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Thread: Potential fixes...

  1. #1
    Z8 Madness 2112's Avatar
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    Potential fixes...

    In the event that the factory does not come up with a reasonable fix, I would think that some of the potent thinkers here may be able to come up with a good resolution. At least the discussion may be interesting.

    I will start....

    Welding a dissimilar metal (steel) is miserable under the best of circustances and longevity is questionable. Adding enough aluminum, even a higher grade, will be bulky and difficult and I for one do not my beautiful engine bay ruined by a cobb job.

    Although I believe GM's suggestion of an export brace and shock tower brace will be great and probably part of the solution, I would think that the forces applied to the underside of the tower will need to be distributed to a larger area than just the top cap to prevent distortion.

    My suggestion is a carbon Fiber shell, moulded to fit perfectly to the entire underside of the shock tower. It could be "cold welded" with the same epoxy adhesives they use to glue composite panels to aluminum in Airplane construction.
    The thickness can be minimal and adjusted for by spring height. This in addition to the export/shock tower brace may be adequate.

    GM, Your thoughts? Anyone else?

  2. #2

    Carbon Fiber is a good idea...

    and I had actually been discussing a c/f shock tower brace with Cartridge before all this blew up. I am not an engineer, so this is all simply 'joining the dots' of what we will need in my mind. I think that there are a few components that will be needed.

    FRONT (illustrated below)
    1. A significant 'helmet' to fit underneath the entire crown, and support/distribute the weight of the car in a significant pothole.
    2. A top helmet, to sandwich the aluminum crown, and provide a mounting surface for the carbon brace.
    3. An aluminum lattice structure to anchor and support the shock tower support arms, and upper frame rails, using existing lower and upper mounting points.
    4. A rigid carbon fiber brace that will wrap around (and frame) the air box.

    REAR
    1. A significant 'helmet' or plate to fit underneath the entire crown, and support/distribute the weight of the car in a significant pothole.
    2. A top helmet, to sandwich the aluminum crown.

    FRONT and REAR
    New suspension mounting plates, and suspension tuned to be a bit more compliant with progressive spring rates.
     
    Andrew Macpherson

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  3. #3
    Administrator thegunguy's Avatar
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    Some good ideas

    While we're all hopeful BMW will provide a solution quickly, I believe it's wise to begin tossing around ideas like this. After all, BMW's investigations may conclude that no problem exists, at least not a statistically/financially significant level. In such an event it might be cheaper to develop our own solution than fight BMW in the courts.

    MacFly, I like what you and Bob have concocted here. It certainly seems like a good start, and there's no arguing that Bob and his team are experts in the use of light weight materials like carbon fiber in automotive racing applications. Since you're essentially boxing in the engine, how much tolerance is there for movement?

    There's a potential added benefit of using "helmets" above and below - part number 1 could also be produced to relocate the strut further to the rear as done in the Dinan caster plate.
    thegunguy

  4. #4

    While it is interesting to play with these ideas...

    the only ones who can really come up with a fix is BMW. Should we even touch our cars with any aftermarket alternatives it will give BMW the perfect excuse to wash their hands of us.

    The onus of responsibility lies fairly on BMW's shoulders for sending a structurally unsound car out onto the public roads, and they themselves must come up with a solution. I don't mind sharing ideas for what I would consider a suitable fix, but I'd never take the onus of responsibility for a suitable fix away from BMW.
    Andrew Macpherson

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  5. #5
    Z8 Madness 2112's Avatar
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    Quote Originally Posted by macfly
    the only ones who can really come up with a fix is BMW. Should we even touch our cars with any aftermarket alternatives it will give BMW the perfect excuse to wash their hands of us.

    The onus of responsibility lies fairly on BMW's shoulders for sending a structurally unsound car out onto the public roads, and they themselves must come up with a solution. I don't mind sharing ideas for what I would consider a suitable fix, but I'd never take the onus of responsibility for a suitable fix away from BMW.
    Not not being an engineer, you have put forth some sound thinking. What I referred to as a shell, you call a helmet. Even without the design flaw, adding this rgidity would only improve the handling characteristics of the car.

