Rear end noise help
3/3/18, 10:05 PM
#1
Rear end noise help
i have a '14 GT/CS with some decent aftermarket mods. manual 6 speed trans, one owner car with about 50k on the odometer.....I have recently been experiencing a mild rubbing, whinning or whirring noise from the rear of the car. This only happens once it's been at highway speed for a bit (assuming once it gets warm) and only happens when I'm making tighter turns. This noise is consistent whether I'm turning right or left and there is no feeling in the pedals, steering wheel or shifter. I was told that I may need to change the gear oil in the rear diff with the slip additive. I also should add that I live in northern NJ and have been told he MT-82 trans doesn't like the colder weather up here (have had several Fox body mustangs but this is my first coyote and I used to live in NC). I'm assuming it may be time to do this maintainence on the rear diff anyway, judging by the mileage and the mods. Car has the AdvanceTrac traction control option also. Can anyone help ease my mind and give me any guidance. The car's handling and performance doesn't seem to be effected in any way and runs great. I bought all the necessities for this procedure but want to talk to other mustang folks before I start turning wrenches and run the possibility of screwing anything up and end up in the marital dog house. Thanks.
3/4/18, 06:40 AM
#2
If it is only happening after warm up and while making tight turns it is most likely not the MT82. If I remember correctly most of the MT82 problems were when it was cold and got better as it warmed up. Also, I believe the Ford solved many of the problems prior to the 2014 model year. If it is happening during tight turns I would look at the trac lok differential and the gear lube. It sounds like the clutche disks may be worn.
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THEGT2NV (3/6/18)
3/6/18, 11:12 PM
#3
Thanks for the help. Today something else started as well and I'm not sure if it's related. when I release the clutch in first gear from a dead stop there is a 'shimmy' or a 'shudder' or a 'tremble' that I can feel in the pedal. it happens at the top of he clutch mostly. I'm afraid I need a new clutch. as many vehicles I've owned with manual trans I've never had one break. thanks again
3/7/18, 12:45 PM
#4
Mach 1 Member
Congrats on your first coyote and welcome to TMS.
I'm no expert just sharing experiences, your concerns here sounded familiar and brings some of the discussions back in the day when we first got the 11-14 model years.
If I remember correctly, the GT/CS trims didn't come brembo/track pkg. This means the gear ratio is standard 3.31.
There were many discussions about the high-pitched whine or whirring noise in the rear, and it came down to 3.73 gear ratios that are prone to make more. I've seen a guy replaced the entire rear end assembly only to hear it come back shortly after.
This however was proven to be not always the case when my brother got his 14GT with 3.31, making the infamous whirring noise at highway speeds. Some of the parts were replaced under warranty and the noise was reduced but still present. Also to note, aftermarket mods especially lowering can 'amplify' the noise. My 13GT with 3.55 did NOT have (or could not hear) any rear end noise until the car was lowered and 'developed' whirring.
Not sure about tighter turns though. Most seemed to be in agreement with the fact that other than annoyed by the noise the car ran fine. I vote for the cheap Ford parts and bad design. One of the members here reported resolving the issue replacing the rear end assembly other than factory. Please keep us posted with the gear oil change/slip additive.
I remember this cluck noise whenever disengaging the clutch at low speeds (parking lot), followed by the shudder noise (like an old taxi) when re-engaging and got terrified by them thinking a brand new car shouldn't sound like this. Maybe I got used to how it operates, but not hearing the clunk anymore. The shudder noise is still there sometimes just not as often.
Your case may or may not be the same since you mentioned 'feel in the pedal' and not 'noise'. Some of the owners replace their clutches with brand names like McLeod mostly to improve MT82 knotchy shifting in combination with MGW/Barton shifters.
I'm no expert just sharing experiences, your concerns here sounded familiar and brings some of the discussions back in the day when we first got the 11-14 model years.
This however was proven to be not always the case when my brother got his 14GT with 3.31, making the infamous whirring noise at highway speeds. Some of the parts were replaced under warranty and the noise was reduced but still present. Also to note, aftermarket mods especially lowering can 'amplify' the noise. My 13GT with 3.55 did NOT have (or could not hear) any rear end noise until the car was lowered and 'developed' whirring.
Today something else started as well and I'm not sure if it's related. when I release the clutch in first gear from a dead stop there is a 'shimmy' or a 'shudder' or a 'tremble' that I can feel in the pedal. it happens at the top of he clutch mostly. I'm afraid I need a new clutch...
Your case may or may not be the same since you mentioned 'feel in the pedal' and not 'noise'. Some of the owners replace their clutches with brand names like McLeod mostly to improve MT82 knotchy shifting in combination with MGW/Barton shifters.
3/10/18, 06:05 AM
#5
Cobra Member
i have a '14 GT/CS with some decent aftermarket mods. manual 6 speed trans, one owner car with about 50k on the odometer.....I have recently been experiencing a mild rubbing, whinning or whirring noise from the rear of the car. This only happens once it's been at highway speed for a bit (assuming once it gets warm) and only happens when I'm making tighter turns. This noise is consistent whether I'm turning right or left and there is no feeling in the pedals, steering wheel or shifter. I was told that I may need to change the gear oil in the rear diff with the slip additive. I also should add that I live in northern NJ and have been told he MT-82 trans doesn't like the colder weather up here (have had several Fox body mustangs but this is my first coyote and I used to live in NC). I'm assuming it may be time to do this maintainence on the rear diff anyway, judging by the mileage and the mods. Car has the AdvanceTrac traction control option also. Can anyone help ease my mind and give me any guidance. The car's handling and performance doesn't seem to be effected in any way and runs great. I bought all the necessities for this procedure but want to talk to other mustang folks before I start turning wrenches and run the possibility of screwing anything up and end up in the marital dog house. Thanks.
If this happens when only turning that eliminates the trans. That noise is coming from the rear. It sounds like your posi unit is starting to engage which will cause one wheel to try and drag as you make a turn. Does it feel like the car some what fights you making a turn? If so it's the rear.
You can try changing fluid to the proper type and add Friction Modifier from ford. Not sure if your rear takes it. But it cant hurt. If it does not solve your problem, then its time to pull the rear gears.
The friction modifier dose what it named after. Helps with friction which causes heat. I had my F-150 rear serviced at ford and when I got the truck back. After driving about 20 miles or so. When I made a left or right turn you could hear rear noise and feel the truck slightly fight you. Going straight was NP. Brought truck back and after a 20 minute talk they agreed they did not add the modifier. 2 bottles later and no more problems.
Last edited by boss man; 3/10/18 at 06:06 AM.
3/11/18, 04:47 AM
#6
legacy Tms Member MEMORIAL Rest In Peace 10/06/2021
Join Date: September 16, 2009
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Just something to think about:
When I had my local Ford dealer change my 3.31 gears to 3.73 on my 2011 v6, they added 2 bottles (8 oz) of friction modifier to my gear lube. I asked why? They told me they do that for the break in period. After 500-700 miles I was getting ready to change the fluid so I decided to do a burnout before I changed the fluid. I normally feel the rear end drift to the left, down the slight grade of my street. It didn't do it and I looked, sure enough, "one wheel peel"
. I changed the fluid but only added 3 oz of the 4 oz bottle of friction modifier to the gear lube and I now have 'both tires burning' 
Just saying...........
When I had my local Ford dealer change my 3.31 gears to 3.73 on my 2011 v6, they added 2 bottles (8 oz) of friction modifier to my gear lube. I asked why? They told me they do that for the break in period. After 500-700 miles I was getting ready to change the fluid so I decided to do a burnout before I changed the fluid. I normally feel the rear end drift to the left, down the slight grade of my street. It didn't do it and I looked, sure enough, "one wheel peel"
. I changed the fluid but only added 3 oz of the 4 oz bottle of friction modifier to the gear lube and I now have 'both tires burning' Just saying...........
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