E39 Front Struts Write-up
The following information is provided for reference purposes only and should be used at your own risk
In no event shall Beisan Systems, LLC or its members be liable for incidental, consequential, or special loss or damages of any kind however caused.
Introduction
The E39 Front Struts Write-up covers the OEM Sachs struts/shocks, springs, and associated components found in the E39. Sachs suggests the lifespan of their struts/shocks is 70k-120k miles, though factors like cold weather and bad road conditions can accelerate wear. The Sachs BMW struts and shocks, manufactured in Germany, are identical to those sold on the open market—only the part numbers differ. Sachs also offers a lifetime warranty (“defective or worn-out”) on their struts/shocks, but this is available only through third-party vendors, not BMW.
This E39 Front Struts Write-up will discuss front strut failure symptoms, diagnosis, and a step-by-step E39 Sachs front struts R&R (remove and replace) procedure. Whether you’re troubleshooting worn suspension components or replacing E39 front struts, this guide provides essential details to ensure a smooth installation.
Symptoms
Initially, the front struts will squeak and have an extra bounce on speed bumps. Within a month this will transition to the car landing hard on speed bumps and the suspension feeling stiff on road bumps. A loss of control can also be felt during and after excessively bumpy road conditions.
Over time failing struts can cause inner tire tread cupping and wear.
Badly worn struts can leak lubricating oil.
If the spring pads are badly worn, a clunk could be heard when landing from a speed bump.
Diagnosis
There is no practical DIY diagnosis for struts/shocks. Paying attention to the symptoms is sufficient to characterizing the failure. If one end of the car is presenting with failure symptoms, then it’s likely the other end is not far behind.
Repair Procedure (E39 Front Struts Write-up)
The following is an E39 Front Struts Write-up Sachs front struts R&R (remove and replace) procedure.
A wheel alignment should be performed after the repair.
Repair time ~8 hours.
Parts, Tools, and Shop Supplies
2 x Sachs struts $164.40/each, 2 x upper spring pad (6-cyl, 31-33-1-091-867; 8-cyl, 31-33-1 -091-233) $3.02/each, 2 x bump stop (varies by model/year/suspension) $12.08/each, 2 x lower spring pad (i6 < 10/99 & v8 < 9/99 31-33-1-091-864, i6 >=10/99 & v8 >= 9/99 31-33-1-096-664) $3.44/each, 2x strut self-locking nut (31-12-1-095-420) $0.50/each, 6 x strut tower (collar) self-locking nut (31-33-1-092-887) $0.40/each, 2 x wheel carrier self-locking nut (33-32-1-093-103) $1.80/each, 2 x tie-rod self-locking nut (32-21-1-094-586) $0.40/each, 2 x stabilizer bar link self-locking nut (at stabilizer bar) (31-35-1-095-452) $0.37/each
Note: The Sachs new strut came with a strut self-locking nut, but was size 22mm not 21mm as specified by BMW. The strut mount and BMW ST socket would not have worked with the 22mm nut.
Needle nose pliers, large flathead screwdriver
16mm combo wrench, 18mm combo wrench
5mm Allen wrench
10 mm socket 1/4″, 13mm socket 1/4″, 16mm socket 1/2″, 18mm socket 1/2″
1/4″ ratchet w/ extension, 3/8″ ratchet, 1/2″ ratchet, 3/8″ torque wrench (24 Nm [17.5 ft-lb] – 110 Nm [81 ft-lb]) w/ 1/2″ converter, 1/2″ breaker bar (18″)
Optional: Long socket extension 1/2″ (not shown), for wheel carrier leverage.
Note: I utilized my 3/8″ torque wrench (17″) w/ 1/2″ converter instead of my 1/2″ torque wrench (22″) due to the functionally easier to use arm length. A 1/2″ torque wrench would also work well.
24mm combo wrench, BMW ST ball joint remover (90-88-6-31-2-240) $125/each
Optional: Ear plugs
~1lb dead blow hammer
OEM (company name) strut spring compressor #27036 AutoZone free w/ ~$40 deposit
6mm Allen wrench, wide/full jaw pliers
3/4″ combo wrench, BMW ST strut nut socket 21mm (90-88-6-31-2-210) $33.20/each
3/4″ socket 1/2″, 1/2″ ratchet (listed above)
Note: 3/4″ size is specific to indicated spring compressor
Note: BMW ST strut nut socket can be substituted with 13/16″ (~21mm) sparkplug socket with hex base, and 13/16″ (~21mm) combo wrench.