    My car is already heavily modified although showing little in the way of deformation. None the less, I fully expect BMW to tell me I am on my own should they provide a factory fix.

  6. #6
    Z8 Madness 2112's Avatar
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    Thought I would try ro resurect this thread.

    Any Fresh Ideas?

  7. #7
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    I encourage anyone with connections/relations to reputable engineering people to call them and take a look at the issue and see what they think about possible preventive aids/fixes. I think we should start taking matters into our own hands to protect our cars from future damage as much as possible as soon as possible. BMW will stonewall this thing to death in my opinion and will not provide a fix for years if at all. I am calling Dinan in that regard since I am a past customer, but they may not be interested due to their BMW connection.

  8. #8
    Administrator thegunguy's Avatar
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    I still think Dinan would be a good source

    However, Z8Doc's comments in another post do have validity. So, if Dinan did undertake such a project, they would need to do it under the banner of a performance enhancement, not a preventative fix.

    Please keep us updated on your conversations and findings.
    thegunguy

  9. #9
    Z8 Madness 2112's Avatar
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    Quote Originally Posted by Rjay
    I encourage anyone with connections/relations to reputable engineering people to call them and take a look at the issue and see what they think about possible preventive aids/fixes. I think we should start taking matters into our own hands to protect our cars from future damage as much as possible as soon as possible. BMW will stonewall this thing to death in my opinion and will not provide a fix for years if at all. I am calling Dinan in that regard since I am a past customer, but they may not be interested due to their BMW connection.
    Rjay,

    I totally agree, I just want my car to be something I can enjoy for decades to come. Plese keep us posted with your findings.

    Did Andrew say Cartridge was not interested or just not interested until BMW decides what they are going to do?

  10. #10

    I can't speak directly for Cartridge....

    but in essence they were not comfortable undertaking the burden of responsibility for what they see a potentially serious chassis/safety problem. They felt trying to create an engineering fix would certainly change the crash/crumple zone dynamics of the car, and thus put them in the firing line.

    I did mention this in another post, but for those of you who are wanting to keep driving, you might consider changing the wheels and tires. It was brought to my attention that the very heavy rims we have never bend, and the very stiff runflats also give much less than standard tires, so changing to lighter (read softer) rims combined with normal tires could help minimize the chance of a pothole becoming a 'distortion event'.

    HRE and BBS make good lightweight wheels, and Wheel Enhancements here in LA do a great service on many brands. They are Porsche racers themselves, and are always a pleasure to deal with.
    Andrew Macpherson

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  11. #11
    Sport Button On - DSC Off jim's Avatar
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    Bracing, boxing and helmets

    News Flash: Aluminum is soft, it's very tough to work with not to mention repair. I bought a Z8 because I TRUSTED BMW that they figured it out in the manner of a Supercar. Guess not.
    Never again will I buy a BMW (I own three now) if they do not conduct themselves appropriately on this frame issue.
    As an aside, Shelby Mustangs had a similar problem, although it was more a "pitch and roll" issue but, anyway Carroll designed simple cross bracing (tower to tower) and triangulated bracing to the firewall out of steel. Carbon fiber can be brittle. The helmets are an interesting idea but the aluminum tower walls may not be able to handle the stress. In addition you have a disimilar metals issue.
    I believe this is going to be a very difficult (not to mention hugely embarrassing) problem for BMW to handle as each "fix" has an intrinsic transfer of design/handling & strenght tradeoff cost.
    They need to recognize that they're not dealing with people w/o resources or connections and that sending "Stonewalling" letters will work to their detriment.
    js

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    Repair

    I am asking for anyone who has had the repair to tell us the details. Please answer as I have yet to see or hear of the repair from anyone other than Andrew. I can't understand why no one has yet discussed their experience UNLESS no one has undergone a shocktower/frame repair. This is as important at this stage as hiring an engineer to my way of thinking. Is no one else interested in this info?

