boss3022013

Just put QTP electric cutouts on this winter and now I really notice the rear end wine. Have about 9400 miles on it. I think it always wined, just didnt notice as much. Tried out 3 other Boss's before I purchased this, I thought they all had some wine at certain speeds, but probably didnt notice because I was so enamoured with the car and all of them had the cutouts open. I tried to figure out exactly when I hear the wine. I notice some about 35 or 40 mph. At 50 really noticable. I put the clutch in and I still hear it. My highway cruising speed is about 74 and very noticable, also when I put the clutch in at that speed it is gone or almost gone. Definitely noticable up to 85 and at 90, gone. I havent cruised consistantly at that speed or faster. First of all, does that sound excusively like the rear end? Second, many of the guys on the forums say that adding Fords anti friction to the rear end will cure it. Others have mentioned changing the backlash from 12 to 10 or getting a new ring gear and pinion. I have a 6 year 100,000 mile extended warranty from Ford, so I probably will go that route if necessary. Should I have Ford put in the ant friction first? All your help is appreciated.

David Young

Don't mess with it and use your 6 year 100,000 mile warranty

boss3022013

Thanks, but does that sound like its exclusively the rear end? Does it make a difference that the wine doesnt go away when I put the clutch in at lower speeds but seems to go away when I put the clutch in at higher speeds and why would it disappear at 90 mph? Thanks

Bert

rear end gear whine can vary with load and speed . . . it is hard to sort out, but it could be loading and speed interacting to make it sound different when you disengage the clutch

impossible to say from here whether it is actually rear end whine or not, it's hard to tell for sure when driving in my own car, LOL

it should already have the appropriate friction modifier in it, and that is mainly for the limited slip to work correctly, so I very much doubt it would affect the whine . . . you have Torsen differential in the Boss so I'm not sure what is required for friction modifier . . . I don't think that would be the first thing that I would mess with

since you have the warranty, that would be a good place to start . . . but be prepared for the service manager to say they can't hear it, or it is "normal" . . . I think the only way to fix it is to replace the gear set, and even then it is hit or miss . . . some say they will not whine if properly set-up, some say some whine is inherent in the 3.73 gears and it varies from set to set how loud it is

Mustang Freak

I thought I also had a rear whine problem but I replaced the stock Pirelli's with Michelin's and it went away.

boss3022013

So you have a 2013 Boss also. How long did you have it and how many miles on when you changed the tires? Did they seem worn? So it may be that simple. One of the guys mentioned that I should let 6 lbs of pressure out in each tire and if that changes the wine then that would then be my tires. Maybe I will try that next. Did you happen to try that before you purchased the new tires? Did your rear end ever wine and how many miles on it now?

Mustang Freak

Bought her brand new and never tried the air trick but noticed the whining around 8k. I replaced my tires (Pirelli's great grip for first 4k complete junk after that) at 15k due to the FRONTS failing inspection (yes I corner with her as she was made to do) and the whine was gone. I have 20k on her now and no whine.

Ron11

It's possible that the tires are causing the whine. More likely the ring & pinion gear lash was set incorrectly at the factory. Typically the whine happens when the the lash is set too loose. But wether it's set too loose or too tight, this will cause premature wear on the ring & pinion gears. The lash is the proper meshing of two gears together. Nearly every time I've encountered a rear gear whine, it will start at a certain speed, then gets louder as you go faster, while keeping the throttle fairly steady. It's much easier to hear a rear gear whine while driving over about 50mph in high gear (6th for a stick, and OD in an automatic).That helps you to hear the rear end, as opposed to tranny/engine/exhaust etc. My GT came with Pirelli P ZEROs. Happiest day of my life was taking them off to install a set of Michelin Pilot Super Sports. Quieter, handled much better on dry or wet roads. Oh yeah, rode better too. One other thing that might sound like a whine is a rear axle bearing going out. Hope this helps you while trying to isolate where the whine is coming from. I've never heard of letting air out of tires to see if it changes when a whine might occur. No logic to it. Tire tread design that whines, is gonna whine no matter the air pressure, high or low.

lakeguy77

My 2014 track pack with the same 3.73 torsen has that whine as well. At higher speeds it fades, but peaks right around 100-110 kph, which is highway driving up here in Canada.

