Replacing Trailing Arm Bushes
The rear trailing arms allow independent movement of each rear wheel, and are an essential part of the Suspension. Fresh bushes will keep them moving as they should.
Note: replacing the trailing arm bushes is considered to be part of a complete overhaul of the rear subframe, and is therefore much larger job than simply replacing these bushes.
Courtesy of Trevor M; Illustrations and photo editing by T.Hanson, originally published at FirstFives.org
Overview
Trailing arm bushings are one of those things that does its job in silence. And unless they are making squeaks or groans we really don't pay much attention to them. Their condition is critical for rear axle alignment. Cracked, split or oil soaked bushings will give away causing you all sorts of problems. Having 25+ years on them, chances are they are at the end of their useful life. So here I'm going to attempt to explain the procedure for changing these little buggers out. (Peter's note: as these bushings are the same part numbers as many other BMW's, except e28's, this procedure may work on cars such as 2002's, E12's etc.)
Their replacement isn't as difficult as it may seem with the bulk of the work in removing and replacing the trailing arm itself. This job can be performed as part of a complete overhaul of the rear subframe area, including rear brake lines and other rear bushes
Parts and Tools
Suitable jack and jack stands – no ramps here please Metric wrenches & sockets 8mm hex key or driver that will fit your socket set Air impact & sockets (optional) 11mm & 14mm flare nut wrenches – for the brake lines Torque wrench Fresh DOT4 brake fluid Penetrating oil Piece of 1-1/2” pipe 3 to 6” long (not too long or you will need more threaded rod) Threaded rod – 10 or 12mm Hex nuts that fit the above rod – just a few is needed Flat washers – several of each.
One coupler nut to fit the above threaded rod 17mm 3/8” drive deep socket Some grease or oil to lube the threads of the rod Some cold refreshments to get you through this project. And the star of the show - 33 32 9 061 945 trailing arm bushings.
The bushes are sold as pairs; you will need two sets for both arms, and should be bought from BMW. There are also eccentric bushings (33 32 9 058 822) available, which are covered in a separate fitting guide.
Trailing Arm Removal
1. Jack the rear of the car up and support it on jack stands. The best spot for the stands would be just forward of the rear tires on the rockers. About 10” forward from the wheel well there is a reinforced spot. This gives you lots of free room to work with nothing in your way. A piece of wood between the stand and car body would be a good idea to distribute the weight and protect the car body. Whatever your setup is make sure it's SOLID! You will be under there pulling on rusted bolts real hard and a car falling on you would wreck your day in a hurry. It doesn't need to be real high just as long as it's comfortable to work is ok. If the stands cave in through the rust then you have a real problem… I can't help you any further, sorry.
2. Remove both rear wheels
3. If you had the foresight to spray all the rusted nuts with penetrating oil yesterday, good for you… if not, do it now.
4. Remove the brake pad wear sensor connector. Pull it out from the clip and carefully pull it apart. Disconnect the ground wire also so it's free from the caliper and trailing arm.
5. With a flat screwdriver or some other tool clean the gunk out of the hex headed bolts on the drive shafts. Make sure they are clean so the 8mm hex key or driver sits all the way in, if not the bolt will strip. With an assistant working the brake pedal, loosen and remove the bolts holding the drive shafts to the drive flanges. Do the ones on the differential first so you have brake action up to the last bolt. If you don't have an assistant handy, I've done this myself using a pipe wrench to hold the drive shaft from turning. The drive shafts are hardened steel and the pipe wrench will not want to bite in but with some patience it does work. Mark the shafts so they can be returned to the same side/ position when you are done.
6. With the 14mm wrench hold the brake hose while you turn the flare nut on the brake line with the 11mm wrench. DON'T let the hose turn. Disconnect the two and have a drip pan ready.