  13. #13

    No one has had the time to have the repair....

    and I understand many BMW dealers aren't even looking at Z8's, or quoting for repairs just now, so you are aking an unanswerable question.
    Andrew Macpherson

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  14. #14

    Further thoughts on preventitive medicine.....

    beyond the already discussed 'helmets', struts, braces, light weight wheels and regular tires.

    I wonder if we could also retune the suspension on these cars, going for a true adjustable coil over system, somewhere between the Cartridge and the K&W set-ups that could be tuned to have a softer compression and rebound damping with a progressive spring rate that would give an gentler initial ride, but also help prevent bottoming out. Add to that the use of stiffer swaybars to keep the platform from rolling too much in corners, or wallowing in fast transitions.

    This chain of changes could all combine to push the envelope of an 'impact event' far beyond anything that any of us could ever encounter on any drive on the road, or track.

    The posible chain of changes:

    1. Helmets to go under all four shock towers and spread the load like showshoes.
    2. Helmets to go under all four shock towers to clamp the and maintain the bond, and give an ancor point for the front strut tower brace.
    3. Front strut tower brace
    4. Reat strut tower brace
    4. Regular tires.
    5. Lightweight wheels
    6. More compliant suspension / swaybar set up.
    Andrew Macpherson

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  15. #15
    Team Z8 jawz's Avatar
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    It's very hard to seriously consider possible fixes when we don't have any real data on causal factors. All the data I've seen to date has been sketchy and is very suspect with regard to validity. No one has posted anything definitive because we don't have anything definitive. The latest letter from Her Wunderlich in another thread accentuates this - stating that some of the cars showing this anomaly had been in accidents, had panels replaced, etc.

    BMW is certainly sitting in the cat-bird seat here. They have extensive data that was collected from exhaustive pre-production and production testing. They have records that will support their engineering and construction methods. This would include what material was selected for the construction of not only the shock towers, but everything on the car. It will also support why that particular material was determined to be sufficient for each application.

    On the other hand, we have nothing. What we do eventually get from the Z8 Club testing may not rise to a high enough level to turn the tables in our favor. Don't get me wrong. I'm not saying the BMW data is irrefutable, but to disprove their engineering will prove to be a daunting task. In the end, I'm not sure it'll get us where we want to be at the conclusion of the testing.

    Consider this: The shock tower "doming" could merely be the visible symptom. Designing and engineeering upper and lower "helmets" to strengthen the towers could be exactly the wrong approach. The remedy could very easily mask the real problem which then exhibits itself in a more severe manner.

    Until we get some documented empirical data, we won't know what is causing the shock towers to "dome". It could be something as simple as the shock towers are made of improper material, a bad lot of material, poor engineering, improper welding, etc.. But my experience in military and civil aviation, which includes aircraft accident investigations, tells me it's probably not that simple. There is probably a much more complex problem that hasn't even been considered and one which may appear at first blush to be entirely unrelated to the shock towers themselves. The odds of determining the cause without a full and exhaustive investigation is very slim.

    I want to get a resolution to this situation as much as the next guy, but pontificating fixes appears to me to be premature without more valid data.

    Until then, I'm still enjoying my car every chance I get.

  16. #16

    Keep a close eye on your shock towers......

    Until then, I'm still enjoying my car every chance I get.
    as you may become one of the ones who'll get to experience the 'deformation event' first hand. I've only spoken to one other US owner who knows exactly when it happened, it was a pothole of the FDR drive in NYC, which also fits with what we know from the EU.

    In the Club's last note it still said that the deformations are running at 1 car in 5, after the removal of accident damaged cars. IMHO 20% is an unacceptably high figure. Has any plane in commercial or military application had such a high failure rate since the F104G? (Maybe this their revenge? - joke!)

