Ford 9 inch gears are my nemesis. I have lost track of how many sets I have failed in my life. I do not think it is the fault of the diff assemblers. My data shows it is poor gear manufacturing. I attempt to use real Ford gears and they seem to be the quietest and most durable. Occasionally you will get a good aftermarket set of gears. I found out that most gear suppliers set up there tooling / gear grinding and let it run until it is way out of tolerance. So if you get an "Early" set they may be good and if you get one of the last ones they maybe bad.

US Gear is going to make some "Stealth Gear" that are suppose to be more to OE tolerances. My buddy has a set to test on how quite they using some "real" measuring equipment. (An actual engineering test).

I hope they are good and stay good. Our community needs a better solution than digging though junk yards to find usable old Ford gears to get a quite gear set.

Mark

Glad to see this. Thought it was just my set that is loud. It’s surviving for now but for how long I don’t know.

It is truly the luck of the draw. I went through 4 center sections from very good suppliers for Gunner, before I found a used set of gears on Craigslist. I found a retired Ford guy who had some used gears. For $150 bucks for the gear and $100 to set it up, I had a quite set of gears. I dropped off my perfect center section that I paid $2500 bucks for and he said "You got some nice parts here". He put in the used gear and - dead quite. I kept his phone number... lol

Once you get tuned in to the noise it will drive you crazy. I can't stand diff gear noise.

Mark

I was hoping you were going to give the magic bullet on Ford 9” gears. Mine isn’t loud but I can hear them.

Is there a reason everyone runs a 9 inch? The only benefit I see is the quick change of ratios if you want. You can build a 12 bolt that's pretty stout.

I'm not looking to start a fight, just looking for some more knowledge on the subject!

I did 9" as it was a DSE piece i found a deal on with quadralink brackets in it. And it will support the 1000+rwhp it can make on a regular basis.

I can't stand it either. We seem to have the most luck out of Yukon gears, but like you said, nothing beats a factory set for quiet.

I purchased a Currie Enterprises narrowed 9” for my DSE QLink application and selected their micro polish service ($150 option). My rear end is extremely quiet and I am very satisfied. I understand that GearFX also offers a similar service.

The noise isn't limited to 9" Fords. I had a 12 bolt Chev in my last Camaro that had the same issue. I had them replaced with a set of aftermarket gears (don't recall the brand, and it doesn't seem to matter). Had them set up by a local guy that was a GM driveline mechanic for over 40 years. He has done literally thousands of rear ends. They howled like mad. He shrugged his shoulders & said it's the gears. I could buy another set, but I'd likely have the same result. Same story Mark said...they make some good sets, and a bunch of bad ones. I spoke to every gear manufacturers' reps, and they all said they hear noise complaints all the time. This was 15 or so years ago.

I read somewhere many years ago 9" Fords were quieter because of the greater hypoid angle. Seems to make sense that the greater hypoid angle provides the opposite effect of straight cut gears, which are extremely noisy.

My current Camaro has a 9". I had a 60-70 mph neutral-load whine which drove me nuts. I finally decided to have John's (they advertise in the GG Gazette), build me a QUIET pumpkin.
I was told they have a testing vehicle that has microphone(s) mounted on the axle and speakers in the cab, so they can listen for gear noise like with a stethoscope. For a nominal extra fee, they will install your pumpkin, & drive it to make sure it is quiet before shipping. I thought that was no brainer. They also told me they keep track of gear supplier lot numbers, and when they get a noisy set, they log the lot# and black list that lot. This way, they have a pretty good idea of good & bad sets.
Well, my pumpkin was returned to me in late fall, and when I drove it, the gears seemed perfectly quiet. I only put maybe 20-30 mile on them before winter storage. The next spring, aflter driving maybe 50 miles, the howl was back. I called John, and he said this has been happening, he thinks it is related to heat treating. He said he is going crazy trying to get good gears from ANYBODY, but he would stand behind them & give me another rebuild. This time he wanted to put a 3.60 set in instead of the 3.50's I had because he said he had a known good lot. I agreed & he sent me a very quiet (so far) pumpkin. I have several hundred miles on this one, and so far, so good.

Sorry for the long winded reply.

Bill

Mark,

Just curious, what brands/types of gear oil have you tried ? Also, what weight gear oil?