New Parts, New Whine

[Run_Amok]

You may recall that my 2014 GT is lowered on SR springs with Koni Orange dampers. I also have the Ford Performance aluminum one-piece drive shaft.

Over the weekend I installed these upgrades from BMR:

• Boxed, non-adjustable LCAs with poly bushings (BMR-TCA032H)
• LCA relocation brackets (BMR-CAB005H)
• Adjustable UCA mount (BMR-UCM002H)
• Adjustable UCA (BMR-UTCA032)

The LCAs were set the the top-most position in the new brackets.
The UCA was set to the top-most position in the new bracket.
The UCA was adjusted to 0° on the pinion (per the formula).

Now there is a noticeable high-pitched whine at speeds above 60mph, only when I am on the gas—when I lift, the whine goes away immediately. We then set the pinion angle to 1° up toward the chassis (I don't remember if that is a negative or positive 1°). The whine became worse.

As a side note, previous to these moods I replaced the diff fluid with RedLine 75W/140.

Any ideas as to what may have happened or what needs to be addressed?

Your help / insight / expertise is much appreciated.

Other than the whine, the car feels great! No hop at take off. Yay!

 

[blacksheep-1]

It's possible that some of that whine may be related to harmonics since you have gotten rid of most of the rubber bushings, the 8.8 is in particular, a noisy differential.
I'm going to assume the pinion angle was set while the chassis was loaded and not just sitting in the air on jack stands, or at least the jack stands were placed under the suspension points to simulate loading.
The problem you are describing usually goes with the pinion bearings, which makes zero sense since you did not mess witht he differential itself, other than the fluid fill. I would check to make sure that is the correct weight of diff fluid, and also make sure it has the friction modifier either included or you added it.. I normally run Royal Purple, because that is what I have available, but Redline is a good product, so brand is prolly not an issue.

 

[mwjscn]

Did you do the final torque on the bushings while the suspension was under load? If you tighten them all the way while the wheels are lifted off the ground it can lead to the bushing being incorrectly loaded. Also I noticed some white noise sound when I made the rear end connection stiffer too. For me, it's barely perceivable but also present at high speeds. Hard to describe, but I wouldn't call it a whine per say. Best way I can describe it is like hearing a dishwasher running a couple rooms over.

 

[EF1]

The pinion angle shouldn't be set to 0. It should be around -2 degrees. This is so when under load it migrates toward 0 degrees. You moved it up 1 degree and it got worse. I would rotate it down a couple of degrees and see how it sounds. I would expect more NVH with urethane bushings than with rubber, but since you can make it worse you should be able to make it better.

 

[Run_Amok]

It's possible that some of that whine may be related to harmonics since you have gotten rid of most of the rubber bushings, the 8.8 is in particular, a noisy differential.
I'm going to assume the pinion angle was set while the chassis was loaded and not just sitting in the air on jack stands, or at least the jack stands were placed under the suspension points to simulate loading.
The problem you are describing usually goes with the pinion bearings, which makes zero sense since you did not mess witht he differential itself, other than the fluid fill. I would check to make sure that is the correct weight of diff fluid, and also make sure it has the friction modifier either included or you added it.. I normally run Royal Purple, because that is what I have available, but Redline is a good product, so brand is prolly not an issue.

blacksheep, yes sir, the suspension was loaded when we adjusted the pinion angle (on an alignment rack).

I think you may have nailed the issue though. I misread the Ford Owner's Manual fluid table—I missed the superscript 6 that specifies the friction modifier:


6 - Add 4 oz. (118 ml) of Additive Friction Modifier XL-3 or equivalent meeting Ford specification EST-M2C118-A for complete refill of Traction-Lok or TORSEN axles. Ford design rear axles contain a synthetic lubricant that does not require changing unless the axle has been submerged in water.
When subjecting your car to high-speed or competition use, the axle fluid and friction modifier should be changed after the initial (first) hour of high-speed operation or if the vehicle is subjected to track or competition conditions; thereafter changing the axle lubricant and friction modifier every 12 hours (under these conditions).
----------------------------------

I was under the impression that Torsen LSDs did not require friction modifiers.

I've driven the car approximately 2K miles, with two HPDE weekends included. Facepalm. I hope I didn't destroy the diff.

