Making the Mustang daily driverable after modifying

[Hawaii50]

Hello all, I need some advice on what is likely making my Mustang undrivable on the roads. The car is excessively painful to drive. Driving any road works, bumps, potholes, expansion joints is brutal . In my opinion my car does not have any hardcore track upgrades.

I recently moved to Oahu and the roads are horrific. I'm at the point where I don't want to drive the Mustang anymore.

It's a 2013 GT Track pack. Originally I was not happy with the ride height of the stock suspension and the excessive brake dive of the front end. The plan was not to turn it in to a track car but a fast street car.

I recently drove a 5th gen Camaro ZL1 on bad roads and it was a night and day improvement.

Rather than installing one part at a time and seeing how the car responded, most of the parts were installed at one time when I had returned from a deployment.

The parts include:

20x9 255/35/20, 20x10 305/35/20

Bilstein B6hd struts and shocks
Eibach pro springs
Steeda HD strut mounts
BMR adjustable front endlinks
Boss 302 strut brace
Steeda adjustable front sway bar with poly bushings
Steeda rear sway, endlinks and poly bushings
Whiteline adjustable panhard bar
Whiteline panhard support bar
Steeda Adjustable UCA and poly bushings
Steeda UCA mount
Steeda X brace


I removed the following parts as the rear end nvh at 70mph in 6th was bad:
Whiteline LCA adjustable poly bushings
Whiteline LCA relocation brackets (installed a new pair of track pack LCA)
PolyU diff mount bushing

The reality of it is the car is not likely to see a track for a while, maybe autocross. My main thing is to make the ride not as back breaking like it is now. When I got the car 5 years ago it was nowhere near as bad as it is now.

Which parts are likely causing this?

Should I go for OEM Ford parts from a boss 302 or Laguna seca and completely avoid aftermarket performance parts. The goal is to keep the the improved performance it has now as now as much as possible making the ride comfortable for daily driving.

 

[Coz]

I would first look at your 20" wheels & tires. The lower profile of the 20" results in less rubber available to absorb the harshness.

The brand or model of tires may also contribute to harshness.

 

[Hawaii50]

The front are nitto nt555 and rear bfg comp force 2 a/s. Only reason why the difference in tires was I tried to fit bfg's in the front with 40 profile, however they do not clear with a 20" wheel.

The plan is once the rubber wears out to go back down to 19s, with 19x10/19x11.

 

[Coz]

By the way, the relocation brackets themselves should not have resulted in any additional NVH.

Depending on the model, you may not be able to use the top most mounting hole with stock LCAs.

But, if you need them to correct LCA geometry issues due to lowering your car, without them your LCAs may actually be hitting your body when your spring are compressed on big bumps.

Also, did you install the Ford Performance Jounce Bumpers or cut down your stock ones?

 

[byronj]

I’d start with getting rid of the 20” rims and low profile tires. Even running two different brands of tires could result in some bad characteristics.

 

[stevbd]

Double check this but I am pretty certain the Bilstein B6 HD are designed for use with stock height springs. With a substantial drop like you get with the Eibach prokit you want the Bilstein sports. The damping is similar between the HD and sport but the shock length is less on the sports so the damper stays in its proper range of travel and doesn't bottom out. I think you're bottoming out your shocks on big impacts.

Also agree with higher profile tires and replacing or cutting down the rear jounce stops. The jounce stops are super cheap and easy and actually make a difference.

 

[Hawaii50]

The whiteline relocation brackets only had one fixed hole for the LCA unlike Steeda that has multiple holes.

The springs and shocks come together as the Bilstein B12 kit. I didn't mix and match them together.

I installed the jounce bumpers that come with the B12 kit.

The eibach sportline springs have the bigger drop, the pro kit springs are not as agressive.

Front drop is 1.0 and rear is 1.2.

The B12 kit was the first to go on with the wheels prior to my deployment and from memory, the car wasn't that stiff. It also had the same 20" wheels expect the rear tire profile was even less at 30.

 

[Grant 302]

I recently moved to Oahu and the roads are horrific.

Depends where you are. There are *lots* of places I wouldn't go with a lowered car. I'm surprised at how bad it sounds from with your listed mods. 19s and/or a softer sidewall tire like Michelin might help.

 

[Hawaii50]

Depends where you are. There are *lots* of places I wouldn't go with a lowered car. I'm surprised at how bad it sounds from with your listed mods. 19s and/or a softer sidewall tire like Michelin might help.

