Greenfingers Posted September 12, 2023 Share Posted September 12, 2023 (edited) It was surprisingly hard to find any info on how to do this job. There's plenty about F models with rear air springs, but the G31 is a different procedure with the spring and shock incorporated into one unit, so a mini tutorial may help others save some of the pounds that a main dealer would want. This job shouldn't be too tricky for anyone with a decent socket set and reasonable DIY ability, but bear in mind the car may also need 4 wheel allignment afterwards. Step 1 is to isolate the compressor electrics, either by removing the relevant fuse, or disconnecting the battery (which is what I did). The most frustrating part for me was discovering how to remove the interior trims to gain access to the 3 nuts and 1 bolt holding the strut from above:- Remove the 'C' pillar trim by prying off the airbag symbol and unscrewing the hidden torx screw. The rear seat side squab needs to be removed by pulling up and forwards to expose a couple more torx screws securing the black trim above the carpeted panel. With the plastic trim pulled away from the side window, there are a couple more torx screws to remove the carpeted panel. Once this is out of the way, the 4 strut fixings are accessible with a 13mm socket . The seat belt assembly can remain in situ. You can see the bolts holding the strut in place in the middle of this photo:- The basic mechanics of removing the strut assembly are then simple:- jack up and support the car, remove wheel, disconnect air line and remove the bottom mounting. The drop link bolt and innermost bolt in the lower suspension arm also need removing to provide clearance to extract the strut. Once the wheel is off, there is a plastic panel under the bottom wishbone that needs to come off (2 x 8mm socket heads) and the air hose unscrews with a 10mm spanner. The innermost end of the bottom wishbone connects to the rubber bush via an eccentric bolt and nut (for camber adjustment?). I took photos of the nut and bolt and made sure they were in the same position when reassembled, to hopefully avoid the need for reallignment. Nuts and bolts removed (21mm & 18mm and E14 etorx & 16mm for the drop link). You will be able to pull the strut assembly out through the top of the wheelarch after lowering the bottom part into the void, so a standard jack provides plenty of height to do the job. Reassembly is the reverse procedure, not sure about torque settings, but a good pull on a bar about 2 foot long. Be cautious after reconnecting the electrics - my compressor didn't kick in until I drove the car forward, so it may take a few minutes before the ride height is corrected. As far as I'm aware, no reprogramming or calibration is required. So in all, a more involved job than on an F11, but I would hope to do it in a couple of hours next time - much less than the 5 hours or so someone suggested BMW would quote. I just hope these units are more reliable than the old style airbags, because they aren't cheap at around £750 a pop. I thought the old style bags failed due to exposure to grit etc, but these newer versions have a plastic gaiter, presumably to protect the rubber bag. Obviously that didn't work in this case, because the unit I replaced was leaking at 73k miles. I got a used one cheap this time (manufactured in 2020), so we'll wait and see... Edited September 12, 2023 by Greenfingers Grammer and bullshit removal 1 Quote Link to comment Share on other sites More sharing options...
ally Posted September 12, 2023 Share Posted September 12, 2023 (edited) Good write up. I find ISTA really good for guides, torque settings etc. Its worth having. Edited September 12, 2023 by ally Quote Link to comment Share on other sites More sharing options...
