Things I Wish They Had Told Me Before Fixing My AirMatic: Tips/Info for front Arnotts
07-13-2013, 08:00 PM
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Things I Wish They Had Told Me Before Fixing My AirMatic: Tips/Info for front Arnotts
Time for the next chapter in this thrilling saga....replacing my front air shock with a remanufactured unit from Arnott! Anyone seriously thinking of undertaking this task should know what they’re in for, particularly if you have no access to air tools or a proper lift. It took me a good 8 hours over 2 nights, and I moved relatively slowly and had to make a few extra stops for tools I was lacking. I thought about taking pictures or video, but in the end I just wanted to get it done with. I’m assuming y’all had access and looked at Arnott’s directions previously so I won’t recap the whole thing here. I hope I can save at least 1 person an extra headache or two:
1. The directions from Arnott’s site are for the non-4Matic only! This is where you see 2 bolts to disconnect the bottom of the shock after liberating the upper control arm from the steering knuckle. 4Matics have a pesky sideways ball joint instead……and the ball joint separator you used for the upper control arm is likely too small! For RWD cars, the ball joint is on the lower control arm and not the shock, and it appears easier to separate….no amount of hammering or pry barring worked on my 4Matic without pressing it out, but it was hard to get leverage from the side with suspension components in the way and with the car on jackstands, not high up on a lift. You can use the $250 press that Mercedes uses if you’re not handy with a pickle fork and/or hammer (don’t worry about tearing the boot on the 4Matic shock…it’s junk now anyway!)….or you can use the $24 4” gear puller from Advance Auto like I did. No air tools if you want to get more than 2 uses out of it!
2. Speaking of the upper control arm, it was a deleted procedure for the 4Matics….Apparently Mercedes doesn’t think it’s necessary because you can swivel the bottom of the shock out backwards instead of the vertical connection the non-4Matics have which requires the upper control arm separation. I think they are out of their minds! The new shock is almost always too long to fit, and I had a ***** of a time maneuvering it into position as is even with the lower control arm loose and lowered. The hard part was lining up the 3 bolts on top, it always seemed as if I had to swing the whole thing outward than it could go to get them in place. I had already disconnected the upper control arm so I don’t know if it would have been different had I just left it alone, but I can tell you it took me hours to get the damn thing to fit! Maybe I was just tired and cranky by this point, but I suspect the non-4Matics would be easier. Jacking up the control arm from the bottom was a no-brainer to reconnect the upper ball joint. Mine used a 16mm nut.
3. One thing that wasn’t mentioned anywhere (but probably assumed) was that the upper ball joint has an all-metal (no nylon) self-locking nut that is recommended to be one-use only. If you’re doing this over a weekend, and you can’t find the exact nut i.e. dealer is closed, then you’re SOL if you were hoping to be on the road by Monday morning. Unless…...Yes, some will preach absolutely never to reuse any self-locking nut for any reason, while others will swear a dozen or more uses is totally fine, but being only the second time this particular one was being used (and assumed to be its last), I met them in the middle and reused it, putting threadlock on for good measure. It tightened no problem, but had it kept spinning, pressure on the control arm from a jack would hold enough to allow you to finish tightening. Use your judgment on this, if it’s obviously stripped or been used more than a couple times, probably best to get a new one, and if sudden control arm separation gives you nightmares, get a new one anyway. Also, if there’s any play, you should replace the ball joint while you’re in there. If you have the older style like mine, you’d need to replace the whole upper control arm to do this. Thankfully, the new ones allow you to replace the ball joint only, if necessary.
4. Also not mentioned anywhere is that the old shocks have tapered metal plates on top. These need to go on the new shock. They may stick to the top opening during removal, but mine came out with the old shock so it was something easy to overlook. They also need to be oriented a particular direction. Take note of it, and you can probably line up to the indentation looking up inside the wheelwell.
5. For RWD, Mercedes now specifies that you undo the tie rod from the steering knuckle instead of the upper control arm…..Personally, for reasons above, I think Arnott is right on this, removing the tie rod only gives you room to pull out the shock, but not as much freedom to maneuver the hub assembly around to make the new one fit.
6. The plastic brake line holder is FLIMSY…..I wish Arnott had just included its own so I didn’t feel like breathing on it would break the thing while taking it off and on, but I shouldn’t look a gift horse in the mouth, I could always just pay Mercedes $1300 for a shock and ask for another holder
The 4Matic version is only held on by a cable tie on top vs. two for the RWD, and it’s shorter, but it’ll only slide down a half-inch if it’s not on tight. The cable tie is thick rubber and can probably be reused without clipping if you shimmy underneath the fastener, but I was impatient and just cut it and used a regular 8” tie (which Arnott had said would be included 
)…I didn’t bother seeing if I could buy another sturdier rubber one that fit as well, but I used pliers to get it tight enough. Funny that it looks more like the brake line is what holds the brake line holder in place!
