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MF Review: M7 Strut Tower Reinforcement

Of of the downsides to a stiffly sprung car, stiff side-walled runflats and horrendously bumpy roads is a potential for strut tower damage. It is a problem that has shown up on more than a few MINIs in the form of strut tower “mushrooming”. This damage will effectively create alignment issues and, at least, cause dealers fits trying to straighten it out. But what concerns most MINI owners is that this damage is routinely not covered by MINI dealers. This can leave owners with hundreds of dollars worth of repair work needed for a properly aligned car.

The M7 Strut Tower Reinforcement Plate rectifies this potential issue by doing what the name suggests: reinforcing the strut tower. The SRP (as it’s called by most owners) can be best described as a machined aluminum plate that reinforces the MINI’s sheet-metal and shock plate. The idea is that this will create an ultra stiff top surface that will not flex during daily battles with potholes.

The M7 SRP is dead simple to install and should take just a few minutes from start to finish. For those looking for mods that instantly make your MINI feel different, you’ll want to look elsewhere. Instead think of the M7 SRP as insurance in the form of two little black metal plates under the hood.

With a product like the M7 SRP, performance can only be measured in one parameter: does it work or not? And there’s the rub because you really never know if it’s working until, well… it doesn’t. However I will say this; strut tower mushrooming is a very real issue and the SRP provides the best defense out there other than actually inventing the long awaited hover MINI.

Perhaps more to the point, I’m happy to report after three months of use my MCS (equipped with 18″ wheels) has suffered no ill effects from the 3rd-world road conditions so prevalent in and around Chicago. And during that time I’ve encountered several potholes of glorious proportions. The kind that cause you to bite your tongue, chip your tooth and hit your head against the roof in that order.

So is the M7 SRP worthwhile insurance for those of us living in areas with poor road conditions? For MINI owners who appreciated piece of mind and don’t care for expensive surprises under the hood, the resounding answer would be yes. And with their clean and purposefully design, they look the business too.

MotoringFile Rating: 4.5 (out of five)

Where to Buy: The M7 Strut Tower Reinforcement Plates are available from M7 Tuning for $109 plus shipping.

Written By: Gabe

  • Edge

    I have always had one big concern about the STR… what limitations does it put on installation of a STB (brace)? I would hope that at the very least, M7 makes an STB that is compatible with their STR, but I imagine that the STR prevents installation and use of other STBs (such as the JCW one, which I have). Please correct me if I’m wrong, inquiring minds want to know. :)

  • Kennedy
    what limitations does it put on installation of a STB (brace)? I would hope that at the very least, M7 makes an STB that is compatible with their STR, but I imagine that the STR prevents installation and use of other STBs

    Edge – M7 makes their own STB that comes with slightly different but functionally similiar strut tower reinforcement plates. I think they’re all anodized black now, not brushed aluminum as shown.

    As far as fitting other STBs, I’m not aware of any that are compatible, as both the M7 plates and the STB are looking to use the same strut tower bolts for mounting.

  • YuccaPatrol

    For the first time ever, I am interested in an M7 product now that I have just repaired one mushroomed tower and replaced both of the strut mounts.

    Nice work!

  • Trick

    After researching this issue, I put these on my car within 3 months of ownership.

    Insurance with a $107 one-time premium? Worth every cent.

  • Mark

    Sounds like cheap insurance.

    Athought it doesn’t look as stout as the M7 STR, I wonder if the JCW STB would provide some of the same benefit.

  • agranger

    I would think that any strut tower brace that has a beefy looking mounting plate on each strut tower (one that fits flush against the top of the tower) would provide a similar protection. Unfortunately, very few of the STBs fit like this.

    I’ll be looking at one of these two mods soon.

  • jbing

    How obvious is this mushrooming effect to an untrained eye like mine? I have had H-Sport springs on for over a year now with my crappy runflats but luckily there isn’t a lot of potholes around my town. It is fun to try and avoid them though too.

  • curv872

    It’s SRP, not STR.

  • Kevin

    After lowering my car on M7 springs a few weeks ago, with plans for coilovers and camber plates in the future I installed these as inexpensive insurance. They are nice & beefy and should prevent this specific problem. I would like to have installed the entire STB but didn’t want the added expense (for now).

