Suspension Help!!

Mtorres1992

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Mar 3, 2015
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I recently put new rims and tires on my mustang 19x9 in the front 19x10 in the rear. And I've been having this problem during acceleration the rear axle seems to be kicking out and turning the entire body and giving he wheel 2-3 inches of play to the right and when I let off the gas the car shakes back into place. I have new upper and lower control arms for the rear and have replaced the Panhard bar but the problem is still there. 2 shops told me nothing is worn out on the rear everything is nice and tight. The only thing I know that is starting to wear is my ball joints could that cause the rear end to go out while accelerating?
 
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Is your car lowered and if so does it have an adjustable panhard bar or stock?

Kinda sounds to me like the axle is moving out of alignment during acceleration...not sure. Ball joints would not affect what the rear does.

You said you "have" control arms, does that mean they are installed or just that you got some? Also what kind are they?
 
Is your car lowered and if so does it have an adjustable panhard bar or stock?

Kinda sounds to me like the axle is moving out of alignment during acceleration...not sure. Ball joints would not affect what the rear does.

You said you "have" control arms, does that mean they are installed or just that you got some? Also what kind are they?
Yes I have a adjustable pan hard bar the upper and lower control arms are all stallion suspension and everything was installed on the car before the new rims the Panhard bar was added after the tires. You can see on the sway bar where the grommets are rubbing the bar on the right side of them.
 
Are they adjustable arms or solid?

I'm really not sure what would be causing that. But, it sounds like you probably need to check to make sure your panhard is adjusted correctly that your axle is centered.
Solid and the rear axle is centered no one can figure it out I'm taking it to another shop Monday to have the Panhard bar support brace, rear upper control arm mount, and front lower control arms changed out to see if that changes anything hopefully it fixes whatever the problem is.
 
If so that may explain the rear squat and direction change under aggressive acceleration. It's helpful to list mileage, tire, control arms, and all suspension mods accessories brand names.

I had similar issue once before and I installed lower control arm relocation brackets. My Mustang pushed to the driver's side a little but enough I wanted to figure out how to make it launch straight.

Control arm brackets change the angle and limit axle wrap, rear alignment flex applying more pressure to one tire more than the other. You need your lower control arms to angle lower at the axle compared to chassis control arm mount.

Also sport progressive rate springs improve straight launch, "wheel hop", and ride comfort over OEM.

It wasn't until I completely modded out my suspension before I notice consistent positive results. A little here and there only points to another weak link in the OEM suspension. Several aftermarket companies offers progressive rate springs to improve handling, acceleration, and braking with the same OEM spring length allowing the same factory ride height if desired.
 
If so that may explain the rear squat and direction change under aggressive acceleration. It's helpful to list mileage, tire, control arms, and all suspension mods accessories brand names.

I had similar issue once before and I installed lower control arm relocation brackets. My Mustang pushed to the driver's side a little but enough I wanted to figure out how to make it launch straight.

Control arm brackets change the angle and limit axle wrap, rear alignment flex applying more pressure to one tire more than the other. You need your lower control arms to angle lower at the axle compared to chassis control arm mount.

Also sport progressive rate springs improve straight launch, "wheel hop", and ride comfort over OEM.

It wasn't until I completely modded out my suspension before I notice consistent positive results. A little here and there only points to another weak link in the OEM suspension. Several aftermarket companies offers progressive rate springs to improve handling, acceleration, and braking with the same OEM spring length allowing the same factory ride height if desired.

Thank you. Yes it's factory stock springs. I want to buy new ones but keep OEM ride height but trying to reslove this issue first. if all the parts I have now (Shelby pan hard support brace drake upper control arm mount and FRP gt500 front control arms) doesn't help I'll get the relocation brackets I don't really mess with adjustable stuff so in worried about theowing angles off and making this worse.
 
image.jpg

This is the upper control arm mount. I've never messed with anything adjustable. Which hole would I use?
 
Thank you. Yes it's factory stock springs. I want to buy new ones but keep OEM ride height but trying to reslove this issue first. if all the parts I have now (Shelby pan hard support brace drake upper control arm mount and FRP gt500 front control arms) doesn't help I'll get the relocation brackets I don't really mess with adjustable stuff so in worried about theowing angles off and making this worse.

What name brand of lower control arms and sway bars?
 
Ford engineers designed the Mustang rear axle to articulate thus the 2-piece driveshaft, A-arms rubber spring loaded bushings, Panhard and Rear upper / lower control arms with soft rubber bushings as a result it’s more difficult to drift slide loosing control of the vehicle. But as a negative the rear axle will articulate during hard launches.

OEM sway bars, shocks, and struts are designed to accommodate soft OEM springs. You’ll need to address the shocks/struts, front and rear sway bars to benefit the firmer springs foundation for improved launches. The issue you’re experiencing is OEM limited slip differential engaging one axle before the other. As a result OEM Panhard bar and control arms rubber bushings are flexing allowing the rear axle to articulate off center by design and the soft OEM springs, shocks, struts, and sway bars will not apply enough pressure to stabilize the 2nd engaged tire bite from wheel hopping which increases axle energy in the wrong direction. Once power is discontinued the rear axle whips back into position producing the 2nd experienced affects.