Did you do the final torque on the bushings while the suspension was under load? If you tighten them all the way while the wheels are lifted off the ground it can lead to the bushing being incorrectly loaded. Also I noticed some white noise sound when I made the rear end connection stiffer too. For me, it's barely perceivable but also present at high speeds. Hard to describe, but I wouldn't call it a whine per say. Best way I can describe it is like hearing a dishwasher running a couple rooms over.

Yes sir, the final tightening and torqueing was done while the suspension was loaded.

I'm most definitely hearing a whine. I kinda hope it's the friction modifier because I will have ended this investigation. At the same time I kinda hope that it's not the diff internals because I don't want to repair or replace a diff that has <25K on it.

The pinion angle shouldn't be set to 0. It should be around -2 degrees. This is so when under load it migrates toward 0 degrees. You moved it up 1 degree and it got worse. I would rotate it down a couple of degrees and see how it sounds. I would expect more NVH with urethane bushings than with rubber, but since you can make it worse you should be able to make it better.

Thank you, sir. I will recheck the formula and confirm where the angel should be. I had an opportunity to measure the pinion angle on a S197 GT500 on a stock suspension—my angle finder read -2.5°. Maybe mine should be at least -1.5° given that it's lowered an inch...

**QUESTION** Do I need to drain and refill the diff fluid to add the friction modifier, or can I add it to the existing fluid?

Thank you all for your help!

 

[EF1]

I have used the Red Line 75w140 gear oil for years with the friction modifier already in it. If you used the 75w140NS it does not have it. Check the bottle before adding more. If you need it, you do not need to drain the diff to add it. You just need to have enough room to get it in there. Also, Ford specifies the friction modifier for both TracLoc and Torsens. Torsen says to not use any friction modifier with their differentials. There has been a lot of debate on why Ford says yes and Torsen says no.

 

[2012-Boss]

Remember that pinion angle is in relation to the transmission angle. You need to check your entire driveline angles and their relationship to each other.

 

[Run_Amok]

I have used the Red Line 75w140 gear oil for years with the friction modifier already in it. If you used the 75w140NS it does not have it. Check the bottle before adding more. If you need it, you do not need to drain the diff to add it. You just need to have enough room to get it in there. Also, Ford specifies the friction modifier for both TracLoc and Torsens. Torsen says to not use any friction modifier with their differentials. There has been a lot of debate on why Ford says yes and Torsen says no.

Great point and thank you, sir. My memory is not what it used to be... I did use the RedLine product that has the friction modifier.

Remember that pinion angle is in relation to the transmission angle. You need to check your entire driveline angles and their relationship to each other.

Yes sir, we will do that. Thank you.

 

[Run_Amok]

Gear Whine after Whiteline rear upper / lower arms installed

So I've installed my whiteline lower rear and upper rear control arm. Immediately after the install, I noticed that there is now gear whine coming from the rear diff. I was already expecting some increase in NVH but I wasn't expecting things to get this loud. It's not TOO bad, but it's...

trackmustangsonline.com

This gentleman had the same experience. I suppose what I hear is a normal result for introducing much more rigid upper and lower arms and mounts, with poly bushings to boot...

 

[blacksheep-1]

Just for fun, reinstall the stock upper link and see what happens. Most competition cars used a stock or Gt500 upper link. It might be enough to remove the harmonics and IMO, help you with a little extra forward bite.

 

[Run_Amok]

Just for fun, reinstall the stock upper link and see what happens. Most competition cars used a stock or Gt500 upper link. It might be enough to remove the harmonics and IMO, help you with a little extra forward bite.

Great idea. Thank you, sir.

 

[Run_Amok]

We swapped in the OE upper control arm and bracket, and the whine is reduced by at least 50%.

I would consider the GT500 upper control arm, but it will not allow adjustment to achieve the desired -2° angle.

So... the BMR parts will go back on, and I will deal with the whine.

Thank you all, again, for your help and time.

 

[mwjscn]

Though the sound is likely coming through the chassis due to the way these components connect, you could ask vibration insulation companies like Dynamat or DEI (boom mat) if stick-on insulation sheets would attenuate the noise at all. Usually, these deal only with low-frequency vibrations, but there may be a different product out there that they're familiar with or have produced.

