Review: Unibrace XB


Back in December, I jumped on a Unibrace Group Buy on the MK6 Forums. I picked up the UB and RB braces and reviewed them thoroughly here: Unibrace UB and RB Review. After talking with Bruce@Unibrace for a while, he assured me that if I enjoyed the UB/RB combo so much, it would behoove me to get the final piece of the puzzle…..the XB. If I had to rate the prior combination (UB/RB) I’d give it a solid 5/10, in relation to the sway bars. With the addition of the XB, I’d give a mind blowing 10/10. Why? Dive in the find out.

Most of the research has been done initially in the first review, so this review can get down to Brass Tax.


Think of your car as a cardboard shoebox; flimsy and unsettling at times while cornering. When taking a turn, your lateral force is transferred outward to parts of the vehicle that are X amount of distance away from the COG. The furthest point is around the roof area:

No Brace

Negating the Sway bar effects, you essentially shift your COG of your vehicle more towards the driver’s side of the entire vehicle. This will place more force on the outside wheel and create more understeer. It will react the same as sway bars, but with more of a dramatic effect. With the addition of sway bars, your chassis stiffness will become the weaker link in the multivariable system and cause more torsional twisting of the chassis. This gives an unsettling feeling and could cause more numbness in the steering.

By adding the XB, you keep your COG of the body planted in the middle of the suspension. This will allow the suspension to work a lot more to output its given dynamic, rather than dampen the torsional flexion that the body will apply to the system when cornering. Think of it as taking the “unaccounted” stiffness and damping dynamic out of the ¼ model formula.

 With Brace

This results a more “planted” feeling across the chassis. The car will feel and corner in a predictable manner and become less unsettling over mid corner bumps, giving the operator better ability to control power out of the turn. With sway bars, this combination (given the right tires) can out corner many higher end vehicles.

[U]Further Detail Needed (Per GolfMK6)[/U]
As a user mentioned, the shifting of the COGy is not particular to this instance. While my model represents an exaggerated apporach to detail the flexion, I assure that the process and dynamic reaction of the suspension is a little more complex.

On the simplest level, we have a damping coefficient, stiffness, and mass. Each variable acts accordingly in the dynamic controls formula as follows:

Mass*(Xdot2) + Beta*(Xdot) + Stiffness*(X) = 0 (In this case, it’ll be a response whether it be impulse and/or step input)

To focus on JUST the damper dynamic would be too vague to exert on a full car model. Our body has its own dynamic response. Believe it or not, there are damping and stiffness properties within the sheet metal that are often “compromised” and/or simply cannot be all accounted for. We cannot simply place a brace across every point in the car and expect the customer to enjoy their ride with bumping their heads on the chassis bar.

Eventually, your displacement vector will become a multivariate system on the account of variating mass and stiffness coming from the body to settle itself. Helping ease these variations will allow the suspension to exactly what it is supposed to do….dynamically reponsed to a fixed entity rather than a separate dynamic system.


photo 4

Install was a breeze, but tedious. To properly mount the XB, you must drill into the Rear Inner Panel and apply rivet-nuts to give the XB something to mount to. I used an undersized 0.5” drill (~0.498”) and over bored the holes if I need extra space. Too much will not allow the nut to properly crimp against the sheet metal. This will cause the nut to spin when fastening the XB, thus rendering the joint useless to apply its force transfer.

photo 3

The package included a optional ($35) Nutsert Tool to crimp the Rivet-nut to the body using a socket and wrench. Pretty straightforward process, but could get confusing for the casual user who is not accustomed to the tool. Luckily, there are instructions included.

The tedious process was as follows:

  • Take out the Spare Tire
  • Take out the foam around the spare
  • Take out the Folding Seat
  • Take out the Seat Base
  • I had to vacuum a lot of dirt underneath the seat 🙂 (See Below)
  • Align the Brace
  • Mark the mount points and punch the proper center point
  • Use a 1/8”, 1/4”, 1/2”, to drill the holes. You cannot drill the 1/2″ hole immediately because it is thin sheet metal and will cause the drill to bind.
  • Use the Nutsert tool to install the Rivet-Nuts
  • Install carpet back
  • Install Brace
  • Install the rest and Enjoy

photo 1

photo 2

Overall, it took roughly 1.5 hours. That’s including a 10min restroom break. I suggest proper planning prior to install to understand what you’re getting yourself into.

Personal Account of XB Performance

The first day I installed the Brace, I didn’t have much time to get her out on the backroads and beat on it. I did get a chance to drive into town and do a few errands. At this point, I was curious to see if I could tell even the slightest change in driving dynamics.

As I pulled into the parking lot, I IMMEDIATELY noticed the steering feel and the overall nimble ability of the car. It seemed more point-and-shoot. Knowing this, I decided to get on it a bit more through the turns in the city whenever I was entering a parking lot and/or side access roads. I was shocked it was noticeable in casual driving. This had me excited for the next morning.

My occasional commute consists of back road bends, long sweeping turns, S-Bends, Rough roads, and everything that could make a commute more fun by hammering the throttle a lot more. I flipped the car into M-Mode and kept it in 4th or 5th gear. Immediately, I could the car was no joke anymore. It felt sharp and gave great feedback to the steering. The “sluggish butt” syndrome where the car felt like a bubble in turns was eliminated and it felt the car wanted to lean inward towards the turn a lot more. This gave the car a neutral to a slightly oversteered feeling when punching it hard out of a turn. At certain moments, I obtained the lateral limits of the vehicle and was crossing my slip ratios of my tires and could easily rotate the back end a little with some off-throttle oversteer. It was ridiculously fun.

I feel I can drive the car a lot harder now. With Stage 2, I feel the suspension finally over powers the engine and can easily be manipulate now. At WOT in 4th gear, all the power was being applied mid corner and followed all the way through the turn with a nice blasting shift to 5th and peak torque being applied, the car just screamed out of it. At this moment, I gave a solid “HELL YEAH” salute and kept on my pace. The car has been transformed in a way I never expected. Kudos Bruce……you’ve made a splendid upgrade.

Overall Thoughts

My current suspension modifications are as followed:

  • MK6 Driver Gear Springs
  • OEM Dampers
  • S3 Control Arm Bushings
  • APR Front and Rear Sway Bars (Front: Soft & Rear: Medium)
  • Tyrol DeadSet Collars
  • Unibrace XB, UB, and RB
  • Hankook V12s
  • BFI Engine and Transmission Motor Mounts
  • ECS Dogbone Insert

I’ve never been happier with a setup so solid as this. This product is everything I had hoped for. Again, the UB and RB felt like a nice 4-5/10 in terms of output, but it left me with a sense of wanting for something slightly more. Everyone that owns the XB, has mentioned the biggest difference in driving dynamics. I’m now a 100% believer in that statement. This deserves a solid 10/10.

Again, Bruce is one heck of a person to work with. He truly cares about offering the best product he can. If he can’t, he takes it a step further, pushes himself beyond the customer service realm, and goes out of his way to make the end customer as satisfied as he can. Fortunately, this sale was as straight forward as it could be.


7 thoughts on “Review: Unibrace XB

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