Earlier this year I needed to replace a blown front strut, and after a bit of research here, decided to take the opportunity to upgrade to Ground Control coil overs front and rear, and replaced all the moving part up front while I was at it, control arms, outer and center tie rods, and sway bar end links. At the time i only replaced the struts in the rear.
I had ordered the subframe bushings at that time as I figured they could use upgrading based on the thump in the trunk over every bump. At the time, I couldn't get the bushings out on the morning I had to throw at the job and had to postpone. I recently revisited this job and followed on with all the rubber behind the drive shaft. This article covers this rubber upgrade...
Note: most of the individual bushing replacements could be accomplished without removing the subframe, but since I was doing all the bushings, dropping the subframe made it all MUCH easier!
Tools required:
Jacks and stands:
- 1x 3 ton floor jack
- 2x 2 ton dolly jacks
- 2x 8 ton bottle jacks
- 4x 3 ton jack stands
- 2x 6 ton jack stands
Decent socket set including both 3/8 and 1/2 in drives
Hex sockets or good hex wrenches
Decent spanner set
11mm brake line spanner - Grabs more than 2 corners but fits around the brake line. Use it or strip it...
6" puller
Heat gun (if you're really patient) or a propane torch
Hardware to make required pullers... more details to come.
Dremel or similar cut off tool
Parts:
Bushings:
- 2x Subframe mounts
- 2x rear differential mounts
- 1x front differential mount
- 4x rear trailing arm bushings (RTABs) I upgraded to K-Macs
- 2x rear sway bar bushings
- 2x rear swaybar end links
- 1x rear differential mount... rear subframe mount. Its the big block the rear subframe mounts to. Don't know why they call it a rear differential mount.
- P80 bushing lube. Call them, ask for a sample. They seem really eager to give small amounts of this stuff away. It works wonders!!!
4x exhaust bolts and nuts
1x exhaust flange
2x exhaust hangers
2x subframe nuts
2x swaybar bracket nuts
6x driveshaft nuts
if you're realy festidious, 24x axle bolts if you have locking M10 bolts
Dot 4 Brake fluid - ~1.5 L
80-90w synthetic Diff oil
2x diff bolt crush washers
beer
Procedures:
*Lift the rear of the car
-Right, for those without an impact gun that can actually remove lugs, loosen the lug bolts a hair with the tires still in contact with the ground, then lift.
-For me this involves lifting the body on either side with the dolly jacks, then lifting the rear subframe with the 3 ton floor jack. Support the rear of the car on the 6 ton jack stands at the body lifting points. Do not support the car by any subframe parts... it's coming out, remember?
-Remove the rear wheels.
*Drop the rear exhaust
-Don't even bother trying to undo the bolts. Are you really going to reuse them? Break out the dremel and cut off the lower two between the flanges behind the cats. Once cut, the flanges will rotate with some encouragement, to allow you to cut the two that were on top. This took about 20 minutes.
-Support the exhaust with the floor jack at the resonator, just take the weight for now.
-Remove the rubber exhaust hangers at the front of the subframe.
-Remove the 2 13mm bolts on either side of the rear muffler.
-Slowly lower the exhast on the jack. Once clear in the rear, slide back and pull out. One pipe is a contact fitting, the other side, the rear pipe section slide into the cat section. Once free, remove the exhaust from under the car.
-Remove the rear heat sheild. Don't miss the two 13mm bolts over the cats. Easy to get out... hire someone with very small hands to get hem back in or be prepared to drop the cats as well... or leave them loose.
*Free the Trailing Arms for Removal
Do this if you are replacing RTABs. You're welcome to try with them in the car, but good f*ing luck!!
Here's what you're looking at
Speed sensor wiring, brake wear sensor (passenger side only), brake line, parking brake cable on top, and the axle underneath.
Start with the axles.
-Pull the handbrake tight.
-Clean the heads of all the bolts securing the axles. You should be able to reach 3 at a time on each end of each axle. Loosen the ones you can reach without damaging the CV boots.
-Release the handbrake and rotate the axles 180*. Pull the handbrake.
-Loosen the remaining bolts and remove the axles.
-Release the handbrake.
- Remove the bolt holding the rear strut to the hub. Some people have had trouble loosening the strut, but mine just popped right out, even the stock one before the upgrade. Let the strut hang freely by the upper mount.
-Using a flathead screwdriver, carefully prise up on the rear edge of the white tabs holding the wiring and it will pop open.
-Using a 14mm spanner and an 11mm brake line spanner, loosen and remove the brake line from the front lower mounting bracket of the trailing arm.
-Undo the brake line completely, pull both lines above the trailing arm unclipping the line from the clip pictured above, and reconnect the brake line to the hose to prevent excess brake fluid loss.
-Repeat disconnection and reconnection of brake line from rear mount also freeing the plastic wiring harness.
-Remove the brake caliper and hang with heavy wire (like a coat hanger) on the rear spring.
-Remove the speed sensor using the correct size hex nut. Clean the inside of the screw to avoid stripping.
-Remove the rotor retaining screw. Ensure the handbrake is released and remove the rotor. If it is stuck on the handbrake shoes, use a block of wood against the inner side of the rotor and gently tap with a hammer and rotate. It will pop loose.
-You do not need to remove the handbrake shoes, but it gives you a bit more room to work with. Remove the retaining springs and adjuster. Rotate the retaining pins on each shoe 90* and release the shoes.
-Unfold the expander and press out the retaining pin holding it to the cable. This will work loose easily with a screwdriver. Don't lose the pin!
-Pry open the tabs securing the handbrake cable to the trailing arm and release the cable. Pull (hard) the cable housing out of the back of the rear hub assembly.
It is now possible to remove the pitman arms, sway bar end links where they connect to the trailing arm, trailing arm mounting bolts and drop the trailing arms if that is all you're doing. If you're dropping the subframe, I wouldn't bother yet.
*Dropping the Subframe
-Remove the bottom of the rear seat and outer seatbelt buckles (17mm spanner). Pull back the insulation and under the seatbelt you will see a small tar patch. Remove the patch.
-Put the transmission in 5th gear if a manual, or park if an auto to give counter torque to the driveshaft. Loosen the driveshaft bolts. Unless you have really shallow sockets, you will need a box end wrench to get to the nuts. Access is from inside the differential bell housing.
Do not pull the drive shaft forward to release at this point. You will risk dislodging the internal bearings and end up having to deal with a mess getting them all back in place.
-Support the subframe using bottle jacks so you can lower it later.
-Remove the subframe mounting bracket by removing the two 13mm bolts just behind the body lifting point, and the large 22mm subframe mounting nut.
-Re-thread the nut onto the end of the mounting bolt and drive the bolt up into the car. The top of the bolt is splined and tapered and will pop loose eventually.
-At the rear of the differential, disconnect the speedometer sender - The yellow plug in the picture bertween the axle and fuel filters.
-Support the rear of the subframe with a 2x4 on the floor jack.
-Remove the bolt holding the rear of the subframe to the unibody behind and above the diff - The single bolt facing up in the middle of the picture below.
-The rear subframe is now loose, but anything but free.
-Drop the front slightly onto dolly jacks if it is not already.
-Put a jackstand under the driveshaft but give it a few inches to drop so you don't bend it.
-Drop the rear about 4-6 inches.
-Drop one side of the front of the subframe several inches being careful not to stress the driveshaft as it will still be inside the diff housing.
-Work one side of the subframe out from under the body.
-Carefully from under the car, pull the driveshaft connecting flange forward slightly to clear the differential and support the driveshaft on the jackstand and high as possible so you are not stressing the center pivot.
-Drop the rear subframe and pull out from under the car.
You'll notice my axles are still attached when I pulled the subframe. I regretted that later when I had to put my wheels back on to get enough counter torque to remove them.
-Remove the pitman arms
-Remove the rear sway bar and end links
-Remove the trailing arm bushing bolts and remove the trailing arms.
*Drop the Final Drive
This is easily done with everything else in place. If in place the car still:
-With the car raised and parking brake set, loosen and support the axles on either side.
-Paint a mark at the mating point on bot the driveshaft and the final drive for alignment later.
-Remove the driveshaft nuts
-Support the rear of the final drive with a floor jack and a jack pad
-remove the two rear final drive mounting bolts
-support the front of the final drive with a dolly jack
-remove the front mounting bolt
-drop the rear of the final first by several inches
-slowly lower the front without binding the driveshaft
-move final drive towards the rear of the car a few inches
-from in front of the final drive, pull the CV joint free of the final drive
-drop the final drive and remove.
** Note - if you have removed the subframe from the car, simply support the final drive, remove the bolts and drop it out out of the frame.
-While you have it out, change the oil and check the seals. Mine was dry all around so I left the seals.
That's day 1. Have a beer and try not to think about having to get it all back together.
*Replacing the Trailing Arm Bushings
From my experience, the RTABs are the most difficult to remove of everything in the rear end. I would highly recommend dropping the trailing arms if you are planning to replace these. They are the only bushings in the rear that are mated metal to metal. I had the trailing arms out and using the RTAB press peice included in the K-Mac kit and an 8 ton bottle jack in my rig of a press, could not move these things at all.
To remove, in summary, melt the rubber out of the center and cut and collapse the bushing sleeve.
I used the 6" puller as a press by simply putting one of the subframe nuts over the end of the puller and putting the hook around the trailing arm ends.
Using a heat gun or a plumber's torch, heat the outside of the trailing arms.
-Once they've started to heat, position the puller and apply pressure to the center of the bushing until stretches significantly.
-Continue heating until the bushing begins to slide out.
-Tighten the puller and press the rubber part of the bushing through.
-Using a sawzall with a metal blade or equivalent and cutting fluid, cut through the bushing sleeve being carefull not to cut into the cast trailing arm.
-Use a drift to split and collapse the sleeve and remove.
Only 3 more to do.... 
Installation of the K-macs is easy as they are poly bushings. Just follow the directions.
If you have the subframe out and have more bushings to pull, continue with the next step.
If you have only dropped the trailing arms to replace the RTABs, jump to "Reinstalling the Trailing Arms to the Subframe".
*Replacing the Subframe Mounts
This procedure can be completed without removing the subframe, as many will attest. It can also be achieved without the use of a sawzall and making a huge mess!
E34.net has an excellent writup on what is required, but the one step I can not emphasize enough is the use of heat when removing the mount. Heat it up and use the rubber skin about the bushing sleeve as a lubricant and the mount slides out like butter. Ok, maybe not that easily. WARNING: Don't heat your fuel lines!!!
You will need a tool to pull and press in the mounts. Below a description of how I built a puller tool for the mounts using the BMW tool pictured on E34.net as a guide.
Theory: you need to pull the mount from the top down using a plate on top of the bushing, and using the subframe to push against as shown on E34.net. See step 8 in the link.
I'm sure this design can be improved upon, but the $15 in misc hardware to piece it together sure beats the $300 or so for the BMW tool...
Parts:
Harmonic balancer puller
6" puller (two of the arms removed)
1/2" threaded ss rod - Minimum 12" long
2x 1" or larger washers. Not 1 inch round washers, but washers for a 1" bolt. Outside diameter should be ~ 2.5"
3x 1/2" washers (as above)
3x 1/2" nuts
6" long 1/2" flat steel bar or angle iron
To build:
-Disassemble the 6" puller. One end of the hooked puller arms will be wider than the other. Grind down the ends of the wider hooked ends to produce a flat surface that will mate to the subframe. They will be best to tapper slightly so the the arms will want to slide inward rather than outward.
-Slide the narrow end through the slots in the harmonic balancer puller
-Drill two holes in the 6" flat bar ~ 4" apart (slightly more than the width of the subframe mount). Bolt the bar tot he holes in the puller arms. This will offer the assembly support against torquing while you crank on it.
This is it in use on one of the diff mounts:
Removing the subframe mount:
-After pulling the seat, seatbelt latch, tar patch, subframe mount bracket and subframe nut, driving out the bolt and dropping the subframe a few inches:
-Slide the 1/2" threaded rod through the center of the mount.
-Reach up around the top of the mount and slide the 1" washers over the end of the rod. These will act as the puller. I ground down the edges of mine so that they fit nicely inside the tabs on the mount. No point distorting the mount and making things more difficult.
-Add 2 of the 1/2" washers over those.
-Thread one of the nuts onto the top of the rod.
-Slide the puller assembly built above onto the bottom of the threaded rod and hold in place with the last washer and nut.
-Position the arms against the subframe. You will notice there are cutouts in the mount exactly for this reason.
-Begin applying pressure - enough to significantly stretch the mount but so that the puller doesn't slip off.
-HEAT the subframe around the mount until the mount starts to slide out.
-Continue heating if possible, and crank away on the puller.
-Be glad you haven't been sawing for the past hour and aren't covered in rubber bits and metal filings. 
Installation:
-Clean the inside of the subframe where the mount will go. Any residual rubber, rust, dirt etc will impede installation.
-I had a small amount of rust forming around the bottom so sanded down well, sprayed with black rust paint and sanded again with 1000 grit to make it smooth for install.
-rebuild your 6" puller using two arms, and have a washer and one of your old subframe mounting nuts handy.
-take 4-6" long 1" angle and drill a 1/2" hole in one side
-Slide the angle above the subfarme and run the threaded rod through the hole.
-Hang it by one of the nuts and a washer.
-Break out the P80 lube
-Wet the rubber mount thoroughly, and coat the inside of the subframe.
-Slide the new mount over the threaded rod and follow it with the harmonic balancer puller, a washer and nut.
-Align the tabs on the inside of the subframe with the grooves along the sides of the mount.
-Square it all up and begin to tighten. It should square itself up pretty well as it goes in.
-Crank it to a bit more than half way in - it will start to get very tight.
-If needed, remove the current assembly and swap in the 6" puller to press it in the rest of the way. Use the harmonic balance as a press. DO NOT simply press on the center of the mount or you will destroy it before it moves at all!
My subframe is out, so this was a breeze! Took 20 minutes to do both sides! BTW, the schmurg on the outside of the subframe is not rust, the car has oversprayed undercoating everywhere! Tar based, and it melts when it's heated.
If you have the subframe out and have more bushings to pull, continue with the next step.
If you have only dropped the subframe to replace the mounts, drop the pin back in from inside the car, tighten 'er all back up (don't forget the 13mm bolts on the bracket!) and have another beer... 
*Replacing the Final Drive Mounting Bushings
This can be completed with the subframe in the car, but be aware of the limited access you will have to both pull and press the bushings.
-remove the final drive as above if not already out
-* note the orientation of all the bushings - they are not symmetrical!
Rear bushings:
-I used the same puller assembly as I did for the subframe mounts, but drilled a second hole in the angle at about 2.5" to close the arms of the puller.
-I used a 7/8 deep socket driven by the 1" washer to pull
-Pulling from the inside of the frame out, put pressure on the bushing enough to significantly stretch.
-Heat until it starts to slide and crank it out. See picture above.
Front bushing:
-If the subframe is out, use the puller above using 3/8" threaded rod and appropriate nuts and washers.
-If the subframe is in, you will not likely get the puller in front of the bushing due to space limitations. When I did mine, I didn't realize the hole in the bushing was smaller and didn't have any 3/8 rod, so I improvised with a solution that may work for an in-car removal.
-carefully support a bottle jack between the rear part of the subframe and use a socket extension to reach the bushing. (GHETTO!!! but it works
)
-Heat and press it out from the inside.
Installing
These require something resembling the right size press to press in. I used my 1 1/2" socket ground to have a flat face. This socket is a bit too big so I had to grind down the OD slightly so it fit. I would guess a 1 3/8" would work. I suppose I could measure it... Test it before you start pressing.
-Using the threaded rod with a 1 1/2" washer on the inside of the frame and the socket on the outside with a washer between the socket and nut os it does not rotate the bushing.
-Slather the bushing in the P80 bushing lube
-Align the bushing and press in as far as the washer inside.
- swap to the 6" puller and hook the arms onto the inner edge of the frame and drive the bushing the rest of the way in.
This process works well for all 3 bushings.
*Swaybar End Links and Bushings
Bushings are easy, undo the bolts, drop the bracket and slide the bushing off. Install is reverse.
End links are surprisingly awkward! the bar end bushing is extremely tight!
-Remove the 13mm nuts and bolts from the trailing arm and free the end link.
-Rotate the link on the arm while pulling and work it off the end of the bar.
-Clean the bar end thoroughly and apply P80
-Clamp a length of 2x4 along the sway bar to use to apply pressure.
-Position the new link and clamp a C-clamp around the link and the 2x4.
-Tighten the C-clamp and rotate the end link until it stretches over the bar end.
-Rotate and push into place.
-Remove the 2x4
-Replace the 13mm bolt and nut attaching the end link to the trailing arm.
*Reassembly
Replace the rear subframe mount by removing the 4 13mm bolts and replace.
*Installing the Trailing Arms
-With factory bushings, position the trailing arms and insert and tighten the bolts.
-With K-macs; follow the instructions carefully for bushing positioning etc.
-Using a clamp and a small bar or piece of angle, compress the outer toothed washers onto the bushings.
-Position the trailing arms and tap into the brackets
-Release the clamps and drive the trailing arms into place. These bushings are a very tight fit. Make sure the outer washers are properly positioned. The inner bushing should fit through the middle of the toothed washer.
-Insert the bolts, lock washers and nuts.
-Remove the cross brace from the diff housing to the pitman arms and do not reinstall the pitman arms with K-Macs. I put mine back in originally and they caused a great deal of sticktion in the rear when trying to corner balance and align. They made the alignment near impossible. We took them out and had to redo the corner balance and alignment and it all went much smoother.
*Install the Subframe
-Position the subframe on a dolly and position under the car.
-Lift the subframe, front first towards the driveshaft.
-Rotate the subframe slightly to position one side of the frame in front of the wheel well panel
-Lift and bring the frame forward and position the driveshaft into the subframe
-Carefully maneuver the other side of the subframe under the wheel well panel and raise into place.
-Raise and bolt the rear of the subframe
-Support the front of the subframe on axle stands
Install the Final Drive:
-Place the final drive securely on a floor jack and position under the subframe
-Lift and maneuver so that the front goes into the housing first
-Align the markings made during disassembly and carefully position the driveshaft so the bolts line up and insert into the final drive flange
-Finger tighten three opposite nuts of the six using new nuts.
lift the final drive into position.
-Use a narrow screwdriver to align the mounting holes and thread all three bolts in by hand before tightening to torque
-In a cross pattern, install and tighten the driveshaft nuts.
-Install the axles using new bolts and toothed washers. Install the final drive end first, then compress the axle to fit into the trailing arm.
Reassemble the trailing arms
-Insert the parking brake cable into the trailing arm
-Assemble the parking brake - reverse of removal - If the cable seems too short on one side, pop off the handbrake surround in t he car and be sure the cable hasn't slid out of the bracket and is catching. Ask me how I know...
-Attach the speed sensor
-Assemble the rear rotor and caliper
-Reconnect the brake lines in reverse of removal.
-Before you forget, bleed the brakes! ASC users; no worries, as long as the fluid didn't drain from the valve body, bleeding normally is acceptable. You simply won't have new fluid in the valve body.
This is what my old fluid looked like. I think it was original...
-Relocate all piping and wiring appropriately in the tabs
-Position the subframe and drop the subframe pins into place from inside the car
-Lift the subframe and install the the bracket. Tighten the nuts and 13mm bolts.
-Install the exhaust heat shield
-Using new bolts and new mating flange, position the exhaust and lift into place.
-Raise exhaust enough to install the new exhaust hangers, then bolt the front flanges and position and bolt the rear brackets. I found it easiest to loosely bolt the brackets and then lift the exhaust into place. When loose the brackets will maneuver into position and suspend the exhaust. Tighten bolts.
-Install the wheels, lower the car and tighten to torque.
-Get an alignment!
I'll proof later. I probably missed some major component somewhere....
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Originally Posted by EAJ4
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