Thump w/ Medium to Heavy Acceleration from Stop in 1st Gear Only

[P.R.]

My car has had a slight thump/thud noise almost since the car was new. I feel over the years it has slowly grown more noticeable.

It occurs when I accelerate without slipping the tires under medium to hard acceleration. Almost immediately as my car begins to move from a stop the thud or double-thump noise will happen without fail. The noise emanates from the rear of the car. I have searched and read that noises like this are somewhat common but I have never found exactly this same case. It seems other people experience noises while shifting into other gears as well which I do not. This only occurs from a dead stop. Is the differential or other drivetrain components moving enough to cause this noise? Could some bushings need replacement? Or is this some slop in the driveline?

This is a stock 2015 GT Performance Package with a manual transmission.

Anyone know what this could be? If this is an issue what could resolve the problem?

I was about to install a good amount of new suspension components. But I have a few months left on a mechanical warranty. Thinking it may be best to wait on the install and take advantage of the warranty one last time if this is a real problem.

Thanks!

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[JJSSI]

My car has had a slight thump/thud noise almost since the car was new. I feel over the years it has slowly grown more noticeable.

It occurs when I accelerate without slipping the tires under medium to hard acceleration. Almost immediately as my car begins to move from a stop the thud or double-thump noise will happen without fail. The noise emanates from the rear of the car. I have searched and read that noises like this are somewhat common but I have never found exactly this same case. It seems other people experience noises while shifting into other gears as well which I do not. This only occurs from a dead stop. Is the differential or other drivetrain components moving enough to cause this noise? Could some bushings need replacement? Or is this some slop in the driveline?

This is a stock 2015 GT Performance Package with a manual transmission.

Anyone know what this could be? If this is an issue what could resolve the problem?

I was about to install a good amount of new suspension components. But I have a few months left on a mechanical warranty. Thinking it may be best to wait on the install and take advantage of the warranty one last time if this is a real problem.

Thanks!

My car had the same symptoms. At 6000 miles I installed the Steeda IRS Subframe Bushing support system and the thump stopped. I had also previously installed the Steeda IRS support brace which did not stop the thump. The rubber IRS bushings were ok.

 

[P.R.]

I have the Steeda Subframe Bushing Support System and Support Brace sitting in my garage. Those are a few of the parts I plan to install, and maybe they will solve it too. But as excited as I am to install it all right now I'm gonna wait. I'll take my car in and see if they find anything while it's fully stock. I'll post whatever they may find.

 

[P.R.]

Heard from the dealership today and they diagnosed that:

1. The differential to subframe bushings are torn.
2. The driveshaft center bearing is worn out.
3. The driveshaft coupler is torn.

Apparently Ford doesn't make replacement bushings for the rear subframe so they typically order an entire new subframe. However, my warranty won't cover that portion of the repair since the subframe is not technically part of the driveline and more the frame of the car.

My dealership has convinced the insurance company to allow them to order and install the M-4425-M Ford Performance differential subframe bushing kit since they are the only bushings with a Ford part number for the job (2015-2016 MUSTANG REAR DIFFERENTIAL TO SUBFRAME BUSHING KIT).

I'm concerned that these solid aluminum, steel, and derlin bushings will really increase NVH for my daily driven car. Anyone have experience with replacing these bushings? What product would you recommend?

I take my car to the track a few times a year and am about to install:

• Ford Performance Track Handling Pack
• Steeda Subframe Alignment and Support Kit
• Steeda Rear IRS Subframe Support Braces
• Steeda Front Roll Center & Bumpsteer Correction Kit
• Steeda Camber Plates / Rear Camber Adjustment Kit

I'm ok with a firmer/sportier ride but I've read that stiff diff bushings can really add a lot of unnecessary NVH.

I've seen BMR, Whiteline, and Energy Suspension all make these bushings but am open to suggestions. Thanks!

 

[P.R.]

I did some research and had decided to go with the Whiteline KDT933 bushing kit. But it's was recently discontinued.

Unfortunately, I spoke to the North American office for Whiteline and was told they stopped it due to the bolts failing. They informed me that some version of the kit is being taken over by Steeda. Does anyone know how much NVH the BMR kit or Energy Suspension Kit has? From my research it looked like Whiteline was the softest of the aftermarket bushings.

