Suspension Modifications and Noise - Advice Sought

[Mr. Haney]

So you hear the same whirrling background sound that is prevelant when the car moves generally? If this is true and my mechanic agrees with your assessment then I will return the whiteline UCA and just get the roush UCA. It seems though the watts link and LCA were fine to use its just that stupid UCA. I guess no matter what there is no UCA on the market that is quiet like stock because that stupid thing is mounted right on the body. And apparently dynamat would help this situation.

 

How far are you from bethesda?

 

Yes, I hear the whirling noise that changes with road speed. The LCAs are mounted directly to the body under the back seat of the car also.

 

I live 3 miles from the intersection of Route 267(Dulles Toll Road) and the Route 28 entrance to Dulles International Airport. If you want to ride in the car it will have to be no later than 9:30AM as I have a family gathering to attend later in the day.

[Mr. Haney]

I feel that you are hearing the clunk of the gear lash(air gap) being taken up inside the rear axle assembly as you apply power to the driveline. This gear lash clunk will never be eliminated as it was always there in the first place. The factory soft rubber bushings didn't allow the noise transmission of it to the body for you to hear it before the mods. The much harder and smaller diameter bushings are allowing the noise to transfer to the body now

[07SGT2899]

I feel that you are hearing the clunk of the gear lash(air gap) being taken up inside the rear axle assembly as you apply power to the driveline. This gear lash clunk will never be eliminated as it was always there in the first place. The factory soft rubber bushings didn't allow the noise transmission of it to the body for you to hear it before the mods. The much harder and smaller diameter bushings are allowing the noise to transfer to the body now

 

 

i agree, harder bushings will ALWAYS increase noise in some way, no matter what a vendor tries to tell you

[svt13]

I found the problem today with my mechanic. The backlash is set from the factory wrong which causes the gear whine and the clunk. We put the car up and if you turn the driveshaft there is too much play and it makes a huge ass clunk. So he doesn't have time to fix it this week but the week after we will get it done. The whirling sound is from the gears because of the watts link. It has quieted down but dynamat will be put to silence it.

 

I will have a factory quiet car when this is all over and no gear whine and no clunk. Mad lock check ur driveshaft make sure it doesn't clunk when you twist it. Make sure it's the end that's towards the back of the car

[07SGT2899]

you can't check backlash by twisting the driveshaft by hand.

 

the rear diff cover needs to come off and have the axleshafts removed and the clearance gets checked with a dial indicator. the clearance spec is .008 to .012 of an inch.

 

to twist the driveshaft by hand and say it has too much clearance is absurd.

 

if you layed under a hundred cars in a parking lot and twisted their driveshafts by hand you'd say they all have too much clearance.

 

twisting it by hand moves alot of other parts in the diff making it feel loose.

 

he needs to isolate the ring and pinion only by disassembling the differential.

 

not trying to sound like an ass but i don't wanna see someone steer you wrong and do a poor job "fixing" your diff.

 

in my experiance i have never seen a car have the backlash out of spec from the factory, in reality, most folks can't set up a diff as good as the factory can

 

you really need to understand that suspension control arm mods will ALWAYS increase NVH.

 

all the noise you're hearing now was always there, it just those new components, while they add suspension control, are doing a better job of making sure you hear all the noise now by the very nature of their design

[07SGT2899]

if you want a factory quiet car then leave it FACTORY! there is no two ways about it, any mod you do will have an upside and a downside. in my honest opinion, the factory parts are the best compromise between performance and comfort.

 

i mean, come on, you bought the best mustang ever produced, designed by a team of genius enginneers, and feel as though some aftermarket company can make the car that much better by slapping a few new parts on it?

 

i'm sorry but i don't care who designs the parts, for overall performance, comfort and saftey you just won't beat the SVT engineers

[svt13]

you can't check backlash by twisting the driveshaft by hand.

 

the rear diff cover needs to come off and have the axleshafts removed and the clearance gets checked with a dial indicator. the clearance spec is .008 to .012 of an inch.

 

to twist the driveshaft by hand and say it has too much clearance is absurd.