7. The shock that Arnott sent me had a busted side tab on the air shock electrical connector that snaps to the other connector, so they wouldn’t stay together without pressure. It took a good half hour on this since they get inserted as a pair way up the inner fender in a tiny space between the brake line, ride height hardware, and assorted cables. There’s a metal clip that goes over it you’ll no doubt drop and contribute to a cuss jar a few times before getting it to stay on.
8. The nut connecting the shock to the lower control arm on the old one (for 4Matic) was 21mm….the new shock used 22mm. Many socket sets only go up to 21mm, so make sure you have one on hand, and if it’s deep socket, you may have a hard time getting it to fit without tightening the nut most of the way first, and if your wrench is thick enough, might not fit at all! That’s because another piece is in the way not far behind.
9. Set ‘er down easy boys! That shock shouldn’t be loadbearing until it’s gotten some air…..so lower the car enough that the wheels are touching the ground and at least a few inches of space between the top of the wheel and the fender, then start the car, wait a few minutes, and push the AirMatic button. Arise, mighty Mercedes!
10. Thought I’d also mention that the wheel lugs are major PITA without the right socket, especially if your dealer torqued them to hell the last time out. My 17mm sockets INCLUDING THE ONE THAT CAME WITH THE CAR wouldn’t fit on 3 of the lugs, and the other 2 would be laughably bad attempts with the tiny wrench from the spare kit. I tried using a 11/16 that some recommended and still too small, while the 18mm only stripped the lugs. Do yourself a favor, pony up the $7 and order the special convex thin-walled impact socket from Ultimate Garage and be done with it…..if you can find the one with the protective rubber and don’t mind more $$, even better. Get a real breaker bar while you’re at it, why stop at 24”?
I couldn’t get the socket on the stripped lugs
, what was I ever going to do?? Oh that’s right….hammer that sucker on 
! A good half-inch or so….then they’re a piece of cake to remove! It had the side effect of reshaping the lug heads back to normal so I was good to go! If it gets stuck in the socket, just bang it on the ground a few times to knock it loose.
Also, if you’ve never taken a wheel off the car before, you’ll notice that the bolts don’t stick out of the hub like most cars, but instead you screw them IN to holes in the hub. These wheels are heavy! So lining up the holes on the wheel and the hub can be tricky although there’s a small lip on the inner wheel that makes it a bit easier.
11. Oh yes, torque specifications:
Upper control arm to steering knuckle: 20NM (15 ft lbs) stage 2 - 90 degrees (tighten to 20NM and additional quarter turn)
If you elected to undo the tie rod instead: 90NM (66 ft lbs)
Air shock bolt to lower control arm (4Matics): 110NM (81 ft lbs)
Two bolts on shock to lower control arm (RWD): 20NM each (15 ft lbs)
The 3 top bolts: 35NM (26 ft lbs) 4matics, 30NM (22 ft lbs) non-4matics, but do this after you’re done and the car is on the ground.
Air line hose : 5NM….10mm crow’s foot attachment was easiest without having an open socket
Overall it was a pretty straightforward task….Though more complex than a similar job on a Town Car, it’s less frustrating as most of the components are well thought out and shouldn’t be rusted to crap so you needn’t resort to using a blowtorch like on my old Lincoln! I have nothing but kind words to say about Arnott during this process, and this is not the first time they came to the rescue! I feel like I was just dealt a Monopoly card “Bank Error In Your Favor, Collect $1100.” There will be frustrating moments for sure
, but the first time you see your car magically picking itself off the ground again, you’ll know it was worth it all!
1. The directions from Arnott’s site are for the non-4Matic only! This is where you see 2 bolts to disconnect the bottom of the shock after liberating the upper control arm from the steering knuckle. 4Matics have a pesky sideways ball joint instead……and the ball joint separator you used for the upper control arm is likely too small! For RWD cars, the ball joint is on the lower control arm and not the shock, and it appears easier to separate….no amount of hammering or pry barring worked on my 4Matic without pressing it out, but it was hard to get leverage from the side with suspension components in the way and with the car on jackstands, not high up on a lift. You can use the $250 press that Mercedes uses if you’re not handy with a pickle fork and/or hammer (don’t worry about tearing the boot on the 4Matic shock…it’s junk now anyway!)….or you can use the $24 4” gear puller from Advance Auto like I did. No air tools if you want to get more than 2 uses out of it!
