Afternoon

On the mk5 golf Platform there is a US company that have developed a set of cross braces to increase torsional rigidity of the chassis.

The following is quoted from a guy called Robin who did a review on it. It explains it all better than i will.

WHAT ARE THEY?

The XB is a structural cross brace added to a car to increase body rigidity and the UB is an underbody chassis stiffener, both specifically designed and produced for a variety of hatchback bodies such as VW Golfs, R32's, and some of the Audi range. The producer Bruce Levin, a professional architect and product designer, continues to develop applications for different car versions where possible. But are either of these products something you really need?

^ UNIbrace XB - Both XB and UB products are available in red or black.

^ Product quality is beyond any question - Absolutely faultless! You can tell how well the products have been considered and that this reflects the standards of a professional designer.

The UNIbrace XB is constructed of super strong 6061-T heat treated 0.187 inch (~4.75 mm) aluminium ('aloooominum' if you are American!) with high temperature automotive powdercoating. The UNIbrace UB is slightly thicker at 0.25 inch (~6.35 mm). They are waterjet cut and CNC bent.

WHY INSTALL A UNIBRACE XB?

A hatchback car body is inherently an open box and consequently a potentially weak structure. Volkswagen have made improvements from generation to generation but the Golf platform is primarily designed to meet the requirements of their general market which is aimed at a more pedestrian consumer than the typical enthusiast who will be reading this review. The phrase "Designed by German Craftsmen and Modified by Mad Englishmen" comes to mind - In this case it's a Mad American.

There is more body distortion in such an open box hatchback structure than may be initially obvious. I have heard some folks say that the rear seats contribute to reducing the distortion but, as the following photo shows, the bench seat is attached to the floor pan and the seat backs are split in two separate units. So, although I'm not a structural engineer, I believe that any claimed contribution by the seat units is pretty insignificant.

WHY INSTALL A UNIBRACE UB?

The ex factory car merely has two independent thin aluminium straps across the exhaust pipe 'tunnel' fitted at some distance apart. The UNIbrace UB uses the same fixing points but is a shaped latticework brace which structurally accommodates all four fixing points instead of just two independent pairs. The result is a stiffer chassis, reducing twist, and hence advantages to suspension and handling when driving enthusiastically. And when I say "enthusiastically" I do not mean "irresponsibly".

When I showed him a photo of the UNIbrace UB, a friend in the motorsport industry described it as "A solid piece of kit, somewhere between a sump guard, a grass shield, and a piece of undercar jewellery".

Okay, so that's the simple theory of how they work in layman's terms but how do they feel to drive? What do they contribute to the enjoyment of driving?

THE XB DRIVING EXPERIENCE:

I decided to fit the XB first, feel what that contributes, and then add the UB a week later and then report how their combination feels to drive. So the 'The XB + UB Driving Experience' info is added later.

Immediately following installation I set off on a pre-planned route which takes in a variety of roads which I am very familiar with. I always do this when testing so that my shared opinions and findings might be as realistic as possible by virtue of comparison. I think it's very important to fight the placebo effect and euphoria of a new toy. If you are not as objective as possible it can be rather like having a new girlfriend in that she always appears to be absolutely perfect to begin with! To be non-sexist I have no doubt that the same applies to a new boyfriend.

The first section is an A-road with a long sweeping uphill to a fast bend and then heavy-ish braking flattening to a 5-junction roundabout. To my horror, as I accelerated up the hill I became aware of very loud road noise and an occasional short zingy vibration sound. I was driving with both my back seats folded down. It sounded as if the XB was transmitting undesirable sounds but on taking the B-road off the roundabout the sounds had disappeared. [i'm very glad to say that I have since tested for unwanted sounds on the same stretch of road and discovered that the resonance problem was the road surface of one lane at high speed]. I was immediately aware of how very flatly planted she felt on that first roundabout and so felt confident to throw the car at the first sharp right hander on the B-road somewhat harder than usual. A couple more bends, one with an awkward camber and I was grinning from ear to ear.

