C8 General Discussion The place to discuss the next generation of Corvette, be it mid-engine, Zora, or whatever form it may take.
Sponsored by:
Sponsored by:

Handling?

 
Old 01-20-2019, 05:56 PM
  #21  
Shaka
CF Senior Member
 
Shaka's Avatar
 
Member Since: Nov 2002
Location: FLL Florida
Posts: 2,669
Liked 430 Times in 270 Posts
Default

Originally Posted by Bill Dearborn View Post
Mike, most Corvettes built since 1963 have had a 50/50 weight distribution or even a 49/51 weight distribution since from the 63 on they have all been front mid engine cars (engine behind front axle). The ones that went to 51/49 ratio were the cars with the big block engine which weighed 150 pounds more than the small block.

Bill
Check post 10. Since the C5, the engine has been placed over the front axle.
Shaka is offline  
Old 01-20-2019, 06:40 PM
  #22  
Shaka
CF Senior Member
 
Shaka's Avatar
 
Member Since: Nov 2002
Location: FLL Florida
Posts: 2,669
Liked 430 Times in 270 Posts
Default

Originally Posted by jcp911s View Post
Shacka,

Your posts are extremely interesting. It is clear that you are expert in your field. But, to simplify, there are two takeaways...

1. Us layman are misusing the term "polar moment of inertia", so we should rethink this.

2. When we are discussing a high-performance/racing environment a rigid, well engineered chassis will always handle better than a cheaply engineered, flexible chassis regardless of the location of the mass.

That said, given chassis of equally good design, does a mid/rear configuration (where the mass is closer to the CG) have an advantage over a design where the mass is located at each end.

In the former case, would you agree that the car is more likely to spin, but also more likely to change direction with less cornering force from the tires?

Also, given a very experienced race driver, does this not create an advantage on a road circuit where the car needs to change direction quickly from turn to turn?
Right on all counts. A mid engine sports car is going to be easier to drive than a FE car but it took a hell of a lot of money to beat the push rod engined, leaf spring sprung, cheaply engineered Vette and the Viper around the Ring. The Vette chassis is hardly a cheaply engineered chassis, They are brilliant designs that answer to the stock holder's needs first. The American way. A Miata sells more cars globally but a Vette sells that much locally. The C8 will be no different but I don't think it will go much faster than a C7 around the Ring or where the C7 holds lap records on domestic circuits currently.
There will be a direct comparison between these two cheaply engineered flexible chassis pretty soon.
A Ferrari is a wonderful car to drive and the first thing you notice is how stiff the chassis feels but the Vette gets the job done almost as well being so damn cheap. The C7 gets it done in a way that is against accepted norms. You use a different yardstick to measure its brilliance. That is the true beauty of the American beast. I'd rather go touring the USA in a FE Vette than a ME one or a Ferrari or a Porsche.
Do you know that Red Bull spent more money on designing Loeb's Pikes Peak winning Citroen than both their F1 cars, which would be slower up Pikes Peak anyway.
A Hummer and a Unimog are front engined vehicles. A Lexus is much more comfortable because of it's FE V8. Modern cars depend on technology to make them drivable. You can't drive a LaFerrari or a Veyron without their grannies turned on. The C8 is gonna need them but Randy Pabst can drive a ZR1 without them.
Shaka is offline  
Old 01-20-2019, 07:23 PM
  #23  
VetteDrmr
CF Senior Member
 
VetteDrmr's Avatar
 
Member Since: Dec 2000
Location: Hot Springs AR
Posts: 7,732
Liked 256 Times in 156 Posts
Default

Originally Posted by Shaka View Post
Check post 10. Since the C5, the engine has been placed over the front axle.
Um, I'll disagree with that one. I had to replace the front main seal in my C5, and had to do all the work either right on top of or right behind the front axle. Had to pull the steering rack due to interference with the damper. I'm not sure about the C4, but I *know* the C5's engine is behind the front axle.

Have a good one,
Mike
VetteDrmr is online now  
The following 2 users liked this post by VetteDrmr:
ArmchairArchitect (01-20-2019), Shaka (01-21-2019)
Old 01-20-2019, 07:31 PM
  #24  
JD_AMG
CF Senior Member
 
Member Since: Dec 2018
Posts: 182
Liked 70 Times in 44 Posts
Default

Originally Posted by Shaka View Post
Some scribe in a auto magazine long ago used this term incorrectly and now everybody uses it in that manor. I design and build chassis. Now make a note of this please. First: Polar moment of inertia would apply to the chassis properties contained within it's structure only as an indication of rigidity. The Corvette chassis in this case, has a low PMI. IE, it flexes like a bitch. Two: The correct term for what you are describing is Polar or Planor second moment of inertia which is the mass moment of inertia or the rotational motion resistance of an object, in this case the whole f.....g car. Third:


As you can plainly see, since the C5, Corvettes are hardly front ME cars by design. I analyzed this design somewhere in this forum. Check it out. The C7, including the ZR1 have two large mass centroids placed at each end of the chassis where the bending moment is the least. (Allows a lighter structure than ME cars). .
You can see here



The engine is clearly behind the front axle. The C5 and later years are front/midship layouts.