    In Luftwaffe service, the F-104G got a bad reputation because of the large number of accidents, many of them resulting in fatalities.

    Intensive flying operations with the Starfighter did not start in Germany until 1961, when only two crashes took place. There were seven crashes in 1962, 12 in 1964, and 28 in 1965, or more than two a month. By mid-1966, 61 German Starfighters had crashed, with a loss of 35 pilots. At the height of the crisis, the Starfighter accident rate peaked at 139 per 100,000 flying hours.

    As a result, the German press went into a feeding frenzy and the F-104G was given derogatory nicknames such as the "Flying Coffin" or the "Widowmaker", which brings to mind all of the flak that surrounded the Martin B-26 Marauder during World War 2. One running joke at the time was that if you waited long enough, just about every square mile of Germany would have a Starfighter crash onto it.
    Andrew Macpherson

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  17. #17

    Lightweight Wheels.

    I spoke to Wheel Enhancements today to find the very lightest wheels on the market for our cars. They said that the HRE Competition Wheels are the very lightest and best made wheels out there. The fronts are 20lbs, and the rears are 22lbs, so the weight saving on each corner will be over 10lbs swapping from our 18" rims and Run Flats to these HRE 19" rims with a normal tire.

    Here is a comp I made up to try and show how they'd look as 19's on our car, with OEM for easy comparison.
     
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    Dinan WILL look at potential fixes

    GM has posted on the other site regarding his conversations with Dinan. I also called Dinan and encouraged them to "engage", but got no committment, but GM got it from the horse's mouth.

    I consider this great news, however still far from having a confident solution (after all, the "problem" is not even fully vetted). Current thinking is a strut brace and possibly some suspension modification along the lines of Dinan's current S3 suspension package (springs, camber plates, anti roll bars). All is preliminary and no time-line as yet, but I am heartened that Dinan will at least look at it seriously.

    Hopefully some other talented and experienced engineering folks will also take a look at it and weigh in. And of course, if BMW were ever to actively participate in finding a solution........but this is a start of activity.

  19. #19

    I'm thrilled that there is movement....

    and emailed GM as well to thank him. I don't know why he refuses to support this board, it certainly saddens me as a fellow enthusiast who has put a huge amount of time, effort and money into this site. You can lead a horse to water, but you can't make it drink!

    There are some dangers inherent in a single plane strut brace, as it can transfer the force of a bad impact to the shock tower arms on the opposite side, coming from a direction that they were never designed to cope with, which could lead to two deformed towers instead of one. What is needed (along with the tower sandwich & suspension mods) is a strut brace that is also diagonally braced, not just tower-top to tower-top.

    While I'm delighted that Dinan are looking at this, and also certain that any fix they engineer will be of the very highest quality, I am concerned that any non-BMW fix may open another Pandora's box. I would personally like to see BMW's fix first, and then if I felt Steve Dinan's was a better solution make my own choice of which upgrade package to buy. However I don't think that Steve's hard work and enterprise should relieve BMW of it's responsibility to us, the owners who believed we had bought the stiffest aluminum sportscar in the world.
    Andrew Macpherson

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    wheels

    those are great looking wheels, thanks.

  21. #21
    DSC Off Orcatek's Avatar
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    I wonder

    I wonder if this will become a "Secret Warranty" from BMW. On another BMW I owned there were several repairs that were made on out of warranty conditions and BMW covered them. But only if you knew about it, otherwise you had to pay to get if fixed.

    Seems that plan would save them a heap of cash by only fixing those who ask for the fix, instead of pro-actively fixing everyone.

    I am glad to hear Dinan is looking at a fix. I also believe that they have some good contacts inside BMW, so hopefully there may be some sharing of information to produce the best solution quickly.

  22. #22
    Quote Originally Posted by macfly
    I spoke to Wheel Enhancements today to find the very lightest wheels on the market for our cars. They said that the HRE Competition Wheels are the very lightest and best made wheels out there. The fronts are 20lbs, and the rears are 22lbs, so the weight saving on each corner will be over 10lbs swapping from our 18" rims and Run Flats to these HRE 19" rims with a normal tire.