 

if you layed under a hundred cars in a parking lot and twisted their driveshafts by hand you'd say they all have too much clearance.

 

twisting it by hand moves alot of other parts in the diff making it feel loose.

 

he needs to isolate the ring and pinion only by disassembling the differential.

 

not trying to sound like an ass but i don't wanna see someone steer you wrong and do a poor job "fixing" your diff.

 

in my experiance i have never seen a car have the backlash out of spec from the factory, in reality, most folks can't set up a diff as good as the factory can

 

you really need to understand that suspension control arm mods will ALWAYS increase NVH.

 

all the noise you're hearing now was always there, it just those new components, while they add suspension control, are doing a better job of making sure you hear all the noise now by the very nature of their design

 

 

Thanks but you are not correct. 3 people have already had this problem before. It is what caused the gear drone in higher mph for many people. We are guessing the backlash is wrong but the carbon fiber driveshaft on some are not tightened correctly. Birdoc on SVT was the first to fix his driveshaft and backlack and it eliminated all noises.

 

So we will see once this is fixed. Its no sweat off my back. I trust my guy he knows what he is doing. I trust him way more than my incompotent dealership.

 

It's not about their being twist the point is that when we twist it a little bit it makes a HUGE CLUNK. There is nothing else under that car that can move. There is a clunk just like madlock and something obviously has to hit to make that happen. Clunks just don't happen out of thin air. Some metal piece has to hit another metal piece to make a clunk. So now given how this has been a past problem on other shelbys this is the iikely culrpit and I never heard it before because the rubber bushing hid it.

 

Other than that your assessment about aftermarket parts is also wrong. The rest of my car is dead silent. Minus the clunk.

[HyperStangs]

The metal to metal clunk upon quick throttle changes could be the backlash of the gear set in the rear axle. When the driveline is free floating under a no load situation any change in throttle position will cause the contact between the ring and pinion to change. You may be hearing the gears making contact with each other as they float back and forth on the backlash adjustment in the rear. You won't get rid of this without replacing UCA and LCA with the stock pieces.

 

 

Nine times out of ten this is exactly what it is. Reducing all that nice, compliant, squishy stuff between the axle and your car makes every little bump in the drivetrain chime all the way up into the cab. You might want to have the backlash on the gears checked just to see if they might need one more shim to tighten them up, or you could remove the UCA and go with a torque-arm. But the same may be true of that setup as well....

[Kevin Patten]

Thanks but you are not correct. 3 people have already had this problem before. It is what caused the gear drone in higher mph for many people. We are guessing the backlash is wrong but the carbon fiber driveshaft on some are not tightened correctly. Birdoc on SVT was the first to fix his driveshaft and backlack and it eliminated all noises.

 

So we will see once this is fixed. Its no sweat off my back. I trust my guy he knows what he is doing. I trust him way more than my incompotent dealership.

 

It's not about their being twist the point is that when we twist it a little bit it makes a HUGE CLUNK. There is nothing else under that car that can move. There is a clunk just like madlock and something obviously has to hit to make that happen. Clunks just don't happen out of thin air. Some metal piece has to hit another metal piece to make a clunk. So now given how this has been a past problem on other shelbys this is the iikely culrpit and I never heard it before because the rubber bushing hid it.

 

Other than that your assessment about aftermarket parts is also wrong. The rest of my car is dead silent. Minus the clunk.

 

I thought that you only had a clunk not "higher mph gear drone" . Differential gear back lash is NOT checked by rotating a driveshaft back and forth. Incompetent or incompetency is not at your dealership in this case and clunks do not have to come from 2 pieces of metal hitting each other ( like the 2 rocks in your head ) and If your car is DEAD SILENT it's because you have broken it with all nonsense that you have done surfing the forums to seek out "The Ultimate Mods" . JMO P.S. You make me laugh - thank you and I will wait for your final NVH reports. Please be sure to show us the "before and after" charts.