 

[Run_Amok]

Though the sound is likely coming through the chassis due to the way these components connect, you could ask vibration insulation companies like Dynamat or DEI (boom mat) if stick-on insulation sheets would attenuate the noise at all. Usually, these deal only with low-frequency vibrations, but there may be a different product out there that they're familiar with or have produced.

Thank you—based on your recommendation I inquired with Dynamat:

Q: I have installed aftermarket suspension components with poly bushings. The gear whine from the transmission and differential is amplified by the more direct connection to the unibody. Do you have a product that will reduce the volume caused by the reduced dampening of the suspension?

A: "Rubber bushings are use by manufactures just for that reason, to reduce noise transmission. The best solution we can offer is to remove the complete interior of the vehicle, then install our Xtreme, then our DynaPad. Xtreme will Damp vibrations/resonations in the sheet metal to help reduce any structure borne noise. The DynaPad, with its MLV, sound barrier will help block the airborne, lower frequency noise. Full coverage will be required to see any results. The cargo (trunk) area may also need to be treated in the same manor for the best results."

I will look into what it takes to remove the interior to properly install the Dynamat products. Price is a consideration as well.

 

[JDee]

Not to trivialize the issue, but you do get used to it after a while. On track there's so much engine, wind and road noise that you never hear it.

 

[Run_Amok]

Not to trivialize the issue, but you do get used to it after a while. On track there's so much engine, wind and road noise that you never hear it.

I really hope I do!

 

[BKBoss302]

Thank you—based on your recommendation I inquired with Dynamat:

Q: I have installed aftermarket suspension components with poly bushings. The gear whine from the transmission and differential is amplified by the more direct connection to the unibody. Do you have a product that will reduce the volume caused by the reduced dampening of the suspension?

A: "Rubber bushings are use by manufactures just for that reason, to reduce noise transmission. The best solution we can offer is to remove the complete interior of the vehicle, then install our Xtreme, then our DynaPad. Xtreme will Damp vibrations/resonations in the sheet metal to help reduce any structure borne noise. The DynaPad, with its MLV, sound barrier will help block the airborne, lower frequency noise. Full coverage will be required to see any results. The cargo (trunk) area may also need to be treated in the same manor for the best results."

I will look into what it takes to remove the interior to properly install the Dynamat products. Price is a consideration as well.

I recall that sound deadening materials like Dynamat weigh something like .45 to .68 pounds per square foot. How many square feet are in a Mustang interior? My entire interior is out so gear whine is one of the many many noises I hear. I have the Cortex torque arm in my Boss and that amplifies the noise slightly less than my previous BMR upper arm.

 

[Run_Amok]

I recall that sound deadening materials like Dynamat weigh something like .45 to .68 pounds per square foot. How many square feet are in a Mustang interior? My entire interior is out so gear whine is one of the many many noises I hear. I have the Cortex torque arm in my Boss and that amplifies the noise slightly less than my previous BMR upper arm.

I hadn't considered the weight of the sound-deadening mats. Thankfully they are low on the platform and between the axles... the other consideration is determining ROI.

 

[Run_Amok]

Hi everyone. The whine became worse in 5th and 6th, and is now audible in 4th. Not knowing exactly which part in the diff was on it's way south, I ordered the 3.73 gear kit from LMR, which comes with everything. I had a local, trusted shop do the work. Over the course of the teardown the shop found that the inner pinion bearing (IPB) had failed, and coincidentally, my car's IPB is larger than the unit that came with LMR's kit (I ordered the correct one from the Ford dealership).

The good news is that 80% of the whine is gone! Yay and thank You Jesus! Am I wrong to presume that the remaining whine is normal driveline noise that is being amplified through the poly bushings?

The unexpected benefit from replacing the bad IPB is a much smoother and direct interface with the car when shifting gears; apparently there was a noticeable (in hindsight) degree of slop in the diff that has been corrected.

I contacted LMR and they are refunding the cost of the IPB that I sourced from the dealer. Great customer service and overall a great experience with LMR.

 

[67GTA]

The 3.73 are known to make more noise than the other ratios.