Loose Rear-end Sensation (especially when accelerating)

[JayHij]

So to get right into it, I have a good amount of work done suspension wise, I started off with

• Eibach Sportline lowering springs all around,
• Yellow Koni Sport front struts (middle setting)
• Yellow Koni Sport rear shocks (middle setting)
• front and rear Eibach Sway Bars with BMR endlinks (middle setting)

Then I installed

• Steeda Front Control Arms (Lateral and Tension Links w/ Bushings),
• Steeda S550 Mustang Bumpsteer Kit,
• Steeda Billet Aluminum Vertical Links with Polyurethane Bushings .

Could not put my finger on it, but the car did not drive the same after the second list of items installed. One thing that happened that bugged me, is if you turned the wheel all the way to make a turn, unless your turned it back all on your own, the car would get stuck like that. Anyways so months go buy, and I go off a huge curve, and I could tell the car needed an alignment after that, so took it to a shop in to what I thought was a legit suspension shop for an alignment and took the opportunity to the some part swapped out/installed

• Ford Performance Performance Pack Rear Toe Link Kit,
• Hub Centric 25mm Spacers,
• replaced the controls arms with the Ford Performance Front Control Arm Kit Performance Pack (just felt like the steeda ones were off),
• and camber bolts.

So the car drove straight as an arrow but a few issues arose, one I can hear the left front strut when over a dip at higher speed, the steering felt very tight when turning, and when hitting a bump or dip on the freeway, the car in the rear feels like its going to fall apart, like very wobbly (this was my biggest concern). Don’t feel it in the steering, but rather in my rear in my seat.

Took it back to the shop (the last place I had the other items installed), and they saw nothing wrong but decided to give it another alignment. The issue was still there. Took it to another shop (lost hope in the last one). They told me my tires were bald in the rear, but the fronts were ok (oops), so they suggested I buy two new tires of the same brand (pilot sport 4s), put the new ones up front, the old fronts in the rear, gave it another alignment lol, removed the spacers, and now its the worst than it's ever been.

Now if I accelerate hard, or give it gas, the rear feels like it's going to fall apart. It is a side to side (kind of wobble) sensation. Also, still feeling over bumps and long turns (curves on the highway).

Took to a 3rd shop, and after some inspection, he thinks it's my "carrier" bushings in the rear! I asked to please look at my axel bolts, but he insisted he didn't think it was that ( I was annoyed).

I need help guys! I am desperate! I just want my baby to drive well again! Also, I am located in Socal (please any known good mustang shops would be greatly appreciated.

PS - I have a Ecoboost Premium Convertible with FP Tune.

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[2017GBGTPP]

Did the shop guy mean cradle bushings? That could be the problem. Time for a cradle lockout kit or changing the bushings with the Steeda bushings. A Subframe Brace would probably help too.

 

[Mazman]

Have you re-indexed your bushings after lowering the car?

Sounds like your subframe is needs some lock out as well like BMR CB005 and or CB762/CB10

 

[Blue Moon]

Steeda subframe braces made my back end feel more solid. Quick and easy to install, you can do it in your driveway in half an hour.

 

[boB]

First thing is the problem with the steering not returning on it's own, something is binding. Next problem is adding more aftermarket parts when there is already a problem, further confusing the issue and making it so you are likely to never find the original problem.

This is not what you want to read, but... return everything to stock and start from there (assuming it all works like it should at that point). Do one thing at a time and get it working properly before going on to the next mod. I know this is time-consuming and basically sucks but it is the only way to be certain of what went wrong (if something goes wrong, and I hope it does not this time).

 

[Cobra Jet]

There is a TSB out for the 2018’s regarding the steering not returning to center and the fix is a EPAS software update. I had posted that when the 18s first hit the streets.

Currently, there’s nothing like that for the 2015-17 model years.

It’s possible that either it needs some type of a software update or there is an issue with the actual EPAS unit.

 

[JayHij]

Hey Everyone!!!

Appreciate the feedback thus far!

@2017GBGTPP - Thanks for the tip, out of curiosity, how much should a job like that cost?

