Front Subframe: Service and Repair
Removing and installing front axle
Information
Component overview
Overview of front axle
1 - Front-axle cross member
2 - Roll pin
3 - Diagonal control arm
4 - Screw, M12
5 - Lock nut, M12
6 - Control arm
7 - Screw, M14
8 - Plate
9 - Screw, M12
10 - Screw, M14
11 - Screw, M14
12 - Lock nut, M14
13 - Spoiler
14 - Diagonal brace (different length for C2 and C4)
15 - Holder (not generally fitted)
16 - Screw, M5 (not generally fitted)
17 - Screw, M6
18 - Sensor (not generally fitted)
19 - Nut (not generally fitted)
20 - Linkage (not generally fitted)
21 - Holder (not generally fitted)
22 - Lock nut, M12
23 - Crash stop (only fitted for all-wheel drive)
24 - Screw, M12 (only fitted for all-wheel drive)
25 - Lock nut, M12
26 - Screw, M12
Preliminary work
1. Raise the vehicle at the prescribed jacking points.
Danger
Vehicle raised incorrectly.
^ Danger of fatal injury or material damage should the vehicle fall down.
- Raise the vehicle at the prescribed jacking points.
2. Remove front wheels.
3. Remove front underbody panel.
4. Drain coolant.
Warning
Hot fluid
^ Danger of scalding
- Let the fluid cool down.
- Wear personal protective gear.
Removing and installing front axle
Removing front axle
The front axle is removed complete with spring struts, wheel carriers, drive shafts (for all-wheel drive), steering gear and tie rods. Drain coolant and remove the brake calliper at the wheel carrier (brake hydraulic system not open).
Overview of front-axle cross member
(1) - Hexagon-head bolt for steering gear, M10. (Must not be loosened!)
2 - Hexagon-head bolt for front axle, M12
3 - Hexagon-head bolt for front axle, M14
4 - Hexagon-head bolt for front axle, M14
5 - Hexagon-head bolt for front axle, M14
(6) - Hexagon-head bolt for coolant pipe, M6. (Must not be loosened!)
(7) - Hexagon-head bolt for coolant pipe, M6. (Must not be loosened!)
(8) - Holder for coolant pipe. (Must not be loosened!)
Brake line holder
1. Remove brake line holder and electric cable plug.
1.1. Remove brake line holder on the wheel carrier at the left and right by loosening and unscrewing the screw -3-.
1.2. Loosen electric cable plug by loosening and unscrewing the nut -2-.
1.3. Disconnect electric cable plug -1- for the wheel speed sensor and brake pad wear indicator.
Removing and installing connecting link and wheel carrier
2. Remove connecting link on anti-roll bar.
Loosen the nut -2- and remove connecting link -1- from the anti-roll bar.
Removing and installing brake calliper
3. Remove left and right brake calliper.
Loosen screws -2-, remove brake calliper -1- from the wheel carrier and hang it to the side. Do not open the brake hydraulic system!
Diagonal brace
4. Remove diagonal braces and crash stop.
Crash stop is only fitted on all-wheel drive vehicles.
4.1. Remove diagonal braces -1-.
Unscrew screws -2- and remove diagonal braces -2-.
4.2. Remove crash stop (all-wheel drive only).
Loosen and remove screws -4- and then remove crash stop -3-.
Removing and installing restraining straps
5. Remove restraining straps on the fuel tank.
5.1. Loosen and remove screws -2- and then remove the restraining straps -1-.
5.2. Remove fuel tank cover.
Removing and installing drive shaft
6. For all-wheel drive vehicles: Remove the drive shafts on the transmission side.
Remove drive shafts -1- at the front by loosening and unscrewing the screws.
Information
Protect drive shafts against mechanical damage (e.g. with a rubber hose that has been cut open).
7. Remove universal joint at the steering spindle.
Information
^ Use only steering wheel holders that do not project into the area of the airbag unit!
^ If necessary, shorten guide rod at top!
Steering-wheel holder
7.1. Move steering wheel into center position.
Secure the steering wheel in center position using the steering-wheel holder -A-.