Materials Needed:
Paper towels, glass cleaner, brake cleaner, spray lubricant, graphite-based grease (such as Sta-Lube, Synthetic Grease, or CRC), a towel, a stainless steel wire brush, 2 x 2ft small-gauge rope, 4″ x 1″ mounting tape.
Not shown: Floor pad (an old quilt), 2 x wheel carrier stands (a bucket and 2 wood blocks).
Optional: Paint (to mark spring position on the strut).
Repair (E39 Front Struts Write-up):
Remove Components: Next, remove the front wheels. After that, take off the engine splashguard to access the struts.
Prepare the Vehicle: First, raise the front of the car and place it on jack stands (ensure you follow the appropriate procedure). Additionally, chock both sides of the rear wheels for safety.
The following procedure shows the left side (driver side). The right side is the same but with minor noted differences.
It’s more effective to perform the left side first since it’s illustrated with pictures.
Removal of spring/strut from car
Remove Brake caliper carrier to wheel carrier 2 mounting bolts (18mm socket 1/2″ / 1/2″ breaker bar & ratchet).
Remove the Caliper Carrier:
Important Note: However, be cautious not to over-expand the caliper, as this could place potentially damaging pressure on the braking system.
Detach the Caliper Carrier: Begin by removing the caliper carrier from the wheel carrier.
Pry Open the Caliper: If necessary, slightly pry the caliper open at the brake pad using a flathead screwdriver to facilitate removal.
Tie caliper carrier onto brake fluid pipe (rope).
Right Side (Xenon Lights):
To start, disconnect the level sensor regulating rod joint. Then, counter-hold the inside nut and remove the outside nut using needle-nose pliers and a 10mm socket with a 1/4″ ratchet. Afterward, remove the bolt and rotate the regulating rod (link) so that it is positioned adjacent to the control arm.
Additionally, check the regulating rod ball joints as described below for the stabilizer bar link.
Disconnect stabilizer bar link joint at stabilizer bar. First, push aside ball joint boot from inside nut (flathead). Counter hold inside nut and remove outside nut (16mm combo wrench, 16mm socket 1/2″ / 1/2″ ratchet). If tool not fitting well on inside nut, then repeat boot removal attempt. Inside nut has only two flat facets, so outside nut might need to be turned to spin inside nut into a tool accessible orientation.
Remove the Stabilizer Link Bolt:
- Detach the Bolt and Reposition the Link: Begin by removing the stabilizer link bolt. Then, rotate the link so that it is positioned adjacent to the wheel carrier.
- Note: If necessary, adjust the stabilizer bar and link to facilitate bolt removal.
Inspect the Stabilizer Bar Link Ball Joints:
2. Check for Proper Movement: This is a good opportunity to inspect the stabilizer bar link ball joints. First, twist the bolt or link on both ends to rotate the ball and socket joints. The movement should feel stiff.
3. Test for Play: Next, push and pull each bolt (ball) in and out of the link (socket) to check for any play or free space. Importantly, there should be no movement at all. Check link rubber boots for tears, especially at base seam.
Any ball joint play (free space) or rubber tear and link needs to be replaced (easy to perform at a later time).
Remove steering outer tie-rod nut at wheel carrier (18mm combo wrench).
8-cyl note: Tie-rod attached at rear of wheel carrier shelf.
Begin by removing the tie-rod bolt from the wheel carrier using a BMW ball joint remover and a 24mm combo wrench. Next, apply graphite-based grease to the outer/leverage spindle for smoother operation. Screw in the outer/leverage spindle clockwise, leaving approximately 1/2″ of thread exposed. Then, adjust the inner/fitting spindle to ensure a secure fit between the lower wheel carrier shelf and the tie-rod bolt end. Insert and twist the lower tool arm fork fully under the tie-rod ball joint boot.Position the upper tool arm press cup on top of the tie-rod bolt end and insert the arm as far in as possible.If needed, adjust the fitting spindle for proper alignment. Finally, tighten the leverage spindle to secure the tool in place using a 24mm combo wrench.