    Here is a comp I made up to try and show how they'd look as 19's on our car, with OEM for easy comparison.
    What's the cost of those ? thanks ...

  23. #23

    I'll post prices for the wheels soon....

    They are getting a wheel in for me to look at, weigh and photograph. I think it might be a part of the solution....however I don't think I love it yet, maybe seeing it in the flesh will help. I still think the HRE 540R is the best suited to our car, but it is over 6 lbs heavier that the Competition wheels shown above.
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    Wheels

    I checked with my wife who has more esthetic taste in one pinkie than I have in my whole body and she agrees that the HRE540 looks better than the Competition wheels shown. I'm curious though, in a case such as this, is it necessary or just a good idea to change up to 19 inches from the stock 18 inches? I'm interested in a balance of comfort and handling and wonder if the ride quality won't degrade with 19 inch wheels. I'm running the stock setup right now with OEM runflats.

    It would be nice to see both wheels compared to stock using the same photo as you have done with the Comp wheels Andrew. Anybody want to paste in an image of 540 wheels to compare?

    harvey2

  25. #25

    I'll do it in a bit...

    I'm on a plane to NY today, so I'll have plenty of playtime at 35,000ft.
    Andrew Macpherson

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  26. #26
    DSC Off Gammaman's Avatar
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    How about the 547R? The split 5 spokes would retain some of the character of the original wheel. Andrew, could you do some photoshop magic showing them?

  27. #27
    Administrator thegunguy's Avatar
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    I'm still a fan of Dieter's RD2s

    They seem to be only available in Europe anymore, but I'm narrowing in a source in the States.

    There are some great pics of Dieter's car with the RD2s in the Wheel/Tire section.
    thegunguy

  28. #28
    Z8 Ate My Homework! Norcal's Avatar
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    How about the 840s?

    The 840s are the upper pic, those are what I was considering in 20s
     

  29. #29
    Z8 Madness 2112's Avatar
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    Quote Originally Posted by Gammaman
    How about the 547R? The split 5 spokes would retain some of the character of the original wheel. Andrew, could you do some photoshop magic showing them?
    Here is what I am using
     

  30. #30
    Z8 Madness 2112's Avatar
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    a close up
     

  31. #31

    The whole HRE family as promised....

    I think it all comes down to personal choice, but IMHO the 540 or 540R are the best suited visually, but the extreem lightness of the C21 is also really tempting.

    .
     
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  32. #32

    Norcal....

    What about the C21's with black spokes, those would look great on your car!!
    Andrew Macpherson

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    Thanks for the photo comparison. I really like the 540/540r the best. They are complex with just the right amount of bling. Sort of a stylized modernization of a spoke wheel but with more curves to catch the eye. The others are either too severe, that is, too little flow or too geometric, or they are excessively boring in my opinion.

    I don't see the difference between 540 and 540R so will have to do some research on that one.

    harvey2

  34. #34

    540 - 540R differences

    The reflections of the bolts make it hard to tell, but the 540R has a flat inner rim/lip thus slightly longer spokes, while the 540 has a stepped inner rim/lip and a slightly shorter spoke. It is really hard to know which I prefer without seeing them side by side, but I have always thought this shot of the 19" 540 on Claus's car is about the most handsome thing I've seen on a Z8.
     
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  35. #35
    DSC Off Gammaman's Avatar
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    Quote Originally Posted by macfly
    The reflections of the bolts make it hard to tell, but the 540R has a flat inner rim/lip thus slightly longer spokes, while the 540 has a stepped inner rim/lip and a slightly shorter spoke. It is really hard to know which I prefer without seeing them side by side, but I have always thought this shot of the 19" 540 on Claus's car is about the most handsome thing I've seen on a Z8.
    Yes, they are very good looking wheels, but a lot of work to clean. I swore after having the basket weaves on my old 325iX that I'd never again get wheels that were hard to keep clean

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    Those wheels on Claus' car are georgous. It doesn't hurt that his car is a dark colour, but even my Silver paint would work well with the nice level of sheen from those wheels. I like 'em.

