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Old Oct 12, 2020 | 06:51 PM
  #21  
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Originally Posted by Apocolipse
You are all way overthinking a base model car.
Yeah, maybe....but the principles are all the same. Until you know what the suspension geometry is, and what effect that is having on the way the car performs, it is probably not a good idea to start throwing changes at it (like a bump steer kit) until you know if it needs it or not. I think that is the point Shaka was originally trying to make. There are modern, high performance vehicles that, for example, delibertly use bump steer to compliment Ackermann (or lack thereof) to produce the desired effect (generally slight toe out) in a turn. Some of the engineers are pretty savvy, and if you make changes to their design without knowing the possible "unintended consequences", you may be f---g up. To your point, underthinking the problem may be more of a problem.

Last edited by mfain; Oct 12, 2020 at 07:36 PM.
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Old Oct 12, 2020 | 08:42 PM
  #22  
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Default Not a Base Model

Originally Posted by Apocolipse
You are all way overthinking a base model car.
As an FYI - my C8 has both the Z51 package and the Magnetic Control shocks but no front lift kit...
DSC Sport might just have the necessary hands on experience and track seat time in the new C8.
Though there's been a lot of very knowledgeable posts!! Finding a qualified Corvette C8 suspension mechanic will be a challenge.
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Old Oct 13, 2020 | 10:25 AM
  #23  
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Originally Posted by mfain
Out of curiosity, what are your thoughts? You obviously have a difference in opinion. Do you know if anyone has measured/calculated the dynamic caster at full compression (where you would likely be under heavy braking just prior to turn in)? It would be interesting to see what the outside tire's camber is when the tire is turned with the suspension under full compression. Starting with 1.75 degrees of static negative camber, I gain 2.1 degrees of negative camber (outside tire) and lose 2.8 degrees of negative camber (inside tire) with 10 degrees of turn and 3.2 inches of compression (splitter on the ground). My point (respectful opinion) was that if the nose rises from the condition I just described (due to acceleration squat), it will take out 2+ degrees of camber. If you are still in the turn, that is bad. If you have all of the C8 suspension pick-up point measurements, you could use a suspension analyzer program to get the data. I remove the coilovers and use sort-of a poor man's pull down rig, degreed turn plates, camber/caster gauge, and a bump steer gage to get my data. As an aside, the angle (in or out) of the steering arms is not the only thing that defines Ackermann. Moving the rack forward or back also produces changes. I run my rack on slugs so I can move it for adjustment - probably not possible with the C8 however.
This car was designed by fools. Caster angle gain is the result of anti dive geometry. I don't ever use anti dive or squat geometry. It introduces too many binding forces. God knows what it does to bump steer with all that Monkey motion going on.. There are other ways to control pitch. Despite severe anti dive geometry on this car, the pitch changes are unacceptable. Magnaride is not active, it reacts dynamically only. Heavy and expensive also. Squat geometry actually actually makes thing worse for nose dive. A smaller flywheel lowered the engine yet the Cg was raised because they placed the heavy coil springs (and Magnaride shocks) in that dumb *** casting structure way too high. What a clumsy structure, my God. That Cg heads skywould under braking and the transfer is increased to the front. Mid turn, the platform is horizontal longitudinally and on exit, the dive/squat geometry adversely changes the pitch in reverse to the braking. What front and rear geometry transitions are taking place. Golly.
Turn in uncovers other serious design problems. The short rear axles and provision for front drive requires A arms that are too short. 3' neg camber for track settings is because there is insufficient camber gain in roll. Can't imagine what lat.and long. roll couples are. No wonder Michelin had to provide a 'special' structured tire for this car. Who wants to screw around so much preparing your car for track days.











A simplified lighter stronger and more efficient structure.




Stock structure engine far back


Last edited by Shaka; Oct 13, 2020 at 02:20 PM. Reason: Added picture
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Old Oct 13, 2020 | 10:50 AM
  #24  
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Call GM - Shaka’s got this figured out. I’m sure crash testing has nothing to do with the design right?
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Old Oct 13, 2020 | 02:24 PM
  #25  
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There's obviously a lot of serious suspension guys here, so I have a question.

Surely these undesirable effects would have been apparent to the GM engineers. They probably have pretty crazy modeling software, and I really don't think they're simply incompetent. So, why would they design it this way?