5.M0NSTER

Ditto. My ‘14 Track Pack had the same issue between 60 and 70mph. It wasn’t super loud but you could hear it. Disappeared over 75mph.

Ron11

Gear whine doesn't really go away, you are speeds now where basically you are outrunning what you're hearing in the driver's seat. I would suspect that if you could sit in the trunk you'd still hear it. It's nothing terminal unless the gear lash is way off. That rarely happens anymore, as all of the factories are much better than in years past.

Mogumbo

The rear end whine that every ford service manager says is normal.., I’m here to tell you it’s not. Your rear end is on the way out and when it goes and your tires lock up, pray you are not on a crowded hwy.

if anyone wants to see photos of my shattered pinion, seals, housing, exploded differential, an inch of metal shavings in my magnetic diff oil drain and fill plugs... let me know and I’ll post them.

Stop driving the car and take it to a competent repair shop (meaning NOT Ford dealer... I took mine to a custom shop that restores and builds muscle cars).

Mustang Freak

Wow glad you didn't wreck the car that sounds horrible I hope you get her all back together and stronger than ever!

Bert

Oh No! My 3.73 gears have been whining for about 80 or 90 thousand miles now, my rear end must be about ready to explode!

Just kidding, thanks for the warning Mogumbo -- your experience is very unusual, there are lots of Mustangs running around with whiney 3.73 gears practically forever with no major issues other than the annoying noise.

Mogumbo

not familiar with other models, but when the Boss went through the assembly line, the assembly workers were shoddy and untrained on the adjustments needed for the Boss rear end. A combination of a lower suspension and change in angle degree of back half of drive shaft with enclosed cv joint led to almost all rear ends suffering from grossly out of tolerance backlash, leading to movement, vibrations, pinion seal, pinion, ring gear, and differential damage.

I know there are different causes for different “whine” and “scraping” noises... but the pinion damage resulting from backlash issues is very distinct. Any half knowledgeable mechanic (meaning NOT Ford) will be able to diagnose it within 3 minutes.

If you have this issue, it’s not a matter of if it will fail and lock up rear tires, it’s a matter of when and where you are driving when it happens.

I’m not trying to incite a riot here, just pointing out how dangerous this can be if you don’t fix the problem at the first signs of the issue.

Mogumbo

Here, are a couple more. The photo of the bolt looking thing is the drain plug, which is magnetized to catch metal bits... it's pretty much loaded to capacity.

Also, pinion gear marks on differential housing - obviously not the way the rear end was designed to operate. Shows how far pinion had worked it's way into the housing before obliterating the diffential.

I have a short (bad) 2 second video clip I'll try to upload showing two inches of play at where pinion yoke attaches to pinion (couldn’t get video, but here’s a screen shot)

SpectreH

Get that rear checked just to be safe. The cost of the diagnosis is worth the peace of mind. Locked rear tires at highway speeds is an eye-opener for sure. When the lead frame in my 6R80 went bad it sent bad speed data to the ECU, downshifting to 1st at 70 MPH, essentially locking the rears. Either my instincts were good or there was Divine help, because it could have been disastrous.

SilrBult

It's a relatively simple matter to pull the back cover on the differential and check the backlash and the wear pattern on the gear set. Backlash is best checked with a dial indicator at 90* increments around the ring gear. An experienced mechanic will [ should ] have a pretty good sense of feel for clearances so if it's really off the dial indicator won't be necessary, but still the best way to do it. If everything is OK with the clearances and the pattern isn't really off, you'll either just have to live with it since once the pattern has been established changing things is generally fruitless and may even make it worse, or replace the ring and pinion with a new set. Bad pinion or side bearings can also be source of noise and can make a whining or howling sound. Usually it's the pinion bearing that does this. You didn't say anything about rear control arms. Are they stock or aftermarket? Stock arms have rubber bushings that allow for a bit more movement, but they're also better at damping noise. Poly bushings tend to transmit sound and heim joints [ great for racing ] are even worse in this regard. All rear ends generate some normal noise in operation and aftermarket arms can transmit this and make you think something is wrong. It can take an experienced ear to know the difference between the beginning of a real malfunction and what's normal when the car has aftermarket control arms.

Mogumbo

Ha! That’s pretty funny that your signature say “Whiny 3.73”

Bert

^ yeah but I wasn't sure how to spell "whiney" LOL