How to Modify a MINI for Better Stabilization (Sway Bars, Stress Bars and Cross Braces)

Ways To Revive An Aging MINI, to Stabilize A New MINI, and More: Stress Bars, Sway Bars, Cross Braces, and Knee Braces.

(This sponsored post is part of an ongoing series coming from our friends at OutMotoring. This week it’s all about MINI models and how can decode them to better understand what the heck they mean.)
By OutMotoring.com

MINIs, from the factory, handle great and are constantly being praised for their go-kart like handling characteristics. It’s true; MINIs handle great. Even the Countryman model with the added weight and higher ride height has been highly favored for its performance handling characteristics. Many will ask ‘Why mess with a great thing?” We prefer to ask “Why not improve on a great thing?” Our customers agree and often call or email us to get advice on how to take their MINI to the next level. They want even better handling. They want to go through twisty sections of favorite nearby roads and feel a bit more stable, and have more confidence doing so.

Some MINI owners use their MINIs as dual purpose cars. During the week the MINI handles the duties of commuting, while on the weekends MINI owners run their trusty MINI ragged on the track at high speed or at fun-inducing, low speed autocross events in a nearby parking lot. In either case, the MINI chassis can be improved and we offer plenty of great options for every MINI owners needs. The end goal of installing any of these products is to help keep the chassis from twisting while turning. Twisting or flexing of the chassis results in less control and less tire contact with the road that is critical to safe high speed or technical driving. Keeping the chassis as flat as possible will keep more tire surface area touching the ground which improves traction and stability. Both are what keep you AND your MINI on the road.

Why Is My MINI So Stressed That it Needs a “Stress Bar?”

So, let’s dive right into what all of these chassis stiffening products are and what they do.

Front Upper Stress Bars

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Various Front Upper Stress Bars for gen1 and gen2 MINI models.

Upper or Lower Front or Rear Stress Bars are added to the front or rear suspension towers or chassis mounting locations and create a bridge between both sides of the car that helps reduce chassis flex. Upper Stress Bars mount to the left and right side of these strut mount locations to create a bridge or connection between both sides of the chassis. Lower Stress Bars mount to the under chassis of the car typically where front control arms or other suspension components mount to the chassis. There are NOT that many Lower Stress Bars on the market for MINI but there are a decent selection of Upper Stress Bars to consider. Here’s a introduction to stress bars.

The MINI engine and trunk area are so compact that Upper Stress Bars are less effective than they are on a much longer vehicle where the front or rear suspension towers are considerably further away from each other. This does not mean they are ineffective on a MINI; they still serve a purpose and will help stiffen the MINI chassis, especially those that are aging (2002 model cars are now 16 years old). As cars get older the metal and related joints fatigue which can leave the car feeling less ‘perky’ than when it was new. Adding a Front Upper Stress Bar can help revive an aging MINI chassis.

Adding a Front Upper Stress Bar is the easier of the two types to install. Typically, they require removing a few upper shock tower nuts, adding the stress bar, and re installing the nuts. Some manufacturers add special nuts to offset the thickness of the bar while maintaining correct thread contact on the existing studs from the shock mount bushings. These typically require some planning as some aftermarket intake systems may not be compatible with all Front Upper Stress Bars. And in some cases the Front Upper Stress Bars cross directly over the intake system; this can be a potential problem that is worth researching before buying.

Rear Upper Stress Bars

A Rear Upper Stress Bar on a MINI crosses directly behind the back seats and in most cases will also require angling the seats forward a few degrees. This is engineered into the mounts provided with the Stress Bar to allow room for the brackets that connect where the seat back latch attaches to the shock tower. While this is less than ideal for rear passengers a Rear Upper Stress Bars is still a effective way to stiffen the MINI chassis for improved handling.

What Are Sway Bars and Why Do I Need Them?

Actually, your MINI already has Front and Rear Sway Bars as do most modern cars. Sway Bars are mounted to the front or rear main subframes and are an “U” shape with the mid-section spanning roughly from the left inner wheel to the right inner wheel lip (but set back a few inches). The outer parts of the “U” can usually be seen by looking through the wheel directly behind the brake caliper/rotor. Their main job is to help reduce chassis and subframe flex by connecting the right and left suspension components. NOTE: It will be more visible through the rear wheel than the front as the front Sway Bar is set back further in behind the brake rotor and suspension components.

More Info About Sway Bars

Increasing/decreasing the diameters of the metal bar used can change handling characteristics for better and possibly worse.