Matthew Posted September 14, 2023 Share Posted September 14, 2023 On 12/09/2023 at 15:51, Greenfingers said: It was surprisingly hard to find any info on how to do this job. There's plenty about F models with rear air springs, but the G31 is a different procedure with the spring and shock incorporated into one unit, so a mini tutorial may help others save some of the pounds that a main dealer would want. This job shouldn't be too tricky for anyone with a decent socket set and reasonable DIY ability, but bear in mind the car may also need 4 wheel allignment afterwards. Step 1 is to isolate the compressor electrics, either by removing the relevant fuse, or disconnecting the battery (which is what I did). The most frustrating part for me was discovering how to remove the interior trims to gain access to the 3 nuts and 1 bolt holding the strut from above:- Remove the 'C' pillar trim by prying off the airbag symbol and unscrewing the hidden torx screw. The rear seat side squab needs to be removed by pulling up and forwards to expose a couple more torx screws securing the black trim above the carpeted panel. With the plastic trim pulled away from the side window, there are a couple more torx screws to remove the carpeted panel. Once this is out of the way, the 4 strut fixings are accessible with a 13mm socket . The seat belt assembly can remain in situ. You can see the bolts holding the strut in place in the middle of this photo:- The basic mechanics of removing the strut assembly are then simple:- jack up and support the car, remove wheel, disconnect air line and remove the bottom mounting. The drop link bolt and innermost bolt in the lower suspension arm also need removing to provide clearance to extract the strut. Once the wheel is off, there is a plastic panel under the bottom wishbone that needs to come off (2 x 8mm socket heads) and the air hose unscrews with a 10mm spanner. The innermost end of the bottom wishbone connects to the rubber bush via an eccentric bolt and nut (for camber adjustment?). I took photos of the nut and bolt and made sure they were in the same position when reassembled, to hopefully avoid the need for reallignment. Nuts and bolts removed (21mm & 18mm and E14 etorx & 16mm for the drop link). You will be able to pull the strut assembly out through the top of the wheelarch after lowering the bottom part into the void, so a standard jack provides plenty of height to do the job. Reassembly is the reverse procedure, not sure about torque settings, but a good pull on a bar about 2 foot long. Be cautious after reconnecting the electrics - my compressor didn't kick in until I drove the car forward, so it may take a few minutes before the ride height is corrected. As far as I'm aware, no reprogramming or calibration is required. So in all, a more involved job than on an F11, but I would hope to do it in a couple of hours next time - much less than the 5 hours or so someone suggested BMW would quote. I just hope these units are more reliable than the old style airbags, because they aren't cheap at around £750 a pop. I thought the old style bags failed due to exposure to grit etc, but these newer versions have a plastic gaiter, presumably to protect the rubber bag. Obviously that didn't work in this case, because the unit I replaced was leaking at 73k miles. I got a used one cheap this time (manufactured in 2020), so we'll wait and see... The bolts and screws should be replaced and the torque settings observed: Loosen nuts (1). Remove cover (2) of the camber control arm. 12 – Removing the camber control arm Remove the expansion nut (1). Unfasten nut (1). (2)Pull out screw. Loosen nuts (1) and (2). Loosen the nut (3) and remove the eccentric washer. Pull out the eccentric bolt (4). Pull out screws (1) and (2). Remove the camber arm (3). MAIN WORK 13 – Removing the rear air suspension strut CAUTION Residual pressure in the air suspension strut. Danger of injury! The air suspension strut remains under a certain amount of residual pressure after the pipe has been connected. Do not disassemble the air suspension strut. RISK OF DAMAGE Damage to the air spring system. Even the smallest of dirt particles can cause leakage in the air suspension system. Ensure utmost cleanliness within the connection face of the pipes during disassembly and installation. For this purpose, also see the additional information: 37 00 ... Information for the air spring system. Carefully loosen the banjo bolt (1) on the air suspension strut (2) until you hear escaping air (fizzing noise). Wait approximately 2 minutes until the pressure in the air spring system has been completely reduced. The fizzing noise stops. Completely loosen the banjo bolt (1) after having fully bled the pressure from the system. ▶ If installed: Disconnect plug connections Detach the cable (1) from the holder (2). Unlock the plug connections (3) and disconnect from the air suspension strut. Put the cable (1) to one side. TECHNICAL INFORMATION Secure component against falling. Secure air suspension strut against falling out. Loosen screw (1). Loosen nuts (2). Remove air suspension strut. 