Air Suspension Technical Info?

[R1Tom]

There was a salvaged compressor on eBay a few months ago. It had AMK parts numbers on it, it’s one of these models:

https://amk-group.com/en/products/air-suspension-compressors/passenger-cars/lfk/

Unfortunately I could not tell precisely which model based on the photos available and AMK has only very basic information available on their website. I’m an engineer and love tearing things apart, but I didn’t want to spend $300 on the salvage compressor to learn more.

I had a Land Rover LR3 that I personally maintained so I am very familiar with their design and function. My Land Rover had a Hitachi compressor (JLR later switched to AMK) and Dunlop air springs. The systems are very similar.

The compressors have a temperature sensor on the compressor head to shut off power if the compressor overheats. The internal seals are all plastic so heat destroys them. My LR3 compressor shut off around 190F.

The system pulls in fresh make up air to compensate for system leaks and vented off pressure when the ride height is lowered. The desiccant should be changed every 1-2 years depending on climate. In marine climates (like the PNW) the humid air saturates the desiccant quickly and when the temperature drops enough for a hard freeze the desiccant dryer will freeze up, restricting air flow. This makes the compressor work harder to move air into the system, leading to premature failure. We’ve already seen cases of air lines freezing up in the PNW with @jjswan33 ‘s R1T. I have not heard of a premature compressor failure, however.

Thanks! That AMK literature says those have self-regenerating dryer units. That seems to mean the desiccant is being regenerated by I am assuming heat? So then would the desiccant still require periodic replacement?

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[Forager]

Thanks! That AMK literature says those have self-regenerating dryer units. That seems to mean the desiccant is being regenerated by I am assuming heat? So then would the desiccant still require periodic replacement?

They “regenerate” by blowing the dry, exhaust air through the dryer as it is vented. This process is not 100% efficient so more moisture is deposited into the desiccant than is removed.

 

[R1Tom]

They “regenerate” by blowing the dry, exhaust air through the dryer as it is vented. This process is not 100% efficient so more moisture is deposited into the desiccant than is removed.

Makes sense. That does mean that replacement is necessary. I wonder if Rivian will make any recommendations on this or perform the service during one of the service intervals?

 

[White Shadow]

I wonder how the desicant works in these types of systems. Does the desiccant need replacement at some point or does it run a resistance heater at some point and drive the moisture out?

I know Land Rovers need to change the desiccant to keep the moisture under control, so I'm guessing the same thing applies to Rivian. I've never heard of a desiccant dryer in an air suspension system having a heater used to dry it out, but I'm only really familiar with the Land Rover system and the Jeep system (which is basically the same thing as the Mercedes Benz system)

 

[White Shadow]

Buy a report from Munro. Then you’ll have allllll the knowledge.

I didn't realize they sold that information. I would be nice to know if they have all the info available. I know those guys like to do teardowns and reverse engineer everything, but that's more mechanical than software and some of the stuff I'm wondering about is in the software for sure.

 

[White Shadow]

There was a salvaged compressor on eBay a few months ago. It had AMK parts numbers on it, it’s one of these models:

https://amk-group.com/en/products/air-suspension-compressors/passenger-cars/lfk/

Unfortunately I could not tell precisely which model based on the photos available and AMK has only very basic information available on their website. I’m an engineer and love tearing things apart, but I didn’t want to spend $300 on the salvage compressor to learn more.

I had a Land Rover LR3 that I personally maintained so I am very familiar with their design and function. My Land Rover had a Hitachi compressor (JLR later switched to AMK) and Dunlop air springs. The systems are very similar.

The compressors have a temperature sensor on the compressor head to shut off power if the compressor overheats. The internal seals are all plastic so heat destroys them. My LR3 compressor shut off around 190F.

The system pulls in fresh make up air to compensate for system leaks and vented off pressure when the ride height is lowered. The desiccant should be changed every 1-2 years depending on climate. In marine climates (like the PNW) the humid air saturates the desiccant quickly and when the temperature drops enough for a hard freeze the desiccant dryer will freeze up, restricting air flow. This makes the compressor work harder to move air into the system, leading to premature failure. We’ve already seen cases of air lines freezing up in the PNW with @jjswan33 ‘s R1T. I have not heard of a premature compressor failure, however.

Good info. So it seems like Rivian is basically using a very similar system to Land Rover. I think that's a good move for sure. The system in my Jeep is a sealed nitrogen system and although it works really well, the one bad thing about it is that it too will pull in atmospheric air if the system pressure gets low enough. And once it does that, then the moisture present will cause freezing issues in subzero temperatures. And of course then all the Jeep guys go crazy, complaining abou the air suspension system not working in cold weather, when the whole issue could have been avoided in the first place if they recognized that they had a small lead and fixed it to make sure the system remained full of high purity nitrogen. So in that regard, I like the Land Rover system better because it's more user friendly since it just uses air rather than nitrogen.

 

[crashmtb]

I didn't realize they sold that information. I would be nice to know if they have all the info available. I know those guys like to do teardowns and reverse engineer everything, but that's more mechanical than software and some of the stuff I'm wondering about is in the software for sure.

It's their entire business. They tear down vehicles/other components and sell the resulting information to whoever wants it. Most typically OEMs and suppliers.

 

[electruck]

It's their entire business. They tear down vehicles/other components and sell the resulting information to whoever wants it. Most typically OEMs and suppliers.

With prices targeted accordingly, I'm sure. Likely not worth the cost for the average Joe.

 

[Ecupip]

You can always go down to your local auto parts store and pick up one of these bad boys

 

[Trandall]

You can always go down to your local auto parts store and pick up one of these bad boys

You got me, I actually googled that to see if it was real.

 

[White Shadow]

You can always go down to your local auto parts store and pick up one of these bad boys

That's funny....but seriously, it's a good thing to know/understand how vehicles work if you keep them beyond the warranty period and want to do your own repairs. There's very little info out there on Rivian vehicles that I can find so far.

 

[R1Tom]

You can always go down to your local auto parts store and pick up one of these bad boys

I would immediately buy that....if it was real....

 

[White Shadow]

I would immediately buy that....if it was real....

Haynes stopped printing manuals years ago. I think they still do digital stuff for newer vehicles though.

 

[crashmtb]

Haynes stopped printing manuals years ago. I think they still do digital stuff for newer vehicles though.

They still do printed manuals.
https://haynes.com/en-us/

 

[White Shadow]

They still do printed manuals.
https://haynes.com/en-us/

Only for older vehicles that already have print versions of their manuals. I'm pretty sure they only offer digital versions for newer vehicles that didn't already have print versions.

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