The Official Suspension Guide

Got this from MM. Re-post, I (The CheeksMcDuke) didn't write this myself
Original thread can be viewed here

Thought I would write this up so I can stop explaining it every time I come across one of these suspension questions.

The Mustang suspension was poorly designed for High Performance Driving. It was originally designed to be good but not great. The 4 Link design that was incorporated in to the rear of GT’s between 96 and 2004 is poorly created concept. It uses 2 lower control arms and 2 oddly angled upper control arms to position the axle side to side, prevent axle wind up and transfer force from the wheels to the chassis.

The front suspension is no better. With a flimsy sheet metal K-member that weighs double what tubular parts do while offering half the rigidity and prevents easy access to just about everything. The Strut design also leaves something to be desired with caster camber needing to be carefully monitored and tweaked to optimize handling. The Modified Macpherson strut is the design of putting the spring about half of the distance from the pivot point on the K member to the ball joint at the spindles. And the Strut being placed on the spindle it self. This leads to a slow and clumsy wheel rate ( the speed the wheel reacts to changes in the road) and a poor ride. You can’t get good handling without punishing your low back.

The body is also flimsy and allows for huge chassis twist and rebound. But HOLD ON! It sounds like you are screwed but your not. In fact you are in a pretty good place. The mustang once fixed, all possible for a couple of grand, will out handle just about any car around. Including ferrari’s ( check the video at )

The solutions are as follows.

Chassis Rigidity: The first thing you need to fix for your safety and for any kind of racing is the Chassis rigidity. Poor chassis rigidity leads to poor weight transfer, sloppy handling and poor ride. Not to mention the inability to take advantage of any mods that affect the movement of your car… think about it, that’s everything.

Solution: Subframe connectors and/or a roll cage. A good set of subframe connectors will connect the front and rear suspension with a strong steel subframe, kind of like every other good car in the world. You can also do a cage, which will work better, but not required for your average joe. I recommend any good companies kit. Maximum Motorports, Griggs, even steeda makes a decent set. They weld to the frame underneath your car and cost less than $200. Not only does it make your car safer, it will make your car doors keep from getting out of alignment after a couple years of hard driving. It happens

The Macpherson strut. The true macpherson strut is what you would normally see on a car. The shock is inside the spring. This links the recoil and spring rate together. It also means that you can place a smaller spring a lot closer to the wheel, giving you a better wheel rate and a smoother ride, while reducing weight. A coilover, is simply a macpherson that allows you to adjust the height of the spring, allowing you to adjust the ride height of your car to the application. In the case of our cars, converting to coil overs actually means you get a better designed suspension component and adjustability. A Double Wammy! Coil overs are recommended for the front of your car and require no more modification than the parts them selves. Unless you plan to go hard core, I don’t recommend the rear coil overs, as the ride quality will suffer due to the MUCH higher spring rates. The front ones will improve ride quality to a point, depending on the stiffness of your springs.

Springs. Should you decide that coil-overs are too much of a step for you, you can purchase a good set of springs for your car. Stiffer springs improve handling. Of course there are limits, but lets assume they don’t matter. For a drag car there are many spring combinations available. Generally soft springs in front and semi soft in rear are the desirable set up. But there are better sources for exactly what spring rate you should get for drag. A good source for those rates is available at They have a table on their web site of just about every spring out there. They are also very knowledgeable if you have any questions. Just remember with stiffer springs, comes a harsher ride. I recommend H&R, Steeda, FRPP, Eibach springs. I had the H&R Race springs. They were very stiff, and I loved them, but it was not for everyone.

Shocks: They are an important part of buying your coil overs. High quality coil-overs will be customized to your shocks. There are many choices for shocks and many are specific to certain applications. Regardless, do NOT buy suspension components from an exhaust company. The shocks you get also has just as much to do with your ride quality as the springs. Your shocks are what keep the spring from bouncing after absorbing a shock. This means that you can over or under dampen your springs very easily. If you buy some amazing springs and keep your stock struts/shocks. You will hate life. The springs will overpower your shocks and you will spend all day bouncing down the road. Good companies for Shocks/Struts are harder to find. They cost more money. I will break it down for you in a few different ways. I don’t recommend adjustables unless you truly plan to adjust them a lot.

