I need some opinions from some gear heads. I my self have been a mechainic for 35 years as a job, I was also a certified ASE master mechanic when I was 25. I have a 2002 Z06 that I built up a LS2 427 549 rwhp and 540 tq. I have a Mini tub with 335 tires
I have NEVER run it on a track or a dyno since the rear end change outs.
Here is the story. I had a well know company build me a 3:90 rear end, I broke it in correctly and gently and after 2K miles and 2 months I had a bad gear whine, Sent it back and it was fixed under warranty, but invoice stated " I ran wrong fluid or didnt break it in right. I also was told the DTE strut could have caused the problem (distorting the housing) so I didnt install the second time. I ran GM OEM fluid. After install again ,I broke it in like a baby and even changed the fluid at 2k. Now at 3k miles I have a whine again, bad!! I pulled it out and after looking at the tooth pattern I see that the pattern is at the top of the ring gear (high contact or heal contact) I sent pics of the pattern to the company and was told I overheated the rear. I said HOW??? I said I broke it in right and the fluid was correct, never ran on track or dyno. I told him the pattern was on the top of the ring gear and I have built a pile of gear sets in my time and the contact should be in the middle. He ask me if I knew what a Phoenix cut gear was. I said no. He said "then dont tell me the contact pattern isnt correct" which didnt explain to me, where was the pattern suppose to be. Now he is asking what size tires I am running, I told him the size and now that might be the problem. I am not going to list the company name as I am not writing this to condem the company or trash his name on this forum. I just what some feed back on other people with mini tubs that have big HP and opinions of MY ring and pinion issue. OR experts in Phoenix cut gears. He has told to to send it back to him and if he has done something wrong he will back it up,but once it is out of my hands I am depending on his opinion. I have other quotes from reputable companies that have given me opposing opinions.
Thanks
Here is a picture of the pattern. I marked two teeth with balck marker to see, The other teeth can be seen also. They almost are OFF the ring gear

 

PM sent

 

edit after the pic

 

Was the whine there from the time it was first installed, or after it had some miles?

 

Kind of hard to tell, With LG long tubes, and Borla stingers it is loud as crap and I cant really answer that, But after the first real time spent on the highway for any extended time it became loud enought to say there was an issue. All or most of the other time, the car has been driving just in town and had no real sustained 70 miles drive time

 

With your experence you most likely checked this, but was the pinion rotating torque within the 1.4-2.8 N·m/12-25 lb in range before the install?

 

I didnt check that. I know that test, You are suppose to check that with the ring gear out to determine if the pinion bearings are preloaded properly. You are suppose use a spring gauge and check the rolling torque, When I got the rear it was complete, That being correct or not correct wont put the contact up near the edge of the ring

 

 

I'm no expert but based on the looks of your pattern you have incorrect shims under the pinion carrier, not centered in the case.

 

Around 2005 or so, Getrag and several other note worthy gear manufacturers switched to Gleason "dry" CNC cutters in an effort to increase production efficiency. This "dry" CNC process was dubbed "Phoenix cutting" (there have been several revisions to the process since inception, so a number designation corresponding to the specific Phoenix process is often attached). Why this manufacturing process would have any affect on pinion depth/shim selection eludes me. All of the C6 Getrag ring gears that I have personally viewed all have centered wear patterns. There is a 2008 C6Z diff (produced by Getrag) sitting in my garage right now.


Proper wear pattern (Thanks ragtopws6):


Here is a close-up of your wear pattern:

Does it look as though the wear pattern "walked" towards the edge?

 

I had a photo at one time that showed the proper wear pattern but haven't been able to find it. I'll look more this evening. To the OP, do you have any other photos? It maybe my computer, but I'm having a hard time seeing the pattern in your photo. There should be a margin area around the contact area and not running off the end of the tooth.

Update:
SilentFright, Great photo! In fact better than the one I was looking for.

 

Does it look as though the wear pattern "walked" towards the edge?


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Last edited by SilentFright; Today at 07:02 AM. Reason: added picture

The black marker is on the two middle teeth. I understand your questioin about walking and I would say no. The shadow makes it look like that. The pattern hasnt moved, It is in fact at the edge of the gear, No QUESTION. His responce was that if I didnt know what a Phoenix cut gear was that dont talk about the tooth pattern and tell him it is incorrect

TOM
PLEASE DONT TELL ME ABOUT THE PATTERN I BUILD 150 A MONTH NO PROBLEMS THIS IS THE SECOND REAR, I WILL TELL U WHY ITS BAD WHEN I SEE IT ALSO DO U KNOW WHAT A PHOENIX CUT GEAR IS?

TOM
THIS ALL NICE BUT WHEN U TELL ME THE PATTERN IS WRONG AND DONT KNOW WHAT TYPE OF GEAR CUT IT IS DONT TELL ME ITS WRONG ( ITS WRONG FROM WHAT U KNOW AND HAVE SEEN) U HAVE BEEN DOING THIS SINCE CHRIST WAS A BABY SO HAVE I. LET ME SEE THIS AND I WILL GET BACK TO U REMEBER I DO ALOT OF ROAD RACE GUYS YOU HAVE A LOT TORQUE IN THIS MOTOR WHAT SIZE ARE THE TIRES?

THE TIRES ARE AND MAY BE THE PROBLEM I HAVE TO SEE THE PINION FIRST

 

A good rear end should not whine period. Engine torque and tire size have no say in the matter.

I now even question fluid type and break-in. I always followed the recommendations of the builder, but my last rear end was built by a local shop. We filled it with Mobil 1 fluid and strapped it to the dyno. First pass the car made 754 rwhp, 18 months later this rear end has never whined. Maybe I got lucky.

This vendor needs to step up to the plate and provide a free rebuild. If he can't build a non-whining unit, then you need a refund.

 

He has called me and ask me to send it into him.

 

99.9% of gears purchased by builders in the US use gears made by Motive Gears(at least for the 3:73,3:90,4:10 sizes). Motive does not provide A & B nominal values for setting up these rear ends(they don't even know what this means), which is how Getrag sets these up. Factory gears are set up using mathematical calculations, it's a set it and forget it way of getting "proper" alignment, and just so happens to work out perfectly.

I don't believe that the "Phoenix cutting" would have anything to do with how these gears would be set up, it sounds more like the builder trying make excuses on why they would be noisy. I have been told that it's not uncommon for Motive gears to be a bit louder than stock gears, and that it's normal. However this wear pattern clearly shows a diff that was not set up properly.

(If this diff was built by a company that starts with a D, then my recommendation would be to try a company that starts with and R )

 

Phoenix could be the model name of the Gleason machine used to cut the gears. It makes no difference on the proper rear-end set-up.

Sometimes, you put the pattern a little to the inside or outside so that it moves to the middle under power. However, this is just a slight offset from the middle. This also depends on the usage and power of the vehicle.

Can you post some closer to straight-on to the face pictures of the untouched contact faces? On the one to the left it appears to go off the outer end of the gear but the one on the right doesn't look to be that far off so I just can't tell for sure. It does appear the wear pattern goes right off the end which is completely wrong.

The wheels on the car make no difference either.

Peter

 

 

Just for clarification of any possible confusion of your "D" insinuation.... This is **NOT** our differential....

Cheers!

 

Not ours either.

 

FWIW,

Gear set whine noise within the differential assembly

A whine type noise will increase or decrease relative to the vehicle speed (approximately 50-60 mph). Typical causes of a gear set whine type noise may include incorrect backlash and/or pinion depth adjustment or worn or scored gear set teeth.

1. Check for the proper fluid level. Fill as required.
2. Repair or replace the unit as required.