When it comes to racecars, everyone seems to have a number of passionate opinions about setup, how things work, and that one part that will save you 2 seconds per lap. Regardless of the multitude of changes you can make to a car, it is important to make those adjustments with some kind of plan and sensibility. Just bolting new internet parts on a car rarely makes it handle better right out of the box. It takes little adjustments to get things right. Today we are going to talk about one part that requires those little adjustments to help things work correctly: adjustable sway bar end links.

In stock form, this Ford Fiesta ST likes to lean way over while in a hard corner. This car could benefit from a larger front sway bar and correctly adjusted end links to help reduce body roll.

What are we talking about here? We are discussing the pieces of a sway bar that attach the ends of the bar to the suspension. They’re called end links. The sway bar is attached to a car in four places. First it’s attached the chassis of a car with a bushing. Here the bar is allowed to rotate allowing for undulations in the suspension. The part of the sway bar that actually makes it work as designed is at the end of the bar, which attaches to the suspension on both sides of the car with end links. These end links connect both sides of the car through the sway bar. As a car goes into a corner, weight transfer goes to one side of the car and it begins to lean. Then the sway bar and its end links connect both sides of the suspension, so when one side squats from weight transfer, the other side is pulled down from the sway bar. This sets up for a flatter car in a corner, helping wheel alignment stay optimal for the correct tire patch interface with the racetrack surface, which is the ultimate goal. A sway bar is not complicated. If one side of the car leans, the other side follows suit because of the sway bar.

The above diagram illustrates a front suspension system. The red bar connecting the left and right sides of the suspension is the sway bar. The thicker the bar, the stiffer it is and the greater the ability of the sway bar to decrease body roll in a corner. The green arrow is pointing to the end link, which attaches the end of the sway bar to the suspension.

There is an immense amount of flex in a sway bar, which is a good thing. This is not a rigid system. We design cars to have independent suspension systems for a reason: so they will handle better over bumps in the road. Then, to fight weight transfer and vehicle lean, we connect both sides of the independent suspension system with a sway bar making them less independent. Weird right? Actually, it’s not that weird. We only want the sway bar to begin to work when we really need it to, in a corner. How much that sway bar works is dependent on its thickness (stiffness). We can adjust a sway bar’s effect by how stiff a bar we add to a car.

The red arrow in the photo above is pointing to the OEM fixed-length end link, which connects the sway bar to the strut.

Cars from the factory generally come with a front sway bar with a fixed-length end link. What that means is the left- and right-side end links are identical in length. This is fine for taking kids to soccer practice in your minivan, however, when setting up a racecar for track duty, this is not an optimal setup. Because we don’t want the sway bar acting from one side of the car to the other until we are in a corner, that means we want the sway bar in static form — while going straight down the road — not to have any tension. This is done by using adjustable-length end links, which are setup so that when the car is on level ground the bar isn’t pulling on one side of the car or the other. We want the sway bar in a chill state, not acting on the suspension, until it’s time to do its job.

The end of the bolt on the end link has an interior with an Allen-head fitting to hold the bolt steady while using an end wrench to remove the nut.

On almost every car I have ever removed a sway bar from, I have found that there was unneeded tension in the sway bar when it was attached to the suspension with fixed-length end links, regardless of whether it was a stock car or a Spec Miata. If you have ever installed a sway bar and you had to push or pull on the sway bar to align the bolt from the end link to poke through the bar, congratulations you added tension to the sway bar the moment you connected it. Whoops! Don’t worry, I’m going to tell you how to fix it.

Here you can see the OEM fixed-length end link (top) and the adjustable end link from GodSpeed (bottom).

Adjustable-length end links allow us to install a sway bar without any tension in a static setting. However, this non-tension installation only works if you follow a simple order of operations while bolting the end links on the car. Like any other adjustable part for a racecar, the adjustability means there are more ways for us to put these parts on a car the wrong way. Trust me, we are going to get this one right.

Cars don’t sit perfectly level, especially when weight is added to the vehicle — like a driver who likes to eat donuts. The car in the top photo is static without a driver, nearly level. The car in the bottom photo has driver weight in the left front seat causing the left side of the vehicle to sit lower compared to the right side, visibly leaning to the driver’s side.

The trick to ensuring you install a sway bar correctly using adjustable end links is to complete that installation while the car is sitting on the ground with all of the correct weight acting on the suspension. This is the part where you ask, “Hey, dummy, how are we going to bolt on new parts under the car when the car is sitting on the ground?” That is a valid question. All will be revealed. We can install 95 percent of the sway bar while the car is up on jack stands with the wheels off. We only need the car on the ground for the very last bolt.

At the Double Nickel Nine Motorsports shop, we keep gym weights around to replicate a driver’s weight in the car for corner weighing, alignments, and installing end links. You can see we have weight in the seat to represent the driver’s butt and weights on the floor near the pedals to represent the driver’s resting leg weight while sitting.

