Replacement of the BMW E30 rear subframe bushings

The rear axle carrier – also called cross-member or sub-frame – is attached to the chassis with a pair of sturdy bushings made of metal and rubber. Over time the rubber in these bushings weakens. Some bushings break, others merely sag. The overall effect is that the whole rear of the car feels a bit loose, as if it were moving sideways on its own when you turn. Shifting may result in a loud “clunk” when the clutch is pressed; momentum pushes the chassis forward while the final drive is suddenly decoupled; since the bushings are weak the subframe will jolt and bang against the chassis.

My car showed three different symptoms of mechanical failure in the drive train:

• A loud clunk when I shifted while accelerating, especially from first to second gear, louder when moving uphill – presumably caused by front-to-back play in the bushings. Let’s call this “the big clunk”. This one felt like the car was coming apart.
• A sudden bang when driving over certain small bumps or cracks in the road – probably caused by up-down bushing play that makes the subframe hit the supporting plate or the chassis
• A weak dangling sound when pressing the clutch, as if something were swinging side to side and banging against metal. Not sure what this sound is caused by. I can hear it even if the “big clunk” doesn’t occur. Let’s call this the “little clunk”.

Click on each picture to see a larger version and access the image notes. Click here for the whole set (contains some additional photos not included in this article).

Sagging subframe

A good indication of the condition of the bushings is the gap between the cross-member and the support plate. If the bushing bottom touches the support plate, the bushing is worn out. The rubber that holds the bushing’s central hollow rod anchored to the outer sleeve weakens, making the subframe sag.

Preparation

Normally I raise the rear and place the jack stands under the crossmember. Since you will be lowering the crossmember, the jack stands have to go somewhere else - the jacking point is right in front of the subframe support plate. The standard jack stands fit there, but the body rests on them in a rather precarious position. Maybe this support point is meant to work with a special BMW stand or a lift, neither of which can be found in my tiny garage.

The exhaust pipe is merely an inch or so under the subframe. Release the support brackets that hold the muffler and lower the exhaust to make place for the subframe. I am not sure this step helped at all.

To create more space below the subframe, unhook the differential from its support bracket and lower the final drive (which is attached to the subframe with bolts). You should support it with a jack or blocks of wood. I forgot to support it for some time but luckily no damage occurred.

I thought that by lowering the trailing arm I would gain some additional space for the subframe, so I unscrewed and removed the shock absorber bolt. In retrospect this turned out to be unnecessary. I did not do the same on the right side and the subframe dropped just fine. Support the trailing arm if you chose to go through with this step.

Give a good tug with a large wrench or breaker bar to the 22mm nut on the subframe bolt to loosen it. I had to use my large torque wrench for this; the nut wouldn’t budge with the regular ratcheting wrench. Support the subframe with a floor jack. Remove the 6mm Allen bolts that hold the support plate to the chassis. They come out easy, together with the reinforcement piece.

Remove the subframe nut and the support plate.

Worn out bushing

The rubber insides of the bushing look quite worn. Start banging on the bolt with a mallet or a hammer until it slides up the shaft. This part wasn't easy; it took a lot of hitting, sweating and cursing. There wasn't much space between the bottom of the car and the garage floor so I couldn't take a wide swing at it. It finally budged a tiny bit, then a little more until finally I was able to push it out with a screwdriver and the tap of a mallet. Some write-ups tell you to cover the top of the bolt inside the car with a towel so it doesn't fly against the ceiling when you hit it. This bolt never flew anywhere - it moved bit by bit with every blow.

Subframe lowered

Release the jack and lower the subframe. It didn't go down too far; I had to push and pull and fight for every inch.

There wasn’t enough space to squeeze the bushing tool between the subframe and the chassis, so I decided to unhook the stabilizer bar from the trailing arm to gain some additional room. In retrospect, just like with the shock, I am not convinced this step was necessary.

The tool

Subframe bushing tool parts

I bought the subframe bushing tool on eBay for $150. It seems to be part of a multi-model bushing tool kit code-named BMW2336, made by a manufacturing company called Sir Tools and sold by resellers like Zdmak and Technictool, for about $300. This kit is no longer for sale; it has been superseded by tool set BMW3026. The tool I bought is limited to the parts that are needed for the E30.