7. The handbrake cables will need to be disconnected. In the factory repair manual it states; a) Remove the boot from the handbrake lever. b) Remove the lock and adjusting nuts from the cable ends. c) From under the car pull the cables out from the tubes. Now, on both cars I've tried this I ended up destroying the cables. Usually by now they have been attacked by rust and will be stuck in the tubes, when you pull on them they will stretch rendering them useless. If you plan to re-use your parking brake cables I suggest disconnecting them at the brake assembly under the brake disc. This involves removing the disc and handbrake shoes. It's not a complex setup; the hard part is remembering to put it back together the way you found it. Take pictures or draw sketches before you take it apart. Or do one side at a time using the other as a reference.
8. Disconnect the stabilizer bar from the trailing arms. Use a 13mm wrench to back it up and keep the bolt from turning. And if you feel the bar is still in your way take out the 4 bolts that attach it to the rear sub-frame.
9. Remove the nut but not the bolt from the shock absorber.
10. Remove both bolts – trailing arm to sub-frame.
11. Slide out the bolt from the shock and lower the arm to the ground. It is somewhat heavy with the caliper still attached.
For installation follow the steps in reverse. You will need to bleed the rear brakes and adjust the handbrakes. The brakes will need to be bled before you tighten the bolts on the driveshafts. Also, some bolts will need to be torqued with the car sitting on the ground in normal position.
Bushes
When I first attacked this job I had it in my mind that I was going to use my press. Why? Because I spent a lot of coin on it and I wanted to get the most use out of the thing. Also reading the service manual it describes the process using a hydraulic press… looks easy… NOT! After much wrestling with the arm holding it still and having it jump out from under the ram I decided to fab a tube for it to sit in while I pressed on it. This sort of worked for one side but not the other. I needed to fabricate a mandrel for both sides? And then what about pressing the new bushings back in, did I need something different there too?
After a couple of hours I gave up. I would have spent more time and effort getting this to work than I cared to spend. Besides, most people don't have a press.
There is an easier way:
1. With the threaded rod technique what you're doing is building a small press to push the old bushing out and pull the new one in. To remove the old bushing, arrange the rod and pipe as shown in this first picture. The two nuts on the end of the rod are locked by tightening against each other. The one on the end is called a jam nut, this prevents the rod from turning here; we only want the nut on the left side to turn. The washers are arranged with the largest close to the pipe and the smallest up against the jam nuts so the rod can't pull through the pipe.
2. Apply some grease or oil to the threads and select a socket to push the bushing out. Peter suggests a 5/8” socket is just right. I used a 17mm deep socket; it was the same length at the bushing. You will want the drive end of the socket pushing up against the bushing tube. Stack a few 7/16” washers over the socket and add the nut. It should all be arranged like shown below.
3. Here is a close up of the socket below. Make sure there is enough meat on those washers so the nut doesn't cave into the socket. Same goes for the pipe end also.
4. Start tightening the nut on the left to push the bushing out. You may need a backup wrench to hold the other side and prevent the rod from turning.
5. It should only take a couple of minutes and the bushing will be out
6. Examine the bore where the bushing was. I had corrosion on the inside of mine that needed to be cleaned out with a die grinder to make smooth again.
7. Arrange the pipe and threaded rod with the new bushing. The collar on the bushing faces outward on both arms so you should only be pushing towards the center. The use of the socket is optional but it would be a good idea to at least have a washer there so the bushing has even bearing. The picture shows me using the socket and washers only because the rod is extra long and I'm too lazy to cut it.
8. Borrow some liquid dish soap from the kitchen. Don't let the Mrs. see you take it or she might assume you are going to do dishes and get all excited, like mine did. It only takes a drop or two to make the bushing all slimy & ready to go in. Start cranking and send it home. For me it too a lot less effort to install the bushing than to remove it. I did find the first rib went in easy but the second was holding back. I think the soap had time to dry out on the second rib. So perhaps soap up one rib at a time while pulling it in, might go easier that way.
9. With the new bushes pressed into place, refitting as always is the reverse of removal.