Because a sway bar starts to take effect when lateral weight transfer occurs, it is important we set the car up with the correct static weight on both sides of the car. That means having your tire pressure correct, driver weight in the car, and basic alignment completed prior to the final installation of the sway bar. This will help us to install the sway bar tension free for going straight down the track.

Using two end wrenches, you can adjust the length of the adjustable end links to the exact dimensions you need.

At our shop, Double Nickel Nine Motorsports, we really nerd out on alignment setup. We take all necessary steps to ensure our static setup is accurate and that we nut and bolt everything to the correct torque specifications. After removing our non-adjustable OEM end links we baseline our new adjustable-length end links to be the same length as stock. Then we get to work installing the new end links in the correct order of operations.

This photo represents exactly why we are doing this project, two end links with matching lengths on the right and left will not fit into the sway bar without adding torsion to the bar.

This is the correct order of operations for installing an adjustable-length end link:
1. Remove OEM end links.
2. Adjust new adjustable-length end links to match OEM end link length.
3. Install one new end link on one side of the car, tighten at suspension and at sway bar.
4. Install new end link on other side of the car, tighten only at suspension. Leave it loose from the sway bar.
5. Place vehicle on the ground with driver weight in car.
6. Adjust the length of the non-attached end link so it easily slips into sway bar without tension.
7. Tighten final end link portion to sway bar.
8. Win races.

If your car is too low to access the end links while the car is on the ground, which is required to set the correct end link length, use a set of ramps to help gain access to the sway bar. These are Race Ramps we use for loading our car on the trailer.

As I stated before, 95 percent of this project can be done with the vehicle in the air, tires off, making for ease of access to bolt on the new parts. However, to take advantage of what an adjustable end link can provide your car setup, you have to install the last side of the end link when the vehicle is on the ground. If the end link won’t easily slip into the hole on the sway bar, do not connect the bar. Do not bend the bar up or down to force the end link bolt through the bar. Instead, adjust the length of the end link until the bolt slips through the sway bar without tension. Once that is done tighten all the adjustment bolts and you are good to go.

This is the last bolt that should be tightened, one side of the sway bar, one end of the end links.

If your car is so low to the ground that accessing the last end link bolt is impossible, use ramps to drive the car up on to assist with ease of access. Do not use a jack to raise one side of the car, that will instantaneously add a twist to the chassis and torsion to the sway bar. If you adjust the end links and connect the bar in this manner as soon as you lower the car off the jack you will add torsion and tension to the bar. This tension can be a bad thing because it could be pushing up on the suspension changing the spring rate for that side of the car. You want the springs to do their job and you want the sway bar do its job. You don’t want the two complicating the situation for one or the other. You don’t want to connect the two sides of your independent suspension for no reason. There is a reason drag racers remove their sway bars to go faster down the quarter mile.

With the project complete, we realigned the car using Smart Strings —since we threw a little more negative camber into the car while we had it on the lift — and were ready to hit the track.

For those of you who have coilovers and corner-weight your vehicles, you must disconnect your sway bars prior to doing any corner weighting adjustments. Once that is complete, then follow these instructions to adjust your end links prior to reconnecting your sway bars.

Long story short, too late, you want a happy static sway bar. You don’t want an added unneeded spring in your suspension connecting one side of the independent suspension to the other. This can be done by installing adjustable end links and installing them in the correct manner following the order of operations as detailed above. Good luck and enjoy being on your back and having stuff fall into your eyes while you try to access that pesky last bolt. Good times at the shop!

Image courtesy of Rob Krider

3 COMMENTS

  1. Good stuff, thank you. I didn’t know about torquing the bolts after dropping the vehicle down onto the wheels. g2k.

  2. If you know you have tension/ preload in the rollbar already, is it recommended to perform an inital alignment without the droplinks attached?

  3. I must be missing something. You say “On almost every car I have ever removed a sway bar from, I have found that there was unneeded tension in the sway bar when it was attached to the suspension with fixed-length end links”.

    Are you saying that the sway bar somehow got bent and that you need to install adjustable links to compensate? Or are you saying that cars are actually manufactured incorrectly and that car makers should be shipping vehicles with one end link shorter than the other so that there’s zero tension at rest?

    I have a 2007 Sienna AWD that I’ve modified for light off-roading. I’ve lifted the front end slightly by installing 40 mm spacers on top of the struts. When I started researching whether a lifted vehicle needs adjustable end links, I thought the reason was to eliminate tension that was introduced by the lift. But now that I am actually installing adjustable end links, I am confused. The sway bar rotates within the bushings which eliminates any tension regardless of the link length. Lifting a vehicle may cause suspension components to come into contact with each other. Adjustable links are installed and tuned so that suspension components don’t touch. It has nothing to do with tension. Am I missing something?

    I roughly followed your directions. I attached the tops of the end links. With the vehicle on the ground at rest I rotated the sway bar all the way to the top and all the way to the bottom and then positioned it in the middle. Then I adjusted the adjustable links so that the bottom bolt slides into the sway bar easily. The adjusted links are now shorter than the OEM links and there’s no contact between any suspension components.

    Thanks,

    Roger

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