LocostUSA.com

RHS tubing is still flat stock that was bent into a square tube and welded along the seam. Not enough difference there for me personally. The suspension load are then trying to flex the unsupported radii. And unless you've got a bracket large enough for 4 bolt mounting, it will additionally be prone to additional flexing about the bolts themselves. While it may be less brittle, that's not necessarily a good thing either.

_________________
-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie

Gale,

I know you are already running the gussets on the mount/s in question. My new chassis will have such.

That's sounds at least like one plausible explanation. Once fractured, firmly applying the brakes could prossibly provide the remainder of the rearward force to tear it apart...But there are still too many assumptions required to draw any real conclusions at that level of detail.

I doesn't shock me after factoring in the low mounted front wing with aluminum under tray, even lower mounted oil pan, and 3 corners still mostly supporting the center of mass.

I don't follow. Generally, I've attributed it more to the one-size-fits-all front suspension support structure, all in the name of mounting the lower body panels exclusively to the frame.

_________________
-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie

Jack, perhaps this will help clarify. And I’d truly be interested in learning what your long-term recovery results have been since your accident.







horizenjob is asking the right questions and is pondering in the right direction regarding what actually happened with the mount.

If you break down the complete failure of the mount into two parts, it helps to understand what took place. A) Impacting the pothole was the onset of the failure; it caused the lower portion of each of those mounting tabs to rip/tear from the bottom of the tabs upward, to partially ‘fail in tension’. They didn’t rip away completely. However, just exactly how much of those tabs were still attached to the car is (and always will be) an unknown. After reviewing the damage to the RH tab, following the impact from the vertical drop that took place during the accident, I’m fairly certain the initial damage was substantial; the impact with the pothole was extremely hard. B) following the impact with the pothole, the mounting tabs were exposed to five minutes and thirty-two seconds worth of metal fatigue during braking for corners; this caused the majority of the rest of the damage to the (still attached) portion of the tabs which, in turn, led to their complete failure as I braked for turn 11.

After contact with the pothole, I slowed down and began evaluating the car and picked up the pace a little with each successive lap. I drove approximately 2 and a half more circuits before the suspension broke down. During the five minutes and thirty-two seconds that followed (after impacting the pothole), the car drove perfectly and exhibited no abnormalities in handling…..nothing whatsoever…..right up to the point the suspension broke down in the braking zone of turn 11. Having said that, my personal thoughts are this; even though there was well over five minutes of fatigue time to account for (again, after impact with the pothole), the breakdown (the separating of the rest of the tabs) was aggressive and sudden. I dare say that as I braked for turn 11, the forward tab (the most damaged of the two) was the first to completely fail. The complete failure of the rear tab followed. All of this, obviously, literally happened in a fraction of a second. That this happened during braking, in turn, caused the rearward bending of the ‘remainder’ (the still-connected portion) of the tabs.




[/quote]I'm surprised there isn't more damage to the frame. Wouldn't that front corner drag on the pavement/ground when the front suspension gave away? [/quote]

See the photos below. The front wing mount and the oil pan took the brunt of the impact after breakdown; this resulted in very little ‘visual damage’ to the frame.

There’s been a lot of speculation, and sometimes, presumptuousness, thrown on the table regarding my accident. The difference is that I had a front row seat and back stage pass, and luckily, I’m still here to tell the tale. The bottom line is this; the accident happened. Period. I didn’t post the information on this forum because I didn’t plan on discussing the information on this forum. It was brought up by another…and that’s fine. But now that it’s here, I ask, that unless your criticism is constructive and carries merit, to please keep it yourself. And that truly interested parties simply carry away something positive and instructional from all this so that it doesn’t jump up and bite you in a$$ that the way it did me.

They do a "pressure" bend in a manner that we could never duplicate which leaves the grain finer. I've watched it being done and have been told it leaves the bend extremely strong and not a normal failure point.

2 bolt mounting ought to be enough.

But this is still presuming you are using the proper thickness of material. After looking at this, what is the proper thickness?

_________________
mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.

OK, so a rearward force from the pothole would pull on the tabs producing tension, but I haven't been able to understand how an upward force was applied to the tabs. That wouldn't come from bottoming out the suspension in a pothole.

What happens is when the suspension bottoms out a very large vertical force is applied thru the coilover to the frame. The coilover is somewhere near a 45 degree angle though, and that would produce an outward pull on the bracket of an equal magnitude to the upward force. Since the bracket is at a bit of an angle that force might be stronger on the bottom edge of the bracket and start the tear there.

So both the rearward force and the vertical force are adding up to produce tension in the bracket...

Justin if that bracket could be taller so that it would make a cap for the bottom tube of the front bulkhead, which would work better if the front bulkhead was vertical - or at least if they were all in one plane and a rod end was used on the control arm; it would be much stronger. That's a pretty bad sentence . I'll try to make a drawing for the thread mjalaly started.

_________________
Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.

This is confusing, we have carguy and xcarguy.....

End of the day, until someone gets that broken bracket under a microscope to look at the grain, it's going to be guesses as to root cause of failure. Unless I am mistaken, either way the bracket was too thin. It either flexed,hardened, and broke, or it was still nice and soft and tore apart due to loads. My money is on a combination of both. The flex point of that bracket is VERY abrupt, and the HAZ is in the same spot so bracket design can definitely be improved. I'd also like to see the loads spread out more before going into the 16?ga tube.

In terms of the Oval track design, the only real reason they do it that way is because that's how the OEM upper control arms mounted to the chassis on most GMs, and it has continued on. They typically overbuild their mounts, and let the control arm and cross-shaft get destroyed in a wreck. Cheaper/faster to repair that way. Most race-cars should be designed to do that. It also allows for quick alignment changes at the track. Just throw pre-measured shims in and set toe.


Also, I didn't realize this was they same car but thanks for taking so many pics during your build. I looked through your build log fairly in depth while building mine.

Cheers.

_________________
Build log: viewtopic.php?t=9291

You've nailed it.

Believe it or not, I'll try to be brief:

My first neurologist was so convinced I was doing a lawsuit scam on Day 1 that he didn't even send me for a CAT until Day 3--he was convinced he was going to get famous writing a "hysterical paralysis" paper on Day 2 (nobody had ever had hysterical paralysis symptoms that included inability to urinate before, but he felt it was because I was overeducated) and it wasn't until I came off the CAT machine that he acknowledged that indeed, I had a spinal injury (he'd put me down as uncooperative because I refused to do such things as "...hop on over to the X-ray department..." until there was evidence that I -didn't- have a spinal injury). I was fortunate that a number of my clients/customers had spinal injures and I knew that my primary care physician would be Yours Truly.

My second neurologist (who was great, by the way) concluded that since I'd gone through three days of self-immobilization despite considerable pressure to get off my ass, and since a certain amount of knitting had already begun, that I should keep myself immobilized for 90 days before we dove into surgery (L1 through L4 broken, L3 shattered and the nerve column was 60% obstructed by bone fragments) because, hey, it was 1984 and spinal operations were more likely to cause damage than to not (they'd have had to go through the abdomen to get the fragments) and I was in pretty good shape, considering (I still had EF, and after a few days the swelling etc in my nerve column had abated and I could pee on command, both of which were YMMV issues if I had them start picking bones out of my spinal column through my belly button). I'd shown I had the necessary discipline, and they gave me an air-powered mattress that inflated alternating coils so I wouldn't get bedsores...and I moved (via stretcher and van) into a nearby motel for a month (where I learned who my friends were, by asking visitors, "As long as you're here...do you see that bedpan? Mind scootching it over this way? And could you bring a washcloth?").

Then a couple months on a mattress in my GF's living room, then a couple months in a back brace learning to walk again (amazing how weak my various muscles got from three months on non-use) and thirty years later, I'm pretty much okay, except I'm kinda fragile and I can't jog (or do any other high impact activities, such as roller skating...which in theory is zero impact, but in practice, hey, why bother skating if you're not going to play roller derby) and I'm not going to get off so lightly next time.

My accident was much like yours, from a medical standpoint. People underestimate what a big deal a small fall can be, but going from tabletop height to the ground can put you in the hospital if there's nothing energy absorbent between you and the ground.

_________________
Locost builder and adventurer, and founder (but no longer owner) of Kinetic Vehicles

A stronger bracket could look like this... There would be other ways to do this and I'm not saying this would be the easiest to build either but it's a simple improvement.

_________________
Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.

Thats more like it

The more I think about the failure the more I think this is purely a fatigue issue . If a strain was attached to the end of that wishbone with a straight pull and increased tonnage applied I think the bolt would simply tear through the end of the bracket before the bracket detached from the chassis or lugs broke off.