[Squirrel 007]

 

in my experiance i have never seen a car have the backlash out of spec from the factory, in reality, most folks can't set up a diff as good as the factory can

 

 

 

That is because the backlash is all done by "computerized" machines at the factory. The older machines still required operator to select correct shims that the machine identified as required but the newer machines do that themselves now.

[svt13]

I thought that you only had a clunk not "higher mph gear drone" . Differential gear back lash is NOT checked by rotating a driveshaft back and forth. Incompetent or incompetency is not at your dealership in this case and clunks do not have to come from 2 pieces of metal hitting each other ( like the 2 rocks in your head ) and If your car is DEAD SILENT it's because you have broken it with all nonsense that you have done surfing the forums to seek out "The Ultimate Mods" . JMO P.S. You make me laugh - thank you and I will wait for your final NVH reports. Please be sure to show us the "before and after" charts.

 

 

Oh my god I never said he checked it that way. We are guessing that is the reason given the clunk the shaft makes but ok forget it I am just wrong in everything. Excuse me while I drive the car off a cliff now because I am just so embarrassed by your sea of right guessing

[Madlock]

Not that I don't appreciate the effort, but I'm glad so many seem to have decided upon exactly what the problem isn't.

[Kevin Patten]

Madlock - let us know if indeed you get a chance to change out the UCA back to stock and what you find while you are still regrouping from Hurricane Sandy. Really do hope that you find what your looking for. The 2013 GT500 is a wonderful car from the get go but for those who can not accept the car for what it is and feel that they can mod it out better than anyone else but can not find happiness in what they have done to the car should think about this - Maybe it just isn't the right car for you - buy something different . Good Luck and Enjoy the Ride !

[svt13]

Not that I don't appreciate the effort, but I'm glad so many seem to have decided upon exactly what the problem isn't.

 

 

Madlock check your driveshaft. Mine makes a very loud clunk. And from inside it sounds identical to the clunk I hear. Birdoc had the same problem.

 

Some of these cars don't have the driveshaft properly tightened and also the backlash is slightly off causing the gear resonance to happen at high speeds that so many people have.

 

Just check the driveshaft its very easy to do if you have jackstands you can do it in your driveway.

[redwingone]

ok i am going to chime in only because i seem to remember that back in the 2007-2008 days when this was a problem and someone took their backseat out and carpet and had a buddy lay back there and i believe they discovered that the attachment point for the uca was flexing like a sardine can creating the clunk. I dont know what the fix was and i am no expert but i can only imagine how irritating that is. Good luck mr madlock and happy thanksgiving everyone.

 

ken

[07SGT2899]

hey man, i've got alot of experiance with this kind of stuff, don't tell me i'm wrong. i just don't want to see you having your mechanic rip into an essentially brand new diff just to find nothing wrong

 

sometimes you just have to accept that mechanical things make noise, if it has moving parts, it will make noise

[Tob]

 

 

i've always found aftermarket UCA's to make a car very noisy and clunky inside. don't forget, you've taken out a stock, complient and insulating rubber bushing and replaced it with a stiff and hard, non-complient poly bushing in a mechanically noisy part of the car. right above the differential that has several moving parts inside all with their own clearances. you're bound to hear some clunking.

 

 

The UCA on our beloved S197 chassis vehicles is a direct path between the gear housing of the rear axle assembly and the cabin. The factory employs a very large diameter, soft bushing in an attempt to address the direct transmission of gear mesh, hum, impact, suspension undulation, etc. Substitute a stiffer bushing(s) and you are almost guaranteed that noises that were once able to be 'absorbed' by the OEM blubber bushing will instead follow a more direct path to the interior of the vehicle and ultimately, your ears. My friend you are absolutely correct.

 

...you are only now hearing them because you reduced the size and changed the material of the factory UCA and LCA bushings that hold the rear axle assembly to the car.