    Thanks for the photo.

    Oh, and cleaning may be an issue, but I kind'of enjoy fussing over my baby to bring out the shine.

    harvey2

  37. #37
    Z8 Ate My Homework! Norcal's Avatar
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    C21

    Quote Originally Posted by macfly
    What about the C21's with black spokes, those would look great on your car!!
    Yes, those with the black centers could be beautiful. One thing I like about the 840s is the hidden bolts, makes for a sleeker (like the car) look. I suppose if the centers are painted out in black, the actual pattern of the centers is far less critical. One thing I've wondered is how much it would cost to take the centers back to clearcoat silver, if I tire of the black some day. I've also have been thinking that 19s would probably look nice, and ride better.

  38. #38
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    I agree- I like the 840 series too for those reasons.

  39. #39
    DSC Off Gammaman's Avatar
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    I wonder if we could arrange a group buy, direct from HRE?

  40. #40

    I would caution everyone to wait a moment...

    and see what exactly BMW comes up with too, as buying lightweight wheels, or any other quasi-fix may well be throwing good money after bad.
    Andrew Macpherson

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  41. #41
    Z8 Ate My Homework! Norcal's Avatar
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    Good money after bad

    I don't see the wheels as a fix. I'm no engineer, but it seems that 3,400lbs of car/inertia impacting a pot hole etc. at speeds over perhaps 40-60 mph, multiplying the actual weight of the car many times, is far more relevant than an extra 10lbs moving up and down. I suspect the energy transfer at impact is in the high 100s if not thousands of pounds. As for good money after bad, you are right, but if you are comitted to keeping the car, what's a few thousand to dress her up? I'm confident that some kind of fix will be developed within a year. Even if she becomes a trailer queen/cruiser, which she won't, all the more reason to bling the wheels. It might be fun to dress her up sexy for my private enjoyment, even if I can't take her out much. Perhaps researching and doing some mods would be a good way to pass the time while were waiting for "THE FIX". Tinkering is fun too.

    Still smitten, what can I say?

  42. #42
    Administrator thegunguy's Avatar
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    I still like the idea of lighter wheels

    To me it seems that the mass of the wheel is one of the primary determinants in the force applied to the shock tower during an impact. With an independent suspension, only the wheel hitting the hole will travel up and down. In an impact, the suspended wheel is accelerated quickly in the vertical plain. At the top of this stroke, the wheel instantly reverses direction back to its resting position. This instant deceleration transfers the force of the traveling wheel into the shock tower (F=ma). The springs absorb much of this force (interacting with the 'a' in F=ma). Stiffer springs will carry more force into the mount, softer ones less. Andrew's wheel suggestion works on the 'm' side of the equation. Essentially, lighter wheels have less mass and result in less force. I'm guessing the (de)acceleration 'a' at the top of the stroke is HUGE. So, even small reductions in the weight of the wheel will have a large impact on the resulting forces.

    You're correct the weight of the car is also at play. So, lowering the weight of the car will also lower the forces at work, but as we know, there aren?t very many options for reducing the weight of the car. Also, it's only a corner of the car that hits a hole - partial mass.

    Softer tires (assuming the same weight as regular tires) absorb the initial force that is transferred into the suspension arm, thereby reducing the force that is carried to the top of the stroke.

    I could easily be wrong at any of the above - it's been a while since I've had physics, but it seems reasonable. Bob, GM, and others can likely give a much better description while confirming or refuting my illustration. Although, Bob?s multi-phrase sentences reminding me a reading A. A. Milne?s original Winnie the Pooh.

    I will say that if anyone wants to change out the wheels for aesthetics, feel free. We all need a pick-me-up these days.
    thegunguy