Is my rear subframe bushing missing/broken?

[redhatpat]

I've owned my 325i for about 8 months now, and have been trying to get caught up with the maintenance and bushing/bearing replacement.

My next set of projects will be the rear suspension and I've always wondered about the rear subframe bushings. At best, they're badly worn, and at worst missing altogether. Not having a second e30 to compare to, I don't know what this area is supposed to look like. What do these pics of the rear subframe bushing look like to the rest of you? When I jack up the car by the large washer under the subframe, it moves up about 1/2" before the car lifts. Does this also indicate bad subframe bushings? These pics are of the right side, and with the car jacked up by the frame, and the wheel off, suspension in full droop.

[dude8383]

omg those need replacement asap.

[MarkH]

Gee, those look like mine did before I replaced them. DO IT NOW!!!!!

Bushings that worn make for very unpredictable handling. I would either change them, or have them changed, ASAP.

[Garageaholic]

How difficult is it to change them urself? any special tools needed for the swap??

[808BMW]

PITA.

I just got my subframe bushings (fuh raze urethane) and my toe/camber kit, so I'll be putting in my new subframe and diff sometime soon (I got a whole subframe+diff waiting to go in so my car isn't stuck for long)

[redhatpat]

Yeah, that's exactly what I thought. That gap looked ominous and I've had the rear end step out suddenly a couple times now.

I ordered IE's street urethane bushings a few days ago - still waiting for them to process the payment and ship the darn things out though. How long does IE usually take to fill orders?

[MarkH]

The answer depends on which bushings you are going to put in. I went with stock which are a bit of a pain to press in, most people seem to go with the urethane bushings which are much easier to install. Here is what I did to remove and install my rear subframe bushings. If you go with urethane bushings, you can pretty much ignore the installation instructions. I found it easier to just remove the entire subframe, but this can be done with the subframe still in the car. You should also replace your brake lines when you do the subframe bushings as the two above the subframe are much easier to replace with the subframe lowered or removed.

After reading the instructions for the tool that is sold online for removing the bushings, I cobbled one together from some plumbing and hardware parts. Here is what I used.

1. 3 inch male to male steel/iron pipe connector
2. 3 inch pipe cap
3. 2 inch pipe cap
4. 1.5 inch pipe cap
5. 1.25 inch pipe cap
6. .5 inch threaded rod with lots of nuts and washers

I drilled a 1/2 inch hole in the center of all pipe caps to allow the threaded rod to go through.

To Remove.
1. Place 1.25 inch pipe cap on top of the subframe bushing, wth the opening of the pipe cap facing the bushing
2. Run a length of the threaded rod through the bushing and pipe cap, and secure with two nuts
3. Place the 3 inch pipe cap on the 3 inch pipe connector and slide over the bottom of the threaded rod and then place a washer and nut on the bottom.
4. Crank away on the bottom nut to pull the old bushing out. I found it came out easier when I tightened it down some and then heated the subframe a little with a torch, but not enough to set the bushing on fire or melt it.

A word of caution, the 1.25 inch cap will fit into the bushing opening on the subframe but will not come out the bottom as it there is a dimple near the bottom of the opening that catches it. So you will need to dismantle the setup once the bushing is out and take the 1.25 inch cap out the top. The 3 inch sleeve will not sit level due to the design of the subframe, but this did not seem to be a problem.

To Install

1. Place 2 inch cap on top of the subframe, wth the opening of the pipe cap facing the bushing
2. Run a length of threaded rod through the cap and secure with two nuts
3. Place the new bushing over the threaded rod on the bottom of the subframe and place the 1.5 inch pipe cap over the bottom of the bushing with the opening of the pipe cap facing the bushing
4. Place a washer and nut over the cap and tighten away

I used a water with small amount of dish soap as a lubricant. I did find that the threaded rod may strip out depending on how much force is required to press the bushings. When I had the first bushing almost all the way in I stripped the threaded rod and had to cut it off. I then enlarged the hole in the two pipe caps to allow me to use the subframe mounting bolt, I was replacing them anyways, which is a higher grade stronger nut and bolt. This pressed the bushing in the rest of the way with no problem. I also strongly recommend that you get a Gearwrench, or similar ratcheting wrench, as it makes the job go much quicker.

