I am not in an armchair, but, I will make a pass......lumber that big would have fully compressed the front shock, (coilover or not)and when the shock bottoms out hard enough, this happens. That said, I still don't think I would coilover a C6Z
If you had the stock suspension in place, the same thing would have happend. You used up all the travel in the shock absorber, so it was acting like a solid structure pushing against it's mount. Something had to give. The coilover setup had nothing to do with the failure. It was the result of running over an 8x8.
If you had the stock suspension in place, the same thing would have happend. You used up all the travel in the shock absorber, so it was acting like a solid structure pushing against it's mount. Something had to give. The coilover setup had nothing to do with the failure. It was the result of running over an 8x8.
I respectfully disagree if you have a chance take a good look under your car. You will notice on the stock setup the weight of the car is primarily supported by the K frame in which the stock leaf lies. On a true coilover setup that load is now passed onto the shock tower supports.
Location: Defending the US Constitution in Northern CA
I don't think that this failure had anything to do with it being aftermarket at all!!!
I think that some of you are missing the obvious...
Point 1: the stock shock (at stock ride height) has about 3" of compression travel before it bottoms out, once bottomed out should the suspension continue to be driven upward, the shock becomes a solid shaft connecting the lower control arm shock mount to the upper chassis shock mount, should the lower control arm be compressed any more, the weaker of the two mounts will fail. I would seriously inspect the lower control arm for damage as it was exposed to considerable force as well.
Point 2: the coilover shock setup once bottomed out will transmit the same force against the upper and lower shock mount should it be bottomed out as well.
This failure was not caused by the suspension traveling through its normal range of motion. The guy ran over a 6' or 8" tall chunk of wood at speed, of course one of the shock mounts failed. He effectively compressed a suspension over 6" in a fraction of a second, that which can only be safely compressed 3" (and if the car was already lowered, it may have only 2" of safe compression travel).
I would venture that this failure would have happened with the stock suspension or with the coil over. Of course had the stock spring remained in tact once the shock got nearly driven up through the hood, the car wouldn't have had such a sinister low stance, but I'll bet that the shock mount would have broken just the same.
I'll bet that if one of you guys wanted to "Loan" your Z06 to the "Myth Busters Show", that they could develope a duplicate test to see if a stock suspended Z would remain unscathed.
I think that some of you are missing the obvious...
No we are not.
Do you some how think we fail to understand or comprehend that he drove over a railroad tie and that this would result in the shock mount being subject to huge forces?
Why do people assume that everyone else is a complete idiot? Some of use are incomplete...
We are simply of a different opinion - so how many STOCK suspension C6 Z06's do you think have punched their STOCK shocks thorugh the fender liner like that?
I mean surely there must be a stock suspension C6 Z06 that has driven over a railroad tie somewhere..
Are you guys 100% sure the stock front leaf spring would not have born much of the force and helped reduce the effect on the shock?
The next quesiton is if the aluminium shock mount is any weaker than the steel setup on a C5/C6 frame?
All I am certain of is that when it comes automobiles, never say never hehe
Coilovers had absolutely nothing to do with this. The driver drove over a friggin log the size of a 6x6 or an 8x8.
Quote:
Originally Posted by RC45
Hmm - coil overs had nothing to do with this?
So in your opinion, the forces acting on the upper shock mount are no more with a coil over setup than a transverse leaf setup while driving over an 8x8 log?
I would rather say that it is possible the use of a coil over contributed to this failure - afterall, we really dont know do we?
Anyway - there were a number of comments from supposed GM source about the weaker aluminium upper shock mounts.
*shrug*
Quote:
Originally Posted by C6400hp
So you believe if he had hit the same thing with stock suspension that the factory shock would have punched through/sheared off the the upper shock mount?
This has been said many times and is in the FAQ, no matter what is mounted in the stock damper location, the stock shock or a coil-over, it can go to infinite load, a bump at speed or a pot hole can cause complete compression and the entire weight of the car or that corner will have to be carried by the top shock mount. He hit a large object with the side of his wheel placing loads that it was not designed for, he had an accident and broke something, happens every day.
