Wobbling Issue

[GrayS550]

For about 3-4 months now I’ve been experiencing a wobbling issue when I drive fast. Driving normal speeds is fine (60-70mph) but once I get on it, the car starts wobbling and it feels unsafe. It stops when I release the throttle. It feels like the suspension gets floaty and the car shakes its hips back and forth. I’m not losing any traction when this happens. I’ve checked out the suspension already twice and was told everything checks out. A les Schwab employee told me it could be because my tires are a hard compound tire.

My tires are Delinte Thunder D7 275/35R19 (boxed setup) My thread is still super good.

Any insight on this issue? Les Schwab recommended me VREDESTEIN Hypertrac All Seasons. 275/35R19 96Y. They’re a softer compound tire.

Sponsored

 

[KingKona]

Well, you bought $150 tires.....so there's a possibility it is the tires. But the all-season tires Les Schwab (???) is recommending are NOT a softer compound than the tires you've got.

It's also possible that it's just the IRS needing the normal help, or it could be wheel bearings. Or even lose wheel nutz.

 

[K4fxd]

Get the rear subframe stabilized. Steedas stop the hop starter kit should fix you up.

 

[glockholiday]

I've heard of a new set of shocks clearing up that problem. My 17' did the same thing like 100+ and a new set of tires didn't fix it. I sold the car and the new owner replaced the rear shocks and said it never did it again.

 

[K4fxd]

The IRS bushings are so soft in the GT that mine felt like the rear was held on by rubberbands.

IRS braces, and IRS bushing support system will take 90% of the unhooked feeling away. Vertical links round it out.
Braces
https://www.steeda.com/steeda-s550-mustang-rear-irs-subframe-brace-2015-coupe-555-5754.html
Bushing supports
https://www.steeda.com/steeda-s550-mustang-irs-sub-frame-bushing-support-system-2015-555-4437.html

Vertical links

https://www.steeda.com/steeda-555-4129-s550-vertical-links-poly-bushings

or bite the bullet and get the stop the hop kit wich also has other items to make the IRS a solid unit. No NVH is added

 

[Hack]

For about 3-4 months now I’ve been experiencing a wobbling issue when I drive fast. Driving normal speeds is fine (60-70mph) but once I get on it, the car starts wobbling and it feels unsafe. It stops when I release the throttle. It feels like the suspension gets floaty and the car shakes its hips back and forth. I’m not losing any traction when this happens. I’ve checked out the suspension already twice and was told everything checks out. A les Schwab employee told me it could be because my tires are a hard compound tire.

My tires are Delinte Thunder D7 275/35R19 (boxed setup) My thread is still super good.

Any insight on this issue? Les Schwab recommended me VREDESTEIN Hypertrac All Seasons. 275/35R19 96Y. They’re a softer compound tire.

So, prior to 3-4 months ago I'm assuming you didn't have this problem?

Did you change anything 3 - 4 months ago?

One thing I'm not clear on is whether the problem only occurs at Mexico type speeds, or if it occurs when you step on it no matter what the speed.

Without any of my questions answered yet I'm leaning towards cheap all-season tires being the problem. I would get at a minimum something like Michelin 4S all season. However, my opinion is you would be much better off with a summer only tire for performance driving and then plan to take it a little easier when you have the all-seasons on during the winter months.

Edit: the stock suspension is also overly soft, which can make Mustangs difficult to control in a performance situation. But if you are just stepping on the gas in a straight line, you probably are ok with the stock setup.

 

[Shifting_Gears]

I’d go on a limb and say your tires are playing a factor. Those are really budget tires and not going to perform well on a Mustang.

 

[GrayS550]

So, prior to 3-4 months ago I'm assuming you didn't have this problem?

Did you change anything 3 - 4 months ago?

One thing I'm not clear on is whether the problem only occurs at Mexico type speeds, or if it occurs when you step on it no matter what the speed.

