Hello,

I am a noob to NAM and planning to purchase either a R53 (2006-2007) or R56 (2007) sometime in the near future. I scanned countless number of NAM treads discussing mushrooming (and even searched google images) but I am having difficulty interpreting photos of struts towers that have mushroomed. I saw a couple of images of damaged towers but for the life of me, still cannot see what is wrong with them. Can anyone help me better this? (or draw a red arrow to what I should be paying attention to when looking for used MINIs?). Thanks.

 

Okay,

https://www.northamericanmotoring.co...94-post81.html

I actually replied to my own post. Amazing to see these photos (from someone knowing little about MINIs)

 

Hi toughluck -- good on you for continuing to research your question on your own.

The picture you found seems to show a pretty extreme case. I think in a lot of instances it might be a bit more subtle. The giveaway clue for me has always been the degree to which the three strut tower bolts are not parallel to each other. I think they are pretty darn close to parallel--if not fully so--when there's no mushrooming. This is corroborated by the design of most aftermarket strut tower plates, which seem to have a planer surface against which the mounting bolts are tightened.

In fact, in the pic you found labeled "flat tower" I would say there's already a bit of mushrooming starting to manifest itself.

Edit: These are 1st Gen observations only...I'm not sure how different the design is on the R56

 

When I am shopping for a 2006, should I expect all vehicles to have a little bit of mushrooming? At what point should I back away? After focusing on the three strut tower bolts, I do see the differences now, and I also notice the pic labeled "flat tower" is not exactly parallel either.

If I buy a used 2006 with a bit of mushrooming, should I assume 2x4 and buying an M7 will more than likely permanently address these problems?

 

Pounding it down flat is a really bad idea unless you can't get the splayed bolts out of the holes. Pounding on it just causes metal fatigue in the thin sheet metal, won't bring it back to truly flat (it will wrinkle instead of flattening) and that's not what you want there.

Instead, get a Mini-Madness or Cravenspeed tower protection plate that goes UNDER the tower top, between the strut and the sheet metal, protecting it from impacts from the bushing-carrier. It's a much more effective approach than any tower-top plate.

It's not a bad idea to replace the strut-top bushing/carrier too, if it is badly bulged.

BTW, you can evaluate mushrooming with a short straightedge across the tower top. It started out life flat on top. The splaying of the bolts is just telling you that the bushing carrier is bent upwards from the middle.

 

Well, you're starting to venture beyond my level of mushrooming expertise so I'll just share my opinions and we can wait for the NAM greybeards to weigh in and refute or support.

Mushrooming is such a commonly observed phenomenon in the 1st Gen MINIs that I can't imagine a little bit of it being dangerous or prohibitive. Just recognize that the worse it is the more likely you may have front end alignment issues--unless it has been realigned since the mushrooming. Also, repeated bending of the metal through mushrooming and pounding it back flat will weaken the metal as OldRick states and make the car more susceptible to repeat occurrences. I'd be leery if I observed cracking paint or a damaged lip to the strut tower opening, which would be a sign that previous owners had been conducting some 2x4 action of their own.

When I purchased my M7 STPs a couple of years ago, I did so as a preventative measure because I thought my strut towers were perfectly flat. When I installed them and as I was torquing down the bolts, I could tell it wasn't entirely true. With two bolts snug on the passenger side, the plate was still about an eighth of an inch off the tower at the third bolt. As I snugged down the last nut I could feel and even hear the strut tower being "flattened" by the plate. So in my case, I did have a minor case which never caused a problem prior to the plates and has never been a problem since. The under tower plates and camber plates are probably better measures if you're willing to pay the extra $$ and do a bit more involved install.

As to how much you're willing to live with, that's a personal call. Recognize that severe mushrooming could correlate to the car having been driven hard, which might end up manifesting itself later as other maintenance issues.

 

Sorry, but that was not a corrective action, what you heard and felt was deformation. Under low light conditions, shine a light from behind and under the upper plate and the illusion of occlusion will be shattered.

The first photo is of a healty strut tower, take a look at any 1st generation tower and it will "appear" to have an angled engine side rear bolt.

Having performed the corrective flattening several times on other MINIs, the procedure does not create wrinkles. Any ripple that has occured from the guide support profile being stamped into the metal during the course of the mushrooming act, will remain, but it is not created by the fix process. So far none of the repaired vehicles have exhibited any stress cracks. The alternative is replacement of the skin section of that area, a far more indelicate procedure involving air hammer/chisel, grinder, and welder.

Kudos to you toughluck for developing educated observation skill before the purchase. Another item worth inspecting on 1st gen models is the front lower control arm bushing. This isn't as easy as looking at the strut tower from eye level, but a quick look while under the hood, down behind the engine on the passenger side, can reveal a completely seperated bushing. To detect a torn bushing will require a test drive with a hard turn while on the brakes, a close up view, and manipulation of the control arm with the wheel removed.

 

Um, K - you cannot make a stretched-out piece of metal flat again - not ever. Once it has stretched into a dome, it is literally impossible to flatten sheet metal again.

The domed metal winds up creating what I called "wrinkles" for lack of a better term, or creating splits in the metal. These may wind up deforming the stiffening ribs and not be apparent, but one cannot flatten a dome of sheet metal any more than you can make a flat map of the earth without distorting distances - it's geometrically impossible.

The geometry of a dome is cannot be flattened without the stretched-out radii of the bulging parts going somewhere, because the sheet metal will never ever become thicker again. That is what would be required to make it flat again, and there is No way to make that happen.

Sorry about that, but mushrooming is pretty permanent...

You can stop it from getting worse, by putting something flat under it, which basically redistributes the stress to the edges, where it is unlikely to progress, and which keeps the crappy OEM bushing carrier from bulging again, by using an under-tower reinforcement plate.

 

The tower metal is not absolute flat to begin with, and if forced flat, you've gone too far, but that's splitting hairs. Your welcome to your speculation, but it doesn't make my experience with this repair method for the majority of deformation cases any less valid.

There is indeed a point where only replacing the metal is appropriate but this degree of "no turning back" damage is rare.


As I mentioned the strut tower is not flat to begin with, placing a flat object beneath it will actually concentrate the load on edges (as you mentioned) and not evenly across its surface. Remove any camber plate or add-on under plate after it has been in use for a fair amount of time and that fact will become evident from the difference between clean and dirty impressions. What happens in that load arrangement is added stress on the seam's spot welds. I know of two cases where the tower seam ruptured in off-track excursions where camber plates were used, however, I'm aware of no instances of post mushroom fix failures of the strut tower sheet metal. You are overthinking the repair consequences OR.

 

That is something I've occasionally been accused of...

Just out of curiosity, those cars that damaged the tower: they wouldn't have been running adjustable camber plates with no rubber in the bushings and coil-overs set firm for the track, would they?

 

this thread needs to be stickied. it has very valuable info in it that could lead to many other good searches.

I dont feel as worried about this issue as i did before.

 

i too am a noob at this, so what are the "fixes" when the mushrooming is really bad? will the mini dealer take care of this? or will us owner's and potential owners have to fix this ourselves?

 

first read this...
https://www.northamericanmotoring.co...ollection.html

it helped a lot. then search "mushrooming" in the advanced search under 1st gen minis and that should give you everything.

basically look for either the M7 STB or get the Ireland Engineering strut mounts or both.

it will explain the repair procedure also

hope that helps as i am no longer worried and fully prepared to get an 05-06 cooper S now

 

I dont get it, lol. Mainly because I have no idea what I am looking for. Can someone possibly post some pics of what 'mushrooming' looks like, and maybe a before and after? Im in an R50, thanks