He hit a large object with the side of his wheel placing loads that it was not designed for, he had an accident and broke something, happens every day.
So this has been reported as a common failure/occurance with the C5 and C6 steel frame then?
I'd like to hear about other coilover related issues mated to our aluminum Z06 frames.
But suffic to say, wouldn't we all agree you just can't drive your car over rairoad size objects and expect a "lightweight high performce car" to survive too well?
I don't think that this failure had anything to do with it being aftermarket at all!!!
I think that some of you are missing the obvious...
Point 1: the stock shock (at stock ride height) has about 3" of compression travel before it bottoms out, once bottomed out should the suspension continue to be driven upward, the shock becomes a solid shaft connecting the lower control arm shock mount to the upper chassis shock mount, should the lower control arm be compressed any more, the weaker of the two mounts will fail. I would seriously inspect the lower control arm for damage as it was exposed to considerable force as well.
Point 2: the coilover shock setup once bottomed out will transmit the same force against the upper and lower shock mount should it be bottomed out as well.
This failure was not caused by the suspension traveling through its normal range of motion. The guy ran over a 6' or 8" tall chunk of wood at speed, of course one of the shock mounts failed. He effectively compressed a suspension over 6" in a fraction of a second, that which can only be safely compressed 3" (and if the car was already lowered, it may have only 2" of safe compression travel).
I would venture that this failure would have happened with the stock suspension or with the coil over. Of course had the stock spring remained in tact once the shock got nearly driven up through the hood, the car wouldn't have had such a sinister low stance, but I'll bet that the shock mount would have broken just the same.
I'll bet that if one of you guys wanted to "Loan" your Z06 to the "Myth Busters Show", that they could develope a duplicate test to see if a stock suspended Z would remain unscathed.
I should have read your post before typing mine, you are correct.
This is precisely why we build shorter shock bodies in our Coil over Pacakge. We never want the shock to bottom and become a solid connection.
if you take a sledge hammer and pound as hard as you can on a spring, you will never transmit the full force on whatever you are pounding on. But if you hit directly onto something with that sledge hammer you will soon break whatever you are hitting
The point is that any car, Corvette included, was not built to be driven on a solid connection between the ground and the frame. These are not go carts.
Any engineers out here that can figure the force=mass x acceleration in this equation?
Where the mass is the wheel, tire, suspension, and the acceleration is determined by the speed of the car and the size of the log that it hit. I would say that the resulting force is pretty high. and then transmit it through a solid bottomed out shock and you have a direct 1 : 1 relationship of the force that was delivered.
I would suspect that you will find a bent "A" arm also that bent at the location of the lower shock mount on the A arm.
The forces involved if transmitted through a bottomed out shock (whether coil over or STock) are a one to one relationship if there is no spring in between to reduce the shock. It is like a Tire Barrier at the race track. If you hit 5 rows of tires with your race car it it better than hitting the concrete wall behind them directly with no tires in between.
I would also venture to guess that the failure will be found to be the bayonett (SP) top mount with rubber bushings that plunged through the top mount first, then if the shock was bottomed out, it had no where else to go but up.
This is all conjecture until the photos come in but I have tested the shock mount on these cars and they are more than strong enough for a coil over.
WHat they will not do is allow a car to be connected solid to the suspension which is what happens with a shock body that is too long. And this would happen with a stock long body or any other long shock body.
We need photos to come to an intelligent conclusion.
I look forward to seeing the total picture.
Thanks
Lou Gigliotti
__________________ LG Pro LT Headers, MOST HP, MOST TORQUE
Yep - the very same arm chair quarterbacking done by the actual pro-race teams who decided to go with the steel chassis vs the aluminum chassis of the C6 Z.
I am guessing there is a reason for this - besides cost.
I do believe Short Throws car is based on a steel C6 chassis, not the aluminum one - and I think it is safe to say that was a not a decision based purely on the cost of the steel vs aluminum chassis.
The steel chassis was mandated by SCCA. There is no way to weld a steel roll structure to an aluminum frame. And bolt-in isn't allowed.
