I went ahead and ordered the conversion kit. Hopefully it will work alright. Once installed I might try to sell the old struts on ebay or just sell them to Arnott's at $50/each.

Put them in eBay if they're still good
You'll get $250-350 each

Hoping that it won't take forever to sell but I'll try. Would offset some of the cost of the conversion.

Picked up the car Saturday. Drives nice. Didn't notice any rolling.

The front seems a little high. Hopefully will adjust to right height in a few weeks. I hear the springs compress a little over time.

I managed to replace both lower ball joints but the strutmasters still didn't performed better. I still don't have firm control when cornering.
ABC conversion next?

How fast are you cornering?

In this pictured stretch, I'm comfortable doing 75mph with the S430 airmatic but not with the S600 Strutmasters. The speed limit is 65mph and the yellow warning limit is 40mph

Did you believe that replacing the factory system, which compensates for cornering loads, with a strut system, which has no such provision, would result in similar performance?

The struts were never going to handle as well as the OEM system...unless you fitted some roll/sway bars...and even then, it's still compromised.

I thought folks did the strut conversion to avoid paying to properly fix the factory system.

My 05 S600 came with the converted strutmasters. The sale pitch was for better reliability without mentioning performance lost. I didn't expect the strutmasters to perform worse than the airmatic.

My current Michelin PSS tires are OEM setup 245/45/18 front 265/40/18 rear. I ordered the Eagle F1 265/40/18 all around with hope that they would improve the cornering slightly.

It seems I'm no longer driving a S class with these strutmasters.

Yeah...I'm sorry to say, that the sales pitch isn't going to mention the downside. The ABC system is maintenance-intensive...no doubt...but I've never owned a car that rode so smoothly and then cornered so well.

So, the valve block rebuild, the line replacement, the strut replacement (one), and the purchase of STAR/DAS to be able to troubleshoot and rodeo the system, were all worth it to preserve that exceptional combination of handling and ride.

I've been shouted down for criticising the decision to go with the strut conversion...the proponents all discuss the cost savings and the "over engineering" of the ABC...but that ABC does make the big sedan handle...and that's part of what makes the W220 such a great car...

You're the first person to openly admit to the loss of performance. I appreciate that...but going back to ABC at this point will be challenging, and likely more costly than the repair that was avoided by the previous owner.

I'll have to find a spot on I-95 with a big curve to test it out.

The Strutmasters cost about the same as repairing the ABC system (about $2k with labor). But I was afraid of future repairs down the road. I plan on keeping the S55 for another 5-6 years and didn't want to spend $10k repairing the ABC system over time.

I also forgot to mention the rodeo ride when it get to the exact 75mph. Strutmasters bonus feature.

Would be willing to sell the 4 ABC struts if anyone is interested. About 64k miles on them.

My rough cost this spring, when I went through the ABC system in detail:

Pressure regulator accumulator: $225
Valve block o-rings: $12
ABC pump output o-rings: $16
10 L Pentosin: $130
2 filters: $75
Front valve block accumulator: $250
Rear valve block accumulator: $225
Rear accumulator: $250
Repair of line from front block to right strut: $125
Pulse damper line: $275
Arnott right front Strut: $650

Total: $1775

And about 20 hours of labor. Replacing the pulse damper line requires lifting the engine about an inch. It can't be done without doing that. Getting to the pump output o-ring (where the pulse damper line connects) requires removing a lot from the front of the engine. Ironically, the right front strut failed a week after the rest of the work. An internal sensor croaked. That strut was only two years old and the rest of the 11 year old struts are working just fine.

I won't mention that I replaced the spark plugs, had a coil pack repaired, installed a new intercooler pump and bled the system, replaced the serpentine belt and idler pulleys, and changed the oil and brake fluid at the same time...

And this fall, I've got a line that looks suspect (from the rear valve block to the left rear strut) that will be replaced, as well as the two lines under the engine. I'm looking at $600 + another 10L of Pentosin.

Now, in total, I've owned the car for 4 years. This is the first real ABC maintenance that I've had to do. The right front strut was replaced (because of a leak) while the car was under the warranty that I purchased when I bought it in 2012. So, if I'm out roughly $600/year for ABC maintenance, that doesn't seem excessive in the context of what the rest of this car costs and how well it performs...