  • Trick

    Oh. . . I should say, I didn’t go with SRB because I didn’t want to get punted out of GS. Although to be safe, I’ll probably pull these SRPs for non-local events.

    Speaking of which, it’s important not to go Grape Ape when tightening those nuts. I think M7 spec’d as little as 25 ft/lbs when reinstalling.

  • Jono

    For those readers who live in California…

    CalTrans website has an insurance form that motorists can file claims against Caltrans and/or their contractors for poor road conditions leading to suspension damage. I can think of quite a few San Francisco Bay Area roads that have the potential to cause shrooming towers and mis-aligned wheels.

    Cheers

      Jono
    
  • http://paulr.us Paul

    Great review. I couldn’t agree with you more Gabe. For the price, every MINI driving on less than perfect roads should have a pair of these.

  • Blomm

    I just picked up my Mini 6 days ago. But I’m definetaly getting these strut tower plates. It seems like a no brainer to me.

    I would really like to know if the plates that come with the M7 STB are the same. If so them I might just go with the STB and get the benefits of both.

  • Max

    I was going to get the M7 STB and kill two birds with one stone. But I read that there’s clearance issues under the bonnet with the insulation. So I just got the plates.

  • Dave

    What response has anyone gotten from MINI on warranty coverage? I guess I have a hard time accepting that a stiff suspension and runflats that are all factory equipment will cause non-warrantable repairs by driving on roads with POTHOLES! What roads DON’T have potholes (I live in the Indianapolis area). It’s not like you’re taking if off-road. . . $107 seems like a lot of money to me, but maybe that’s because I’m still trying to justify my $26k commuter car (MCSC) to my wife. . .

  • http://www.dickdavid.com dickdavid

    Will these work on both Cooper and Cooper S? I think I know the answer to this question, but I wanted to make sure.

  • Brian Hsieh

    Does this mean that if we use M7 SRP/STB instead of JCW’s, the warranty might be void due to the use of unauthorized/unapproved modification parts on Mini?

    Do we need longer screws cuz of the increase of thickness after applying the plate?

  • Bogie

    Not covered by warranty? And to have to add a part to correct the design defect is simply ridiculous.. Such BS. I must look at other cars.

  • Mike

    Good stuff. Has anyone tried the under carriage brace system made by them? I’m curous about a review on that. The labor seems far less intense and easier for the do it yourselfer.

  • http://www.motoringfile.com/ Gabe

    Good stuff. Has anyone tried the under carriage brace system made by them? I’m curous about a review on that. The labor seems far less intense and easier for the do it yourselfer.

    We’re installing one this weekend with a review to follow.

  • Trick

    Brian you don’t need longer screws. In fact, the strut towers have studs pressed into them. What you remove is the nut on top.

    The plates (and bar I believe) are machined to give you plenty of thread to grab hold of when reinstalling them.

    When in doubt, contact M7. They’re stand up guys. I think Peter even tried to talk me out of buying them since I was 16″ wheels at the time and was deemed to be low-risk.

  • Crashton

    Bending the strut turrets was a concern to me so I bought the M7 strut brace to get the plates in combination with the strut bar. The plates for the strut bar are essentially the same as the ones reviewed here. The only difference I see is that the ones for the strut bar have a place machined out to take the cross bar mounting. As far as clearance issues go, yes there is a bit of interference on my 2006 MCS. I soaked the underhood sound insulation with water & then shut the hood. I kept it closed for two days & that let the insulation conform to the bar. It’s not perfect, but it’s close enough for me.

    dickdavid, I believe those plates will go on a MC with no problems. I don’t think the cross bar will work on a MC though.

  • Dave
    The plates (and bar I believe) are machined to give you plenty of thread to grab hold of when reinstalling them.

    With the SRP and the stock strut mounts, there are zero threads protruding. Standard practice is to have at least two threads protruding beyond the nut. This is because the last two threads or so are tapered (to make installation of the nut easier). As a result, the last two threads are not fully engaged by the nut. The remaining threads are the only thing restraining the plate when a strong vertical load is applied to the strut tower from below.