Since the parts did not come with instructions I emailed both Sir Tools and Zdmak asking for a courtesy copy (it was quite obvious how it worked, but nonetheless). Sir Tools answered a week later and actually sent me a copy by email.

Instruction sheet

These are the tool directions as found on the internet. The removal steps are accurate but the installation instructions go against common sense. In order for the tool to push the bushing in the subframe when the bolt is tightened, the top piece (#R) must sit on top of the collar (#J) which sits on top of the subframe. The instructions say something else. They must have been written by someone who has never seen the underside of a car.

I could have tried to build a similar tool myself, but I just felt like spending the money this time (unexpected bonus at work helped too). Building a tool requires some pipe fittings and caps, a few nuts, a long threaded bolt and a bit of drilling. The sizes of pipe fittings must be carefully chosen to ensure they match the subframe cavity. You can find examples of home-made tools here and here.

Removal

Place sleeve (B) over bottom plate (A) and ring (C) on top. Slide bolt through plate. Grease the threads well.

Tool in place for removal
View from the top

The ring pushes against the bottom of the subframe “cup” that holds the bushing. The bolt is threaded through the bushing and screwed onto the cap, which sits on top of the bushing. The vertical notches in the “cap” must line up with the dimples in the subframe, otherwise the cap won't slide down when the bolt is tightened.

The ring is designed so that the metal collar at the bottom of the bushing can slide through it in the sleeve, while its two opposing protrusions push against the subframe.

The tool must be perfectly centered - if it's not, it may slip on one side and the ring bites through the subframe exterior coating - which is what happened to me. I re-centered the tool and it stayed in position this time.

The actual removal of the bushing only took a couple of minutes.

The inner metal cylinder of the old bushing is higher up in the sleeve than the new Lemforder bushing. This is because the rubber around it has weakened. This is probably the original 21-year-old bushing.

Installation

Tool set up for installation
View from the top

Set up the tool for installation. The top cap piece sits on the collar which rests on the subframe. The top of the bushing will pass through the collar and go into the cap. The slits at the bottom of the cap engage the tracks that jut out of the collar, so the cap doesn't move when the bolt is tightened. The threaded bolt must go through the chassis hole where the knurled bolt was; otherwise the bushing can't rise in the subframe cup.

Installation

The rubber is lubed with a very thin solution of water and dish soap. It evaporates almost instantaneously. The vertical groove in the bushing must be aligned with the dimples in the sleeve of the subframe.

Remove the tool. Raise the subframe. Don't forget to put the washer back on top of the bushing before raising the subframe.

Done!

To make the knurled bolt drop all the way down and lodge itself in the chassis I had to push and pull on the subframe to align the bushing with the hole in the chassis, I raised the sagging differential a bit, and then hammered away on the bolt head from inside the car. The hammering was needed because the last inch or so would not go down freely and when the nut was tightened the bolt would just turn on its axis. I couldn't find out if the nut was supposed to be a single-use self-locking nut, so I used some red Loctite and 120 foot-pound of torque. I found the number somewhere on the BFC forum; it may not be accurate, but the Bentley does not say anything about the subframe, so there...

Notice the healthy gap between the support plate and the bushing. It will become smaller when the car is back on the ground.

Installing the right-side bushing

Now do the same thing on the passenger’s side. The subframe dropped much easier and lower than on the driver’s side without removing the shock absorber bolt. Actually, everything went easier on the passenger’s side: I didn’t have that much trouble removing the bolt (it moved after a few hits with the hammer) or putting it back in.

Cost

Tool: $150+shipping.
Parts: $45.50 for Lemfoerder bushings on Pelicanparts.com

Time & effort

Around 8 hours – I started at 9:30 AM; the car had its wheels back on the ground shortly before 6PM. This includes jacking up, a short trip to the auto parts store and lunch. Most of the time was spent ratcheting, banging on stuck bolts and in procedures that weren’t strictly necessary. The actual removal and installation of the bushings was a matter of minutes. I can’t imagine how long this procedure would have taken without the special tool. It’s one of the most complex procedures I have completed, albeit less complex than the front suspension upgrade. It was very demanding physically: that evening my hands and forearms were so sore and swollen I could barely turn a door knob. Lifting the glass of beer to my mouth was painful. I hurt until the following Tuesday.