Tighten leverage spindle to press tie-rod bolt out of wheel carrier shelf (24mm combo wrench). There will be a “big bang” when bolt releases, and tools will drop to ground. Be careful!!
Note: It’s helpful to protect ears from shock (ear plugs).
8-cyl: Turn steering wheel to opposite side to facilitate space for tie-rod ball joint to drop out of wheel carrier.
Check tie-rod ball joint as described above for stabilizer bar link.
Disconnect wheel carrier strut bearing. Counter hold bolt and remove nut (16mm combo wrench, 18mm socket 1/2″ / 1/2″ ratchet). Remove bolt.
ABS/speed & brake pad sensor bracket will be removed.
Protect fender middle to back rim. Cover rim inside, bottom lip, and outside (2″ mounting tape).
Start by removing the strut plastic center cap (flathead) at the strut tower (under the hood).Next, loosen and remove the three strut mount nuts at the strut tower using a 13mm socket with a 1/4″ ratchet and socket extension. Then, detach the filter box spring clip at the strut tower and partially lift the filter box assembly to allow easier access to the rear nut.
Optional: Insert a bar into the wheel hub center for foot leverage using a long 1/2″ socket extension. Before proceeding, verify that the ABS/speed sensor and brake pad sensor cables have enough slack to accommodate the lowering of the wheel carrier in the next steps. Next, position the tie-rod to the side of the wheel carrier. Optional: For better clearance, turn the steering wheel—for 6-cylinder models, turn to the opposite side; for 8-cylinder models, turn to the work side—which will draw the tie-rod inboard toward the car.
Press down on wheel hub with foot while holding onto spring coils with hands. Lower strut assy top out of strut tower and pull into outer wheel well.
Note: Allow strut assy top to lower strait out of tower first before pulling into outer wheel well. Otherwise strut assy will hook onto wheel well liner and become difficult to extract.
Press down again with foot, tilt strut assy top to rear ~10″, lower strut assy, and slowly lean strut assy top out of wheel well.
Note: Allow strut assy top to lower away from fender rim before pulling out of wheel well. Otherwise strut assy will hook onto fender inner rim and become difficult to extract.
Note: Do not use heavy force. If strut assy is not clearing rim, stop, and reconsider components positioning.
Cover fender to protect from strut assy (towel).
Remove strut from wheel carrier. Lubricate wheel carrier bearing top and bottom at strut (spray lubricant). Wait a few minutes for lubricant to take effect.
Pry open wheel carrier bearing (flathead), while simultaneously twisting spring coil and pulling up on strut.
Support wheel carrier to relieve pressure on suspension arms bushings.
Repeat procedure for second side.
Replacement of strut
Clean spring thoroughly (glass cleaner / towels). There should be no debris or grease on spring when done; clean and dry.
Coat both spring press spindle (bolt) threads with grease lubricant (graphite based grease). Also coat both spindle heads clasp contact surfaces.
Note: This is essential for proper function and maintenance of tool.
Clean spring press clasps (coil seats) (brake cleaner / towels).
Lay strut assy down horizontally (floor pad). Place a spring press at each side of spring, and alternate spring press directions so there is a spindle head at each spring seat.
Working with spring press with spindle head at upper spring seat (strut mount seat), place spring press head clasp on coil as far to end of spring as possible. Jar spring press clasp a few times to push further to end on spring (dead blow hammer). Clasp should be just below spring end tip.
Place spring press tail clasp on spring two coils away, keeping spindle strait on strut axis.
Tighten spindle to maintain clasps positions.
Perform same as above with second spring press. A notch in lower spring seat (strut perch) facilitates positioning spring press head clasp further to end of spring.
Spring presses need to be as far on opposite sides of spring as possible. This will help keep spring presses from slipping during press process.
First, tighten the spindles using a 3/4″ socket and 1/2″ ratchet, alternating frequently between spindles. It is crucial to maintain proportional spindle clasp-to-clasp lengths to prevent the spring press from sliding. If the spring press shifts out of position, it can cause significant complications. To avoid issues, rotate the spindles often and handle the spring presses carefully to prevent jarring.
. The strut mount is then positioned so that its notch indentation mates with the spring upper tip.
Optional: Place a mark on the spring lower coil at the perch nose tip to provide an orientation reference for reinstallation (paint).
Note: It’s best to have strut horizontal when performing press process (floor pad).
First, tighten the spindles using a 3/4″ socket and 1/2″ ratchet, alternating frequently between spindles. It is crucial to maintain proportional spindle clasp-to-clasp lengths to prevent the spring press from sliding. If the spring press shifts out of position, it can cause significant complications.To avoid issues, rotate the spindles often and handle the spring presses carefully to prevent jarring.
Spring press with spindle head at upper spring seat will need open face tool on last 1/3 of press process due to spindle head proximity to seat (3/4″ combo wrench).
Spring coils need to be pressed until almost touching. Press process is complete when spring has some play between upper and lower seats.
Remove the Strut Mount Nut:
Reposition the Allen Wrench: Additionally, note that the Allen wrench will need to be repositioned by half a rotation for every half turn to complete the process.
Break the Nut Seize: First, counter-hold the strut piston rod using a 6mm Allen wrench and pliers (for added leverage). Then, unscrew the strut mount nut to break the nut seize using a BMW 21mm socket and a 1/2″ ratchet.
Important: This step requires significant effort and leverage. To make it easier, perform it with the strut standing upright on a floor pad.
Fully Unscrew the Nut: Next, counter-hold the strut piston rod again and fully unscrew the strut mount nut to remove it using the same tools.
Dismantle strut assy.
Clean (brake cleaner (metal) | glass cleaner (rubber) / towels) reusable parts; strut mount, 2 washers, strut mount seat, end coils of spring.
Note: Above picture shows exact positioning discussed below. Second assembled strut assy can also be referenced.
Install New Spring Pads:
- Position the Spring Pads: Begin by placing the new spring pads on the corresponding lower spring seat (new strut perch) and upper spring seat (strut mount seat). Make sure they are positioned appropriately.
Tighten the Strut Mount Nut:
2. Secure the Strut Mount Nut: Next, counter-hold the strut piston rod using a 6mm Allen wrench and pliers. Then, tighten the strut mount nut using a BMW 21mm socket and a 1/2″ ratchet.
- Note: The Allen wrench will need to be repositioned by half a rotation for every half turn during this process.
Note: This step requires significant effort and leverage. For ease, I performed this with the strut standing upright on a floor pad..
Fully Tighten the Nut: After that, fully tighten the strut mount nut to 64 Nm (47 ft-lb) using the 6mm Allen wrench, pliers, BMW 21mm socket, and a 3/8″ torque wrench with a 1/2″ converter.
Note: It’s important to have strut standing on end when initially uncompressing spring presses to insure proper positioning of components (floor pad).
Unscrew spring presses, rotating often between spindles (3/4″ socket 1/2″ / 1/2″ ratchet | 3/4″ combo wrench). Maintaining proportional spindle clasp to clasp lengths is essential to keeping a spring press from sliding. Be careful not to jar spring presses.
Watch component positioning and adjust as needed (dead blow hammer).
Once spring has seated well, it’s best to complete uncompressing process while strut is horizontal (floor pad). Rotate often and be careful not to jar spring presses. Watch component positioning and adjust as needed (dead blow hammer).
Once spring has fully seated and spring presses are loose, remove spring presses.
Repeat procedure for second side.
Installation of spring/strut on car (E39 Front Struts Write-up)
Clean (brake cleaner / towels, wire brush) following parts:
- Wheel carrier strut bearing shaft and bolt/nut contact surfaces, mounting bolt; ABS/speed & brake pad sensor holding bracket contact surfaces.
- Strut tower bolt/nut contact surfaces.
- Tie-rod bolt and washer, and wheel carrier contact surfaces.
- Stabilizer link bolt and stabilizer bar contact surfaces.
- Right side: xenon lights: bolt and nut, and regulating rod contact surfaces.
- Caliper carrier and wheel carrier contact surfaces and mounting bolts.
Fully insert strut, with alignment tag facing car inboard side, into wheel carrier bearing. A strut shelf will define insertion end point. Adjust strut to align L or R tag indication, respectively for left or right side, with bearing seam.
Insert strut assy top into wheel well. Position tie-rod to side of wheel carrier.
Press down on wheel hub with foot while holding onto spring coils with hands.
Tilt strut assy top to rear, ~10″, and slowly lean strut assy top into wheel well.
Note: Do not use heavy force. If strut assy is not clearing rim, stop, and reconsider arms positioning at wheel carrier.
Install the Strut Assembly:
Reinstall Components: Finally, reinstall the filter box spring clip at the strut tower and replace the strut center plastic cap.
Position the Strut Assembly: First, press down again with your foot and push the strut assembly top into the strut tower using your hands.
Align the Strut Mount: Next, place one hand in the wheel well and push up on a spring coil. Simultaneously, rotate the strut mount from the top (under the hood) with your other hand to align it properly. Be sure to reference the key peg for correct positioning.
Secure the Strut Mount: After that, insert the bolts into their respective strut tower holes and screw on the new self-locking nuts by hand.
Tighten the Nuts: Then, fully tighten the nuts to 24 Nm (17.5 ft-lb) using a 13mm socket, 1/4″ ratchet, and socket extension.
Ease Installation of Rear Nut: To make the installation easier, partially lift the filter box assembly to provide better access for the rear nut.
Place ABS/speed and brake pad sensor bracket at wheel carrier mounting position.
Left side: When oriented properly, wires will show from car outboard side.
Right side: When oriented properly, wires will show from car inboard side.
Insert wheel carrier bearing mounting bolt from front end of wheel carrier. Screw bolt in as needed to fully insert. Screw on new self-locking nut. Counter hold bolt and tighten nut (16mm combo wrench, 18mm socket 1/2″ / 1/2″ ratchet). Fully tighten, 81 Nm (59 ft-lb) (16mm combo wrench, 18mm socket 1/2″ / 3/8″ torque wrench & 1/2″ converter).
Install the Outer Tie-Rod Bolt:
Note: Since torque tool access is not feasible in this step, tighten the nut by feel (it should feel hard).
Insert the Bolt: Begin by inserting the outer tie-rod bolt into the wheel carrier mounting hole.
Secure the Bolt: Next, place the washer on the bolt and screw on the new self-locking nut by hand.
Tighten the Nut: Then, counter-hold the bolt end using a 5mm Allen wrench and tighten the self-locking nut with an 18mm combo wrench.
Fully Tighten: After that, fully tighten the nut to 65 Nm (48 ft-lb) using the 18mm combo wrench.
Install the Stabilizer Bar Link Bolt:
Insert the Bolt: Start by inserting the stabilizer bar link bolt into the stabilizer bar mounting hole. If needed, adjust the stabilizer bar and link to facilitate bolt insertion.
Secure the Nut: Next, screw on the new self-locking nut by hand.
Tighten the Nut: Then, counter-hold the inside nut and tighten the outside nut using a 16mm combo wrench and a 16mm socket with a 1/2″ ratchet.
Fully Tighten: Finally, fully tighten the nut to 65 Nm (48 ft-lb) using a 16mm combo wrench, a 16mm socket, a 3/8″ torque wrench, and a 1/2″ converter.
Right side: xenon lights: Insert level sensor regulating rod bolt into level sensor mounting hole. Screw on self-locking nut. Counter hold inside nut and tighten outside nut (needle nose pliers, 10mm socket 1/4″ / 1/4″ ratchet).
Untie brake caliper carrier. Install caliper carrier on wheel carrier with mounting bolts. Fully tighten bolts, 110 Nm (81 Ft-lb) (18mm socket 1/2″ / 3/8″ torque wrench & 1/2″ converter).
Repeat procedure for second side.
Reinstall engine splashguard. Reinstall front wheels. Lower front of car (follow appropriate procedure).
Start car and pump brake pedal several times to tighten brake caliper pitons.
This is very important!!
A wheel alignment should be performed after the repair.
To my mom, may she always be blessed.
Rajaie (Palestinian)
E39 Front Struts Write-up.
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