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Thread: Bottomed out HARD

  1. #1
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    Bottomed out HARD

    Just bottomed the passenger side suspension HARD. Metal on metal sound ? not a good sound. I was VERY surprised how easily it bottomed. I have only driven this car for a few miles. It has 2100 miles on it (it?s an ?01) and the original Bridgestone run flats. Perhaps they have gotten even harder sitting around for 10 years.[

    I was coming up out of dip when it bottomed so there were additional downward forces. Along the right side of the road, the pavement had sunken in but it wasn?t a pothole or sharp edged. I drove back to the ?scene? to see if there was more to the sunken part of the road than I originally thought but it did not look that bad.

    Do these cars bottom out this easily and with a bone chilling sound?

    The spacing between the hood and fenders seems correct on both sides so I don?t think I damaged the frame. This car does not have the PP.

    Philip Thackray

    61115 Topaz/Crema

  2. #2
    With the run flat tires and stock suspension this can happen more easily than you might expect, which is why we have been imploring owners to ditch the run flats and fit the PP.

    The most important question is are the shock tower crowns still flat?
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  3. #3
    Z8Mania
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    I agree with Andrew, I would add you should change any tire that is 10 years old. My own personal rule of thumb is 5 years. Relative to the cost of these cars the tires are a small % and even if these cars were 1/10th of the value Id still argue to change the tires- the tires are the 2nd most important part of the car (you are #1). I'm also sorry to say that it sounds to me you had the kind of impact that could cause the damage. Don't get too freaked out just yet but I agree that you should have a look at that shock tower. Supposing the shock tower is not domed at all- in your shoes I would:

    1- immediately switch the tires to MPS2
    2- get the PP installed.

    If you have doming then its another issue that we will have to explore.

  4. #4
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    Andrew, Jerry,

    Thanks for the responses. The odd thing is, based on what I had been reading here about the shock tower and frame issues, I was being careful. I was in the 50-60 mph range on a Western PA back road that was not in perfect shape but the area in the road that bit me did not look all that bad. Curiously too, I have been thinking about replacing the tires (due to age and shock/frame concerns) and have been reading extensively here about the PP and shock/frame issues.

    The car is stored off site and the weather is turning back to ?late winter style? so I won?t get to check the shock towers for a few days.

    I have seen pictures of the PP. It looks like the rings on the shock tower help prevent the tower deformation. From what I can see in the pictures, it does not seem like the cross link does much to prevent damage. Maybe it improves handling somewhat.

    I have read here about switching to a softer suspension (Alpina) but wouldn?t that just bottom out sooner??

    While the rings may stop the towers from deforming, if the suspension can still bottom out so easily, it seems that I could eventually bend the frame. Can the tires make all the difference??

    If I have tower deformation, what then?

    Regards,

    Philip Thackray
    61115 Topaz/Crema

  5. #5
    Z8 Addict Scott Pettit's Avatar
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    The PP does not prevent tower deformation. It minimizes lateral torque on the frame which in turn minimizes movement of associated body panels. If the tower is distorted, it will need to be straightened out and the best folks to do this is a BMW aluminum shop of which there are 3 (I believe) in the country. Your dealer will set that up for you. If your budget allows, I recommend this route for the repair. If not, and you know a shop that is EXPERT in working with aluminum, then have them look at the car with an experienced (very familiar with the Z8) BMW tech on hand to discuss the cars nuances. Finally, get the PP installed.

    Also, take a hard look at the road as you may have a liability case with the city / county / state and time to file a claim is of the essance.

    Best of luck.
    Scott Pettit
    61930
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    Scott,

    Thanks for your suggestions.

    Relative to government liability for the road, the road was not that bad. That is one of the great disappointments about bottoming out. It was not a pot hole, just a smooth depression along the edge of the road. I was dumbfounded that I bottomed out given my speed and the road conditions.