The C7 chassis' lack of torsional and bending rigidity and a very compliant suspension, optimises the friction circle at each tire and is much more efficient than other sports cars in this regard. It's beautiful by design. Oh yeah, you can't corner weight it either. I cover that also. If you loose it in a ME car, chances are you will crash. Radiators are not efficient at the rear especially now that HP numbers are out of sight. This why Ferrari and everyone else moves them up front. Quit making stuff up
This is the first time Ive heard anything close to this, the C5 was supposed to have the stiffest chassis of any production car of its time. Ive never heard anyone refer to a C5 or newer chassis as anything but stiff.
JD_AMG is offline  
The following users liked this post: JD_AMG
ArmchairArchitect (01-20-2019)
Old 01-20-2019, 07:57 PM
  #25  
*C7*
CF Senior Member
 
*C7*'s Avatar
 
Member Since: Nov 2004
Posts: 2,107
Liked 23 Times in 17 Posts
St. Jude Donor 05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16-'17

Default

Originally Posted by VetteDrmr View Post
Um, I'll disagree with that one. I had to replace the front main seal in my C5, and had to do all the work either right on top of or right behind the front axle. Had to pull the steering rack due to interference with the damper. I'm not sure about the C4, but I *know* the C5's engine is behind the front axle.

Have a good one,
Mike
I would say the front of the harmonic balancer is about 2" in front of the center line of the front axle. Give or take
*C7* is offline  
The following users liked this post: *C7*
Shaka (01-22-2019)
Old 01-20-2019, 10:07 PM
  #26  
Clairvoyantwolf
CF Senior Member
 
Clairvoyantwolf's Avatar
 
Member Since: Nov 2014
Location: NJ
Posts: 182
Liked 30 Times in 16 Posts
Default

Originally Posted by JD_AMG View Post
This is the first time Ive heard anything close to this, the C5 was supposed to have the stiffest chassis of any production car of its time. Ive never heard anyone refer to a C5 or newer chassis as anything but stiff.
For a production convertible.

"The first structural mode of the ‘C5’ in open roof configuration approaches typical values measured in similar size fixed roof vehicles."
(emphasis added)

https://www.sae.org/publications/tec...ontent/970089/

Last edited by Clairvoyantwolf; 01-20-2019 at 10:08 PM.
Clairvoyantwolf is offline  
Old 01-21-2019, 12:53 AM
  #27  
NORTY
CF Senior Member
 
NORTY's Avatar
 
Member Since: Dec 2005
Location: Carlsbad Ca
Posts: 8,672
Liked 44 Times in 28 Posts
Default

Originally Posted by Travelor View Post
Our C7's are practically 50/50 in weight distribution. My question is this, how will the C8 compare to the current GS C7 in handling?
The weight (eng on one end, and trans/diff on the other) makes for a vehicle with it's mass on the ends. Great for truck pulls, but not so good for rotating the vehicle around turns. "Mass centralization" is where it's at. Having the engine/trans as close as possible to the midpoint of the wheelbase/track is ideal.
In other words... the C8 should be able to out handle the C7. It wouldn't be noticeable in traffic though. Speeds are too slow.
NORTY is offline  
The following users liked this post: NORTY
ArmchairArchitect (01-21-2019)
Old 01-21-2019, 06:49 PM
  #28  
Shaka
CF Senior Member
 
Shaka's Avatar
 
Member Since: Nov 2002
Location: FLL Florida
Posts: 2,669
Liked 430 Times in 270 Posts
Default

Originally Posted by JD_AMG View Post
You can see here



The engine is clearly behind the front axle. The C5 and later years are front/midship layouts.


This is the first time Ive heard anything close to this, the C5 was supposed to have the stiffest chassis of any production car of its time. Ive never heard anyone refer to a C5 or newer chassis as anything but stiff.

Another view. Perform the door gap test. That won't happen on any other modern sports car. Not a bad thing though.
Shaka is offline  
Old 01-21-2019, 08:30 PM
  #29  
GOC
CF Senior Member
 
Member Since: Aug 2017
Posts: 232
Liked 58 Times in 42 Posts
Default

Regardless of weight distribution, the C7 GS is very hard to beat in handling. I believe it recorded the highest lateral Gs at the time during testing by C&D or R&T and out dueled the 911 Carrera S in head to head competition.