All cars will react differently to changing the factory installed front and Rear Sway Bars but, for the most part INCREASING the thickness of the Rear Sway Bar may cause the car to oversteer which means the back end will swing forward in a abrupt turn. Increasing the thickness/diameter of the Front Sway Bar will do the opposite and may make the front end ‘plow’ into a turn which means you lose some of the steering control. It’s not always this cut and dry as there are soooo many variables that play into how a car handles including the air temperature and how much gas is in the tank!

Car manufacturers typically want to sell neutral handling cars and MINI is no different. During testing MINI determined what diameter Sway Bar is best for MOST types of driving, under normal conditions, normal driving speeds, normal driver skills, and a slew other variables. Most MINI drivers are not normal. Therefore, knowledgeable guidance is needed to make effective suspension upgrade decisions.

Over the years of working with MINI parts we have found it is best to leave the factory installed Front Sway Bar as it is. Upgrading the Rear Sway Bar with a larger bar will help the cars handling characteristics in a more positive way than ANY other single suspension component. For example, the rear sway bar on most MINIs is about 16 or 17 mm and upgrading to a 19 mm or 22 mm bar that is adjustable will give you many options to fine tune how much oversteer you want. This is based on how and where you drive, how your suspension is setup, and what your end goals are. There are many other variables to consider such as tire selection, brake pad compound, spring weights, amount of lowering in the suspension, type of shocks and weight of the vehicle. Each owner will need to do some testing to figure out which diameter and which setting they need to set their aftermarket Adjustable Rear Sway Bar.

My personal preference is to go with the larger 22 mm Rear Sway Bar and then adjust the settings to match my needs depending on what springs/coilovers/shocks I have and what tires I’m running. The 22 mm bar gives the flexibility to go from mild to wild. The smaller 19 mm can offer similar benefits. I prefer the 22 mm at the FULL STIFF setting — even for street use. I’m sure if I spent more time at higher speeds or on the track I would back that off a bit but for street use at street speeds under normal safe driving conditions I have found this setting is most effective at reducing chassis flex and keeps the most amount of tire on the road.

Traction is your friend. When I’ve taken my MINIs on the track I can feather the throttle going into a turn, adjusting braking, or adjusting front or rear tire pressure to fine tune the way the car handles. Understanding how Front and Rear Sway Bars affect handling is a important part of how a car handles. These products, when upgraded, have an effect on many other components that determine how your MINI will react in every situation. It is best to be methodical with upgrades and be sure to take the time to research where to start and which upgrades may help you be a faster driver on the track and a safer driver on the street. Other experienced MINI owners will likely have additional feedback and experience.

Chassis Cross Braces

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These are a bit more complex looking, but they are designed to do a simple task much like the other types of bars we’ve discussed. Chassis Braces are installed under the chassis, have 4 mounting points, and mount to the body (not to the subframe as a Sway Bar does). Cross Braces help strengthen the chassis by adding a bridge from one side of the underbody to the other. Currently, Way Motor Works offers MINI specific braces.

I personally have not had a Cross Brace on my personal MINIs, but I have many customers that do and have reported positively after installing one.

Knee Braces for Your MINI?

Ok, so that last thing about ‘knee braces’ was totally made up. There is no such thing as a knee brace for a MINI. Now, back to more serious matters.

So What Do I Do? What Do I Need?

There are many options on the market to help stiffen and reduce chassis twist on your MINI. Depending on your needs, track experience, budget, and end goal you can go from mild to wild.

I recommend starting with a larger Rear Sway Bar such as the NM Engineering or Alta. Get used to it and see how the handling characteristics of your MINI evolve. From there, consider lowering springs, and a Front Upper Stress Bar. It’s best to stagger the installs of these upgrades so you can get a feel for the results of each upgrade.

If you spend a lot of weekends on the track your needs will be different from the person that enjoys long weekend drives on curvy mountain roads. A MINI that is set up for the autocross circuit on the weekends will need different upgrades than a dedicated track car. Sway Bars, Cross Braces and other suspension components need to work together to get your MINI to perform.

We’re Here To Help.

We’re here to help and based on our knowledge of various chassis stiffening products we offer the following way to start. First, replace the factory Rear Sway Bar with a larger Rear Sway Bar. Then, you test drive your upgraded MINI for a few weeks. We predict the upgrade will amaze you and make you fall in love with your MINI all over again. Your MINI chassis will feel “flatter” while turning and the car will feel more connected to the road in high speed turns. This will give you confidence in selecting the next suspension upgrade. Who knows? As you push your MINI to a new limit you may find yourself signing up for a track or autocross event!

Best regards

Aaron Cornaby- Head Motorer
www.OutMotoring.com