Next time I see an Apex sale on here I'm in for 19"s. Before I sold my 19" track pack wheels I tested them. The ride was a little bit better but not by a significant amount.

 

[VoodooBoss]

Welcome to TMO and I like your ID! Like Grant stated a softer sidewall tire would help even on the 20" wheels. 35 series tires are pretty standard these days. Also a 305 on a 10" wheel is not the best setup. Dropping back down to a 285R might also help a bit with a smaller contact patch to catch every little imperfection on the road. You might also look at the UCA. The live axle on your S197 doesn't have a lot of travel so by dropping your car so low there's not much back there to absorb the bumps. Raise the car up.

 

[Hawaii50]

Hello, I've been lurking on here for sometime, it was about time I sign up.

I'm going to sell the 20's also due to wanting lighter wheels. What tires do you recommend?

What should I do regarding the UCA?
The polyurethane bushing in the diff housing was removed and replaced with a new OEM bushing. The only UCA I am aware of that has a rubber bushing is the roush third link.

 

[VoodooBoss]

If you're using the stock bushing in the UCA you should be fine.

Where were you stationed before Hawaii?

 

[Hawaii50]

If you're using the stock bushing in the UCA you should be fine.

Where were you stationed before Hawaii?

The bushing in the Steeda adjustable UCA is the polyurethane that came with it. I was at Ft Campbell, KY.

 

[Coz]

The whiteline relocation brackets only had one fixed hole for the LCA unlike Steeda that has multiple holes.

I have the Track Pack LCAs and they fit on my CHE relocation brackets which have one setting.

https://www.cheperformance.com/products/che1l

 

[Hawaii50]

I have the Track Pack LCAs and they fit on my CHE relocation brackets which have one setting.

https://www.cheperformance.com/products/che1l

Do you really think they are needed with a mild drop? You don't feel the brackets would add any added stiffness to the ride?

 

[Grant 302]

The live axle on your S197 doesn't have a lot of travel so by dropping your car so low there's not much back there to absorb the bumps. Raise the car up.

Looking at the Pro-kit rates and drop, I think Rick is right. It might 'only' be about a 1.5" drop, but losing that much travel with that soft a spring (softer than Boss or LS stock) is very likely to bottom out on any road. I suggest trying P springs or something similar in the back.

Do you really think they are needed with a mild drop? You don't feel the brackets would add any added stiffness to the ride?

I think some sort of bracket is 'needed' even for just a 1" drop. And that's for both handling and drag applications. As-is your lower arms are probably pretty steeply angled down to the front. I'm going to guess about 2" to 2 1/4" lower in front comparing the height of the bolt centers. Closer to level should also improve ride quality a bit.

 

[Coz]

Do you really think they are needed with a mild drop?

As Grant302 mentioned, the LCA should at least be level if not slightly upward towards the front. Have you checked your underbody over the LCA just forward of the axle? If your LCAs are pointing down towards the front, the vertically thicker stock LCA (as compared to the tubular LCAs) may be hitting the body on bad bumps. You'll see some paint scuffing. The relocation bracket will cure that.

You don't feel the brackets would add any added stiffness to the ride?

Not at all. They do not get rid of any rubber bushings. They simply extend the mounting location.

You mentioned that you got rid of the LCAs and the upper diff poly bushing because of "rear end" NVH @ 70mph. Can you be more specific? I'm guessing this was due to gear whine. Did it cure the gear whine? And did the harshness from bumps only occur after you removed those items? If so, then I would be 99% sure it was your removal of the relocation brackets. If the Whiteline ones won't fit the stock LCAs, the CHE ones will and so will the lower holes of multiple hole versions such as BMR or MM. If I recall the Steeda brackets need to be welded in.

Attached is an article on LCA's that I have found useful.

 

[Hawaii50]

I will check the position of the LCA. Yes the car at 70-80mph in 6th while on Accel would whine from the rear end. The sound is still there but not as bad as it was. Regarding the che brackets, the pictures show the anti vibration axle weights removed, can they remain in place?

 

[Coz]

It's good that the whine subsided but is this also when the harshness from bumps started too?

With respect to the weights, I didn't even think twice about removing them so I'm not sure if you can retain them. They certainly didn't make any difference in NVH when I removed them.

 

[Hawaii50]

It's good that the whine subsided but is this also when the harshness from bumps started too?

With respect to the weights, I didn't even think twice about removing them so I'm not sure if you can retain them. They certainly didn't make any difference in NVH when I removed them.

The harshness got bad when I installed the swaybars, UCA and lca.