The C7 is one of the best front mid engine, rear wheel drive sports cars ever made when you compare every trim (Stingray, GS, Z06, ZR1) to its respective competition.
GOC is offline  
The following users liked this post: GOC
Shaka (01-22-2019)
Old 01-21-2019, 11:04 PM
  #30  
The HACK
CF Senior Member
 
The HACK's Avatar
 
Member Since: Apr 2018
Posts: 546
Liked 261 Times in 145 Posts
Default

Not having the engine block up front opens up a world of possibilies regarding suspension design. You can have a double wishbone with push-rod actuated springs and dampers like open wheel cars, and mount all that at or near the centerline of the front wheels thus lowering the front roll center.

Something you simply canít do with an engine in the way.

Thatís THE biggest handling advantage of a rear midship engine layout. With a lower roll center, lower front center of mass, and a much smaller fulcrum from roll center to CoM, you can virtually eliminate front body roll and still promote efficient and fast side to side weight transfer. Suspension travel, bump, wheel rate, steering rack geometry and everything that makes the front end bite can be improved.

Watch them ditch the leaf spring with the move of the engine behind the driver.
The HACK is offline  
Old 01-21-2019, 11:57 PM
  #31  
gthal
CF Senior Member
Support Corvetteforum!
 
gthal's Avatar
 
Member Since: Feb 2013
Posts: 4,133
Liked 198 Times in 90 Posts
Default

Originally Posted by GOC View Post
Regardless of weight distribution, the C7 GS is very hard to beat in handling. I believe it recorded the highest lateral Gs at the time during testing by C&D or R&T and out dueled the 911 Carrera S in head to head competition.

The C7 is one of the best front mid engine, rear wheel drive sports cars ever made when you compare every trim (Stingray, GS, Z06, ZR1) to its respective competition.
i agree it is one of the best but donít confuse measuring lateral G force with the ability to change direction and balance handling characteristics. The C7 GS definitely feels like it grips for days (moreso than a GT4) but the car does not like to change directions as easily and isnít as controllable at the limit. Thatís what the C8 will add to the already amazing grip of the C7.
gthal is offline  
The following users liked this post: gthal
Zaro Tundov (01-24-2019)
Old 01-22-2019, 08:00 AM
  #32  
VetteDrmr
CF Senior Member
 
VetteDrmr's Avatar
 
Member Since: Dec 2000
Location: Hot Springs AR
Posts: 7,732
Liked 256 Times in 156 Posts
Default

Originally Posted by The HACK View Post
Not having the engine block up front opens up a world of possibilies regarding suspension design. You can have a double wishbone with push-rod actuated springs and dampers like open wheel cars, and mount all that at or near the centerline of the front wheels thus lowering the front roll center.

Something you simply canít do with an engine in the way.

Thatís THE biggest handling advantage of a rear midship engine layout. With a lower roll center, lower front center of mass, and a much smaller fulcrum from roll center to CoM, you can virtually eliminate front body roll and still promote efficient and fast side to side weight transfer. Suspension travel, bump, wheel rate, steering rack geometry and everything that makes the front end bite can be improved.

Watch them ditch the leaf spring with the move of the engine behind the driver.
You're not really serious about this, are you?
VetteDrmr is online now  
Old 01-22-2019, 08:52 AM
  #33  
Shaka
CF Senior Member
 
Shaka's Avatar
 
Member Since: Nov 2002
Location: FLL Florida
Posts: 2,669
Liked 430 Times in 270 Posts
Default

Originally Posted by The HACK View Post
Not having the engine block up front opens up a world of possibilies regarding suspension design. You can have a double wishbone with push-rod actuated springs and dampers like open wheel cars, and mount all that at or near the centerline of the front wheels thus lowering the front roll center.

Something you simply canít do with an engine in the way.

Thatís THE biggest handling advantage of a rear midship engine layout. With a lower roll center, lower front center of mass, and a much smaller fulcrum from roll center to CoM, you can virtually eliminate front body roll and still promote efficient and fast side to side weight transfer. Suspension travel, bump, wheel rate, steering rack geometry and everything that makes the front end bite can be improved.

Watch them ditch the leaf spring with the move of the engine behind the driver.
What a total load of wrot. How many chassis or cars have you designed and built yourself? I love this forum.
Shaka is offline  
Old 01-22-2019, 02:43 PM
  #34  
HMDS
CF Senior Member
 
HMDS's Avatar
 
Member Since: Dec 2015
Posts: 136
Liked 39 Times in 16 Posts
Default ...

Originally Posted by shaka View Post
right on all counts.
A hummer and a unimog are front engined vehicles

i am gonna say that the hummer is a mid front design. The belt is clearly behind the front axle. That is all. Well-it also has independent coil-overs at each corner-and possibly the original driver centric cockpit
.
.
...
HMDS is offline  
The following users liked this post: HMDS
Shaka (01-22-2019)
Old 01-23-2019, 07:51 PM
  #35  
rgregory
CF Senior Member
 
rgregory's Avatar
 
Member Since: Oct 1999
Location: Arlington TX
Posts: 7,758
Liked 71 Times in 49 Posts
Default

Originally Posted by jcp911s View Post
First, handling has more to do with suspension tuning and tires than configuration.

