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Shock mount mushrooming
- Thread starter DMC63
- Start date
BMWZ4MC said:Is there an advantage over separate springs and dampers?Ed Doe said:BMWZ4MC said:
Ah OK. Yeah mine was back to divorced spring and damper when I bought it, but I went back to true rear coilovers when I bought a new set of intrax for it
Easier to set up, and a bit more travel without the inboard spring going coil bound
I'm torn though on whether I'm running a risk. I had lengthy discussions with Ms motorsport about it, apparently for our chassis the risk of turret failure is very low as the turrets are stronger than with the e36/46 chassis. I'd feel happier if I had the rear turrets tied into a rollcage but equally the first owner of my car ran true coilovers for most of the first 50k of its life, including multiple ring and spa trips a year - the car has probably seen more karrussel action than I've had hot dinners and the strut tops look absolutely fine! :lol: I think it's one of those things where it's happened to a few people who've made a lot of noise about it and it's caused a bit of a panic. I also think there's a misunderstanding/confusion between topmount failure (which is far more common but more often from very old parts or bad quality replacements failing) and failure of the chassis strut turret itself which appears to me to be vanishingly rare and often the result of corrosion or significant impact damage (ie hitting a rock or pothole!)
Just my thoughts anyway!
I agree, the risks are probably minimal given the car’s history and lack of evidence of harm so far. Also, I agree that top mount failure is likely misdescribed as strut tower failure in some cases.Ed Doe said:BMWZ4MC said:Is there an advantage over separate springs and dampers?Ed Doe said:Ah OK. Yeah mine was back to divorced spring and damper when I bought it, but I went back to true rear coilovers when I bought a new set of intrax for it
Easier to set up, and a bit more travel without the inboard spring going coil bound
I'm torn though on whether I'm running a risk. I had lengthy discussions with Ms motorsport about it, apparently for our chassis the risk of turret failure is very low as the turrets are stronger than with the e36/46 chassis. I'd feel happier if I had the rear turrets tied into a rollcage but equally the first owner of my car ran true coilovers for most of the first 50k of its life, including multiple ring and spa trips a year - the car has probably seen more karrussel action than I've had hot dinners and the strut tops look absolutely fine! :lol: I think it's one of those things where it's happened to a few people who've made a lot of noise about it and it's caused a bit of a panic. I also think there's a misunderstanding/confusion between topmount failure (which is far more common but more often from very old parts or bad quality replacements failing) and failure of the chassis strut turret itself which appears to me to be vanishingly rare and often the result of corrosion or significant impact damage (ie hitting a rock or pothole!)
Just my thoughts anyway!
Why not get a roll cage? There’s a German cage that bolts in that I would fit if I could. Unfortunately, they won’t ship to Australia. No one locally will fabricate one for our cars (I suspect because they’ve never seen one before, so it would be entirely a new project for them). If you’re interested, I’ll try to find the name of the company I contacted a few years ago.
If I'm not mistaken the bolt in cage is the Weichers one, which is nice as it is designed to work with the existing trim but is compromised for that very reason. It's great for proper harness mounting but does not tie in with strut towers so isn't any use for strengthening that area.Ed Doe said:
Weichers
Mine for example
HTHEd Doe said:
As you can imagine I looked into it a fair bit.The cage was done by a fairly reputable outfit, SW Motorsports, I'd be surprised if they hadn't saved the design. I would recommend them.
You need to be fairly committed to go down this route as you will kiss goodbye to ever having a 3 point belt again due to bulkhead removal. On the other hand the cage can be so much more efficient, mine mounts to the upper/boot floor behind the seats rather than the weichers which goes to the floor (so drill 8 holes through the floor). The actual cage itself is tiny relatively.
With the risk of a major thread diversion... The bulkhead is an interesting discussion, well in my mind at least! I used to have my upper harness eyelet mounting points drilled through a single skin piece of said bulkhead. Now granted, the 4(5/6) point harnesses spread the load as opposed to a 3 point, but if you look at how the 3 point is anchored (and through the size of the metal) in the bulkhead it made me uneasy continuing with the single skin eyelets.
I have no evidence to back this up but I have heard that the bulkhead structure doesn't significantly increase tortional rigidity of the chassis as one might think, but is there for 3 point strength and roll over protection (a legacy of it's e85 origin). It weighed a lot when we cut it out! 30kg or something iirc. Either way whatever was or wasn't lost in its removal is made up by the cage for sure.
Very interesting; the bolt-in cage is from Weichers. I stopped researching when I found that I wouldn’t be able to ship one to Aus, but I hadn’t realised that their cage doesn’t bolt to the shock tower. It’s academic for me at the moment, but I wouldn’t want a harness attached to a single skin bulkhead either.
The harnesses in my Exige attach to a harness bar that itself bolts directly to the rollover bar at pre-drilled mounting points. It’s very straightforward to fit, but the intended use of that car is somewhat different from a Z4!
If it’s still of interest, this is the thread on z-post I read back in 2018:
https://www.zpost.com/forums/showthread.php?t=1489265
and this is a link to Weichers:
https://www.wiechers-sport.de
Reading the Z-post thread again, a fair amount has been added in the last few years, including what looks to be a post by you Tom!
At risk of going back in the original direction of the thread, what have you done about your front strut towers?
The harnesses in my Exige attach to a harness bar that itself bolts directly to the rollover bar at pre-drilled mounting points. It’s very straightforward to fit, but the intended use of that car is somewhat different from a Z4!
If it’s still of interest, this is the thread on z-post I read back in 2018:
https://www.zpost.com/forums/showthread.php?t=1489265
and this is a link to Weichers:
https://www.wiechers-sport.de
Reading the Z-post thread again, a fair amount has been added in the last few years, including what looks to be a post by you Tom!
At risk of going back in the original direction of the thread, what have you done about your front strut towers?
I reckon it would probably be fine 99% of the time, but I came very close to a really big accident and ever since then I've gone as big as I can on the safety stuff.BMWZ4MC said:
Not me, someone posting the photos I put up here I think of my cage?BMWZ4MC said:
I had it welded, all seems fine. I'm of the mind to cut the tops off anyway and box it properly as the stock tower opening doesn't play well with the top mount bolt adjustments on top of the fact that they're not really fit for purpose.BMWZ4MC said:
TomK said:
I don’t blame you. I’m more cautious these days than I used to be, especially when there’s little run off.
TomK said:
He seemed to agree with your sentiments as well as liking your pics!
TomK said:
You’re heading in the direction taken by our friend in the deserts of Dubai… :lol: