Silverado Aerodynamics

[Hersbird]

More ground clearance doesn't necessarily mean higher ride height, just the lowest point of contact is something to do with the 4wd system. I would bet the frontal aera on a 4wd version is greater than a 2wd version.

[Piotrsko]

Originally Posted by Hersbird

More ground clearance doesn't necessarily mean higher ride height, just the lowest point of contact is something to do with the 4wd system. I would bet the frontal aera on a 4wd version is greater than a 2wd version.

Ok then, how do you avoid the higher ride height if all the other factors tend to remain the same

[kach22i]

Originally Posted by Hersbird

More ground clearance doesn't necessarily mean higher ride height, just the lowest point of contact is something to do with the 4wd system. I would bet the frontal aera on a 4wd version is greater than a 2wd version.

Are you talking about the use of a bigger/lower rear differential (commonly the lowest point) or actual body and suspension lifts?

Body Lift vs. Suspension Lift

[Hersbird]

Originally Posted by kach22i

Are you talking about the use of a bigger/lower rear differential (commonly the lowest point) or actual body and suspension lifts?

Body Lift vs. Suspension Lift

At least on a Ram 1500 the rear suspension is the same, 2wd or 4wd, the front suspension although independant on both 2wd and 4wd, the 2wd had a crossmember that doesn't drop as much and no transfer case hanging down a few inches. On the 2500 and 3500 Rams with a solid front axle, that front pumpkin is much lower than the rear and non existant on a 2wd.

I had a 2003 Ram 1500 2wd and it was much lower in the front than it's 4wd brothers although it may have had more ground clearance (probably not back then), the roof was a few inches lower than a 4wd. They may have tried to eliminate that raked look my 2003 had but i bet they do it by raising the front not lowering the back. IMO having the tailgate high and the nose low is a better aero setup than the nose and tailgate high although the best of all is nose and tailgate low. The suspension low points, hence ground clearance, probably don't move at all except when dire diameter is changed.

[Hersbird]

Originally Posted by Piotrsko

Ok then, how do you avoid the higher ride height if all the other factors tend to remain the same

Well I bet my 2003 Ram 2wd with it's lower front "rake" didn't have more ground clearance than a 4wd, but it had enough. The 4wd had to be higher in the front or it would have been a problem aera offroad with a couple of really low points. So now if the 2019 Ram has more ground clearance on the 2wd it is just because they jacked it to be more level with the rear to look like a 4wd but because it doesn't have those 4wd bits hanging low it has more ground clearance. The solid axle rear on both trucks is the same. The ground clearance is just a matter of tire diameter, the body can be raised or lowered over a huge range there and not change that a bit.

[Hersbird]

sort of getting off topic here, but I found these numbers for the new 2019 Ram 1500 4x4.

"Here are the figures related to "ground clearance" for the non-Rebel, non-Off-Road, Crew cab/5'7" bed (or Quad cab, 6'4" bed), 4WD trucks. For the same trucks with the long bed (6'4"), subtract .1" from EVERY number. I cannot say why this is so. These figures are taken from the 8/28/18 edition of the Specs document.

Ground Clearance at Front Axle - ALL MODELS - 8.2"
Ground Clearance at Rear Axle - ALL MODELS - 8.7"

Ground Clearance without Skid Plates - ALL MODELS WITH STANDARD SUSPENSION - 8.7"
Ground Clearance with Skid Plates - ALL MODELS WITH STANDARD SUSPENSION - 8.2"

Ground Clearance w/o Skid Plates - ALL MODELS WITH AIR SUSPENSION - 6.7" - 10.7" (or 10.8" - probably the correct figure)
Ground Clearance with Skid Plates - ALL MODELS WITH AIR SUSPENSION - 6.1" (OR 6.2") - 10.2" (or 10.3" - probably the correct figure)

Models with air suspension show the skid plate measurements in 4 columns corresponding to the 4 ride heights (entry, normal, off-road 1 and off-road 2). In all cases the figure in the normal column is 8.7" without skid plates and 8.2" with skid plates (same as normal suspension).

There is an implication that the low point on the chassis is the front axle, otherwise giving the measurement for that would be of no value."
-off 5thgenrams.com

So that air suspension is really the best of both worlds, low when you want it, and high when you need it. And the front is obviously the low point without it.

[Hersbird]

Now for body height, measured at the base of the door sill on the same 2019 Ram 1500 above it is 8.7 inches as the "normal". The air suspension does this to that measurement...
"* Normal Ride Height (NRH): 8.7 inches of clearance (measured from the base of the door sill) is the
default, load-leveled ride height
* Aero Mode: Lowers the vehicle 0.6 inches from NRH. Aero Mode improves fuel efficiency by up to one
percent and is activated by vehicle speed, adjusting for optimal performance and fuel economy
* Off-road 1: Lifts the vehicle 1.2 inches from NRH, reaching 9.1 inches of ground clearance, helping to
clear obstacles
* Off-road 2: Delivers more off-road capability, increasing ground clearance by 2 inches over NRH to 10.1
inches
* Park Mode: Lowers the vehicle 2 inches from NRH for easy entry/exit and cargo loading

Using the stated measurement of “8.7 inches of clearance to the base of the door sill” that would mean that the other 4 settings, measured in the same manner would be:
Park Mode (elsewhere known as Entry/Exit Mode): 6.7 inches.
Aero Mode: 8.1 inches.
Off-road 1: 9.7 inches, and not the 9.1 inches shown. (Or maybe 9.9 inches if you want to use the number "1.2").
Off-road 2: 10.7 inches, and not the 10.1 inches shown. (Or maybe 10.9 inches)."
-again from 5thgenrams.com

[Taylor95]

That's pretty neat to have variable suspension like that in a truck. I can see it being very useful, especially the aero mode. Although I'm sure the cost of having the truck basically sitting on hydraulics is pretty expensive...

[kach22i]

Sidebar, if anyone is curious where and how some of these dimensions are taken per SAE standards (going back to the 1970's) check out the link below and it's graphics.

Motor Vehicle Dimensions
SURFACE VEHICLE RECOMMENDED PRACTICE
https://law.resource.org/pub/us/cfr/...1100.2001.html

Second aside:

10 Highest Ground Clearance Trucks
https://www.autobytel.com/trucks/car...trucks-130986/

[Tahoe_Hybrid]

Not with leaked information
this suggest 0.55 classic brick silverado
this suggest 0.48..2003-2005
this suggest 0.49 for 2006(HD hood)


ACTUAL drag coefficient of 0.412 for the 2007-2013 Silverado

this suggest '14,15 has .40
this suggest 16-19 are .38-.36



just estimation based off of the leaked "actual" 2007-13 DATA