    My 10 year old original run flat tires must be a large part of the problem. I have a ?97 six cylinder Z3 and a ?98 540i Sport that I have driven along these roads for years, driving them harder than I was the Z8, and I have never bottomed out.

    Regards,

    Philip Thackray
    61115 Topaz/Crema

  7. #7
    Philip, though not a common fault on these cars it does occur to me that you should check your shock, as I have heard of shocks failing early in life. It is rare, but it can happen. If there is an wet oily residue on your shock that could explain it.

    There is a thick white nylon ring on the OEM Z8 shocks, and that is what you feel 'hitting' when the car bottoms out. It transfers the weight right up into the shock tower crowns, while with the non-run flat tires you will get a great deal more absorption from the tires before the shock bottoms out.

    The Alpina suspension uses a different shock and spring, and while more compliant it also doesn't seem to have nearly as much propensity to bottom out. In 5,000 miles of rough and bumpy Californian back roads I haven't had one bottom out moment, while on the OEM suspension I've bottomed out several times in my different Z8's over the years.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

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    Andrew,

    Thanks for the info! I will check the shock next time I get to the car. The ?ride? of the car does not seem like a ?bad shock ride?. It is firm and responsive with no wave-y motion. Is the Alpina change just the shocks and spring? Did I read somewhere that the Alpina conversion lowers the car slightly? Do you change the front and the back?

    -Update to scene of bottoming out-

    Upon further inspection, the road hazard was far worse than I could tell from the driver?s seat of the Z8. From a low vantage point it looked like a depression, however, when surveyed this morning from my SUV, I see that there is a HOLE at the bottom of the depression. And I mean hole ? it goes through the road to a culvert pipe beneath the road. The sides slope down to the hole ? that is why I could not see it while approaching in the Z8. After I hit the hole yesterday I returned in the opposite lane trying to see what I had hit. I could have seen the actual hole from there but I was concentrating my search about 20 yards up from the actual location of the hazard. So bottoming out may have been normal under these conditions.

    Regards,

    Philip Thackray
    61115
    Topaz/Crema

  9. #9
    Then I would seriously photograph and document the hole, and get your insurance company to inspect it as well, because if your shock towers are domed you will end up with a $50k repair bill, no joke.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

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    Andrew,

    I don?t carry any collision insurance on my vehicles (seven of them right now). (PA only requires Liability insurance). I figure past some point the statistics go in my favor across a lifetime of owning many vehicles. This one may be the time I get to ?pay the fiddler?!

    Did you see my Alpina questions?

    Regards,

    Philip Thackray
    61115 Topaz/Crema

  11. #11
    There is a full review of everything you could want to know about the Alpina suspension here.
    Andrew Macpherson

    Expert Z8 Inspections, with full support for both Z8 sale and purchases.

  12. #12
    Z8Mania
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    Phillip, you should still go and document the hole because the town might be responsible. If you need to repair the shock tower I am afraid I think the only repair is to replace the frame section. Scott is right about the cross bar. But you should know the PP has a steel ring that mounts to the shock tower top AND bottom- so its a sandwich. If you need to get some kind of repair let us know as some of us might be able to help with contacts.

  13. #13
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    Thanks Andrew!

    Jerry,

    Unfortunately I live in Hooterville. Western PA, Butler County farm country.
    However, the road I bottomed out on is maintained by the State of PA. I?ll photograph the hole just so I have that in case there is damage.

    I?ll keep you all posted.

    Regards,

    Philip Thackray
    61115 Topaz/Crema

  14. #14
    Z8Mania
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    Actually the fact that the state maintains it is a good thing- deeper pocket. You definitely should get a photo record and write a summary of what happened. Then have the car looked at.

  15. #15
    Z8 Addict Scott Pettit's Avatar
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    I agree with all points. The RF tires and any tire in fact, should not cause a bottoming out. I would look at the shocks and struts. A 10 year old car with little use can start leaking fluids as "O" rings and gaskets dry out.
    Scott Pettit
    61930
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