@Mazman - I did not re-index them (had no clue)

@Blue Moon Thanks for the tip


Before adding any more ports and doing more work as @boB already pointed out

But focusing on the major concern at hand which is the loose rear-end sensation I am feeling when accelerating. It is pretty bad. I feel like it's a botched alignment issue. The issue really came about, after the last alignment.

I was hoping to get y'alls feedback on what they did, where I should make adjustments, or if anything really stands out that may be contributing/causing the issue:

 

[Bluelightning]

Hey Everyone!!!

Appreciate the feedback thus far!

@2017GBGTPP - Thanks for the tip, out of curiosity, how much should a job like that cost?

@Mazman - I did not re-index them (had no clue)

@Blue Moon Thanks for the tip


Before adding any more ports and doing more work as @boB already pointed out

But focusing on the major concern at hand which is the loose rear-end sensation I am feeling when accelerating. It is pretty bad. I feel like it's a botched alignment issue. The issue really came about, after the last alignment.

I was hoping to get y'alls feedback on what they did, where I should make adjustments, or if anything really stands out that may be contributing/causing the issue:

What's going on with the rear camber? You've got a huge difference between the right and left...

 

[krishelnino]

OP, i have the exact same steering wheel issue on my 2018 GT - not returning to center on full turns and binding. I noticed this issue started happening after installing Steeda control arms and bumpsteer kit. My car was looked at by Steeda and they didn't find anything wrong - suspected it might be a problem with EPAS or front struts. I took my car to dealership to check the EPAS system for software updates, they said it had the latest. They refused to further diagnose blaming the aftermarket parts for causing the issue. Steeda then came back to me saying the 25mm spacers at the front might be causing the issue. I still have to test this theory when i get some time.

And your alignment is very bad, you need to get that corrected first.

 

[Dr. Norts]

Was your alignment guy drunk?

He's got toe in on the front driver side

Toe out on the front passenger side

rear camber is 2x the amount of the driver side

rear toe is positive on the passenger side and the driver side rear is barely negative.

Also his alignment rack could need to be calibrated, but if he's sending out alignments like that I'd say alignment calibration isn't high on his list of priorities.

If the rack is out of Cal your car could be setup even worse than the numbers on your sheet are showing.

 

[Rjames18]

and this is why you stick to the stock suspension instead of replacing shit..

 

[2017GBGTPP]

Hey Everyone!!!

Appreciate the feedback thus far!

@2017GBGTPP - Thanks for the tip, out of curiosity, how much should a job like that cost?

The Steeda Stop the Hop starter kit should lock down that subframe nicely, it's about $350. If it is your cradle bushings going bad, you can just get the Steeda ones alone for $50.
https://www.steeda.com/Steeda-S550-Mustang-Stop-The-Hop-Starter-Kit-555-4455

But before doing that, definitely get that alignment fixed. I don't know much about how to read an alignment sheet, but even I can tell that's jacked up.

 

[Ecoboosted]

When I had my 15 GT non PP. I hated the floaty feeling that car had. I installed the Ford Track Pack Suspension. When I gave it hard throttle the back end felt very loose from side to side. Could never figure out what it was until my right rear hub bearings needed to be replaced. Brought it to the dealer who replaced the hub with a new one. The car was fine after that. I don’t think i torqued that hub properly. Hindsight is 20/20 lol

 

[Dr. Norts]

and this is why you stick to the stock suspension instead of replacing shit..

Ummm no. This is why you go to an alignment shop with actual numbers in hand (BMR's) and make sure they know wtf they are doing.

First ask if they know how to adjust the rear camber. If they say yes quiz them how just for your own sanity, you'd be surprised how many shops don't know how to do it but will tell you they do. Also ask when their machine was last calibrated, if they don't know walk away lol.

The camber is the hardest adjustment to get at during the alignment but no where near impossible. They'll have to get just a bit creative with extensions / swivel. If they know where this is and can/will adjust it they shouldn't have any issue adjusting front or rear toe.

All bushings clocked + full alignment should take no longer than 1.5 hours providing the guy / girl knows what their doing.

 

[boB]

The PP2 turned 2:53.8 at VIR, beating everything that cost up to $125,000, without any aftermarket suspension parts.

Car and Driver had this to say: It turns in instantly, steers with perfect clarity, and changes direction with the kind of neutral balance you wouldn’t expect from a front-engined car.

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