Now the reason I mention lower control arm bracket was because I assumed you lowered your Stang just like the rest of us. If you drop the rear more than ¾” you’ll need relocation control arm brackets to maintain rear axle control. Keep that in mind…!

It’s really difficult to maintain control of your Stang with a little here and there. You’ll have to get deeper into your suspension for the best results and naturally deeper into pocket.

Suspensions components in kit form offer the biggest bang for the buck in the long run. Eibach Pro-Kit is probably the most affordable suspension kit with the least drop of 1.0” front and 1.5” rear. Other has 1.0” front and back but tend to cost more.

As a bonus performance suspension kits not only improves launches and aggressive handling response but also provides an overall better quality ride in general. For I it was money well spent that I enjoy daily and we can’t say that about many things in life…lol.

Roush is the only manufactured I know of today with improved handling springs close to factory height with only ½” drop compared to OEM. Roush Performance Suspension kits have a high standard of quality and a little pricy.

Mustang Coil Springs, Rear (2005-2014)
 
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Ford engineers designed the Mustang rear axle to articulate thus the 2-piece driveshaft, A-arms rubber spring loaded bushings, Panhard and Rear upper / lower control arms with soft rubber bushings as a result it’s more difficult to drift slide loosing control of the vehicle. But as a negative the rear axle will articulate during hard launches.

OEM sway bars, shocks, and struts are designed to accommodate soft OEM springs. You’ll need to address the shocks/struts, front and rear sway bars to benefit the firmer springs foundation for improved launches. The issue you’re experiencing is OEM limited slip differential engaging one axle before the other. As a result OEM Panhard bar and control arms rubber bushings are flexing allowing the rear axle to articulate off center by design and the soft OEM springs, shocks, struts, and sway bars will not apply enough pressure to stabilize the 2nd engaged tire bite from wheel hopping which increases axle energy in the wrong direction. Once power is discontinued the rear axle whips back into position producing the 2nd experienced affects.

Now the reason I mention lower control arm bracket was because I assumed you lowered your Stang just like the rest of us. If you drop the rear more than ¾” you’ll need relocation control arm brackets to maintain rear axle control. Keep that in mind…!

It’s really difficult to maintain control of your Stang with a little here and there. You’ll have to get deeper into your suspension for the best results and naturally deeper into pocket.

Suspensions components in kit form offer the biggest bang for the buck in the long run. Eibach Pro-Kit is probably the most affordable suspension kit with the least drop of 1.0” front and 1.5” rear. Other has 1.0” front and back but tend to cost more.

As a bonus performance suspension kits not only improves launches and aggressive handling response but also provides an overall better quality ride in general. For I it was money well spent that I enjoy daily and we can’t say that about many things in life…lol.

Roush is the only manufactured I know of today with improved handling springs close to factory height with only ½” drop compared to OEM. Roush Performance Suspension kits have a high standard of quality and a little pricy.

Mustang Coil Springs, Rear (2005-2014)
Thank you for the info I just saw it today. on the rear I have stallion upper and lower control arms with lower relocation brackets and upper mount, stallion Panhard bar, Shelby Panhard bar brace and I still have the issue. The springs shocks struts and sway bar are factory. One tech did mention one tire (the right) may be engaging first and causing the axle to warp. On the sway bar the bushing have rubbed the bar clean to the right of it. I'll look at shocks/struts, springs and sway bars tonight. Hopefully I can find some for a good price this rear end issue has drained me :(
 
UPDATE: I put on the eibach pro system shocks struts springs bars and all. Same problem. Took it to a 7th shop 8 technicians worked on it said MAYBE it's something in the drive train. My car has had a limited slip differential installed and 3.73 gears by the previous owner. What are the chances of something in the drive train causing that? They can't check out the drive train till Monday and my grand total on my repair is 2678.53 so far with no luck fixing this problem :(
 
Does the speed at which you accelerate change this at all? AKA if you accelerate at 60 vs from a stop...

Maybe post a video so we can see exactly what's happening. I'm skeptical that anything in the drivetrain is causing this, at least at this point in time. I'm suspecting either worn or incorrectly installed suspension components, bad alignment, or tires out of balance even
 
Does the speed at which you accelerate change this at all? AKA if you accelerate at 60 vs from a stop...

Maybe post a video so we can see exactly what's happening. I'm skeptical that anything in the drivetrain is causing this, at least at this point in time. I'm suspecting either worn or incorrectly installed suspension components, bad alignment, or tires out of balance even
Any time I accelerate the right wheel kicks forward and up twisting the whole body and when I let off the gas it shakes back into position. Tires balance fine, alignment is fine, everything's nice and tight and put on the correct way now they are saying it might be that the rear differental is sending more power to the right wheel then the left causing the axle to warp and twist the body till I let off the gas because the left will can't make enough torque to even it out.