Air dam
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Joined: Jan 2016
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Air dam
I purchased a brand new 2017, C7 Stingray in March, 2017. It has 6,200 miles on it. I recently noticed the center rubber air dam under the front bumper has a 5 inch tear on each end where it was attached to the metal piece that is bolted to the frame. I am constantly aware of the ground clearance and always avoid pulling over low objects such as those pesky parking stops. I feel the lack of support for these ends simply allows air passage over a period of time to cause the ends to flap resulting in the tearing. I'm sure GM has a reason for not making the entire dam on piece, thus the need for the two end pieces. Repairing seems impossible and replacement only guarantees recurrence. What are the pros and cons to leaving it off such as increased engine temp., gas mileage, minor debri damage to under carriage, warranty or any other thoughts ? Thanks guys.
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 35,005
Likes: 12,393
From: NE South Carolina
I purchased a brand new 2017, C7 Stingray in March, 2017. It has 6,200 miles on it. I recently noticed the center rubber air dam under the front bumper has a 5 inch tear on each end where it was attached to the metal piece that is bolted to the frame. I am constantly aware of the ground clearance and always avoid pulling over low objects such as those pesky parking stops. I feel the lack of support for these ends simply allows air passage over a period of time to cause the ends to flap resulting in the tearing. I'm sure GM has a reason for not making the entire dam on piece, thus the need for the two end pieces. Repairing seems impossible and replacement only guarantees recurrence. What are the pros and cons to leaving it off such as increased engine temp., gas mileage, minor debri damage to under carriage, warranty or any other thoughts ? Thanks guys.
1) at highway speeds it reduces drag enough to improve gas mileage. That is why the Chevy Volt has one that sticks down as far as the one on the Vette!
2) at speeds above 100 mph it provides some front downforce. That helps stability. At 150 mph according to GM's Chief Aerodynamicist it become critical to stability.
3) I like the side air dams on mine as they provide and early warning that the next lowest thing to hit are the aluminum skid pads on either side and behind the air dams. If you think the flexible rubber air dams, designed to bend make and objectional noise wait until you hear that aluminum on pavement! It can happen as It have to me in my C6 and C7! The PDF below shows a solution I use.
This is a PDF that discusses more than you probably want to know about air dams and aero in general but will answer your questions and some you didn't know to ask: http://netwelding.com/Air_Dam.pdf
Last edited by JerryU; Nov 13, 2018 at 11:42 AM.
Melting Slicks
Joined: Apr 2002
Posts: 2,439
Likes: 590
From: Tellico Plains Tennessee
I removed mine years ago, just after I bought my '15 coupe. I also added a splitter at that time. Looks great. No problems, but I don't track my car.. There's been many post about what the dams do. Stability, downforce, and fuel economy are the leading theories. Oddly enough, the fastest Corvettes don't have the center air dam, only the two side ones, so high speed stability must not be the paramount concern. Also, the economy cars all have them and say its for fuel economy. Tadge mentioned in a post that downforce balanced slightly heavy toward the front is the engineer's target but I don't remember if he meant having the center dam helps that or removing it does . If I've read posts correctly, the base Stingray gets all of them (mine did), the Z51 Stingray doesn't get the center. The base Z06 gets them, provided the dealer installs them, yet the Z07 optioned cars don't. Not sure, but I don't think the GS gets the center dam. It is a dealer installed item so not having them on a particular car doesn't mean much. Dealers can be lackadaisical about such things.
For me, I hated the look of scuffed air dams and they're going to get scuffed. I also don't like seeing them dirty, yet I hate washing them. I get down on my knees enough for this car as it is. So, this is my understanding on the subject, your mileage may vary.
For me, I hated the look of scuffed air dams and they're going to get scuffed. I also don't like seeing them dirty, yet I hate washing them. I get down on my knees enough for this car as it is. So, this is my understanding on the subject, your mileage may vary.
Melting Slicks
Joined: Apr 2002
Posts: 2,439
Likes: 590
From: Tellico Plains Tennessee
Hey Jerry, I didn't read your PDF yet since I was composing my post as you were posting yours. But quickly if you can, explain why any, and every, model Corvette that can easily exceed 150 mph doesn't have the dams if it's critical for stability. That doesn't seem to make sense to my simple mind. And I know my mind is simple. 
Thanks.
Thanks.
