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2005 STS N*, 1SF, 144K mi.
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650 Posts
Discussion Starter #1
Were the only 'air shock' rear dampers the MRC ones?

I guess a better question is, if the rear strut has an air bladder, is that a guarantee it's an MRC one?
 

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08 STS4 V8 1SG & 04 SRX4 V8 & 01 Monte SS
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Yes, all MRC rear shocks have the air bladder on them.
The non-MRC shocks are 'self leveling' and I don't believe they have an air bladder.
 

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2005 STS N*, 1SF, 144K mi.
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Discussion Starter #3
Okay.

I wonder how the non-MRC dampers level the car, then.

Anyone? Anyone? Bueller?
 

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08 STS4 V8 1SG & 04 SRX4 V8 & 01 Monte SS
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4,988 Posts
but they aren't compatible with MRC...
You'd have to bypass the MRC system to use it.

----------

Do you have the F55 RPO option on your truck RPO label?
 

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2005 STS N*, 1SF, 144K mi.
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Discussion Starter #7
Oh, they're MRC, because I've replaced them once.

I found a pair at a salvage yard, and as long as they're not leaking, I'll get them, as, if nothing else, I can likely use the air bladder from one of those on the almost guaranteed newer one I have have now, which currently has a hold in said air bladder.

I meant "this is good for my situation" in that, I don't have to rely on a salvage yard's knowledge. They are air-assist, which means they're MRC.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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FWIW, In MANY of these models, as well as the earlier Seville/Deville/Eldorado lines, it makes NO difference which level of suspension control or type the vehicle has/had - ALL of them incorporated ELC in the rear shocks.

ELC has nothing to do with suspension controls except for the fact that it maintains correct rear ride height in order to allow the suspension controls (if any) to do their job.

ELC is NOT "air assist", "Air ride" or any other suspension system type - it is (rear height) Electronic Level Control. Period.
 

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08 STS-4 N* 1SG, 08 DTS Luxury II, 04 Bonneville GXP N*
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... ALL of them incorporated ELC in the rear shocks.
In the 2005+ STS, only cars with RPO F55 have the ALC compressor. Unlike some other GM lines where the compressor was controlled by the Rear Integration Module, in this vintage of STS, ALC is controlled by the Electronic Suspension Control module used by the Magnetic Ride Control system. I was quite surprised when I found this out myself.
 

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08 STS4 V8 1SG & 04 SRX4 V8 & 01 Monte SS
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In the 2005+ STS, only cars with RPO F55 have the ALC compressor. Unlike some other GM lines where the compressor was controlled by the Rear Integration Module, in this vintage of STS, ALC is controlled by the Electronic Suspension Control module used by the Magnetic Ride Control system. I was quite surprised when I found this out myself.
This is also true of the SRX, I was surprised when I discovered that as well.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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OK - In light of that info, what type of system physically changes shock length to maintain rear level control ?

or, in the mentioned models, there is no active level control used ? Something has to physically change that shock length.
 

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08 STS-4 N* 1SG, 08 DTS Luxury II, 04 Bonneville GXP N*
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This would be the system demonstrated by the video in Post #4 by Luda.
 

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08 STS4 V8 1SG & 04 SRX4 V8 & 01 Monte SS
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The nivomat style shocks I would assume have a desired ride hight set in them from the manufacturer for each model car that it fits on. Once installed as the shock moves up and down it 'inflates itself' to the desired height and then releases excess pressure as you drive to maintain that desired height.
 

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2018 Camaro 2SS/NPP/F55/AQJ, Sold: 2015 Camaro, 2006 STS (EXP) 1997 Seville STS (EXP)
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...no ELC/no compressor/no "electronic" for rear height at all on 2005-up "FE1" (the non-F55-version) sigma-STS...they use the Sachs/ZF "Nivomat" self leveling shocks...

...again...different animal...;)

Edit: ...ok...you guys were faster...:D
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Clever - Now we (I, us) need to talk the manufacturer into a 2002.5 - 2003 STS retrofit :rolleyes:


Lotsa luck ................. but there must be a reason that the F55 MRC cars still have active external rear level control.
 

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08 STS-4 N* 1SG, 08 DTS Luxury II, 04 Bonneville GXP N*
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I'm curious also since the compressor and wiring add a lot of overhead. It may offer a little more precise control but I'd like to know the official answer.
 

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Its probably more reliable and a luxury to have the compressor setup as it will actively balance your load before you even start driving preventing any potential rubbing issues from load.

on the other hand it could simply be that they are mutually exclusive technologies meaning the movement of the MRC damper is unable to provide the same pumping action created by the Nivomat technology.
 

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2006 STS V8 AWD, '95 Ford Ranger
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Its probably more reliable and a luxury to have the compressor setup as it will actively balance your load before you even start driving preventing any potential rubbing issues from load.

on the other hand it could simply be that they are mutually exclusive technologies meaning the movement of the MRC damper is unable to provide the same pumping action created by the Nivomat technology.
Bingo! We have a winner!
 
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