14 – Installing the rear air suspension strut RISK OF DAMAGE Damage to the air suspension strut. Moving the vehicle when the air suspension struts are not completely filled will result in damage to the air suspension strut. Make sure the air suspension struts are completely filled. The residual pressure in the air suspension strut is not sufficient. For automatic filling of the air suspension struts: Connect the battery and turn on the ignition. If the vehicle is in "vehicle lift mode": Fill the air suspension struts via the diagnosis system. For additional information see: 37 00 ... Drain/fill the air spring system. Renew the aramid seal (1) between the air suspension strut and the body. Parts: Aramid seal Position the air suspension strut in the wheel arch and secure to prevent it from falling down. Renew the screw (1). Parts: Screw Tighten down screw (1). Rear air suspension strut to body M8 Renew screw. 30Nm Renew nuts (2). Parts: Nuts Tighten nuts (2). Rear air suspension strut to body M8 Replace nuts. 30Nm ▶ If installed: Connect connector Position cable (1). Attach the cable (1) on the holder (2). Connect the connector (3) to the air suspension strut and lock. Check banjo bolt (1) for contamination; clean if necessary. Carefully screw in the banjo bolt (1) on the air suspension strut (2) by hand to prevent damage to the thread on the spring strut. Tighten the banjo bolt (1). Air pipe to air suspension strut Tightening torque 2,25Nm POSTPROCESSES 15 – Installing the camber control arm Position the camber control arm (3). Renew the screws (1) and (2) and the nuts (4) and (5). Parts: Screws and nuts Insert bolts (1) and (2). Tighten the nut (4) hand-tight. Tighten nut (5). Camber arm to wheel carrier M14 Replace screw and nut. Jointing torque 165Nm Angle of rotation 90° ▶ Pretightening joint bush in air suspension strut TECHNICAL INFORMATION In order to prevent losses in drivability, the joint bush from the spring strut or air suspension strut must strictly be screwed in the camber control arm free from tension. This is possible only with the following special tool. Observe the procedure to install special tool 2 456 679 on the air suspension strut. Mount the clamp A (1) at the air suspension strut. Special tool for spring strut/air suspension strut Clamp A for spring strut/air suspension strut Tightening torque 40Nm Mount the clamp B (2) on the joint bush of the air suspension strut. Special tool to joint bush Clamp B to joint bush Tightening torque 40Nm Position special tool 2 456 679 onto air suspension strut. Note Position tool vertically downwards. The knurled screw (2) always points towards the centre of the vehicle. Tighten clamp A (1). Special tool for spring strut/air suspension strut Clamp A for spring strut/air suspension strut Tightening torque 40Nm Turn back the knurled screw (1) up to the limit position. Turn the knurled screw (1) until the support (2) is in contact at the clamping jaw (3). Tighten clamp B (4). Special tool to joint bush Clamp B to joint bush Tightening torque 40Nm Pretighten joint bush in air suspension strut: Turn the knurled screw (1) until the value to be adjusted can be read flush at the scale (2) on the clamping jaw (3). Value to be set on scale = 9 TECHNICAL INFORMATION The vehicle ride height may change as a result of turning the eccentric bolts for the adjustment of toe and camber. When renewing the bolts, make sure the eccentric bolts are correctly positioned to keep the ride height change to a minimum during the adjustment work. Position the eccentric bolt (1) during renewal in a way that the eccentric points vertically upwards! Press the camber control arm (1) upwards and position on the rear axle support. Renew the eccentric bolt (2), eccentric washer and the nut (3). Parts: Eccentric bolt, eccentric washer, nut Apply the screw connection (3) of the camber control arm on the rear axle support with 5 Nm. Renew the bolt and the nut (4) of the anti-roll bar link on the camber control arm. Parts: Bolt, nut Apply the screw connection of the anti-roll bar link (4) hand-tight. Tighten the screw connection (1) of the spring strut on the camber control arm. Rear spring strut/air suspension strut to camber control arm M14 Renew screw and nut. Tighten in normal position. Tightening torque 165Nm Angle of rotation 90° Remove special tool 2 456 679. TECHNICAL INFORMATION Tighten the screw connection in the normal position. For additional information see: 33 00 Overview of Technical Data Tighten screw connection of camber control arm at rear axle support (1) in normal position. Camber control arm to rear axle support M14 Renew bolt, nut and eccentric washer. Tighten in normal position. Tightening torque 175Nm Tighten screw connection of anti-roll bar link at camber control arm (2) in normal position. Anti-roll bar link to camber control arm M10 Renew screw and nut. Tighten in normal position. Tightening torque 56Nm Angle of rotation 90° Install the expansion nut (1). 16 – Install the cover of the left camber control arm ▶ Installing the cover of the camber control arm Position the cover (2) of the camber control arm correctly on the camber control arm. While doing so, note the direction of installation. The arrow (3) has to point in the direction of travel. Renew nuts (1). Parts: Nuts Tighten nuts (1). Cover to camber control arm M6 Replace nuts. Tightening torque 6Nm Quote Link to comment Share on other sites More sharing options...