Effects

I drove for a few days on steep Seattle streets full of potholes before posting this. I can confidently say that clunk #1, “the big clunk,” is gone. Going over bumps and cracks feels more solid now as well – I don’t get the impression anymore that the rear of the car would fall apart, but this may be just wishful thinking – I have sport suspension, the ride is a bit rough anyway. Clunk #3 is still there, though. Now with the subframe bushings out of the way I can only ascribe it to the differential dangling in the center support bearing. Or something. The quality of ride has definitely improved, but not dramatically.

Conclusion

Do it. If you get “the big clunk” changing the bushings will result in a clear improvement to your shifting. If you decide to do it the barbaric way – removing the subframe entirely, cutting through the bushing with a saw, burning the rubber, taking the cross-member to a mechanical shop to have the bushings pressed in, doing whatever you need to do - it could take much longer, depending on your experience and whether you're working alone or with a helper. Things have been done that way many times and you will find a few write-ups online to guide you. To each his own.

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Replacing shock absorbers and coil springs on the rear axle

This is not a travel post, it's a car post.

In my crusade to fix, upgrade and polish the old piece of junk (1988 BMW 325) I finally decided to tackle the rear axle suspension, which had felt horribly loose for a while. Moreover I kept hearing squeaking and screeching noises coming from the left side of the back of the car while driving. Since my car is primarily a daily driver and will never see the track in its remaining days on earth I chose to upgrade the suspension with Bilstein Sport shock absorbers and H&R OE Sport springs. This combination is supposed to lower the car but not too much - about one inch - and the ride won’t become too harsh as it would be the case with stiffer lowering springs.

Parts and tools:

• Bilstein Sport shocks (rear)
• H&R OE Sport springs (rear)
• Shock mounts for the convertible model (sturdier design)
• Self-locking nuts for the shock mounts
• Shock mount gasket
• Reinforcement plates – didn’t fit
• Bunch of metric wrenches and sockets
• Floor jack and jack stands
• Blocks of wood tp put between the jack and body
• Working light

Click on images for better-resolution photos.

The rear wheel
before the procedure

Shocks, mounts, gaskets and reinforcement plates are from Bavarian Autosport. The springs came from a guy who runs a high-volume automotive store on eBay. He had the best price, including the shipping charges, but in retrospect he was a deceitful jerk since he had advertised his product as “in stock” but instead had to order it from H&R. Because of this delay the package arrived in Seattle right as the snow storm was settling in, and then got stuck in the local UPS service center for 12 days before it was finally delivered. But I digress.

Right side shock mount

Left side shock mount, damaged

Start by raising the back of the car and put it on jack stands, of course. Remove the wheels.

Partially remove the trim in the trunk to expose the shock mounts. Bending the trim is not an easy affair; it’s relatively rigid and hard to peel off and snap out of the grooves where it’s tucked in. That’s when I noticed that the right side shock mount had to be broken – there was a 2-3 millimeter gap between the upper cupped washer and the rubber piece. What do you know!

Remove shock mounting screw

Support the trailing arm

Disconnect the shock from its lower mount on the trailing arm. Not supported by the shock, the trailing arm will drop a couple of inches. Be sure to support it before removing the shock mounting screw; the Bentley indicates that the sudden jerk of the trailing arm may damage the CV joints. I forgot to support the left trailing arm when I disconnected the shock absorber and it dropped quite sharply. Fortunately it doesn’t seem to have broken anything, the car rolls fine now; the Bentley understandably errs on the side of caution. Of course, I can never be sure unless I inspect the joints. After disconnecting the shock I supported the trailing arm with the jack for most of the time, to avoid unnecessary pressure on the joints.

The old Sachs shock

Loosen the two self-locking nuts that hold the shock mount to the frame. Supporting the shock from below, remove the mounting nuts and then the shock. In my case, if there had been a gasket between the shock and the car frame it has long ago turned into dust.

Broken left side shock mount

The right shock absorber looked worn out yet not too damaged, but the left one was downright broken. There is a metal tube which sits in the middle of the hard rubber at the center of the mount, that the shock absorber’s piston rod slides through. That tube was completely disconnected from the surrounding rubber. No wonder I had been hearing those noises coming from the rear left side of the car while driving! And no wonder that each time I went over a sudden bump in the road (like when the asphalt/concrete plates aren’t properly aligned, and the end of the current one is a bit lower than the beginning of the next) the whole back of the car felt like it was going to fall off.

Lowered exhaust, supported with zip ties

Next, the spring had to be removed. This needed a little more work.

The Bentley says to disconnect and lower the rear part of the exhaust system from the brackets that support it, to allow for more room when the trailing arm is lowered. I did just that, but in retrospect I think this step didn’t help much. I supported the exhaust by hanging it with zip-ties from the upper brackets.

Final drive mounting nut and bracket

Disconnecting the final drive

Final drive lowered

Again, to make more room for the lowered trailing arm so that the spring can come out, I disconnected the final drive from its mount and pulled it down. It didn’t go too low and I didn’t want to force it. This didn’t seem to create any significant room for the trailing arm which was already lowered to the maximum anyway.

Disconnect the stabilizer bar link

Disconnect the stabilizer bar connecting link from the trailing arm. This seemed to lower the trailing arm a little bit more, but again, there was no significant help (the stabilizer bar is called “sway bar” by some).

The old stock spring
ready to be removed

At this point the Bentley leads you to believe that the spring can be simply removed by hand, but I realized that any attempt in that direction was hoplessly futile since I didn’t have the necessary superhuman powers to compress the spring by my bare hands. With the trailing arm lowered to the max the spring was still compressed and the ends of the spring were snug against the rubber mounts. Moreover the top and bottom spring supports have conical protrusions that fit inside the spring and secure it in position. There’s no way that spring was coming out on persuasion alone.

Spring with compressor on

I squeezed in my spring compressor, but this was no simple task. There isn’t enough space to easily wield a wrench in there. While one of the spring compressor rods can be attached on the outside of the spring inside the wheel cavity, thus offering better access, the other one has to go on the opposite side, and gets wedged between the axle and the exhaust (on the left side) making the task of tightening the compressor bolts extremely painful. It took quite a while and a lot of sweat.

New H&R Spring compressed

New and old springs side by side

After removing the old spring, I tried to put the new spring in without compression, thinking that maybe its shorter size would allow for it – but that initiative was doomed from the start as well, due to lack of superpowers. I compressed the H&R spring and installed it, after which - of course - I had to uncompress it in place, which takes an equally frustrating amount of time. Make no mistake: operating a spring compressor on mounted springs is hard work.

Done!

After the spring was finally in its cradle I installed the shock (reverse of removal). The two cupped washers on the old shock mount should be reused but everyone says the self-locking nuts should be used only once. I’m not sure why and didn’t bother investigating yet, so I got new nuts.

I had also ordered the reinforcement plates that were recommended by other people and by Bavauto. These metal plates are supposed to go inside the trunk between the body metal and the shock mount nuts, but they didn’t fit on my model. On one side of the body plate hole for the shock mount, the body plate has some sort of reinforcement bar which is about a quarter of an inch high. The shock reinforcement plate is too wide and goes over that bar; as a result, it doesn’t sit flat on the body and the lock nuts can’t be tightened against it. Useless!

Wheel after "surgery"

The right side went easier due to the absence of the exhaust and the experience that I had already gathered by working on the left side. Finally, the car was ready to have its wheels back on and go out for a drive. However, as I was tightening the left-side shock mount to spec using a torque wrench, one of the threaded bolts broke in half and popped out with the nut on it. So close to victory, so close to showing off, so close to dinner! Damn it! Despair! Frustration! I didn’t want to keep the car lying useless on jack stands until I got a new mount so I installed the old right-side mount instead, which seemed to be still usable. On Monday I called Bavauto and they offered to send me a replacement shock mount at no cost. Great customer service! I hope it doesn’t get caught in the next snow storm...

After working on the rear suspension all Saturday I was planning to tackle the front the next day. But when I woke up I was in so much pain after the previous day-long workout that I had to schedule the front axle adventure for the next weekend.

Working Time - about 8 hours, with breaks. With more experience and better organization (the right tools always at hand, more space in the garage, etc) this could take significantly shorther, even for an amateur.

Difficulty - technically not too challenging, but it involves a lot of physical work.

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