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 35,005
Likes: 12,393
From: NE South Carolina
^^^
The PDF outlines lots of "speculation" and "marketing speak" as to why no center air dam on for example the Z51 when it came out. Since My C6 Z51 had one and my September 2013 built 2014 did not I have followed the issue closely. GM's Chief Aerodynamicist was quoted in an article on October 2013 re C7 aero said it was removed on the Z51 for high speed stability but did not say what that was. Other GM folks talked about rear brake cooling but I was suspicious having seen the Chief Aerodynamicists comment that is was:"marketing speaK' to confound the real reason. It may have been a small factor but the answer came out ~2 years later when Tadge said: "We design the cars to have slight underster at high speeds and the center air dam was creating some oversteer at high speeds! Having a modified Corvair knew all about oversteer as did Porsches of that era! With understeer when your going too fast for a corner turning the wheel in the direction you want it to go is natural and what most folks will do. If lucky and you hit some dirt etc off the road it MAY gain some traction go where you want.
With Oversteer, as soon as you feel the rear move out because your going to fast, if you don't instantly turn away from where you want the car to go it will come around very fast and your off the road rear first! It's like when watching dirt track cars. To go fast you actually turn in the opposite direction of the turn! Takes a different skill and very quick reactions. .We had a saying at the time "If your going to fast for a curve you'll go off the road and could hit a tree. Better to hit it with the rear with an oversteering car than plow into it with the front with one that understeers." Ploughing is another term used for understeer or it's what NASCAR folks call understeer as being tight and oversteer being loose!
What is funny is my Grand Sport, which has the Stage 2 aero option that includes a large splitter and full length side skirts (same with the Z06) does not have a center air dam. But the base Grand Sport (and Z06) with what some call the small plastic poverty splitter and 3/4 side skirts has a center air dam! GM has not said why but they do wind tunnel testing and as Tadge said their computational fluid dynamic programs come very close to expensive wind tunnel testing. They know doubt have run all models and aero options though those programs. They know we can only guess that the larger splitter, that provides more high speed downforce is similar to the smaller splitter and a center air dam!
The PDF outlines lots of "speculation" and "marketing speak" as to why no center air dam on for example the Z51 when it came out. Since My C6 Z51 had one and my September 2013 built 2014 did not I have followed the issue closely. GM's Chief Aerodynamicist was quoted in an article on October 2013 re C7 aero said it was removed on the Z51 for high speed stability but did not say what that was. Other GM folks talked about rear brake cooling but I was suspicious having seen the Chief Aerodynamicists comment that is was:"marketing speaK' to confound the real reason. It may have been a small factor but the answer came out ~2 years later when Tadge said: "We design the cars to have slight underster at high speeds and the center air dam was creating some oversteer at high speeds! Having a modified Corvair knew all about oversteer as did Porsches of that era! With understeer when your going too fast for a corner turning the wheel in the direction you want it to go is natural and what most folks will do. If lucky and you hit some dirt etc off the road it MAY gain some traction go where you want.
With Oversteer, as soon as you feel the rear move out because your going to fast, if you don't instantly turn away from where you want the car to go it will come around very fast and your off the road rear first! It's like when watching dirt track cars. To go fast you actually turn in the opposite direction of the turn! Takes a different skill and very quick reactions. .We had a saying at the time "If your going to fast for a curve you'll go off the road and could hit a tree. Better to hit it with the rear with an oversteering car than plow into it with the front with one that understeers." Ploughing is another term used for understeer or it's what NASCAR folks call understeer as being tight and oversteer being loose!
What is funny is my Grand Sport, which has the Stage 2 aero option that includes a large splitter and full length side skirts (same with the Z06) does not have a center air dam. But the base Grand Sport (and Z06) with what some call the small plastic poverty splitter and 3/4 side skirts has a center air dam! GM has not said why but they do wind tunnel testing and as Tadge said their computational fluid dynamic programs come very close to expensive wind tunnel testing. They know doubt have run all models and aero options though those programs. They know we can only guess that the larger splitter, that provides more high speed downforce is similar to the smaller splitter and a center air dam!
Last edited by JerryU; Nov 13, 2018 at 03:56 PM.
Melting Slicks
Joined: Apr 2002
Posts: 2,439
Likes: 590
From: Tellico Plains Tennessee
Thank you Jerry. 
It still boggles my mind but I'm no engineer. As you've said, they had surely tested every variation of the platform and know a hell of a lot more than I do. For me, it's not a problem. I've never had my C7 above 110 mph and likely never will. I bought it cuz its an awesome car at 30, 50, 80 mph, whatever floats your boat. Guess speed hasn't impressed me much. Again, thank you very much for your timely reply.
It still boggles my mind but I'm no engineer. As you've said, they had surely tested every variation of the platform and know a hell of a lot more than I do. For me, it's not a problem. I've never had my C7 above 110 mph and likely never will. I bought it cuz its an awesome car at 30, 50, 80 mph, whatever floats your boat. Guess speed hasn't impressed me much. Again, thank you very much for your timely reply.