2. Speaking of the upper control arm, it was a deleted procedure for the 4Matics….Apparently Mercedes doesn’t think it’s necessary because you can swivel the bottom of the shock out backwards instead of the vertical connection the non-4Matics have which requires the upper control arm separation. I think they are out of their minds! The new shock is almost always too long to fit, and I had a ***** of a time maneuvering it into position as is even with the lower control arm loose and lowered. The hard part was lining up the 3 bolts on top, it always seemed as if I had to swing the whole thing outward than it could go to get them in place. I had already disconnected the upper control arm so I don’t know if it would have been different had I just left it alone, but I can tell you it took me hours to get the damn thing to fit! Maybe I was just tired and cranky by this point, but I suspect the non-4Matics would be easier. Jacking up the control arm from the bottom was a no-brainer to reconnect the upper ball joint. Mine used a 16mm nut.
3. One thing that wasn’t mentioned anywhere (but probably assumed) was that the upper ball joint has an all-metal (no nylon) self-locking nut that is recommended to be one-use only. If you’re doing this over a weekend, and you can’t find the exact nut i.e. dealer is closed, then you’re SOL if you were hoping to be on the road by Monday morning. Unless…...Yes, some will preach absolutely never to reuse any self-locking nut for any reason, while others will swear a dozen or more uses is totally fine, but being only the second time this particular one was being used (and assumed to be its last), I met them in the middle and reused it, putting threadlock on for good measure. It tightened no problem, but had it kept spinning, pressure on the control arm from a jack would hold enough to allow you to finish tightening. Use your judgment on this, if it’s obviously stripped or been used more than a couple times, probably best to get a new one, and if sudden control arm separation gives you nightmares, get a new one anyway. Also, if there’s any play, you should replace the ball joint while you’re in there. If you have the older style like mine, you’d need to replace the whole upper control arm to do this. Thankfully, the new ones allow you to replace the ball joint only, if necessary.
4. Also not mentioned anywhere is that the old shocks have tapered metal plates on top. These need to go on the new shock. They may stick to the top opening during removal, but mine came out with the old shock so it was something easy to overlook. They also need to be oriented a particular direction. Take note of it, and you can probably line up to the indentation looking up inside the wheelwell.
5. For RWD, Mercedes now specifies that you undo the tie rod from the steering knuckle instead of the upper control arm…..Personally, for reasons above, I think Arnott is right on this, removing the tie rod only gives you room to pull out the shock, but not as much freedom to maneuver the hub assembly around to make the new one fit.
6. The plastic brake line holder is FLIMSY…..I wish Arnott had just included its own so I didn’t feel like breathing on it would break the thing while taking it off and on, but I shouldn’t look a gift horse in the mouth, I could always just pay Mercedes $1300 for a shock and ask for another holder
The 4Matic version is only held on by a cable tie on top vs. two for the RWD, and it’s shorter, but it’ll only slide down a half-inch if it’s not on tight. The cable tie is thick rubber and can probably be reused without clipping if you shimmy underneath the fastener, but I was impatient and just cut it and used a regular 8” tie (which Arnott had said would be included )…I didn’t bother seeing if I could buy another sturdier rubber one that fit as well, but I used pliers to get it tight enough. Funny that it looks more like the brake line is what holds the brake line holder in place!7. The shock that Arnott sent me had a busted side tab on the air shock electrical connector that snaps to the other connector, so they wouldn’t stay together without pressure. It took a good half hour on this since they get inserted as a pair way up the inner fender in a tiny space between the brake line, ride height hardware, and assorted cables. There’s a metal clip that goes over it you’ll no doubt drop and contribute to a cuss jar a few times before getting it to stay on.
8. The nut connecting the shock to the lower control arm on the old one (for 4Matic) was 21mm….the new shock used 22mm. Many socket sets only go up to 21mm, so make sure you have one on hand, and if it’s deep socket, you may have a hard time getting it to fit without tightening the nut most of the way first, and if your wrench is thick enough, might not fit at all! That’s because another piece is in the way not far behind.
9. Set ‘er down easy boys! That shock shouldn’t be loadbearing until it’s gotten some air…..so lower the car enough that the wheels are touching the ground and at least a few inches of space between the top of the wheel and the fender, then start the car, wait a few minutes, and push the AirMatic button. Arise, mighty Mercedes!