Removing and installing universal joint
7.2. Remove universal joint.
Loosen screw -1- on the universal joint -2- and remove it. Pull universal joint -2- off the steering spindle -3-.
Make sure not to pull the red lug -4- down as well because this will only increase the amount of assembly work required.
8. Pull connector off the range adjustment sensor (left side of vehicle only).
9. Remove pressure and return lines at the steering gear.
Information
^ Before the feed and return lines are loosened, place a suitable container underneath to collect steering fluid.
^ Wear protective goggles and gloves.
Tension shackle for steering-oil lines
9.1. Place an oil collection pan underneath the repair area.
9.2. Remove tension shackle -2- for steering-oil lines on the steering gear. Unscrew screw -1- and remove tension shackle -2-.
10. Disconnect coolant lines at the front and rear.
10.1. Disconnect front coolant lines (at the left and right).
Coolant lines on front axle
Loosen spring clamps on the couplings and pull off coolant hoses -1-.
10.2. Disconnect rear coolant lines (at the left and right).
Loosen spring clamps on the couplings and pull off coolant hoses -2-.
11. Loosen spring struts at the spring-strut dome.
Removing and installing spring struts for front axle
11.1. Loosen trim panel in the luggage compartment.
11.2. Disconnect cable plug -1- for the PASM line.
11.3. Loosen spring struts at the spring-strut dome by loosening and unscrewing the nuts -2-.
12. Remove front axle.
12.1. Support the front axle and fuel tank.
Cross member support
Stud on transmission support (all-wheel drive)
12.2. For all-wheel drive: Loosen and unscrew the nuts -2- on the transmission support -1-.
Loosen and unscrew studs -3- on transmission support -1- and remove transmission support -1-.
Front-axle threaded joint
12.3. Loosen and remove screws -1- securing front axle to body.
Lower front axle -2- using the spring struts and remove in a downward direction.
Installing front axle
Overview of front-axle cross member
(1) - Hexagon-head bolt for steering gear, M10
2 - Hexagon-head bolt for front axle, M12 x 1.5 x 30, tightening torque: 100 Nm (74 ft. lbs.)
3 - Hexagon-head bolt for front axle, M14 x 1.5 x 120, tightening torque: 160 Nm (118 ft. lbs.)
4 - Hexagon-head bolt for front axle, M14 x 1.5 x 50, tightening torque: 160 Nm (118 ft. lbs.)
5 - Hexagon-head bolt for front axle, M14 x 1.5 x 50, tightening torque: 160 Nm (118 ft. lbs.)
(6) - Hexagon-head bolt for coolant pipe, M6
(7) - Hexagon-head bolt for coolant pipe, M6
(8) - Holder for coolant pipe
Replace all lock nuts. Replace screw(s) securing universal joint (steering shaft) to steering gear and brake calliper to wheel carrier.
1. Install front axle.
1.1. Raise the front axle with the spring strut at the left and right and position it.
Cross member support
1.2. Screw in and tighten screws securing front axle to body -1 and 2-.
Screws -1- = rear: M14 x 1.5 x 50/front: M14 x 1.5 x 120.
Screws -2- = M12 x 1.5 x 30.
- Tightening torque, M14 front: 160 Nm (118 ft. lbs.)
- Tightening torque, M14 rear: 160 Nm (118 ft. lbs.)
Installing front-axle threaded joint
- Tightening torque, M12: 100 Nm (74 ft. lbs.)
Stud on transmission support
1.3. Screw in and tighten stud -3- on transmission support -1-.
- Tightening torque: 20 Nm (15 ft. lbs.)
1.4. Screw on and tighten nuts -2- on transmission support -1-.
- Tightening torque: 65 Nm (48 ft. lbs.)
2. Tighten spring struts at the spring-strut dome.
Removing and installing spring struts for front axle
2.1. Secure spring struts at the spring-strut dome by screwing on and tightening the nuts -2-.
- Tightening torque: 33 Nm (24 ft. lbs.)
2.2. Connect cable plug -1- for the PASM line.
2.3. Secure trim panel in the luggage compartment.
3. Connect coolant hoses.
Information
^ The coolant hoses must engage audibly when pushed into the flanges (Henn coupling).