maximka Posted April 19 Share Posted April 19 (edited) On 14/09/2023 at 09:13, Matthew said: The bolts and screws should be replaced and the torque settings observed: Loosen nuts (1). Remove cover (2) of the camber control arm. 12 – Removing the camber control arm Remove the expansion nut (1). Unfasten nut (1). (2)Pull out screw. Loosen nuts (1) and (2). Loosen the nut (3) and remove the eccentric washer. Pull out the eccentric bolt (4). Pull out screws (1) and (2). Remove the camber arm (3). MAIN WORK 13 – Removing the rear air suspension strut CAUTION Residual pressure in the air suspension strut. Danger of injury! The air suspension strut remains under a certain amount of residual pressure after the pipe has been connected. Do not disassemble the air suspension strut. RISK OF DAMAGE Damage to the air spring system. Even the smallest of dirt particles can cause leakage in the air suspension system. Ensure utmost cleanliness within the connection face of the pipes during disassembly and installation. For this purpose, also see the additional information: 37 00 ... Information for the air spring system. Carefully loosen the banjo bolt (1) on the air suspension strut (2) until you hear escaping air (fizzing noise). Wait approximately 2 minutes until the pressure in the air spring system has been completely reduced. The fizzing noise stops. Completely loosen the banjo bolt (1) after having fully bled the pressure from the system. ▶ If installed: Disconnect plug connections Detach the cable (1) from the holder (2). Unlock the plug connections (3) and disconnect from the air suspension strut. Put the cable (1) to one side. TECHNICAL INFORMATION Secure component against falling. Secure air suspension strut against falling out. Loosen screw (1). Loosen nuts (2). Remove air suspension strut. 14 – Installing the rear air suspension strut RISK OF DAMAGE Damage to the air suspension strut. Moving the vehicle when the air suspension struts are not completely filled will result in damage to the air suspension strut. Make sure the air suspension struts are completely filled. The residual pressure in the air suspension strut is not sufficient. For automatic filling of the air suspension struts: Connect the battery and turn on the ignition. If the vehicle is in "vehicle lift mode": Fill the air suspension struts via the diagnosis system. For additional information see: 37 00 ... Drain/fill the air spring system. Renew the aramid seal (1) between the air suspension strut and the body. Parts: Aramid seal Position the air suspension strut in the wheel arch and secure to prevent it from falling down. Renew the screw (1). Parts: Screw Tighten down screw (1). Rear air suspension strut to body M8 Renew screw. 30Nm Renew nuts (2). Parts: Nuts Tighten nuts (2). Rear air suspension strut to body M8 Replace nuts. 30Nm ▶ If installed: Connect connector Position cable (1). Attach the cable (1) on the holder (2). Connect the connector (3) to the air suspension strut and lock. Check banjo bolt (1) for contamination; clean if necessary. Carefully screw in the banjo bolt (1) on the air suspension strut (2) by hand to prevent damage to the thread on the spring strut. Tighten the banjo bolt (1). Air pipe to air suspension strut Tightening torque 2,25Nm POSTPROCESSES 15 – Installing the camber control arm Position the camber control arm (3). Renew the screws (1) and (2) and the nuts (4) and (5). Parts: Screws and nuts Insert bolts (1) and (2). Tighten the nut (4) hand-tight. Tighten nut (5). Camber arm to wheel carrier M14 Replace screw and nut. Jointing torque 165Nm Angle of rotation 90° ▶ Pretightening joint bush in air suspension strut TECHNICAL INFORMATION In order to prevent losses in drivability, the joint bush from the spring strut or air suspension strut must strictly be screwed in the camber control arm free from tension. This is possible only with the following special tool. Observe the procedure to install special tool 2 456 679 on the air suspension strut. Mount the clamp A (1) at the air suspension strut. Special tool for spring strut/air suspension strut Clamp A for spring strut/air suspension strut Tightening torque 40Nm Mount the clamp B (2) on the joint bush of the air suspension strut. Special tool to joint bush Clamp B to joint bush Tightening torque 40Nm Position special tool 2 456 679 onto air suspension strut. Note Position tool vertically downwards. The knurled screw (2) always points towards the centre of the vehicle. Tighten clamp A (1). Special tool for spring strut/air suspension strut Clamp A for spring strut/air suspension strut Tightening torque 40Nm Turn back the knurled screw (1) up to the limit position. Turn the knurled screw (1) until the support (2) is in contact at the clamping jaw (3). Tighten clamp B (4). Special tool to joint bush Clamp B to joint bush Tightening torque 40Nm Pretighten joint bush in air suspension strut: Turn the knurled screw (1) until the value to be adjusted can be read flush at the scale (2) on the clamping jaw (3). Value to be set on scale = 9 TECHNICAL INFORMATION The vehicle ride height may change as a result of turning the eccentric bolts for the adjustment of toe and camber. When renewing the bolts, make sure the eccentric bolts are correctly positioned to keep the ride height change to a minimum during the adjustment work. Position the eccentric bolt (1) during renewal in a way that the eccentric points vertically upwards! Press the camber control arm (1) upwards and position on the rear axle support. Renew the eccentric bolt (2), eccentric washer and the nut (3). Parts: Eccentric bolt, eccentric washer, nut Apply the screw connection (3) of the camber control arm on the rear axle support with 5 Nm. Renew the bolt and the nut (4) of the anti-roll bar link on the camber control arm. Parts: Bolt, nut Apply the screw connection of the anti-roll bar link (4) hand-tight. Tighten the screw connection (1) of the spring strut on the camber control arm. Rear spring strut/air suspension strut to camber control arm M14 Renew screw and nut. Tighten in normal position. Tightening torque 165Nm Angle of rotation 90° Remove special tool 2 456 679. TECHNICAL INFORMATION Tighten the screw connection in the normal position. For additional information see: 33 00 Overview of Technical Data Tighten screw connection of camber control arm at rear axle support (1) in normal position. Camber control arm to rear axle support M14 Renew bolt, nut and eccentric washer. Tighten in normal position. Tightening torque 175Nm Tighten screw connection of anti-roll bar link at camber control arm (2) in normal position. Anti-roll bar link to camber control arm M10 Renew screw and nut. Tighten in normal position. Tightening torque 56Nm Angle of rotation 90° Install the expansion nut (1). 16 – Install the cover of the left camber control arm ▶ Installing the cover of the camber control arm Position the cover (2) of the camber control arm correctly on the camber control arm. While doing so, note the direction of installation. The arrow (3) has to point in the direction of travel. Renew nuts (1). Parts: Nuts Tighten nuts (1). Cover to camber control arm M6 Replace nuts. Tightening torque 6Nm Thank you for the instruction. Can you also show how to remove the trim on the right side to get to the shock absorber mount in the trunk? Edited April 19 by maximka Quote Link to comment Share on other sites More sharing options...