Bob

_________________
Build Log viewtopic.php?f=35&t=16640&p=187700#p187700

Mancave http://s1116.photobucket.com/user/mypic ... ow/mancave

I'm sorry to hear about your injury and do not wish it on anyone.

Stupid question...

If you design the bracket not to fail at this load but a much higher one... what is going to be sacreficial then ? Eventually if you design the chassis strong enough the only thing left will be the human body in it.. Nascar realized that after a couple of deaths.

Racing or track days are dangerous its not a question of if you're going to crash but when. When you fully accept this the obvious question is what you want to have break off to dissapate the energy before its absorb by your body. Yes its sounds stupid to design for failure, but this is the real issue in my eyes and a topic that should be addressed... hey I'm still trying to figure it...

Jack,

Thanks for sharing all the info. I went through three neurosurgeons before finding a keeper…..and all had varying opinions of what needed to be done; one was knife-happy and drooled at the thought of cutting on me. Being that surgery would (may very well still) require entry through my chest (and toss a heart surgeon in the mix) as well as my back, I decided to take the high road and try and beat this with long-term recovery in a brace…..we’ll see. FWIW, when I was first admitted to the hospital at College Station, TX, the nurse who admitted me stated on the insurance form that I was complaining of back pain. My insurance co mistook this as meaning nothing more than ‘back pain’ and refused to pay initially because I had been admitted for no apparent reason…..took a bit of doing on my wife’s part to get that one ironed out.

Also, I don’t know if you frequent USA7’s, but you may want to check out this thread; possible sale for you:

http://www.usa7s.net/vb/showthread.php? ... d-assembly

My insurance co mistook this as meaning nothing more than ‘back pain’ and refused to pay initially because I had been admitted for no apparent reason…..took a bit of doing on my wife’s part to get that one ironed out.
[/quote]

Your wife is a keeper then!

Having once worked for a medical billing software company (which shows in the build quality of my car I think?), and confirmed when my ex had a bout with cancer, I can tell you that half of all medical bills are wrong. Now, sitting around with a stack of bills and a spreadsheet on your computer as you do conference calls between provider and insurance company doesn't sound like fun, but it could very well save you enough money to buy your next fun-car.

_________________
***************
Geek49203 aka
Tim Wohlford
Louisville, KY
Hayes front, S10 +2 rear, Lalo body.

Jawfish,

No stupid questions…..just those we never ask. Regarding tradeoffs/sacrifices, I would think the first thing one should ask themselves is “What do I intend to do with the car?” Street, track, both? Is the car’s use for all out racing or will it be used for, as is (was) mine, the enjoyment of the occasional HPDE? As for what would actually be sacrificed when one starts to make changes to a certain component would depend as much on the objective as the component itself. For example, an engine. If your goal is to build horsepower, and your car is driven mainly on the street, at some point (if you continue to shop for power) you’ll begin to sacrifice the car’s street-friendly manners. Eventually, the quest for more power would render the car all but totally useless on the street. To give your question further consideration, here’s an example that’s perhaps better suited. A fellow Brunton Stalker owner had a failure similar to mine; also caused by a hard hit. He had the car repaired and had gussets installed on the lower, forward a-arm mounts (same as I’m having done on my new chassis). Sometime later, his car was involved in a track accident; hit a tire wall. Where the gusset had been fitted to the suspension mount (the same mount that failed on my car), the impact with the tire wall (instead of fracturing the mount) literally ripped away the wall of the frame rail where the mount was attached; hence, a tradeoff. Personally, I’d much rather have the gusset on the mount (increased structural integrity). If I’d had the gussets installed on my car when at TWS, it may very well have prevented the accident. Unfortunately, as is the case with many accidents, I’m finding out/learning about all this after the fact.

Another important question that goes hand-in-hand with your question is that of safety. If it’s an issue of structural integrity, will the design make the car safer? Will the design decrease the chances of a failure and will it increase my chances of walking away following a mishap? Prior to my accident, I had given as much thought as possible (so I thought) to the idea of safety…..with regards to an impact that could happen in a horizontal plane. Not once did it EVER occur to me that I may very well end up going airborne and experience a vertical drop . . . . . But as I continue to mend and prepare for the rebuilding of my car, guess what’s currently at the forefront of my thinking? It’s certainly not the a-arm mounts; that one’s figured out and is now being corrected; by comparison, is an ‘easy fix’. It’s vertical impacts and safe seating that demands thought. Seating that will absorb a vertical impact instead of my back; this has my full and undivided attention at the moment…broken vertebrae are powerful motivators.