Is this O.K.?

Also the noise has disappeared.

Thanks again

[Todd Wilson]

I was always told and understood the sure grip units needed to sure grip additive to keep it from chattering when driving. There are other brands and aftermarket stuff but Mopar makes Sure Grip additive and you can get it at the dealership.



Todd

[cool440]

Here is what the manufacturer say's about it.

BG Ultra-Guard™
Part Number: 75053
BG Ultra-Guard™ is the first "true" multi-purpose gear oil available in the industrial market. It is a synthetic (Polyalphaolefin) gear oil blended in SAE 75W-90 viscosity and can be used in all car and truck axle applications calling for a GL-5 gear oil. It can also be used in all truck standard transmissions and automotive manual transmissions, transaxles and transfer cases calling for GL-4 gear oil, engine oil or ATF, as long as viscometric requirements are statisfied. BG Ultra-Guard™ provides thermal stability, smoother gear shifting, optimum driveline efficiency, quieter operation, protection against wear, pitting and corrosion, seal compatibility and improved seal performance, improved fuel efficiency, reduced maintenance, long drain life, extended component life and application versatility. This product is a part of the BG TDC® program.

my friend is a true car nut and a skilled mechanic, is this the best choice?

[Crazy440]

I know some synthetics don't require an additive.  I'd make sure the the lube, you are using, is one of them.  Better to be safe, than have a unit go out.

Crazy

[moparguy01]

the additive in cheap insurance. I would run the additive even if the gear lube i was using said I didnt need it.