Rear Control Arms

Scotth13

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Jul 13, 2016
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I have an 07 GT that I have lowered 1" in the front and 1.2" in the rear. I am wanting to upgrade the rear control arms and I can't decide which way to go. I do not drag race the car or anything like that. It is just a weekend driver. I have researched a lot of different options and really don't want to make the ride anymore harsh than it currently is. Most all the adjustable arms have the poly bushings that firm up the handling but the trade off is a harsher ride. I have found two choices I am trying to decide between. One is the Ford Racing arms and the other one is the Roush arms. Neither is adjustable and there in lies my question. Is it necessary to use adjustable arms on a lowered car. What are the trade offs of not using adjustable arms. The last question is how much of a difference does it really make in the ride quality if I use arms with the poly bushings. Thanks in advance for any help.
 
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Svtpilot

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No with only an 1.2 inch drop and from how you use the car you do not need adjustable arms. You should get an adjustable panhard rod. Lowering the car causes the differential to shift in relation to the body so it is no longer centered under the car and adjustable panhard rod will allow you to recenter it. It is not an absolute must, it is a recommendation. The other part that you probably do need are lower control arm relocation brackets. Lowering the car cause the differential to sit higher in relationship to the body which affects suspension geometry. Take a look at you rear control arms with the car on the ground, What you want to see is either the arms angled downward slightly from the body to the rear,(body end higher then diff end) or parallel to the ground.If that's the case then you are good, What you don't want is the the arms angled downward from the rear to the body (diff end higher then body end.) If they do then get relocation brackets. I used J&M Extreme arms on my '10 GT with spherical bushings and currently use BMR arms on my '12 with poly bushings. i didn't notice any difference in ride quality between the two or from stock. Both worked as advertised and completely eliminated axle hop. Just about any of the aftermarket arms out there will be a significant improvement over the factory arms. Most aftermarket arms have grease fittings and require lubrication at install, after 500 miles or so, and then regular lubes going forward. So if you are installing them yourself or do your own maintenance I would get an inexpensive grease gun.
One last thing I would avoid the Ford Racing arms. If they are the ones I am thinking of they are GT500 arms which are just stock Mustang arms with stiffer bushings. Many GT500 owners I know end up replacing them.
I know this is a long post but I hope it answers your questions.
 

Scotth13

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Jul 13, 2016
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Thanks for the reply. I think my plan is to get the Roush upper and lower rear control arms. I would like for the car to handle a bit better but not ride any harsher. I did purchase a RTR adjustable pan hard bar when I changed the springs and shocks. It was definitely needed. Along with the lowered stance I changed the wheels to a 20x8.5 size. So the ride is much harsher now than stock.
 

Red_LX

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You may or may not need relocation brackets for the lowers. I can't remember what the threshold is, I have them on mine. With 1" drop you might not need them but they help keep the bars closer to parallel (which is where you want them to be).

And yes, for being that I have poly bushings all around in back, and an upper mount, I really don't notice any additional noise or harshness in the ride.
 

Scotth13

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I believe I am going to need the relocation brackets. I looked tonight and the body connection end of the arm is slightly lower than the axle end. As I was looking at where the brackets would mount I noticed two pieces of metal fairly large that are mounted on each side of the axle. They are sitting just under the axle attached to the side of lower control arm location. Can anyone tell me what they are for.
 

Scotth13

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Hey guys I have two questions. Does anyone use Whiteline suspension products and how good do they perform. I'm mainly concerned with the rear upper and lower control arms. The next question is, does anyone know why my avatar my be upside down.
 

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It's all in the bushing design. If the upper and lower arms you select have hard 1 or 2 piece bushings you will increase bushing bind and therefore harshness. Here are the results of some testing we did with our 3 piece Poly-Ball bushing design versus the standard two piece bushings.

The Testing:

Lower Control Arm Mustang Rear 2005 2014. We built a fixture which simulated a factory control arm mounting and tested how much force was needed to make the control arm articulate (twist) in those mounts and the results where astounding.


Poly-Ball Bushings:
5 degrees of total rotation = 26.1 foot/pounds of torque
7.5 degrees of total rotation = 35.8 foot/pounds of torque

10 degrees of total rotation = 41.7 foot/pounds of torque

Standard 2 piece setup using only 85 durometer bushings:
5 degrees of total rotation = 124.7 foot/pounds of torque

7.5 degrees of total rotation = 156.4 foot/pounds of torque

10 degrees of total rotation = not measurable with fixture. The 1/2″ grade 8 bolt twisted in half at 9.2 degrees which was 210 foot/pounds of torque.
 
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Svtpilot

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I believe I am going to need the relocation brackets. I looked tonight and the body connection end of the arm is slightly lower than the axle end. As I was looking at where the brackets would mount I noticed two pieces of metal fairly large that are mounted on each side of the axle. They are sitting just under the axle attached to the side of lower control arm location. Can anyone tell me what they are for.
If the body end of the lower control arm is lower then then the differential end then you definitely need the relocation brackets to restore the correct suspension geometry.I believe the pieces of metal you are talking about are weights. The only Whiteline part I have used is the transmission mount insert and it does exactly what it is supposed to do. Quality and fit seemed fine (but it is a simple part,)I do know that many people swear by their stuff , and I don't recall ever hearing anything negative about them here, on a Boss302 forum I belong to or or any of the various Mustang and Boss pages I follow on FB.
Assuming that when you switched to 20inch wheels you also went with a lower profile tire, that is likely the main reason for your harsher ride. The shorter sidewalls of low profile tires are stiffer then taller sidewalls and rider harder.
 
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