    The lack of threads beyond the nut was one reason I removed my SRP’s when I had my stock strut mounts. The other being that I wasn’t comfortable reinforcing the backing structure of the strut towers while continueing to use the stock strut mounts (which have a demonstrated history of developing cracks).

    As a result, I now run the SRP’s in conjunction with camberplates that do have longer threaded studs and there are now multiple threads showing beyond the nut.

  • Blomm
    With the SRP and the stock strut mounts, there are zero threads protruding. Standard practice is to have at least two threads protruding beyond the nut. This is because the last two threads or so are tapered (to make installation of the nut easier). As a result, the last two threads are not fully engaged by the nut. The remaining threads are the only thing restraining the plate when a strong vertical load is applied to the strut tower from below.

    There is something I hadn’t thought of. Anyone else have an option on this?

  • YuccaPatrol

    I think I am responsible for bringing up this issue.

    Yesterday, after having my strut mounts replaced by my very experienced BMW/Ferrari mechanic, I showed him the photo of the plate from the M7 website to see if he thought I should order a set.

    He expressed concern that it was not “prudent” to ever use a stud that is too short to allow the nut to fully engage the threads because the strength of the bolt/nut connection would be signifncantly diminished.

    At this point, I do not want to strengthen the sheet metal if it means weakening the critical connection between my suspension and my MINI.

    Since the strut mounts have been redesigned and because it has taken 58k miles for one to crack, I don’t see any reason for me to go through the expense of having the suspension completely disassembled again so that longer studs can be installed to make the strut and reinforcing plate secure.

    When/if this occurs again or if I replace the suspension, I’d probably go ahead and install the reinforcement plates with longer studs.

  • http://www.trackfaq.com MINIAK

    I just installed some KMAC camber plates instead. Costs over twice as much, but now I can dial in lots of negative camber, or none, with just a few turns.

    Of course this is not necessary for the majority of Mini owners, but those that like to do some track days, this helps tremendously towards saving the shoulders of your front tires (and it helps the turn-in performance).

  • rkw
    With the SRP and the stock strut mounts, there are zero threads protruding. Standard practice is to have at least two threads protruding beyond the nut.

    How about using the type of nuts that MINI provides for the JCW strut brace? I believe they have a sleeve that extends down along the bolt for additional thread contact.

    Has anyone tried the under carriage brace system made by them?

    I have the M7 Under Strut System on my MC convertible. I highly recommend it for all convertible owners. The convertible has a significant amount of body flex that makes the car respond with a bit of delayed reaction and loose feeling. The M7 USS improved the handling with more immediate and accurate response. Honestly, when I first got the car I didn’t understand why there was so much hype over MINI’s “go-kart handling”. Now I feel that I really have it.

  • http://www.motoringphotography.com Dave
    How about using the type of nuts that MINI provides for the JCW strut brace? I believe they have a sleeve that extends down along the bolt for additional thread contact.

    I haven’t seen that nut, but it does sound like a good way to get more threads engaged. You may have to use a drill to open up the holes in the SRP’s to be able to get the sleeve to fit.

  • rkw

    You can see a drawing of the nut for the JCW strut brace nut in the Installation Instructions. I don’t have a strut brace on my car yet but I plan to get a set of these nuts for whatever brace I put on.

  • Vanwall

    Speaking as one experienced in the fastener field, the hex nut should have full engagement of threads for the full height of the nut – they are engineered for this. A hex nut’s height is approximately 83% of the bolt’s outside diameter, which is due to the different mechanical requirements between internal and external threads, and this leaves the right amount of engagement to obtain the correct torque values for the nut – there’s considerable history on incorrect usage, and they don’t make ISO standards for nothing. If a Finger-tight Malcolm is telling you any different, he’s depending on luck only.

    I’m not saying there won’t be full engagement for this particular application without seeing one in real-life, but no threads protruding is not usually a good sign unless someone has done some very careful measurements to account for length and thread quality variations – and I’m talking Military Standards here, not SAE. I’m not too thrilled with all the additions to the strut towers as it stands now – do any of them have different fasteners if required? Safe Solution: Get longer studs.

                     BCNU,
                  Rob in Dago
    
  • http://www.motoringphotography.com Dave

    rkw: the nuts shown in part 1, figure B, are very similar to the ones I was thinking of. So, yes, those would be a good alternative.