That particular B-road section is 15 miles of roller coaster bends and ups and downs and consequently a perfect workout of suspension and handling. Something which I didn't expect and don't quite understand is how the steering now feels more direct - I might have expected that behaviour from the UB rather than the XB. In fact, the XB feels as if it is doing more than effecting the rear part of the car where it is located. With KW V3's set up by Volkswagen Racing, Whiteline Anti Lift Kit, Eibach anti-roll bars, OZ lightweight wheels, and Quaife diff, my car has always felt well planted and I was really doubtful and apprehensive about how it might be improved. It would be easy to think that the XB is reducing body roll but it's more about the transfer of physical energy. The difference is that I now realise that the car body was absorbing much of the stresses or energy but now the suspension itself is more independently absorbing the energy and leaving the chassis feeling like it's absolutely horizontally flat and as if on rails! Overall, pushing the car hard feels more settled and confidence inspiring.

After a few days of some more 'testing' of the XB on a particularly fast stretch of dual carriageway with rises and kinks and therefore subjecting the car's body to flex: Whereas my car always feels safe through there, it does have a tendency to show what I can best describe as 'nervousness' - The car stays on course but there are small amounts of movement which test my determination and are somewhat exhilerating! However, as now expected with the XB, all that 'nervousness' has disappeared and it feels rock steady at these high speed kinks even when overtaking through them when it is obviously important to stay in lane and not take the other car's door handles off! It's a short stretch of only about half a mile but one which is very satisfying to attack.

What is left for the UB to bring to the party, I wonder?

THE UB DRIVING EXPERIENCE:

In order to better assess the UB on its own I temporarily removed the XB which is easy to do and takes less than 10 minutes (just! when you fit the Allen bolts back into the nutserts), and drove about 90 miles to JKM to have my UB fitted. I immediately noticed the difference in going back to 'standard' - The car felt slightly fidgety again although actual roadholding was not impaired.

Immediately after leaving JKM and of course being hyper aware of the UB I noticed that I could feel any road surface undulations and imperfections though not in a harsh way. But, compared with the XB the feel through the seat of my pants is not as comfortable when solely the UB is fitted. It's not uncomfortable but you can easily understand why Volkswagen haven't stiffened the underside to the extent that the UNIbrace UB does. It becomes more comfortable at speeds over 30 mph and at very high speed. At very high speed, the UB feels as if it adds more stability and stiffness than just with the XB fitted.

To date I have driven just over 200 miles with only the UB and over all types of roads including my usual B-road 'test route'. This included a mile of speed bumps visiting a friend. To my surprise the raised pairs of pad-style speed bumps seemed less intrusive than when I have been over the same ones before any UNIbraces were fitted. I drive over very slow with my nearside over the pads and my offside in the normal road level area. At speed on a sudden hump on my 'test route' B-road the UB seemed to encourage the car to take off more easily and it kicked in the ESP.

Neither the XB nor the UB do anything other than stiffen the body rather like a roll-cage does but without offering the protection (or making a mess of a car interior). All I have been able to do is assess the UNIbraces by how they feel to drive with and it needs a conscious effort to keep the ever seductive Miss Placebo at bay.

If I were to choose only the XB or only the UB, I would choose the XB. It feels as if it provides a tiny bit more noticeable stiffness and yet more comfort, perhaps because the XB is located behind you and not underneath your seat. However, the UB delivers a very strong sense of being well planted when braking very hard in a straight line - It all feels absolutely rigid as if the floor you are sitting on is utterly solid! In fact, if you dial your brain into it, you can easily feel where the UB is providing stiffness. Additionally, the car with UB fitted seems to go very directly wherever you point it, so turn-in feels particularly direct even in the wet. Of course, this works very well in tandem with my Quaife diff.

THE XB + UB DRIVING EXPERIENCE:

The designer Bruce says that if together the UNIbrace XB + UNIbrace UB equates to 100% stiffness, then the XB is responsible for 60-65% and the UB is responsible for 35-40% of the stiffness. He has designed them to compliment each other but they will each add to your spirited driving enjoyment if only one is fitted.