 

 

I've said it before - this is all about compromise. Want the best articulating, bind free, bushings? Switch to heims, but understand they have no damping qualities. Everything else is a compromise in terms of performance, each with its own idiosyncrasies in terms of NVH and/or maintenance. Unless you road race competitively or drag race quite a bit, I'd avoid a heim joint at the upper. I'd avoid polyurethane as well. A heim at the upper will transmit everything. It'll act as a tuning fork directly to your ear. Poly will cold flow or tear over time allowing more clearance and more noise (greasing them is a PIA as well). This is why for street driving ( as well as some occasional track use) I'd recommend a rubber bushed arm such as the Roush. The bushings are OEM in terms of durability - no maintenance. Roush NVH/vehicle dynamic engineers tested and came up with an upper that is pretty well balanced in terms of 'noise' transferrance/compliance and ultimately, performance. I'd consider one from them.

 

It pisses me off to perhaps chuck $300 worth of hardware, let alone potentially invest another $150, especially if the clunk is owed to something beyond the arm's adjustment mechanism. Welding would be another way to go, but it remains too much of a one-way street for my preference.

 

I'd certainly be willing to try replacing WhiteLine's elastomer bushings with urethane or custom made Delrin substitutes to eliminate any incidental rattles even at the expense of further resonance which Dynamat should be able to tame.

 

 

As mentioned, when properly adjusted, jam nuts and all, the issue isn't one of the adjustable design. It is the bushings, plain and simple. They are allowing a direct path via their construction (material, durometer, dimensions).

 

Delrin would most definitely transmit more noise about the Watt's in addition to offering almost zero torsional compliance.

 

You may be hearing the differential gear lash thru the control arms. You may be hyper sensitive about any new noises as you've been obsessing over NVH throughout the build. There's a reason Ford had spongy rubber bushings everywhere.

 

Nailed it.

 

I feel that you are hearing the clunk of the gear lash(air gap) being taken up inside the rear axle assembly as you apply power to the driveline. This gear lash clunk will never be eliminated as it was always there in the first place. The factory soft rubber bushings didn't allow the noise transmission of it to the body for you to hear it before the mods. The much harder and smaller diameter bushings are allowing the noise to transfer to the body now

 

Nailed it X2.

[svt13]

Tob does your driveshaft make a very loud clunk sound when you turn it?

[svt13]

hey man, i've got alot of experiance with this kind of stuff, don't tell me i'm wrong. i just don't want to see you having your mechanic rip into an essentially brand new diff just to find nothing wrong

 

sometimes you just have to accept that mechanical things make noise, if it has moving parts, it will make noise

 

 

The differentially always had something wrong. The gear whine which I just lived with for the time being. I was always going to fix that. I was just too scared to trust my dealership with their SVT mechanic with his shaky ass hands to touch my car since he seems to be going through some kind of withdrawl everytime I see him there. Plus there are a couple members who when they took the car to the dealership to fix this problem made it 10x worse. I need someone who knows what they are doing to check the backlash make sure it is proper and if its off to fix it. And also to set the gears in properly or even put a new set a 3.31 gears in properly if we can't reuse the current ones.

 

But when we took out the rear seats completely to diagnosis the 2 sounds I had been wearing we discovered 2 things. One the whirring sound I heard was in fact the differential or gears moving or whatever the hell is moving back there which is normal I'm assuming since once we took the seat out it became much louder. So the only solution to that if its a normal thing is to just put some dynamat or more sound dampening material to lessen the noise. Thats fine thats an easy fix. But something interesting is that when my car is moving just a hair like 1 mph when we shift it sometimes clunks or jerk the car. By doing a sudden jerk and stop we got the driveshaft to replicate the clunk over and over again on its own. It actually sounded very werid. Granted at this point we didn't know it was the driveshaft.

 

Then we put it back up we checked everything absolutely everything. Hell I even hung on my watts link and swung around to try and make it clunk and couldn't. Same with the LCA same with everything. The UCA didn't move an inch. Then he touched the driveshaft an granted there is suppose to be some play he said but not to the level mine has. And sure enough everytime we turned it, it made a huge ass clunk. And ironically hey the clunk we hear inside the car comes from that area.

 

COINCIDENCE? Maybe, maybe not. We will see. Worst case the stock UCA will go back on the car.