That said, in a racing situation, braking at turn entry, and getting power down early on turn exit are critical, and here is where rear weight bias is a huge advantage. I raced 911s for years. Rear engine layout has been out of favor for decades, but in full race trim, a 911 with its "obsolete" rear engine is just unbeatable in these two areas.

A mid/rear configuration combines this rear weight bias advantage with lower rotational momentum. Its no coincidence that virtually every successful race car built since 1964 has a mid/rear engine design.
The newer 911 race cars are running mid engine now, I wonder when porche will finaly ditch the back seat and make the 911 mid engine for street too.
rgregory is online now  
The following users liked this post: rgregory
ArmchairArchitect (01-24-2019)
Old 01-23-2019, 09:06 PM
  #36  
Dominic Sorresso
CF Senior Member
 
Dominic Sorresso's Avatar
 
Member Since: Sep 2000
Location: Bartlett IL
Posts: 5,156
Liked 146 Times in 108 Posts
Default

Originally Posted by jcp911s View Post
So, If I take a 5 foot 2x4 and hang a 10 lb weight on each end, hold it at its center of gravity and rotate it, it will tend to continue to rotate until I apply force to stop the rotation... based on my lowly medieval history degree, I'd ball park it at oh, 2.5 feet x 10 lbs of torque or thereabouts. But it will want to continue to spin.

Now, if I place those two 10 lb weights right in the middle, and rotate it, it will tend to accelerate and decelerate more easily, as there is less torque on the CG. Is this correct, or am i missing something?
jcp,

I liken it to fighter aircraft. What is optimum for fighters is a platform that is ďunstableĒ. IOW, the platform does not have a tendency one way or the other. And therefore changes in direction occur more quickly and w less input (less steering input).
Its likely inaccurate, but I like to think that due to the positioning of the motor in an ME platform, the ability for the vehicle to change direction, quickly, is enhanced.More so than w an FE vehicle.

Dominic Sorresso is offline  
Old 01-23-2019, 10:21 PM
  #37  
Apocolipse
CF Senior Member
 
Member Since: Aug 2013
Posts: 2,097
Likes: 0
Liked 141 Times in 128 Posts
Default

Originally Posted by Shaka View Post
What a total load of wrot. How many chassis or cars have you designed and built yourself? I love this forum.
hahahahah it brings joy and pain to me the more time I spend here. Sigh.
Apocolipse is offline  
Old 01-25-2019, 11:27 PM
  #38  
z06801
CF Senior Member
 
z06801's Avatar
 
Member Since: Jan 2008
Location: NSL UT
Posts: 1,778
Liked 49 Times in 44 Posts
Default

Originally Posted by rgregory
The newer 911 race cars are running mid engine now, I wonder when porche will finaly ditch the back seat and make the 911 mid engine for street too.
Only the factory GTLM Cars, 991 cups, FIA GT3s, GTD Car's and PWC are still rear.

Last edited by z06801; 01-26-2019 at 12:15 AM.
z06801 is offline  
Old 01-25-2019, 11:39 PM
  #39  
Dominic Sorresso
CF Senior Member
 
Dominic Sorresso's Avatar
 
Member Since: Sep 2000
Location: Bartlett IL
Posts: 5,156
Liked 146 Times in 108 Posts
Default

Originally Posted by rgregory View Post
The newer 911 race cars are running mid engine now, I wonder when porche will finaly ditch the back seat and make the 911 mid engine for street too.
Doubtful Porsche would do this. The rear engined 911 guys are at least as obstinate as the OHV people on this forum. Besides, Porsche has a ME car called the Cayman/Boxster.
Dominic Sorresso is offline  
Old 01-25-2019, 11:43 PM
  #40  
Dominic Sorresso
CF Senior Member
 
Dominic Sorresso's Avatar
 
Member Since: Sep 2000
Location: Bartlett IL
Posts: 5,156
Liked 146 Times in 108 Posts
Default

Originally Posted by VetteDrmr View Post
Um, I'll disagree with that one. I had to replace the front main seal in my C5, and had to do all the work either right on top of or right behind the front axle. Had to pull the steering rack due to interference with the damper. I'm not sure about the C4, but I *know* the C5's engine is behind the front axle.

Have a good one,
Mike
The balancer on a C4 is midway over the front chassis crossmember and certainly behind the rack.
Dominic Sorresso is offline  

Thread Tools
Search this Thread
Quick Reply: Handling?


Sponsored Ads
Vendor Directory

Contact Us - About Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: