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E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


 
 
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Old Sat, Dec-28-2013, 03:13:11 AM   #1
bimmerfan08
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Default DIY: E46 M3 detailed subframe reinforcement, gear fluid changes, & bushing refresh

This DIY is for the most part, straightforward but time consuming. Depending on what reinforcement method is chosen, plan to have the M3 out of service for 3-5 days. Plan to also inject structural foam into the subframe cavity to increase the stiffness and minimize flexing or use a mechanical fastening method to marry the upper and lower subframe panels.

Tools needed:
3/8" drive ratchet
1/2" drive ratchet
3/8" drive torque wrench
1/2" drive torque wrench
3/8" drive breaker bar
3/8" to 1/2" socket adapter
1/2" to 3/8" socket adapter
3/8" various socket extensions
6mm hex bit socket
7mm hex bit socket
14mm hex bit socket (optional if doing differential fluid change)
8mm hex socket
10mm hex socket
10mm deep well hex socket
12mm deep well hex socket
13mm hex socket
13mm deep well hex socket
17mm hex socket
17mm deep well hex socket
18mm hex socket
18mm deep well hex socket
19mm hex socket
21mm hex socket
E12 socket
E14 socket
12mm open end wrench (for Koch tool)
2 x 13mm open end wrenches
14mm open end wrench
18mm box end wrench
18mm open end wrench
24mm open end wrench (for Koch tool)
30mm open end wrench
3 jaw puller
Chisel
Needle nose pliers
Rubber mallet
Steel hammer
Straight head screwdrivers
2 x jack or lift
4 x jack stands minimum or lift
Angle grinder
Tin snips
Power drill either cordless or corded
Angle grinder or power drill discs & paint removal brushes/wire wheels
Flashlights
C-clamp
Mechanic's work light/lamp
3/8" or 1/2" drive air impact wrench/gun (optional)
3/8" drive air socket wrench (optional)
Air compressor (optional)
Koch BMW E46 rear suspension subframe bushing tool set (highly recommend)

Parts and supplies needed:
1 x center support mount (PN: 26122282495) - includes new bearing
1 x flex disc (PN: 26112226527)
6 x flex disc hex bolt (PN: 26117635643) - optional
6 x flex disc hex lock nut (PN: 26127536563)
2 x header to section 1 exhaust gasket ring (PN: 11627830668)
2 x section 1 to section 2 exhaust flat gasket (PN: 18307830674)
6 x section 1 to section 2 exhaust hex bolt (PN: 07119902901)
6 x section 1 to section 2 exhaust hex nut (PN: 11621744323)
4 x header to section 1 torx bolt (PN: 11621318568)
4 x header to section 1 hex nut (PN: 18301317898)
2 x transmission mounts (PN: 22322282340) or aftermarket mounts (Rogue Engineering)
1 x subframe left front bushing (PN: 33312283573) or aftermarket bushings (AKG)
1 x subframe right front bushing (PN: 33312283574) or aftermarket bushings (AKG)
2 x subframe rear bushing (PN: 33312283419) or aftermarket bushings (AKG)
1 x differential front mount bushing (PN: 33172282484 ) or aftermarket bushings (AKG, Turner)
2 x differential rear mount bushing, requires new differential cover if going with OEM bushings (PN: 33112282482) along with differential cover sealant (PN: 83190404517) or aftermarket bushings (AKG, Turner)
1 x section 2 to rear muffler gasket ring (PN: 18101405737)
4 x section 2 to rear muffler bolt (PN: 07119904533)
2 x rear upper control arm bushing (PN: 33321092247)
2 x rear lower control arm bushing (PN: 33326770824)
2 x subframe reduced shaft bolt (PN: 33326760361)
2 x subframe threaded bolt (PN: 33326760360)
2 x subframe self-locking collar nut (PN: 33326760374)
1 x differential front hex bolt with washer (PN: 33177840535)
2 x differential rear torx bolt (PN: 23001222891)
2 x differential rear bolt washer (PN: 07119931021)
3 x v-brace bolt with washer (PN: 33306760652)
4 x subframe cross member bolt with washer (PN: 33326760345)
3 x BMW differential fluid 0.5 liter (PN: 83222282583) - optional if doing differential fluid change
2 x differential fill/drain plug crush washer (PN: 07119963355) - optional if doing differential fluid change
2 x Pentosin manual transmission fluid 1 liter or 1 x BMW SAE 75W-80 MTF-LT-2 5 liter (PN: 83220309031) - optional if doing transmission fluid change
1 x subframe metal plate reinforcement kit of choice (Turner, Redish Motorsport, VAC, HPF)
1 x 200ml 3M 08115 panel bonding adhesive or 3M DP420 black structural adhesive
1 x 200ml applicator gun
1 x tube blue Loctite (red Loctite can be used, but remember it requires heat)
1 x fluid pump and bottle quart or gallon (optional if doing gear fluid changes)
Various 1/2" inner diameter washers with outer diameters slightly smaller than diameters of control arm and differential bushings
Undercoating paint and primer (POR-15, Rust-Oleum, Rust Bullet, or Chassis Saver)
Rubberized undercoating paint (POR-15, 3M, or Rust-Oleum)
50 grit sandpaper
Brake parts cleaner or liquid metal acid cleaner
Puddy spreader(s)
2 x zip ties
CV joint grease
Anti-seize
PB Blaster
Propane torch
DOT 4 brake fluid
Latex/rubber gloves
Safety glasses or goggles
Respirator
Small plastic bags to contain hardware or paper and pen to lay out hardware
E46 3 series Bentley manual for reference

Notes/additional information:

Also now is a good time to order any parts that require the underside of the car and drive train to be disassembled. Parts such as rear trailing arm bushings, rear sway bar bushings, fuel filter, new exhaust sections, rear brake lines, rear brake pads, coilovers, shocks, rear ball joints, shift assembly parts/bushings, exhaust hangers/hardware, and differential seals.

This video is a great watch to figure out where to look for cracks under an e46 M3. Check for cracks ahead of time to determine the severity of the sheet metal. If cracks are severe, consider welding them or replacing the trunk floor before proceeding. Credit to Redish Motorsport.


Before performing this DIY, ensure you have all necessary parts, supplies, and tools. I chose to use my old chemistry goggles as they completely sealed to the area around my eyes.







The method I use to organize hardware as I remove it from the car.



This is optional, but I have a log book that I use to jot down notes, torque values, and tips when performing work on my M3.



Procedure:

Step 1: Safely jack the car up and have it supported by jack stands. I recommend the safe highest extension the jack stands can support. If you have a lift, this shouldn't be an issue. For comparison purposes, I had 17.5" of clearance from the bottom of the side skirt to the garage floor. Don't ever substitute jack stands or a lift with anything else to support the weight of the car.



I chose to also put cinder blocks underneath the car to support the weight in case of a jack stand failure. Cinder blocks should be laid horizontal to properly support a load (disregard the two cinder blocks in the rear that are turned vertical). Do not, I repeat, do not use cinder blocks or anything else in place of jack stands or a lift. Cinder blocks are what I had on hand, but a wheel turned sideways or a large piece of wood works very well underneath the car. I recommend safety first and having a fail safe method in place to get out from underneath the car in time in case of collapse. I also taped down the latches on the jack stands once the height was in final position. Another method I commonly use and highly recommend, is to have a jack at full reach underneath the car in the area of work being peformed.



Step 2: If your exhaust hardware was rusted like mine, soak all hardware in PB Blaster and let sit for a few hours if severely rusted.



Step 3: Remove the plastic guard panels underneath transmission and fuel filter. The screws require an 8mm hex socket.







Step 4: Locate and remove the headers to section 1 bolts and nuts. If in good condition, the bolts require an E12 socket and the nuts require a 14mm open end wrench. Use a propane torch as necessary to heat up the hardware and break apart rust. Be safe and use appropriate eye wear and gloves. I had to drill through one of the nuts and tap it with a hammer to remove the bolt.







Applying heat.



Section 1 disconnected from headers. Replace one of the old torx bolts through the section 1 flange to the header flange to secure the exhaust up and out of the way until all exhaust hardware has been removed from each section.



Step 5: Locate the 2 section 2 exhaust brackets. Remove the 4 bolts from each bracket as well as the 2 nuts for the section 2 exhaust hanger. All nuts and bolts require a 13mm hex socket.







Step 6: Locate the section 2 to muffler connection. Remove the 2 bolts from each flange (4 bolts total) using a 13mm hex socket. Apply PB Blaster and heat as needed. After removing the bolts, pull section 2 forward towards the front of the car while pulling the muffler gently towards the rear of the car to separate the connection. (My hardware for one of the flanges is different as I broke the flange a year ago and had to compensate with different hardware)







Step 7: Use a jack to take the weight of the muffler off the muffler hangers as well as support it. Position the jack a few inches towards the drive center from the center of the muffler. Locate and remove the hext nuts on the muffler hangers. There are 3 muffler hangers with 6 hex nuts. 1 hanger is on the passenger side and 2 hangers are on the driver side. Use a 13mm deep well hex socket and socket extension to remove the hex nuts. After the nuts have been removed, gently lower the jack while ensuring the muffler doesn't catch any of the body panels/underbody.







Muffler removed from car.





Step 8: At this point, section 1 and section 2 are still bolted together and only remain underneath the car by resting on the v-brace and the 1 torx bolt between the headers and section 1. Jack near the center of the section 1 and section 2 to remove the weight off of the v-brace.



Step 9: Locate the v-brace bolts. There are 3 total. The 2 outer bolts are directly behind the rear jack pads. The center bolt is directly in front and below the differential input flange near the rear center jack point. Use PB Blaster and heat as needed. Use a 17mm hex socket to remove them. Caution when removing the center bolt as the bolt threads tend to be very rusted due to the topside of the bolt hole being open and exposed to the elements. I sheared the bolt removing it and had to have a shop drill it out for me.





V-brace removed.



Sheared center v-brace bolt.





Underside of E46 M3.



Step 10: Position 1 jack near the end of section 2 and jack up to support weight. Reposition the second jack closer to the headers to section 1 connection. Jack up to support weight. Remove the torx bolt from the headers to section 1 connection.



Progressively work both jacks to lower sections 1 and 2 evenly towards the floor. A second person working the second jack can make this part go much quicker.



Remove sections 1 and 2 from underneath the car.



Step 11: Locate driveshaft exhaust heat shield underneath car. There are 5 screws securing it to the body underside. 4 screws require a 10mm hex socket and 1 screw requires an 8mm hex socket. Remove all screws and pull the heat shield down gently. If need be, slide the heat shield forward to unhook the slots from the 2 plastic panel hooks in towards the rear.







Step 12: Locate heat resistant plate underneath driver side front subframe bushing. Remove both screws using a 10mm hex socket. Set aside plate and screws.



Step 13: Locate and remove the driver side fuel tank plastic guard panel. Use a 8mm hex socket to remove the screw. Use needle nose pliers or the special tool to remove the plastic fasteners.



Driver side gas tank exposed.



Step 14: Locate and remove the passenger side fuel tank plastic guard panel. Use an 8mm hex socket to remove the screws. Use needle nose pliers or the special tool to remove the plastic fasteners.







Step 15: This step is optional. My M3 was due for a transmission fluid change. Locate the fill plug on the driver's side of the transmission. Place a catch pan or funnel and jug like I have pictured below the fill and drain plug. Use a 17mm hex socket and breaker bar to remove the fill plug first. Using a 17mm hex socket, remove the drain plug on the bottom of the transmission. Allow the old transmission fluid to drain out for several minutes. My fill plug had a green dot on the head of it. I kept the two plugs separate from each other.





Fill plug with green dot.



Both fill and drain plugs removed.



Step 16: Again, this step is optional as it proceeds the previous step. Use a clean plastic quart or gallon sized container and pour new transmission fluid in the container (PN: 83220309031). Replace the pump by screwing the closure onto the container. Replace the transmission drain plug by hand first. Tighten the plug and then using a 17mm hex socket, torque to 37 ft-lbs. Replace catch pan or jug with funnel under the transmission.







Step 17: This step is optional as it proceeds the 2 previous steps. Slide hose into drain hole on the side of the transmission case. Pump fluid into the transmission until fluid begins to drip out from the fill plug hole. The transmission will take 1.8-2 liters of transmission fluid. Be sure to have enough. Replace the fill plug, tighten by hand, and with a 17mm hex socket, torque to 37 ft-lbs. Clean up any spilled fluid with a rag.



Transmission fluid oozing from transmission fill plug hole.



Torquing transmission fill plug.



Step 18: Place one of the jacks under the transmission behind the transmission brace. Jack up lightly until jack stops. Leave jack in place. It will support the transmission for the following steps.



Step 19: Locate the transmission brace near the back of the transmission. On top of the transmission brace are 2 transmission mounts bolted to the brace. Use a 13mm open end wrench to loosen the nut on top of each transmission mount stud.



Step 20: Locate the transmission brace near the back of the transmission. Peel back the heat shield slightly on the passenger side of the brace to expose the 2 passenger side bolts. Remove the 4 bolts securing the brace to the body of the car. They will require a 13mm hex socket.



Passenger side bolts.



Driver side bolts.



Step 21: Remove the old transmission mounts from the transmission bracket. Use a 13mm hex socket and socket extension to remove the two nuts on the underside of the bracket securing the mount studs. The nuts on top of the studs should twist off by hand. Remove the vibration absorber carefully. Set aside hardware if using new OEM transmission mounts.





Old transmission mounts.



Step 22: Install new transmission mounts (PN: 22322282340) or aftermarket mounts (Rogue Engineering). Ensure the notches in the new bushings line up with the small metal protrusions on the transmission bracket. Secure mounts on top and bottom of transmission bracket using 13mm nuts. Insert the vibration absorber back on to the mount studs. Leave top stud nuts loose. Torque bottom nuts to 15 ft-lbs.



Step 23: Locate the constant velocity joint at the end of the drive shaft nearest the differential. Put the car into gear to keep the drive shaft from spinning. Use an E12 socket and a breaker bar to remove the 6 torx bolts. Break the 3 torx bolts that are easily accessible first. Remove the car from gear. Rotate the drive shaft by hand until the unloosened torx bolts are on the bottom side. Put the car back into gear. Break the 3 remaining torx bolts. Remove all 6 torx bolts and 3 torx bolt reinforcements.





Using a breaker bar and E12 socket to break the torx bolts loose.



All 6 torx bolts and 3 bolt reinforcements removed.



Step 24: Locate the center support bearing in the middle of the drive shaft. Directly behind the center support bearing is the universal joint. Inside the universal joint is an 18mm bolt connecting the 2 halves of the drive shaft. Ensure that the transmission is in gear. Use the box end of an 18mm wrench to fit around the bolt end. Loosen the bolt while the drive shaft is still connected in the car.





Step 25: Locate the flex disc at the end of the drive shaft nearest the transmission. Put the car into gear to keep the drive shaft from spinning. Use a 18mm hex socket with a breaker bar to break the 6 flex disc bolts loose. Break the 3 bolts that are easily accessible first. Remove the car from gear. Rotate the drive shaft by hand until the unloosened bolts are on the bottom side. Put the car back into gear. Break the 3 remaining bolts. Use the open or box end of an 18mm wrench to hold the nut still while removing the 6 bolts.







Bottom 3 bolts removed. Rotate the drive shaft to reach the top 3 bolts.



All 6 flex disc bolts removed.



Step 26: Temporarily reinstall the transmission support bracket. Replace all 4 bolts using a 13mm hex socket and tighten. The torquing of the bolts will come towards the end of the DIY. Remove the jack from underneath the transmission.



Step 27: Locate the center support bearing again. Using a highly visible marker, mark both halves of the drive shaft (the drawn lines on either side of the center support bearing to need to align as straight as possible). Also mark the ends of the center support bracket piece that mates up against the car body. Place a jack at the constant velocity joint end to support the drive shaft. Place another jack directly below the center support bearing to support the two halves of the drive shaft.



Step 28: Remove the 2 nuts securing the center support bearing bracket to the car body studs. Use a 13mm hex socket to remove them. Rest the center of the drive shaft gently on the supporting jack. I recommend a piece of wood laid horizontally across the jack platen to ensure the drive shaft doesn't roll off the jack.







Step 29: Locate the constant velocity joint nearest the differential input flange again. On the sides of the joint are two slots slightly protruding out from the differential input flange. Insert a straight head screwdriver into both slots and work back and forth, prying against the input flange until the joint slides out from the input flange.



Step 30: Gently lower the drive shaft down while sliding the drive shaft toward the rear off of the transmission output flange. It's light enough that it can be supported by your hands. Wrap the constant velocity joint in a plastic bag to keep grease from getting on everything and to keep contaminants out of the grease.





Old and cracked flex disc. Not bad for 137k miles.



Manual transmission output flange.



Manual gearbox shift linkage. I went ahead and replaced all shift bushings, clips, and bearings. I also installed a shorter shift rod. There are separate DIYs out there for this procedure as it is optional depending on the condition of the shift linkage components.



Exposed differential input flange.



Step 31: Open car door to gain access to car interior cabin. Locate the parking brake lever boot near the rear of the center console. Pull up near the base of the boot gently to expose the ends of the parking brake lines.



Step 32: Remove the 2 nuts securing the ends of the parking brake cables. Use a 10mm deep well hex socket.





Step 33: Locate the parking brake lines underneath the car protruding from the channel holes near the fuel tank bridge. Pop both lines out of the retaining clips on the fuel tank bridge. Firmly pull on both parking lines toward the rear of the car to remove them.







Step 34: Locate the passenger and driver side junction boxes for the ABS wheel speed sensor connection. Both junction boxes are inside the wheel wells directly in front of the rear trailing arms. The passenger side junction box will also include the brake pad wear sensor connection. Open the passenger side junction box. Unclip both the gray and black connections. The black connection if the brake pad wear sensor. The gray connection is the ABS wheel speed sensor connection. Repeat disconnecting the ABS wheel speed sensor connection for the driver side.







Driver side ABS wheel speed sensor connection.



Step 35: After removing the ABS wheel speed sensor connection and brake pad wear sensor connections, unclip the wires from the wheel well cable clips to the outer edges of the rear trailing arms. Gently wrap the sensor cable ends around the rear trailing arms.





Step 36: Locate rear passenger side brake caliper. Remove the brake pad wear sensor from the inside brake pad using needle nosed pliers. Pinch the metal ears together and pull the sensor up and out.



Step 37: Locate rear passenger side brake caliper. Remove the anti-rattle clip using a straight head screwdriver. Remove both protective plugs from the guide bolt bushings using a straight head screwdriver. Remove both guide bolts on the backside of brake caliper. Use a 7mm hex bit socket. Repeat on driver side.







Step 38: Slide the caliper off of the rotor by pulling straight back. Wiggle back and forth if need be. The caliper piston can be compressed while still on the rotor with a c-clamp if removal is difficult. Hang the caliper with a piece of wire wrapped around the bottom side of the rear upper strut mount. Repeat on driver side.



Step 39: Locate and remove the brake line bracket attached to the backside of the rear trailing arm. Use a 10mm hex socket. Repeat on driver side.



Step 40: Locate the rear brake line coupler end to the caliper (I've circled the coupler in red). Use a 14mm open end wrench to break the line loose. Be careful not to get any of the brake fluid on painted surfaces. Twist the caliper off the brake line by hand. Quickly reroute the caliper underneath the lower control arm and reconnect the brake line into the caliper. Tighten the coupler. Ensure the caliper and brake line are clear of the entire rear suspension. Hang the caliper with a piece of wire to the fuel tank tension strap. Repeat on driver side.





Step 41: Locate the rear headlight leveling sensor. It is on the passenger side of the subframe connected to the upper control arm, directly above the passenger side axle (I've circled the sensor in red). Pinch the clips on both sides, pull up, and remove.



Step 42: Working from the passenger side of the rear subframe, locate the rear headlight leveling sensor wire. There are 2 black zip ties securing it to the subframe near the rear subframe bushing. Clip both zip ties with pliers or tin snips. The rear headlight leveling sensor should hang free. Tuck it towards the rear of the car out of the way of the subframe.





Step 43: Locate the passenger side rear trailing arm. It is directly in front of the brake rotor, behind the rear end of the side skirt. Use a silver marker or Wite-Out to mark the location of the rear trailing arms. Remove the 3 bolts securing it in place. Use an 18mm hex socket and breaker bar to remove them. Gently pull down on the trailing arm to slip it out of the pocket. Repeat for driver side.





Step 44: Locate passenger side lower control arm to trailing arm connection. Use a jack to jack up gently and contain the weight of the trailing arm assembly. Repeat for driver side.



Step 45: Locate passenger rear shock to trailing arm connection. Remove the bolt at the end portion of the shock tube. Use an 18mm hex socket and breaker bar. Repeat for driver side.





Step 46: At this point, the rear subframe is ready to be removed. Place a jack (I recommend a 2x8 or 2x10 on top of the jack platen) underneath the rear jack point and rear of the differential. Jack up until point of contact is made to support the weight of the differential and subframe only. Do not jack higher, or the differential cooling fins could bend.



Step 47: This step is optional and will provide more clearance for removing the subframe. Locate the active charcoal filter plastic cover panel behind the rear subframe, directly beneath the trunk (I've circled the cover panel in red). There are several nuts and bolts securing it in place. Remove them using an 8mm hex socket. Set the cover aside.





Step 48: Locate the front subframe cross member just above the rear jack point. On both sides of the rear jack point are cavities within the cross member. Inside the cavities are 2 bolts for each side. Remove the bolts using a 13mm hex socket and socket extension. There will be 4 bolts total.



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For those apprehensive about DIYing...

"The most difficult part of figuring out a car, the engineering, has been done. Repairs and maintenance are simply taking parts apart and putting them back together again." - bimmerfan08

Last edited by bimmerfan08; Tue, Nov-01-2016 at 04:23:56 AM.
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Discussing DIY: E46 M3 detailed subframe reinforcement, gear fluid changes, and bushing refresh in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)