I've read about twelve threads on NAM about Strut Tower Mushrooming; and of our four MINIs, only one-- the 05 MCSa Cabrio has it---passenger side. There is enough "rounding" on the engine-side of the tower that it is noticable, especially if you place a straight edge on it.

Yes, the car has 17 in stock MINI wheels (R-91 Bullets) with Runflats; but it also has a bent R/F wheel on the inside lip of the rim (out of round by 9 mm) so I have a pretty good idea where the mushrooming came from; but given the amount of damage, I can't figure out when it happened. It must have been a pretty good whack to cause the damage to the rim, but there's only a slight tear in the sidewall, right next to the rim, which has a significant abrasion. I only discovered the rim damage and mushrooming when I was rotating the tires yesterday after 5,000 miles.

All of the threads I've read discuss the problem and possible causes (poor design, lack of suspension travel, run flat tires' stiff sidewalls); remedies (body shop repair, heavy hammer and block of wood, etc) and preventive measures (dump the run flats, smaller diameter wheels, Ireland Engineering fixed/adjustable camber plates, M-7 strut tower plates, different shocks, etc)

But for all the reading I've done, I don't believe that I've seen what the effects are if you just leave the towers as they are and drive the car. OK, I have mushrooming.....what does that mean in terms of the car's drivability?
Is it now unsafe? Can I expect it to get worse? What does mushrooming mean in terms of the R/F wheel's camber and alignment?
(Yes, I'm going to replace the wheel)

Can someone please provide me some guidance in this regard? What are the downsides to just living with the mushroomed R/F strut tower?

Thanks in advance for your comments.

Charlie

 

Charlie, sorry to hear that you have been bitten by the mushrooming bug....

At the extreme (e.g. the mushrooming turns your strut tower into a something that resembles the top of a bell) you will probably have alignment issues and the car will certainly look off-kilter. Collateral impact of the alignment issues is likely increased tire wear (even with the runflat tires' stiffer sidewalls). Collateral impact of the car looking off kilter could be people beeping and asking if you have a flat tire?

I tend to doubt the lack of safety. Otherwise, BMW would have had some fairly serious pressure put on it by the U.S. Dept. of Transportation to order a recall.

It will likely get worse if you keep the 17 inch wheels and runflat tires. Also, the road conditions in our neck of the woods aren't getting any better. With the rains, a bad situation is now deteriorating.

That is the area of potential exposure. If the alignment is out of spec and since camber is not adjustable absent adjustable camber plates, you could have tire wear problems. As a first step, I would see what the alignment is currently like compared to stock specs.

See my last comment above. You really need to see where the alignment is presently at. If you continue to drive the car without taking steps to stop potential future mushrooming, at some point you will suffer collateral consequences. How soon that will be is a function of how severe the current mushrooming is and how much exposure the car has to further mushrooming opportunities.

 

and you may not know it, but the strut top has a rubber bushing that settles over time as well, so this isn't as rigid a dimension as one would like to think. You'd be fine driving on it as it would take a lot of motion to take the car out of a range where it could be alligned.

It won't affect allignment too much, as the motion is mostly vertical, and the camber is pretty constant as the wheel moves vertially. While toe and camber couple pretty good, toe and suspension compression don't (this is called bump steer, and our cars don't have much).

FWIW, I had one of my struts out a few days ago and decided it was time to "correct" my shock tower. Wood, 4 lb hand sledge, and a few minutes work and I was done. but wear hearing protection, it's noisy!

Matt

 

If one is severely mushroomed and the other is fine, you might have some minor issues with tire wear or steering feel in one direction or other, but it's probably not a serious issue. I JUST had my towers pounded back down the other day before having the IE fixed camber plates installed. Both towers were mushroomed, and the upper strut mount rubber so squished down (up?) that the car with lowering springs now installed also, sits slightly higher in the front than before. I've been running 16" non-runflats for almost two years, and I'm sure I've been driving around on the mushroomed towers for nearly as long, if not longer. I never noticed any problems (didn't even know about mushrooming until I read about it here a couple months ago). No unusual tire wear, no pulling or drifting, no strange noises, no scary handling.

Id get the one tower pounded back down, then install the reinforcing plates or strut tower brace, just because I think that even though it's probably not a serious issue, it's not supposed to be that way.

 

Low profile runflat tires don't help. This is one of the reasons I refuse to put low profile tires in my MCS. 22K miles and no mushrooms.