wbrian63

2007 LS460L. I'd like to lower the car just a bit to even out the tire gaps and improve the appearance.

I can do this easily, but there is a problem. Almost daily I go to a place where the driveway approach is a very steep climb from the street to the parking lot, with a sharp crest over from slope to flat. At this point, if I approach directly (90-degrees to the crest), I just barely make it without scraping (high center).

If I lower the car at all, that will be a problem.

My previous car (2002 MB S55), had the ABC hydraulic suspension, and the transition from normal to high (via a button on the dash) was about 5 seconds.

The LS takes at least 60 seconds, if not more - not an option. I don't want to have to remember to start raising the car a block or two from my destination.

Additionally, it would be nice to have a more reactive system when I have to parallel park against a high curb with passengers. On the MB, it was just a quick press of the button and I had less to worry about a passenger scraping the bottom of the door on the curb.

As I understand the system, the air pump is the only source of compressed air. When I press the "Height High" button, the compressor comes on and raises the car. The slowness is directly related to the available volume that can come from the compressor, which is obviously limited.

There are two ways around this issue, as I see it.

1) Separate reserve tank with separate compressor, holding about 150psi constant reserve. "T" this system in with a valve into the output of the existing compressor, probably with a check valve to control the direction of flow. Have the valve triggered (opened) when the compressor kicks on.

2) Replace factory compressor with a higher volume unit.

Of course, there will still be flow limits imposed by the individual valves at the struts themselves (assuming that's how Lexus has implemented the system). I would assume the factory lines are standard plastic lines that can probably take 200psi.

I'm not looking to create a car that responds like a low-rider, just one where I don't grow old waiting for the suspension to transition from normal to high ride height.

Suggestions are appreciated.

is150

iTrader: (10)

Here is a thread discussing the same issue.

https://www.clublexus.com/forums/ls460-ls460l-and-ls600h/754207-ls460-air-suspension-compressor.html

Tee

Your only choice is to install and aftermarket A/S system that will give you the speed you desire. The OEM A/S system is designed to be limited in its functionality, yes it is slow but I found it is a tad faster when the car is moving vs still.

wbrian63

Speed of slow vs. still probably has more to do with higher available system voltage and consequent greater output of the compressor.

Devh

A lot of times the limited functionality and speed is a result of keeping a system reliable.
A lot of the other makes with aggressive air suspension are more prone for repairs.
If the system is modified to be faster then the way the system is designed it may lead to an early failure.

wbrian63

Reliabilty is #1 priority. That's why I got rid of my '02 MB AMG S55. Great car, but after nearly 200k miles, reliability was beginning to get dicey.

I'll do some more digging to see what the limiting factors are.

For example, It won't do any good to install a higher CFM compressor (assuming I do all diligence to properly power the unit without overloading the factory power circuits) if the flow through the valves is limited to what the factory unit can produce, or if the lines to the struts are so small that they restrict flow.

Devh

Most all electrical systems are based on a 14 volt power availability so I don't think electrical load would make much difference. If the fuses for the air compressor trips you could just go outside the fuse box and directly to the battery with an inline fuse and relay. I also think the failure point will be with the rate at which the air suspension bladder gets filled.
At that point in time you are better off with an aftermarket system because at the very least you know what you are getting.

wbrian63

True, but all things remaining equal, a higher-output compressor will draw more amps than a lower-output compressor. The bigger issue comes from how the computers in the car interact with the pump itself. Looking at AllData, the power plug to the compressor has 4 wires. Only 2 are theoretically needed, so possibly the other two link with the suspension control module for performance monitoring.
It could well be that if I disconnect the factory compressor and use the factory harness to trigger a relay that activates a higher-capacity pump that the control module would store an error when it doesn't see the factory unit running...

Agreed - I've seen some reasonably-priced high-cfm compressors on the web (Viaair brand). It would do little good to mount a 2.5cfm compressor in place of the factory who-knows-how-much-cfm compressor if the hoses and valves only support 1.5cfm.


Given the cost of replacing struts, that may be an option at some point in the future. One thing I wouldn't want to sacrifice is ride quality. I can live without the adjustable suspension (although it is nice to be able to switch to Sport when I've got people in the car over undulating road surfaces - keeps the suspension from bottoming-out at the cost of a slightly rougher ride).
What I wouldn't want to do is create a car that rides like it has been "bagged"...

Devh

If the factory pumps has some kind interface that communicates feedback to a module then you could possibly leave them in line with an external compressor that just gets triggered by a relay. This would be a way to supplement the existing pumps.

wbrian63

Interesting thought. I'll keep that in mind.