Information
^ Check Henn coupling O-rings and replace them if necessary.
^ Clean plug connection and coolant hoses before assembly.
^ Coat O-rings and coolant hoses with Kluberplus Gel (Part No. 000.043.205.93).
^ Remove stoppers before fitting the coolant lines and hoses.
3.1. Connect coolant hoses at the front.
Coolant hoses on front axle
Press on coolant hoses -1- until the spring clamps on the Henn couplings lock with an audible click.
3.2. Connect coolant hose at the rear.
Press on coolant hose -2- until the spring clamp on the Henn coupling locks with an audible click.
4. Fit pressure and return lines at the steering gear.
4.1. Insert pressure and return lines with new sealing rings into the steering gear.
Tension shackle for pressure and return lines
4.2. Fit tension shackle -2- for pressure and return lines at the steering gear by inserting the tension shackle -2- and screwing in and tightening the screw -1-.
- Tightening torque: 23 Nm (17 ft. lbs.)
5. Fit universal joint at the steering spindle. Use new fastening screw!
Steering-wheel holder
5.1. Steering wheel must be in center position.
5.2. Fit universal joint on the steering spindle.
Universal joint for steering gear
Fit universal joint on the steering spindle while paying attention to the installation position -see arrows-.
5.3. Screw in and tighten M8 screw -arrow- on the universal joint.
- Tightening torque: 23 Nm (17 ft. lbs.)
Universal joint
Removing and installing drive shaft
6. For all-wheel drive vehicles: Fit the drive shafts on the transmission side.
Fit drive shafts -1- at the front by screwing in and tightening the screws.
- Tightening torque: 39 Nm (29 ft. lbs.)
Removing and installing restraining straps
7. Fit restraining straps on the fuel tank.
Fit restraining straps -1- and screw in and tighten screws -2-.
- Tightening torque: 23 Nm (17 ft. lbs.)
8. Install diagonal braces and crash stop.
Diagonal brace
8.1. Install crash stop -3- (all-wheel drive only).
Fit crash stop -3- and screw in and tighten screws -4-.
- Tightening torque: 100 Nm (74 ft. lbs.)
8.2. Install diagonal braces -1-.
Fit diagonal braces -1- and screw in and tighten screws -2-.
- Tightening torque: 100 Nm (74 ft. lbs.)
Removing and installing brake calliper
9. Fit brake calliper.
Fit brake calliper -1- and screw in and tighten M12 screws -2- for brake calliper.
Always replace M12 screws -2- for brake calliper before fitting.
- Tightening torque: 85 Nm (63 ft. lbs.)
10. Fit connecting link on anti-roll bar.
Fit connecting link -1- on anti-roll bar and screw on and tighten nut -2-.
- Three-stage tightening procedure (1st stage: tighten to 50 Nm (37 ft. lbs.). 2nd stage: loosen by 90 degrees. 3rd stage: tighten to 65 Nm (48 ft. lbs.).: 65 Nm (48 ft. lbs.)
Removing and installing connecting link and wheel carrier
Brake line holder
11. Fit brake line holder and electric cable plug.
11.1. Connect electric cable plug -1- for the wheel speed sensor and brake pad wear indicator.
11.2. Secure electric cable plug by screwing on and tightening the nut -2-.
11.3. Fit brake line holder on the wheel carrier at the left and right by screwing on and tightening the nut -3-.
- Tightening torque: 10 Nm (7.5 ft. lbs.)
12. Fit connector on range adjustment sensor.
Subsequent work
1. Fill the steering hydraulic system with Pentosin and top up the fluid level in the cooling system.
Then bleed the steering and cooling system.
Information
When topping up or filling in Pentosin, make sure that it does not come into contact with the coolant hoses. Observe the specifications in order to avoid overfilling, and thus overflowing.
^ If coolant hoses come into contact with Pentosin, clean them thoroughly with water IMMEDIATELY.
^ Replace visibly swollen coolant hoses.
^ Tighten all threaded connections to the specified tightening torque.
2. Install front wheels.
3. Install front underbody panels.
4. Perform suspension alignment.