The teams would have loved the weight reduction...gives them more leeway to add weight where they want.
Short Throw built his like he did BECAUSE of these issues...and did a first class job at it too.
Hard to imagine how something THAT big could get under the car to begin with...talk about bad luck!
As for whether the car would have broken similarly IF it hadn't had the coilovers...well now, there's a great reason to keep the car stock. When you're talking to your buddies tell them, "Yeah, I woulda put one of demder fancy coilover systems on my car but I didn't because I wanna be able to run over an 8x8 without doing TOO much damage.".
Hard to imagine how something THAT big could get under the car to begin with...
Thank you!
How in the world do you drive over a "6 x 6 or 8 x 8" chunk of wood - at speed - with enough force to break the suspension - and manage to have a totally unscathed front splitter?? Something about that does not make sense at all.
If you had the stock suspension in place, the same thing would have happend. You used up all the travel in the shock absorber, so it was acting like a solid structure pushing against it's mount. Something had to give. The coilover setup had nothing to do with the failure. It was the result of running over an 8x8.
anyone not understanding this explanation will just keep posting and still not get it. I do run coil-over TYPE penske shocks, just not w/ the coils. Of course if the mount would not have broken, maybe the frame rail would be a little higher in that area The glass is STILL at least half full
Don't all suspensions have bump stops so that the shocks or springs are NEVER fully compressed?
When the limits of suspension travel are reached, and the loads are too great, then something HAS to give, and it is the designer's job to decide what that something is, for example the A-arm. But I was always under the impression that you NEVER design the suspension so that first contact is the shock, otherwise you transmit the overload into the weak (relatively) mount rather than the much more substantial control arm mounts.
Therefore, I would presume that the stock set up would never have caused this failure mode. Suspension arm bending, yes, but not punching through the shock tower.
Well, maybe someone can enlighten me about the 'bump stop' for the stock suspension vs the 'bump stop' for this guy's particular coil over set up.
Don't all suspensions have bump stops so that the shocks or springs are NEVER fully compressed?
When the limits of suspension travel are reached, and the loads are too great, then something HAS to give, and it is the designer's job to decide what that something is, for example the A-arm. But I was always under the impression that you NEVER design the suspension so that first contact is the shock, otherwise you transmit the overload into the weak (relatively) mount rather than the much more substantial control arm mounts.
Therefore, I would presume that the stock set up would never have caused this failure mode. Suspension arm bending, yes, but not punching through the shock tower.
Well, maybe someone can enlighten me about the 'bump stop' for the stock suspension vs the 'bump stop' for this guy's particular coil over set up.
The stock suspension uses the shock for a bump stop.
How in the world do you drive over a "6 x 6 or 8 x 8" chunk of wood - at speed - with enough force to break the suspension - and manage to have a totally unscathed front splitter?? Something about that does not make sense at all.
Z//
I know it's hard to believe but it's true. I was ahead of Just J and saw the 6X6 with my own eyes. I was able to dodge it but Just J had no where to go because of on-coming traffic. We both marveled at the fact that his car was able to get up and over the wood since his car is lower than stock. My only guess is that his right front wheel caught just enough of the wood to go up and over it. We tried to find the offending piece of wood without success. We knew that people would find this hard to believe.
Here are a few pics I took...
The nose, fender, wheel and tire were unscathed...
First of all, sorry to hear about your incident. Glad that no-one got hurt. I know that you run your car lowered, taking advantage of our shortened bodies. Unfortunately, every shock runs out of travel given a big enough hit (like a 6x6).
This is an interesting thread because it is the first time I have ever seen an actual shock tower failure. It will only ever be speculation about whether this same failure would have occurred without coilovers being on the car. My personal feeling is the same as several of the other vendors on this thread in that probably the same thing would have occurred even with stock shocks.
The limiter of the suspension travel in all of the C5 and C6 Corvettes is the shock absorber . Clearly the impact of the wheel with whatever J hit caused an extreme wheel movement. The stock shock would have bottomed out and then likely pushed up through the frame.
Like the others on this thread, I am interested to see more pictures of the damage. Then we can resume our armchair engineering
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