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-   -   Quadra Lift question (http://www.jeepgarage.org/f73/quadra-lift-question-19012.html)

Nouveau Redneck 02-17-2011 01:55 PM

Quadra Lift question
 
I was driving to work this morning and when I got up to highway speed the display said that it had attained "Aerodynamic Ride Height", and my mind got to thinking (I know, that's a scary thing). What popped into my head was this:

You can get the Quadra Lift suspension with a variety of different wheel/tire combinations that must result in at least a few different axle heights.

What tells the car that it is at the "Aerodynamic Ride Height"? Does it actually measure the distance form the undercarriage down to the pavement, or is it simply some preset spot in the range of travel of the suspension? If it is just a specific preset spot in the range of travel, is the computer configured at setup so that it knows what wheel/tire combination it has and adjust the "Aerodynamic Ride Height" position accordingly, or is it the same spot in the suspension travel no matter what wheel/tire combination it has? If it is the same spot regardless of wheel/tire combination, then what wheel/tire combination REALLY gets the CORRECT "Aerodynamic Ride Height"?

Sorry, I told you it's a scary thing when I start thinking.:confused:

2011RitterGC 02-17-2011 02:18 PM

Re: Quadra Lift question
 
I think that the diameter of all wheel/tire combo's are the same. 18" have talled tires than the 20" resulting in the same overall diameter.

Technosavant 02-17-2011 03:17 PM

Re: Quadra Lift question
 
The diameters of the various wheel/tire combos on the GC are nearly exactly identical to one another.

As for how it knows, there are height sensors front and rear. Check this out for a more detailed look:
http://wk2jeeps.com/wk2_quadralift.htm

J13ntv 02-17-2011 03:25 PM

Re: Quadra Lift question
 
I believe I read it lowers the car like .5 of an inch down when in aerodynamic mode..

As per Wk2Jeeps..

"Aero

Lowers the vehicle just over a half inch to maximize aerodynamics and fuel economy at highway speeds. This position also reduces body roll and provides a “sportier” feel. The vehicle will automatically enter Aero Mode when the vehicle speed remains between 62 mph (99 km/h) and 66 mph (106 km/h) for greater than 20 seconds or if the vehicle speed exceeds 66 mph (106 km/h). The vehicle will return to NRH from Aero Mode if the vehicle speed remains between 30 mph (48 km/h) and 35 mph (56 km/h) for greater than 20 seconds or if the vehicle speed falls below 30 mph (48 km/h). The vehicle will enter Aero Mode, regardless of vehicle speed if the Selec-Terrain™ knob is turned to the “SPORT” position. Turning the Selec-Terrain™ knob to the “AUTO” position will return the system to normal operation."

webspoke 02-17-2011 03:59 PM

Re: Quadra Lift question
 
There is a suspension position sensor on each corner (checks the position of the a-arms) that determinse the ride height, so no measurement to the ground directly.

mjw930 02-17-2011 04:11 PM

Re: Quadra Lift question
 
Quote:

Originally Posted by webspoke (Post 358262)
There is a suspension position sensor on each corner (checks the position of the a-arms) that determinse the ride height, so no measurement to the ground directly.

Correct and there is nothing in any of the systems that have any knowledge of the wheel/tire combination. It's based on the stock, factory tire diameter which is essentially the same for the 17, 18 and 20" versions. There's nothing in any system to adjust for larger tires.

Nouveau Redneck 02-18-2011 10:35 AM

Re: Quadra Lift question
 
Thanks for the great replies. So if you buy new wheels/tires down the road that don't match the factory tire diameter then it won't be at the truly aerodynamic ride height when it thinks it is. Plus you'll be either raising or lowering the overall range.

Another thing I don't understand is that the literature claims that the Quadra Lift suspension gives a maximum ground clearance of 10.7". What about the differentials? They don't go up and down with the suspension, so the actual ground clearance should remain the same. I guess they must be talking about the lowest point on the chassis.

Dunecrawler 02-18-2011 10:42 AM

Re: Quadra Lift question
 
Quote:

Originally Posted by Nouveau Redneck (Post 358846)
What about the differentials? They don't go up and down with the suspension, so the actual ground clearance should remain the same. I guess they must be talking about the lowest point on the chassis.

Think about this again. Independent suspension...

Nbtstatic 02-18-2011 10:48 AM

Re: Quadra Lift question
 
Quote:

Originally Posted by Nouveau Redneck (Post 358846)
Thanks for the great replies. So if you buy new wheels/tires down the road that don't match the factory tire diameter then it won't be at the truly aerodynamic ride height when it thinks it is.

I would imagine that lowering it half an inch, would be more aerodynamic regardless of the starting height, no?

mrpositraction 02-18-2011 11:53 AM

Re: Quadra Lift question
 
Quote:

Originally Posted by Nbtstatic (Post 358855)
I would imagine that lowering it half an inch, would be more aerodynamic regardless of the starting height, no?

Yes, the OP is over analyzing this (not a bad thing, this is how we come up with better ideas). We are giving the system to much "thinking" capabilities. It knows what level is and has position sensors in all 4 corners, that is it. The positions are preset with some sort of simple algorithm for keeping it level.

mjw930 02-18-2011 03:08 PM

Re: Quadra Lift question
 
Quote:

Originally Posted by Nouveau Redneck (Post 358846)
Another thing I don't understand is that the literature claims that the Quadra Lift suspension gives a maximum ground clearance of 10.7". What about the differentials? They don't go up and down with the suspension, so the actual ground clearance should remain the same. I guess they must be talking about the lowest point on the chassis.

Quote:

Originally Posted by Dunecrawler (Post 358851)
Think about this again. Independent suspension...

LOL,,,,,,,,,

Then again, he does have Redneck in his handle :D

Nouveau Redneck 02-18-2011 03:14 PM

Re: Quadra Lift question
 
Quote:

Originally Posted by Dunecrawler (Post 358851)
Think about this again. Independent suspension...

Suspension, independent or not, has nothing to do with the height of the differential. The differential is part of the axle, which is directly connected to the wheel, so you can adjust the suspension up and down all you want and the height of the differential will never change.


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