If you tune your senses into the feel of your car while driving hard, the XB on its own very noticeably stiffens the 'box' of the car body whereas the UB on its own noticeably (but not quite as much as the XB) stiffens the flat 'platform' of the car body. When the XB and UB are both fitted together the feel of your car becomes very noticeably solid and extremely well planted as if on rails! Instead of feeling how each of the XB and UB stiffen the car when fitted alone, stiff body plus stiff platform = solid car overall.

I've just returned from another spirited drive on my roller-coaster B-road test route and wow! the car feels not so much stiff but very solid. Even driving round a 90-degree turn at 10-15 mph feels very positive and the car goes exactly where you point it. The UNIbraces open up more scope for the Quaife diff and, of course, the suspension. I have yet to explore the car's limits and think that this should only be done in the right environment and conditions - A trackday with plenty of run off would be ideal.

MINUS POINTS:

- The XB might reduce or restrict the ease of loading certain shaped goods. But it can be easily removed temporarily if necessary.

- Someone totally unfamiliar with braces might wonder what the heck the XB is and think of it as an unsightly loading restriction. But they obviously don't enjoy driving as much as most of us enthusiasts do!

XB SUMMARY:

At this stage until my UB is fitted I can only offer an opinion on the UNIbrace XB. Well, is it a must-have? - If you do trackdays I think it is a must-have. If you only do fast-road it's very worthwhile and not a must-have but a joy-to-have. Your car doesn't know whether it's on a road or a track and behaves totally reactively to conditions and how it's being driven. So, whenever you can grab the opportunities to responsibly drive enthusiastically on the road, the XB puts an extra grin on your face. I have no experience of how it performs on a car with standard suspension but I would expect it to improve things simply because of the ex-factory car's physical structure. When coupled with aftermarket good suspension etc it potentially adds significantly to the package of aftermarket components. It helps driving the GTI feel closer to a purpose-built sports car and that, Ladies and Gentlemen, should put an extra grin on your face.

XB + UB CONCLUSION:

Are the UNIbraces a mod you need? - If all you do is a relatively dull commute or mostly motorways, then the answer is no. But if you tend to grab opportunities to drive enthusiastically on twisty roads or do any trackdays, then the answer is a most definite and resounding YES !! And to get the most out of it, buy and fit both XB and UB. I expect that what suspension and other handling mods you have will add to the benefit. My car now feels even more surefooted and stable.

I quite fancy these for my car, but the company who produce these have no plans to ever produce one for our platform as they dont have them in the USA. Lets be fair the chassis isnt the stiffest around, so i think it could potentially yield bigger benefits than robin noticed on his own car.

Robin does great & though reviews of all his mods, so i thought id post up what he thought of it on his car which was already very heavily modified before this was fitted. He also went to the effort of installing each part indivdually and trialing them before fitting both for a thorough review.

If this is something you would be interested in I will approach a few guys about having these developed and see if they would be interested in a group buy purchase, add yourself to the list below:

1- vRSy Fabia vRS Hatchback

Does look interesting and it looks as simple as fitting a strut brace. Any idea how much for each part? Is it a set or individual?

Depends what cost are we talking about but I would be willing to spend something around 150-200 gbp if it does what this guy said he did to an already lowered and much stiffer car like his! Count me in then.

Edited 27 June, 201214 yr by newbie69

put your name on the list then, and once we have a fair few guys ill contact some people and point them towards this thread

1. vRSy

2. newbie69

Price wise i think the set above came in at $350 for 10+ unit so around £225

Wouldn't it be possible to ask this very same company to do this for our platform you think? After all it looks well engineered and very positively reviewed.

io mentioned this above. they are an american company, and they dont have this platform in their country. I have previously mailed them and they pretty much just said no.

I'm in.

1. vRSy

2. newbie69

3. Hurdy

1. vRSy

2. newbie69

3. Hurdy

4. p1tt8ull

Surely a uk based fabricator can knock these out on a cnc or similar ?

1. vRSy

2. newbie69

3. Hurdy

4. P1tt8ull

5. MillsyVRS

1. vRSy

2. Newbie69

3. Hurdy

4. p1tt8ull

5. MillsyVRS

6. Sib-rs

Surely a uk based fabricator can knock these out on a cnc or similar ?