    The one thing to check is the length of the sleeve section. Just double check that to make sure it isn’t sticking out the bottom of the SRP when installed. If the sleeve is longer than the thickness of the SRP then the SRP will not be clamped and will move freely if the strut tower deforms. You want the sleeve section to be a little shorter than the SRP is thick at that point so that the bolt torque developes some (see warnings above about not tightening the nuts too tight) clamping pressure.

  • Art

    OK I just ordered these after reading about them this am. Now I’m getting concerned. I am not a tech savvy person. 2 questions:

    1. From the pics [even on M7 website] the nuts are flush with the top of the bolt with no threads showing] — is this acceptable or not??

    2. Will the installation void the MINI warranty??

    Thanks

  • http://www.motoringfile.com/ Gabe

    Art – I personally wouldn’t be concerned about either question you posed.

  • Art

    Thanks Gabe

  • vsmini

    i installed the M7 Strut brace and it fits great. the hood buldged intially but i did the soak and slam method and the bulge is gone. It looks really great and fits over my Webb CAI.

  • YuccaPatrol

    As far as I know, there are no reports of anyone having any problems with the studs being too short to make full contact with the nut.

    I may very well be a Chicken Little here, but I won’t ever feel good about a setup like this if I do not have full confidence in the security and strength of the stud/nut connection. My mind just won’t accept weakening one part of a system in order to strengthen another.

    I’d guess that most MINI owners buying these are looking for a quick and easy fix and don’t want to have to disassemble the suspension in order to replace the studs when it is so much easier to just loosen and tighten 6 easily accessed nuts.

    Most people, especially those that don’t track their cars or engage in other high performance driving activities, will be just fine with the simple and easy installation using the short studs.

  • Rick Bro

    The studs are under constant weight of vehicle. Nowhere to go. The nuts keep the strut guide from from falling out of strut tower when airborn, or jacked up. When my mushroom occured it took the strut guide. It was bent just like the strut tower. No harm to the rubber portion. The three studs were looking away from center with the bulge. I got a new guide and the M7 caps. Straightened strut tower. Yes a few threads lacking of a full pull, but for normal driving you could throw them away.(kidding) The M7 cap should counter the mushrooming to a point, I believe much higher than without. A massive hit anyway is gonna take something weather you have or have not. I’d rather buy the guide as its the cheapest. I see maybe the rubber cracking now with my M7 caps, with minor jolts, and normal driving. I think its a good support system.

  • VBG

    There have been reports from a few dealerships that the 06 strut towers have been re-designed topside to help prevent mushrooming. Is there any truth to this?

  • Bill

    DON’T “EFF” AROUND – ORDER EITHER THESE OR THE STB.
    I did in fact notice a marked difference in handling as a result of the brace, but I bought it primarily for reinforcing the towers.

    Seriously, order these a couple of weeks before you take delivery of your MINI, and install them before pulling out of the lot.
    Cheap peace of mind.

    Thanks for the review, Gabe.

  • http://stylizedfacts.com/coruscation/autos/mini/ dc

    Rolls Royce stock shock strut tower reinforcements] (http://www.stylizedfacts.com/STi/2006/10/robust_shock_towers_by_rolls_r_1.html)

    Looks very stock.

  • http://stylizedfacts.com/coruscation/autos/mini/ dc

    [Rolls Royce stock shock strut tower reinforcements] (http://www.stylizedfacts.com/STi/2006/10/robustshocktowersbyrollsr1.html)

    try the html again …

  • http://stylizedfacts.com/coruscation/autos/mini/ dc
  • http://stylizedfacts.com/coruscation/autos/mini/ dc
  • Jim

    I’m obviously not an engineer, nor have I taken the time to read through the numerous links above, but I am having a hard time understanding how these SRP’s can actually make a difference . . .

    As they are positioned on top of the bodywork and after the fact, so to speak, what prevents them from merely being punched up on impact? I’m taking the discussion regarding the length of the studs to be in reference to this . . .

    Would it not be a better investment to have the camber plates replaced?

    Also, I’m keen on installing a STB and not too crazy about the fact that the SRPs compromise the clearance.

    I’m not trying to be presumptious . . . just trying to gain a better understanding.

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