 

[P.R.]

Looks like the Steeda replacement bushings are most likely related to the Whiteline kit. I downloaded the instructions from both Steeda and Whiteline and they are identical just with the Whiteline logo removed.

So I'm moving forward with the Steeda Kit.

 

[JK XLR8]

Interesting.....I have a 2021 GT Stage 2 Roush A10....from a dead stop it definitely has multiple thumpd/clunks in the rear.....1500 miles, headed to dealer soon, will update!!!

 

[JK XLR8]

Looks like the Steeda replacement bushings are most likely related to the Whiteline kit. I downloaded the instructions from both Steeda and Whiteline and they are identical just with the Whiteline logo removed.

So I'm moving forward with the Steeda Kit.

HEY PR, did that fix your issue, I am headed to the dealer on Feb 1st.

 

[P.R.]

HEY PR, did that fix your issue, I am headed to the dealer on Feb 1st.

Parts took a while to come in and then my tech at the dealership got covid so… hoping to get it back any day now. Will let you know.

 

[JK XLR8]

Parts took a while to come in and then my tech at the dealership got covid so… hoping to get it back any day now. Will let you know.

Hey PR, were they able to figure it out? Thanks! Going in Feb 1st.

 

[P.R.]

Hey PR, were they able to figure it out? Thanks! Going in Feb 1st.

Still waiting. Going on a full month now that it’s been at the shop. Pretty certain they put other vehicles ahead of mine and they’re short staffed. I’ve been promised it will be done this Friday.

 

[blue5.slow]

My car has had a slight thump/thud noise almost since the car was new. I feel over the years it has slowly grown more noticeable.

It occurs when I accelerate without slipping the tires under medium to hard acceleration. Almost immediately as my car begins to move from a stop the thud or double-thump noise will happen without fail. The noise emanates from the rear of the car. I have searched and read that noises like this are somewhat common but I have never found exactly this same case. It seems other people experience noises while shifting into other gears as well which I do not. This only occurs from a dead stop. Is the differential or other drivetrain components moving enough to cause this noise? Could some bushings need replacement? Or is this some slop in the driveline?

This is a stock 2015 GT Performance Package with a manual transmission.

Anyone know what this could be? If this is an issue what could resolve the problem?

I was about to install a good amount of new suspension components. But I have a few months left on a mechanical warranty. Thinking it may be best to wait on the install and take advantage of the warranty one last time if this is a real problem.

Thanks!

The same thing happens with my brother’s 2016 scat pack challenger manual.

 

[P.R.]

Hey PR, were they able to figure it out? Thanks! Going in Feb 1st.

Got it back! I’ve only done about 10 miles so far. All of the noises are gone from the 7 or so times I tried to get the thuds to happen. Did some pulls from a stop at varying degrees acceleration.

They replaced the full driveshaft assembly and the transmission mount isolator with factory parts, and then replaced the diff bushings with the Steeda units.

I’ve been very curious about how much NVH would increase and what kind of sound these diff bushings would create. So far there is a slight whirl/gear whine but it’s super faint and I need to focus pretty hard to notice it. Nothing that would cause me any issue so far. Hopefully cruising at freeway speeds is the same which I’ll find out tomorrow.

 

[JK XLR8]

Got it back! I’ve only done about 10 miles so far. All of the noises are gone from the 7 or so times I tried to get the thuds to happen. Did some pulls from a stop at varying degrees acceleration.

They replaced the full one driveshaft assembly, the transmission mount isolator with factory parts and then replaced the diff bushings with the Steeda units.

I’ve been very curious about how much NVH would increase and what kind of sound these diff bushings would create. So far there is a slight whirl/gear whine but it’s super faint and I need to focus pretty hard to notice it. Nothing that would cause me any issue so far. Hopefully cruising at freeway speeds is the same which I’ll find out tomorrow.

Awesome, I hope they do the same for me!!!

 

[JK XLR8]

Well here we are....made an appointment with the Ford Dealer almost a month and a half ago......went in today to drop it off......"sorry, we are booked out 45 days" they say. So, I made my appointment almost 45 days ago....."sorry, we will call you when we have the time"
Classic run around bs, they should have called me....waste of time.

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