I'm guessing there's some sort of tradeoff that they had to make? Is it a cost thing? I would think changes in suspension geometry wouldn't impact cost that much.
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Old Oct 13, 2020 | 02:47 PM
  #26  
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Originally Posted by Shaka
This car was designed by fools. Caster angle gain is the result of anti dive geometry. I don't ever use anti dive or squat geometry. It introduces too many binding forces. God knows what it does to bump steer with all that Monkey motion going on.. There are other ways to control pitch. Despite severe anti dive geometry on this car, the pitch changes are unacceptable. Magnaride is not active, it reacts dynamically only. Heavy and expensive also. Squat geometry actually actually makes thing worse for nose dive. A smaller flywheel lowered the engine yet the Cg was raised because they placed the heavy coil springs (and Magnaride shocks) in that dumb *** casting structure way too high. What a clumsy structure, my God. That Cg heads skywould under braking and the transfer is increased to the front. Mid turn, the platform is horizontal longitudinally and on exit, the dive/squat geometry adversely changes the pitch in reverse to the braking. What front and rear geometry transitions are taking place. Golly.
Turn in uncovers other serious design problems. The short rear axles and provision for front drive requires A arms that are too short. 3' neg camber for track settings is because there is insufficient camber gain in roll. Can't imagine what lat.and long. roll couples are. No wonder Michelin had to provide a 'special' structured tire for this car. Who wants to screw around so much preparing your car for track days.











A simplified lighter stronger and more efficient structure.




Stock structure engine far back

Designing & selling an aftermarket suspension kit that will lower CG and improve handling would be a great goal. Wondering how the C8R is dealing with these issues... Any information available on the C8R?
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Old Oct 13, 2020 | 03:49 PM
  #27  
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Originally Posted by unklejoe
There's obviously a lot of serious suspension guys here, so I have a question.

Surely these undesirable effects would have been apparent to the GM engineers. They probably have pretty crazy modeling software, and I really don't think they're simply incompetent. So, why would they design it this way?

I'm guessing there's some sort of tradeoff that they had to make? Is it a cost thing? I would think changes in suspension geometry wouldn't impact cost that much.
For most of the people who will purchase this car, it will be more than satisfactory. There are too few of us who want a dedicated uncompromised sports car. The numbers don't favor us. The times, they are a changing. There are so many rules and regulations plus the myriad of duties that this car has to perform. Retractable top, golf clubs, 200 speakers, DCT, ABS, e Diff, comfort, styling, powerful, economical, dependable, fit and finish and space for golf clubs. The stock holder needs are paramount, therefore a huge profit must be the focus of the CEO, so it's got to be cheap to manufacture.
It is also the highest selling sports car in the world. With these factors, it is far more challenging to design and manufacture such a sports car than cars that cost $millions. The only thing that can prevent it's success is the adverse outcome of the election. Like governments, the C8 is what the electorate deserves, to paraphrase G.B. Shaw. I'm out.

Last edited by Shaka; Oct 14, 2020 at 11:38 AM.
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Old Oct 16, 2020 | 03:43 PM
  #28  
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For comparison, here is a link to a view of the Audi R8 rear suspension:

https://images.app.goo.gl/XFzX3w14HmoRcfN88 . .

Here is another R8 view:

https://images.app.goo.gl/X4WLU6aEXjCrJ2nf6
.

Last edited by B Stead; Oct 16, 2020 at 04:12 PM.
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Old Oct 16, 2020 | 04:08 PM
  #29  
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Originally Posted by Jacques Albrecht
Many thx for the link B Stead... This is a monoball kit that is available (pre-order) for the 2020 C8. Designed for the suspension for better car control.
LG MOTORSPORTS C8 Monoball Control Arm Kit.
I'm not familiar with the company or their products. Has anyone dealt with them? On the surface, the kit looks to be well machined.

Complete kit for 8 control arms.
We've been around since the late 80's. We're not currently racing but most years have been compromised of a shop, a parts company and a race team. Monoball control arm bushings are eliminating rubber bushings at connection points that deflect under cornering loads. I've driven about 30 miles on the street with prototype monoballs/sway bars on the car it was perfectly compliant but the steering felt unbelievably more sharp, connected and precise. We've made this product for C5/C6/C7 so we are familiar with the product but on the C8 we put a huge focus on fitment to make sure it's a smooth process for the end user. We still plan to install the into the arms for the customer at no additional cost because while it seems straightforward and easy there's a number of ways a pretty capable customer can mess these up trying to press them into the arms. Here's a picture of the car running at COTA and an old pic of the ALMS car and you can see a Corvette Racing car in the background.





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Old Oct 16, 2020 | 05:09 PM
  #30  
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Originally Posted by Shaka
For most of the people who will purchase this car, it will be more than satisfactory. There are too few of us who want a dedicated uncompromised sports car. The numbers don't favor us. The times, they are a changing. There are so many rules and regulations plus the myriad of duties that this car has to perform. Retractable top, golf clubs, 200 speakers, DCT, ABS, e Diff, comfort, styling, powerful, economical, dependable, fit and finish and space for golf clubs. The stock holder needs are paramount, therefore a huge profit must be the focus of the CEO, so it's got to be cheap to manufacture.
It is also the highest selling sports car in the world. With these factors, it is far more challenging to design and manufacture such a sports car than cars that cost $millions. The only thing that can prevent it's success is the adverse outcome of the election. Like governments, the C8 is what the electorate deserves, to paraphrase G.B. Shaw. I'm out.
And let's not forget hauling a bicycle too preferably by adding / using a small tow receiver.
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