Without any of my questions answered yet I'm leaning towards cheap all-season tires being the problem. I would get at a minimum something like Michelin 4S all season. However, my opinion is you would be much better off with a summer only tire for performance driving and then plan to take it a little easier when you have the all-seasons on during the winter months.

Edit: the stock suspension is also overly soft, which can make Mustangs difficult to control in a performance situation. But if you are just stepping on the gas in a straight line, you probably are ok with the stock setup.

It randomly started happening this past Summer 2022. I was on the highway on a bend and the car started wobbling back and forth. Happens at Mexico speeds and regular speeds on bends. It also happens when I step on it and go over 80mph. I didn’t change anything with the car. It’s cold right now in WA so I’m not sure if summer tires are the best right now.

 

[Schwerin]

Do you have any suspension mods?

 

[Hack]

It randomly started happening this past Summer 2022. I was on the highway on a bend and the car started wobbling back and forth. Happens at Mexico speeds and regular speeds on bends. It also happens when I step on it and go over 80mph. I didn’t change anything with the car. It’s cold right now in WA so I’m not sure if summer tires are the best right now.

You say you had the suspension checked out, but I think they are missing something.

The stock suspension is very floaty, but you are saying something changed. I had something like this in my GT350 when one of the drive axle nuts got loose. I took it into the dealer and their tech couldn't figure it out. I jacked it up and wiggled the rear tire and it moved around. It probably took me 1/2 hour to 45 minutes to figure out what part was loose.

Your symptoms really point at something loose or worn out in your suspension. Just because a tech didn't find it doesn't mean there isn't a problem. I say try another shop or get under the car yourself and start checking around. Watch a couple Youtube videos on how to check suspension parts. It's not difficult.

 

[GrayS550]

Do you have any suspension mods?

Stock suspension

 

[Cobra Jet]

Has anyone checked the lug nuts or the rear axle nut torque specs?

I'd also recommend checking the wheel hubs too - the wheel hubs are a common failure area on these S550's, low miles or high... you can do this yourself at home, Jack the car up, grasp the wheel at the 12/6 position give it a few hard push/pull movements and do the same at the 3/9 position. If you feel any "wobble" or looseness, you need new wheel hub bearings.

What's your tire air pressure too? You need to take the tire psi at stone cold, before driving as tire psi can cause some weird drivability issues too.

 

[GrayS550]

Has anyone checked the lug nuts or the rear axle nut torque specs?

I'd also recommend checking the wheel hubs too - the wheel hubs are a common failure area on these S550's, low miles or high... you can do this yourself at home, Jack the car up, grasp the wheel at the 12/6 position give it a few hard push/pull movements and do the same at the 3/9 position. If you feel any "wobble" or looseness, you need new wheel hub bearings.

What's your tire air pressure too? You need to take the tire psi at stone cold, before driving as tire psi can cause some weird drivability issues too.

I’ll be doing a run through of my suspension soon. I’ll check everything that’s been posted. All 4 tires are at 29psi.

 

[NightmareMoon]

My bet is also a bad wheel hub. The only time my car has wobbled at speed (not when launching and spinning tires), it was the hub. They're wear items and don't last forever.

If you have a jack, jack up the rear and get a bear hug on the wheel and see if it moves side to side at all. That would confirm a bad wheel hub.

Do you have any unusual noises? Perhaps a "ping" when starting and stopping at low speeds?

 

[GrayS550]

My bet is also a bad wheel hub. The only time my car has wobbled at speed (not when launching and spinning tires), it was the hub. They're wear items and don't last forever.

If you have a jack, jack up the rear and get a bear hug on the wheel and see if it moves side to side at all. That would confirm a bad wheel hub.

Do you have any unusual noises? Perhaps a "ping" when starting and stopping at low speeds?

I’ll be checking out the wheel bearings soon! I have no noise at all. No ping, no clunking noise.

Sponsored