Hello, just joined the page, I have been a stalker on here for a long time...
Anyways, just received my 3.307 gears from mFactory, I am sending the diff off for the install I will be sure to post pictures
I will try to give a full review and will post pictures and everything else.
Here are pics I have taken of the gearset I received. (Pardon bad phone pics!)
Gears are going into a 2004 MSM Diff.
https://cimg6.ibsrv.net/gimg/www.mia...deaa5ad6d0.jpg
https://cimg5.ibsrv.net/gimg/www.mia...715607bbcc.jpg
https://cimg2.ibsrv.net/gimg/www.mia...b8cc0dca85.jpg
https://cimg0.ibsrv.net/gimg/www.mia...74ba023d53.jpg
https://cimg1.ibsrv.net/gimg/www.mia...7d46225381.jpg
https://cimg3.ibsrv.net/gimg/www.mia...a09bf71d94.jpg
https://cimg4.ibsrv.net/gimg/www.mia...1f42c711cc.jpg

I ended up doing my own install so we'll see how that goes. Everything seemed to go pretty smoothly. Runout was good, dead on for most of the gear with one spot at .001". Backlash I got to max .0045ish, min .0033 or so. I initially checked everything with the original pinion shim but the pattern was a little too much toward the outside for my liking. Went about .008 thicker and the pattern seems to be much more centered on the drive side. Coast side was always centered regardless of shim. Here's a pic of the 2 patterns for comparison. (top=new, bottom=original)
https://cimg4.ibsrv.net/gimg/www.mia...57ef9a7f43.jpg

https://cimg3.ibsrv.net/gimg/www.mia...6ae7cc5d24.jpg

I went thru the gears with the back end up on stands. Seemed quiet until 6th gear and then I started to hear the slightest whine but this is also totally unloaded so I imagine it'll get louder to some extent. I will say, setting up a diff is tedious for a first timer.

Yeah, I just do not have skills, tools, or time to do it myself, I would be scared to mess up the gears and then be out the money if the gearset dies:rofl:
I'll be keeping what is going on my end on here, and will post videos somewhere of the diff whine, if there is any present. Let us know how yours works when it is in the car:skid:

I've finally had a chance to drive the car a couple times. Some regular street cruising and a few hard pulls to 60-70. No sustained higher speeds yet. So far so good though. Not really any noise to speak of. 6 speed now feels just like my 5 speed with 4:10s.

Miata Diff Info
 

So my diff should be arriving today, would it be okay if I were to start a new thread with all the info that is available?

Just drove with mfactory 3.3 for the first time. Makes all sorts of noise on decel. Solid diff mounts too. Also have a weird turbine noise when decel under 15mph

Anyone else with jet engine noise?

^ video?

Soon. Keeps raining around here

Starting my install today, hoping to have it done by tomorrow 😂

Heres a video of the whistle sound. Its only at low speeds when slowing down

And heres one of the decel noise. Does anyone know if this is a normal loud or an unhealthy loud?

Normal for those gears.

Yikes! I thought the Quaife gearset was noisy. That would drive me bonkers.

It is a fraction of the volume of the whine from a Quaife under power or in cruise. Any volume from the radio, any sort of exhaust drone, etc. drowns it out completely. It is really only audible under decel.

Fair enough, Andrew. Hard to tell ultimate volume from a cell phone video. Maybe inconsistent noises are more annoying to me - as a for-instance, the sporadic tire sizzle from RE-71Rs is a big turn-off for a daily driver. With my old Quaife gearset, gear noise was more constant and, to me, acceptable (although I still wore ear plugs any time I was on the highway).

I roll my eyes at whoever gave me a neg-cat for what was a fairly innocuous comment.

Yeah its only on decel. Thanks for the reply.

I dont mind it as my car is already stupid on the nvh scale but i just wanted to make sure it wasn't chewing all the teeth off or something.

Feels so nice to have actual gears now. And cruising in 5th and 6th feels like a normal car now

Diff is finally in!
 

Finally got everything installed currently have about 200 miles on the gearset, noise is definitely there, but not too bad mainly on acceleration, I'll make a video of the noise and post it in the near future. Cruising, it's not there, and with the radio on, the whine completely fades away... Anyways, ended up having Ben Herne AKA puddymod do the install, works great the new gearing is amazing, having 6th on the highway is very nice, like said about, it's just like a 5 speed with a 4.1 in terms of feel, and 6 is nice on the highway... I'll post a more detailed review once everything is finally broken in and I can get some video.

Did you remove the pinion damper? I found removing that, combined with going from void fillers to actual poly mounts added a fair amount of decel whine to the 3.6 gear.

^ Have any of you had REM or WPC treatment to the gearset? I am planning to have that done and I am wondering if it will reduce noise such as mentioned here or if it will only reduce wear / increase service life..?

Based on my personal experience with these gear sets, it will not reduce noise. The machining and finishing process used by Mfactory results in a less than smooth gear face. We have their 6th gear and ring and pinion in our FR-S. It's noisy too. The 3.3 in our NB, also very noisy but it was an early production run that did not get finished the way the rest of their gears do. It was WPC treated but had no effect whatsoever.