MF Review: M7 Under Strut System

This system has a flaw. The frame under the motor is made to collapse in a collision. This provides resistance to that function of the frame. I’d hate someone get hurt because their motor came more into the passenger compartment than under the car in a collision.

This system has a flaw. The frame under the motor is made to collapse in a collision. This provides resistance to that function of the frame. I’d hate someone get hurt because their motor came more into the passenger compartment than under the car in a collision.

Can you qualify your ability to make such a statement? Do you have an engineering background? Just a guess but, the bolts and joints would probably break when put under stress from that angle. It’s a rigid system designed to connect the frame. I feel it would break before bending. I’m not an engineer just a gear head car guy that has in stalled an m7 USS.

Anytime you add a mod you’re playing with the original engineers design and you have no way to know the effect. MCV has a valid point but if you’re a safty nut then you’re probably not in need of such a device, anyway.

Gabe, how much does all this weigh? What was the milage on both cars in the comparison and how were they setup? How much could normal differences between the cars account for the differences you felt?

Yes, what does it weigh? The gain in handling decribed I also noticed with the OMP chassis brace under the engine and additional directer turn-in. I wonder if the points mentioned for the M7 under strut system will also be that noticable if one has a front under strut brace from OMP. In addition I wonder how much of the described gain can also be accomplished with a upper strutbrace behind the backseat?

I’m sure the bolts would break. I too have this installed on my MINI and love the way it makes the car feel. I was just trying to bring attention to the fact that it could possibly hinder what the engineers were trying to accomplish with the front end.

But why are all the pics labelled “R56 Cooper S”?

Thank you rkw for that info, maybe the difference is less on a hatchback but probably the M7 USS will do good work together with the OMP. 10 lbs is not too bad, I’ll get the aluminium GP rear trailing arms, saves 15 lbs :)

Berthil, the M7 USS and OMP lower frame brace cannnot be fitted together at the same time. Unless you meant an OMP upper strut brace.

This seems more like a track oriented mod, but a street MINI would undoubtedly benefit – I like the idea, and the product seems to live up to the promise. Stress transfers would hopefully be minimal for the life of car.

I’m not so sure anyone should be throwing around opinions best left to structural engineers regarding the crash-worthiness, or not, of any product – just about any performance mod changes the dynamics of a car, so adding anything is your responsibilty, regardless.

             BCNU,
          Rob in Dago

Oiy! …

Was the atmospheric pressure at the time of each run the same?

Was the decernable percipitation and humidity during each run the same?

… good lord guys.

Nice review, thanks for the information it covers the basic knowledge one would want to gain I think. For the race nut they’d already know or would seek their own further investigation for the finer facts.

Earl Harris Oct 19th, 2006 Link Has anyone tried it on a convertible Mini? I had a Mini S convertible and sold it because it had to much flex if this would fix most of the flex I would buy another one because I love the car. Thanks

See my comment above

Having said that, I have a few comments to the comments. Actually, I AM a mechanical engineer who happens to work as an auto-safety engineer. I can understand the comments about the safety concerns and I will say that really I shouldn’t comment, nor should you fully take what I say as gospel. The simple answer is (as someone else pointed out), that MINI’s chassis engineers specifically designed the car to perform a certain way in a crash. This is not only to have the vehicle crush in a certain manner, but also control the way it slows down as it is crushing. For example, if it slows too suddenly, by the time your seat belts fully “catch” you, you’re traveling much faster than your car and experience a more sudden stop. Compare this to the scenario where the vehicle begins to slow gradually at first, allowing your seatbelts time to “catch” you, and you ride the rest of the crash down “more gradually” (everything is relative when you’re talking about a serious crash) with your car.

While almost all modifications that you make to your car fall into the category of not affecting your vehicle’s crashworthiness, this one most certainly does fall in the category of POTENTIALLY affecting the crashworthiness. HOWEVER, in almost every vehicle design, the car is designed to crush from the front to the back. That may seem pretty obvious, but generally a car first crushes at the bumper, the radiator and on back, etc. One of the many reasons for this is to protect the integrity of the occupant compartment. Simply put, you need space to survive; you need as much space to slow your body down as gradually as possible. The USS as I understand it, mounts from the front wheels back, and also has a stiffener about mid-point along the wheelbase. So it shouldn’t dramatically change the INITIAL response of the car in an accident.

Now, once you get to the wheels (to the USS) then yes, perhaps it could start to change things. Regardless of whether the bolts fail or not, the brace is going to have to go somewhere as it crushes. I not sure exactly of everywhere it attaches to the car and specifically how strong each of those connections are, but it will either A) pull or shear the bolts off, or B) crush with the car. I’m pretty sure those are the only two potential answers. If it is A, then it’s likely it will not be a big player in changing things. If it is B, then I would assume the long bars, the actual “understrut attachments,” will probably buckle and bend out of the way. If intact, then it will likely make the rest of the crash even slightly stiffer, thus a bit of a “harder” ride down, but by how much, it is impossible to say. Also, that additional rigidity would likely help to keep the occupant compartment more intact, which would potentially benefit the occupants, but again, it is impossible to say.

Ultimately, there is only one way to truly know the answer to how this will affect the MINI in a crash, but that would require resources far beyond what M7, as an aftermarket company could be expected to provide. I think putting something such as this on your car classifies as implied consent to changing your vehicle’s structure. It is unavoidable that this may change some of the crash dynamics. You can only answer for yourself how comfortable you are with that… but it’s on my wish list.

I did the suspension mods to my MINI one at a time so I could better evaluate the effect of each change. I felt like the USS made my car more settled, particularly during aggressive cornering when I am really throwing the car around. All in all a nice addition. Your review reinforces my observations.

Kennedy, Thanks for your comments. Hope your doing well in Winston

Tar Heel MINI Motoring Club

Vanwall – Thanks for the comments. I’m with you 100% about both the appreciation of a nice, quality bolt! I also agree that it seems stainless is probably fine, as evidenced by the performance of the USS in the review, the bolts are good enough to do the job as intended, plus corrosion resistant (and a little under-chassis bling). I think you are right, that whatever the insert in the sheet metal is, it is likely the weak link….

Twister – Thanks, I am back at Tech these days, but looking forward to catching up with the Tar Heels sometime soon. Just not the basketball team, go Terps (and Hokies)! 

DanC – ha, thanks for the vote. I wonder if that nomination would look out of place on my resume? 

Also, as an afterthought… If this were being sold at WalMart/Target, etc. and it was a car-seat, kids toy, or some other device sold to the everyday consumer, I would feel much more adamant that the mfg. company would be obligated to completely ensure that the product was safe in all aspects of its intended application. However, this is a product available to a small group of enthusiast owners, a small sub-set of owners of a particular car, I think it seems a well-intended solution to a specific issue. Like I said, you have to realize if you put this on your car, it is advertised specifically to affect the structure of your car. If it were more mass-market, I would definitely have a different stance on the issue.

-Eric