Matthew Posted April 19 Share Posted April 19 15 hours ago, maximka said: Thank you for the instruction. Can you also show how to remove the trim on the right side to get to the shock absorber mount in the trunk? Turn the screw cap (1)counter-clockwise to the limit position. Open and remove the flap in the luggage compartment trim panel (2). 5 – Removing the right D-pillar trim panel NOTICE Description is for left component only. Procedure on the right side is identical. TECHNICAL INFORMATION The trim panel for the roof pillar can only be removed or installed when the drivers are up. Make sure the drivers (1) are on the left and right top. TECHNICAL INFORMATION When the roller cover for the luggage compartment is detached, both drivers will move down. If necessary, move the drivers up: Hold the roller cover for the luggage compartment (1) in the position shown until the driver (2) travels up. TECHNICAL INFORMATION At the left guide rail, a limit-position switch and a magnet in the handhold detect the position of the roller cover for the luggage compartment. With a missing cover rail: Hold a magnet at the respective position or activate the driver via the diagnosis system. Detach the roller cover for the luggage compartment (1). Loosen screws (1) and (2). Detach the D-pillar trim panel (1) at the clips (2) and guide it out of the luggage compartment capping toward the inside. 6 – Remove C-pillar trim panel WARNING Pyrotechnic components. Danger! Life-threatening injuries! All work on pyrotechnic parts may be carried out by technically experienced and appropriately trained personnel only. Replace any damaged part or ones that have been dropped. For additional information see: 72 00 Safety regulations on handling components with gas generators. NOTICE Description is for left component only. Procedure on the right side is identical. Lever out the cover (1) from the C-pillar trim panel (2) with a suitable tool. Release screw below it. Guide out the C-pillar trim panel (2) from the luggage compartment capping toward the top. 7 – Remove armrest side section Reach behind the backrest side section (1) from the top and unclip the backrest side section (1) from the latch mechanism (2) to the front. Remove the backrest side section (1) from the rear seat in direction of arrow. 8 – Removing the right luggage compartment sill NOTICE Description is for left component only. Procedure on the right side is identical. ▶ Removing the operating handle of the cargo adjuster NOTICE Description is for left component only. Procedure on the right side is identical. Using special tool 0 490 539 (00 9 322), lever the operating handle of the cargo adjuster (1) upward out of the luggage compartment capping (2). Unclip Bowden cable (1) from the operating handle of the cargo adjuster (2) and detach. Release screw (1) and screws (2). Release screws (1) and disassemble clip (2). 9 – Removing right luggage compartment wheel arch trim panel NOTICE Description is for left component only. Procedure on the right side is identical. ▶ Remove luggage compartment wheel arch panel Loosen the expanding rivet (1). Feed out and remove the luggage compartment wheel arch trim panel (2). Quote Link to comment Share on other sites More sharing options...
RoGa Posted April 21 Share Posted April 21 Hello. Any tips to replace strut properly without this special tool? Quote Link to comment Share on other sites More sharing options...
MarekB Posted April 24 Share Posted April 24 Before you will lift your car, measure a height between a wheel rim and fender as a reference. Once a strut is replaced, put your wheel back to the hub and lift/raise the wheel by the jack to the reference position. Tighten screw/nut in this position. Quote Link to comment Share on other sites More sharing options...
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