[2010KonaBlueGT]

I was just too scared to trust my dealership with their SVT mechanic with his shaky ass hands to touch my car since he seems to be going through some kind of withdrawl everytime I see him there. Plus there are a couple members who when they took the car to the dealership to fix this problem made it 10x worse. I need someone who knows what they are doing to check the backlash make sure it is proper and if its off to fix it.

 

 

Find a shop that specializes in 4 wheel drive trucks (4WD Accessories, etc.). They change out front/rear gears regularly and they're generally pretty good at it (EXPERIENCE can't be learned from a book)..

 

We have at least a couple in town and I tried a number of times to suggest that Blackout take his SS to a similar shop but he used the dealer, with disastrous results.

 

 

Phill

[Madlock]

hey man, i've got alot of experiance with this kind of stuff, don't tell me i'm wrong. i just don't want to see you having your mechanic rip into an essentially brand new diff just to find nothing wrong

 

sometimes you just have to accept that mechanical things make noise, if it has moving parts, it will make noise

 

 

Hey man. I'm sure you've got plenty of experience - with cars you've actually happened to work on. Just not this particular one.

 

After swapping the Shelby/BMR adjustable arm and mount with Shelby's single-piece adjustable unit, the car now drives and sounds like it should with no clunk whatsoever - meaning it's been attributable to the particular UCA components being used, and NOT any particular dependency upon using the OE third link assembly to soften and absorb any gear lashing noises that hadn't previously existed.

 

Thanks for your help anyway. Maybe it'll benefit somebody else whose car is exhibiting something entirely different altogether.

[patrickshelby]

Hi Madlock,

So the noise was NOT coming from the WHITELINE watts (?).

The noise came from the BMR-SHELBY UCA (?).

Do you have the OEM rubber bushing pressed in your 8.8 rear axle or did you swap it for a poly bushing?

Which UCA did you finally mount to solve this clunking noise?

This one?

thx

[07SGT2899]

hey man, Glad to see you've sorted it out. There's nothing worse than having your favorite car do something annoying after you tried to make it better!

[Tob]

Tob does your driveshaft make a very loud clunk sound when you turn it?

 

 

Every Ford I have ever owned, whether a 9" or 8.8" rear, could produce an audible clunk if I turned the differential one way and then the other while laying underneath it.

[Kevin Patten]

Hey man. I'm sure you've got plenty of experience - with cars you've actually happened to work on. Just not this particular one.

 

After swapping the Shelby/BMR adjustable arm and mount with Shelby's single-piece adjustable unit, the car now drives and sounds like it should with no clunk whatsoever - meaning it's been attributable to the particular UCA components being used, and NOT any particular dependency upon using the OE third link assembly to soften and absorb any gear lashing noises that hadn't previously existed.

 

Thanks for your help anyway. Maybe it'll benefit somebody else whose car is exhibiting something entirely different altogether.

 

Glad you were able to get -r - done. Maybe you can sell that Shelby/BMR adjustable arm and mount to svt13

[svt13]

Every Ford I have ever owned, whether a 9" or 8.8" rear, could produce an audible clunk if I turned the differential one way and then the other while laying underneath it.

 

 

I said driveshaft not differential

[svt13]

Glad you were able to get -r - done. Maybe you can sell that Shelby/BMR adjustable arm and mount to svt13

 

 

I like how you and the other guy who said it was impossible to fix this now are acting like madlock didn't make you 2 look like for lack of a better word ignorant by fixing his clunk.

[07SGT2899]

Thanks dude. I feel in no way do I look ignorant. Just trying to help. I've had the same experience as Tob with every differential in every car I've ever owned. Its impossible to diagnos noises over a keyboard. I'm not even sure why I got involved here. Best of luck with your respective rides.

 

[0201212]

Glad you got rid of the clunk!!!!!

[Tob]

I said driveshaft not differential

 

 

I know what you said.

 

Since it is highly unlikely that the issue is the CV joint in your driveshaft I'm trying to get the point across to you that the play is in the differential, as explained earlier regarding gear mesh. In other words, the clunk isn't from the shaft, it is from the axle assembly.