Thats exactly what im doing!!!!

Surely a uk based fabricator can knock these out on a cnc or similar ?

Thats exactly what im doing!!!!

Ive spoken to a guy(in the UK), who happens to be a member on here as well, and he has posed a few questions.

Q1

Would you want the XB(boot)brace to be of a similar design to the unibrace XB, ie a steel lattice?

or

Would you be happy with a T45 toll cage tube style brace, which will have a more motorsport-esque style.

Q2

Would you require the brace to be removable?

a few questions to me. What sort of finish would you like. Me personally id like it anodised or powder coated black.

Thats exactly what im doing!!!!

Sorry thought you said USA based company but I'm aware now you have also contacted uk based as well sorry :(

I think I'd prefer the steel lattice and I'd certainly like it to be removable just as it was on the presentation above. After all its an everyday car for me, not a weekend-one so I'd like to keep it practical. Powder coated black would be fine for me.

Lets be honest here, & i will wait to be flamed.

That brace is not adding any stiffness to 'your chassis' for your fast road use because you do not have a Chassis,

you have a monocoque body.

But lets say we call the Car body a chassis and lets asume your one is flexing on the road.

Well how do you know.

You have, even if fitted with 30 profile tyres, flex from the tyres, even if its 2mm of flex,

the Springs going up and down, (Coils are just wound up torsion bars, to make a compact Spring)

the Dampers doinging some damping,

Bushes doing what bushes do.

the whole caboudal doing as designed with a degree of flex to stop Stress fractures of the body and joints.

Otherwise it is like driving a Go Kart down the road or try a Hard Tail trike or bike, with just tyres for suspension.

UK roads have cambers & cars for UK roads are set up 'Handed' to deal with cambers and keep the car running in straight lines and turning corners and suspension to help deal with deviations in road surfaces.

If your road car is really used to the limit and so stiff that you need to reduce Flex in the body,

then you are some driver and thats some vehicle you drive.

I suggest you get an internal roll cage in there and provide rigidity & safety to the vehilce if you actually drive that hard.

The brace in this thread, fitted where it is, is good to bundgy cord some tools to possibly.

'Emperors Clothes' for fashion victims IMHO.

george

Edited 28 June, 201214 yr by sk4gw

I'm not worried about it being removable but my only worry is if its made from tubing how will it fit in terms of being to thick to allow the back seats to remain fitted. I'd prefere the lattice as above.

sk4gw, thanks for that. Shall i put you on the list ;-)

Your welcome.

Hope you get the one you need cheaper or even free by getting some sold on to others that really need them as well.

Great service you are providing in being so helpful to them.

george

George - I was under the impression that whilst the word "chassis" did originally mean the ladder-esque slab of material everything used to be bolted to, its general use has evolved to encompass the running gear and its attachments? Having seen many different vehicles being built up from assorted bent pieces of metal, there is still a set of "chassis rails" or main load bearing members in virtually all monocoque bodies these days. Certainly is on the one I'm staring at being built today..

Agreed that there is compliance in many other parts of the system; virtually all is intentional. The biggest advantage in bracing a "chassis" to to prevent compromise such that an unwanted change in one component (the shell) allows the others (dampers, springs, bushes etc) to have only their effect on the ride and handling. The question is whether or not the benefit is either a) good value or doesn't transfer the problem to a greater weakness. I've never heard or anyone complain about the handling abilities of a car with a roll cage installed getting worse...

One of the stiffest bodyshells produced in the 20th Century was the Austin 1800 - and I think its figures are still not beaten by many vehicles today. Funnily enough, it didn't have a hatchback.. OK, its stablemate the Allegro was de-engineering too far such that you could pop the rear window out by jacking it up on one corner, but they also over-compensated for panel springback in the press tools...

The downside of stiffening up the shell/chassis is increased NVH - which is something 90-odd% of car owners don't want. Those who prefer their cars to be in "quick mode" more often than that are happy to put up with the trade-off.