10. Thought I’d also mention that the wheel lugs are major PITA without the right socket, especially if your dealer torqued them to hell the last time out. My 17mm sockets INCLUDING THE ONE THAT CAME WITH THE CAR wouldn’t fit on 3 of the lugs, and the other 2 would be laughably bad attempts with the tiny wrench from the spare kit. I tried using a 11/16 that some recommended and still too small, while the 18mm only stripped the lugs. Do yourself a favor, pony up the $7 and order the special convex thin-walled impact socket from Ultimate Garage and be done with it…..if you can find the one with the protective rubber and don’t mind more $$, even better. Get a real breaker bar while you’re at it, why stop at 24”?
I couldn’t get the socket on the stripped lugs
, what was I ever going to do?? Oh that’s right….hammer that sucker on ! A good half-inch or so….then they’re a piece of cake to remove! It had the side effect of reshaping the lug heads back to normal so I was good to go! If it gets stuck in the socket, just bang it on the ground a few times to knock it loose.Also, if you’ve never taken a wheel off the car before, you’ll notice that the bolts don’t stick out of the hub like most cars, but instead you screw them IN to holes in the hub. These wheels are heavy! So lining up the holes on the wheel and the hub can be tricky although there’s a small lip on the inner wheel that makes it a bit easier.
11. Oh yes, torque specifications:
Upper control arm to steering knuckle: 20NM (15 ft lbs) stage 2 - 90 degrees (tighten to 20NM and additional quarter turn)
If you elected to undo the tie rod instead: 90NM (66 ft lbs)
Air shock bolt to lower control arm (4Matics): 110NM (81 ft lbs)
Two bolts on shock to lower control arm (RWD): 20NM each (15 ft lbs)
The 3 top bolts: 35NM (26 ft lbs) 4matics, 30NM (22 ft lbs) non-4matics, but do this after you’re done and the car is on the ground.
Air line hose : 5NM….10mm crow’s foot attachment was easiest without having an open socket
Overall it was a pretty straightforward task….Though more complex than a similar job on a Town Car, it’s less frustrating as most of the components are well thought out and shouldn’t be rusted to crap so you needn’t resort to using a blowtorch like on my old Lincoln! I have nothing but kind words to say about Arnott during this process, and this is not the first time they came to the rescue! I feel like I was just dealt a Monopoly card “Bank Error In Your Favor, Collect $1100.” There will be frustrating moments for sure
, but the first time you see your car magically picking itself off the ground again, you’ll know it was worth it all!
07-13-2013, 08:54 PM
#2
Super Member
Congratz with the great result,and many thanks for the write up !!
Sooner or later surely I will refer to this great info.
Few Questions I have though:
Have you done the pair of these bad guys or one side only ?
Any need to recalibrate the ride height on the replaced shock(s) using Star at all?
Cheeers Martin.
Sooner or later surely I will refer to this great info.
Few Questions I have though:
Have you done the pair of these bad guys or one side only ?
Any need to recalibrate the ride height on the replaced shock(s) using Star at all?
Cheeers Martin.
07-14-2013, 06:47 PM
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I really didn't have to do anything else, and the height is back to normal. I did get the "ABS/ESP Unavailable" message for a bit, but that went away not long after I started driving.
I don't think I'm going to do the other one yet as it's already riding wondrously, maybe next year, unless it goes out on me first!
I don't think I'm going to do the other one yet as it's already riding wondrously, maybe next year, unless it goes out on me first!
07-20-2013, 08:25 AM
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I went through similar issues although I was fortunate to have the correct power tools and had no problem with the installation and product. Although after 200 or so miles I'm getting a message abut having the suspension serviced,,, Any similar experiences?
07-21-2013, 03:05 PM
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I've put about 800 miles since then and nothing so far.....It could be an air pump issue, maybe it's detecting a fault there, low pressure or small leak somewhere, or a problem with the ride height, check to see if it's low/uneven. Does the ride height button work ok? You could leave the car alone for a few days and see if it drops. It might also be a loose connector, I'd double check the compressor connections and that the ABS sensor + shock connector went in evenly as a pair and seated completely (Since the tab that clips them together isn't foolproof to begin with, the fact mine was broken made me have to reinsert them several times even after I thought I had plugged them in since I could see and feel that the connectors were uneven. They had a natural tendency to want to separate so maintaining enough pressure to keep them together evenly with the tips of my fingers while maneuvering them in different directions wasn't easy). One more possibility is the relay or one of the other shocks has begun to fail but still functions for now.
I never got "visit workshop" when it first happened, the message I got was "Malfunction", but it went away after I changed the shock without needing to reset anything.
I never got "visit workshop" when it first happened, the message I got was "Malfunction", but it went away after I changed the shock without needing to reset anything.