Drag Adustable – Tokico Illuminas, best adjustable drag shock out there. Its been proven many times.

Road Course Adjustable – Tokico D spec, best adjustable shock/strut out there. And not horribly expensive either.

Road Course Non Adjustable - Bilstein HD’s, and Bilstein custom valved from Maximum Motorports for Coil Overs. Also Koni Yellows are amazing shocks, but expensive and require very good springs.

Cheap Shocks: There are lots of cheap ones out there. Tokico HD’s and KYB’s are ok if you want a stock replacement. Not generally that great for high performance though.

K-Member / A arms - Your K member is the most important part of your front suspension. It is what your engine, struts, A arms and subframe connect to. Your only choice is really a tubular set up. This usually require changing to tubular A arms and Coil-Overs as well. This can be a large change all at once, But definitely worth it. There are some A arms that don’t require A new K member, but most K member require the tubular A arms since they do not allow you to keep your modified macpherson strut. The reason is that they need to add a ton of material to keep that stupid spring where it is; which leads to more weight and less access to the engine and exhaust. A new K-member will give you better suspension geometry leading to better corner loading and body roll. It also adds stiffness to the front end, as well as clearance for new motors, turbo’s, exhaust and flat convenience. It is a big mod, and takes some time, but a worth it one in the end.

And now to the Back of your car.

4 Link - Your stock mustang comes with a brilliant design called the 4 link. I explained its flaws above. The real fix is a package kind of thing. There are too many jobs that the 4 link is trying to do. The following parts work together to fix its flaws.

Lower Control Arms- Lower control arms are the Heart of your rear suspension. They hold the axle in place and transfer the majority of the energy to your car’s body. The stock ones work well, they are just weak. New ones will firm up the rear end, making for better transfer of energy to your chassis, less axle bind and less windup.

Upper Control Arms – Upper control arms are the wonder twins of your rear suspension. They are simply a couple a steel pieces that connect at a funny angle to your upper differential casing. In a normal car, they are fine, but when at the limits, they are plain dangerous. They bind under hard turning making your tire grip unpredictable, they help prevent but in no way stop axle wind up.

Panhard Bar / Watts Link – These two items are pieces designed to take over 1 job from the 4 link. They bolt to your frame and connect to your axle with either a single pivoting bar or 2 bars connected to your differential housing. They both align the axle with the middle of your car. This prevent the rear axle from ever moving out of alignment and eliminates side to side axle bind. This means you can drift or turn hard without having to worry about the rear end skipping off the road and ruining your traction. 05+ models have a factory Panhard Bar installed.

Torque Arm - A torque arm is a piece that takes away the second job of the 4 link. It bolts to the housing of your differential preventing axle wind up entirely. It also runs parallel to your driveshaft and is welded to your subframe connectors. If you install it and the panhard bar. You can remove your upper control arms. This will save you a decent chunk of weight and give you a stiffer yet freer moving suspension. This leads to better wheel rates and solid transfer of energy to the wheels and chassis. Torque arms not only increase the ability to turn and accelerate, it also moves the connection point of the rear wheels to the body, making your car actually stop faster too. Instead of causing the car to dive as much, it keeps the car more level allowing your rear tires to do more of the work than stock.

Most of this information transfer’s to other models of mustang. I’m pretty sure all of the 5.0’s use the same suspension. And the cobra’s have the same front suspension as us. The 05+’s also use the same front and rear with the addition of a panhard bar. There are some other extreme options out there. You can for instance get an unequal length double a arm set up for your front. This gets rid of the strut and cc plates in the front, and replaces them with a shock and two A-arms that make you have a fixed toe and caster with an adjustable camber angle. ( I believe I don’t have those switched) The new set up is far superior but, very expensive. $4-5K for the whole thing. But that is new K-member, coil-overs, and A arms. It’s a worth while change if your car is a track only monster, but not for just about anyone else.

If you have any questions. Feel free to post them. I know a lot more, that I’m sure I could squeeze out if I wanted to spend the time.

I also advise doing some research of your own at the following sites.
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