But that's just my opinion...

Oh...that sucks...I am genuinely sorry...

I'm absolutely with you there. The W220 S600TT in particular has almost unique talent and potential, and it wouldn't be what it is without ABC, in my humble opinion. They're difficult to keep on the road, and it would be difficult to justify the effort and expense without those uncompromised, dynamic talents to make it all worthwhile.

The W215 & 220 were the first mass production cars with fully active suspension, and we're all guinea pigs to a greater or lesser extent. The W221 seems to have much more reliable ABC by contrast. Alternatively, the W220 S55K has most of the talent, but not the space/heat/ignition problems. The E55 is similar, but doesn't have ABC. There are other very fast, luxurious cars from BMW, Audi and Jaguar that have some of the attributes, but not the clean sweep.

Of course Mercedes didn't make it easy by stating "no maintenance - just cross your fingers". So we have to figure it out for ourselves. Most now realise that ABC needs regular oil and filter changes, and routine inspection, like everything else. To that, I'd add that ALL the ABC hoses in the engine compartment should be protected with heat shield sleeves (like the ones around the catalysts).

Get a grip on ABC, and do what's necessary MAKE SURE its reliable, and you can be confident of reaping the benefits. I've done a lot of ABC work on my car, and it amounts to GBP 30 for a hydraulic hose repair or ball joint, GBP 120 for an accumulator, and about GBP 200 for a used or remanufactured strut. That's more expensive than passive suspension, but it is really cost-no-object engineering with a specific purpose.

I really wouldn't keep my S600 if it didn't have ABC.

Nick

Are they still working or do I need to send them in for rebuild before installing?

No problem with the struts.

I enjoy my S55 and my 500SL but trying to contain costs. When things break, they are expensive.

I've spent more on the 500SL in the last three years than I paid for it. And if I were to sell it I would lose all the money spent on repairs.

The first year on the S55 I spent virtually nothing. This last year has been expensive. Probably $3,500. Hoping to contain costs in the future.

Hey I'm a CPA. Can't help but worry about costs.

The Strutmasters might do Ok on yours. S600 is a different kind of animal. That's what I learned. I'm still researching and haven't decided on what to do with it yet.
I might just trade it in if I see a right ones.

My kids (teenagers) tell me that I should trade in the two Mercedes for a more reliable car. One always seems to be in the shop. My mechanic is busy and sometimes takes a month to do non routine work.

Friends tell me I should get a third car to run around in. I'm divorced. Just me. Don't need 3 cars.

Hmm. Both S430 and S600 had been reliable cars for me but I spent more time working on them as I'm trying to keep making improvements.
I enjoy the 15 E350 but it feels cheap. Same with Escalade and H2. Thinking about getting rid of the H2 for the parking space.

Things just wear out over time. Not the engine. Just little plastic parts and gizmos.

For the SL, there have been a lot of top issues. All hydraulic cylinders replaced. Top replaced. Now a limit switch is faulty. Then there is the hot start issue I've never been able to fix.

The S55 had some maintenance issues in the past year. New back brakes. Six new tires (the back wore out with about 8,000 miles). Then the struts. Now my mirror turned brown and the coolant sensor is bad. Last year there was a part in the shifter (plastic) that broke.

I'm with you on the tires. I was just put on a new set of Bridgestone tires and they went ball after 9 months.
I thought I ride them too hard but apparently I wasn't the only one.

Yes these were Bridgestone Potenza. My mechanic said they were racing tires that tend to be softer. Hoping this set will fare better.

I agree 100% about keeping the ABC working, wouldn't be the same car without it. I will note that I felt my prior D4 A8 was the more nimble car, but didn't ride as quietly or smooth(seriously, those A8's are really planted, though.) Toyota had their active suspension in the mid 90's, but it didn't sell that well due the expense, and wasn't available outside of Japan, if I recall. Reportedly, it worked quite well.

Sounds like the two of you need to get in the same shop, and have them swap your suspensions around, Doe.