All parts can be purchased at a local home improvement store, except the 3 inch pipe fittings which I had to get at a plumbing supply store.

[redhatpat]

To Remove.
...

Before I get to this point, what's the best way of getting the subframe lowered enough to start removing bushings? I want to disassemble as little as I have to to do the job. Can I just unbolt the two allen head bots holding on the subframe bracket, and the one large nut on the bottom of the bolt, then lower that side of the subframe? If so, will the brake lines get stretched with this little bit of lowering?

I did find that the threaded rod may strip out depending on how much force is required to press the bushings. When I had the first bushing almost all the way in I stripped the threaded rod and had to cut it off.

I used some washers, threaded rod, etc to change out wheel bearings and found using rod connectors work very well as they engage a lot more thread. I don't know if thats the right name for them, but picture a nut about 2" long. That should keep the rod or nut from stripping. They look like the attached pic.

[MarkH]

To lower the subframe you will need to:

1. Disconnect the rear shocks from the trailing arms
2. Remove the springs, you can also hold off on this until you start to lower the subframe
3. Disconnect the rear sway bar from the rear trailing arms
4. Remove the exhaust system.
5. Remove the heat shields below the driveshaft and remove the driveshaft.
6. Disconnect the parking brake cables and remove them from the trailing arms. If you are only going to lower the subframe you can get away with skipping this step, but be careful not to put any weight on these cables or you may damage the tubes where then route inside the car.
7. Unbolt the rear differential to chassis mounting bolt, make sure the subframe and differential are supported by a jack and maybe some stands.
8. Unbolt the two subframe bushing mounting bolts, the large nut on the bottom
9. Remove the subframe bushing mounting plate by removing the two small hex nuts on the side of the car
10. Remove the rear lower seat cushion
11. Remove the two subframe mounting bolts by driving them up using a large hammer. Place a towel over the area inside the car in case they fly out. I used a 5 lb hammer and they came out pretty quick, but some people have had some trouble getting theirs out.
12. Carefully lower the subframe to where you want it. Make sure you do not break the two flexible brake lines between the subframe and the chasis.

I recommend that you change the brake lines when you are doing the subframe bushings, it is much easier to do with the subframe lowered or removed.

[wastedincome]

VERY nice write up there MarkH, that needs to be in the FAQ section

[NC325iC]

so what about the drive shaft?

[MarkH]

Good question on the driveshaft. I was changing my differential when I did the subframe and trailing arm bushings, so my driveshaft was obviously disconnected. I guess I need to add a few other steps, such as remove the exhaust, and heat shields. Thinking about it, and I just put my rebuilt driveshaft back in today, you probably should also remove the driveshaft to prevent damaging the u-joints or CSB.

[redhatpat]

Just to complete this thread, I had a shop put them in yesterday. $150 to do the job sure beats spending at least a full day busting my knuckles. Guy at the shop said it was a PITA job. Yeah, thats why I didn't want to do it! :) Had a look at the old bushings, and they were garbage. The drivers side was worse than the passenger side shown in the pics above. Shop dude said the rear subframe was crooked! I can believe it.

Anyway, night and day difference driving the car now. Back in stays planted in corners, and accelerating doesn't cause the back end to move around. The IE street urethanes seem like a perfect match for a daily driver. Only one day driving so far, but I love 'em.

Now, as for those clunking front struts...

[MikesJo]

Did you change the trailing arm bushings too? Were the IE street urethane bushings the $80 (pair) ones, green right? Nice to hear what a difference they were :).

[redhatpat]

The IE street bushings are the green ones. Its a good thing they aren't visible to casual inspection. Its tough to run autocross in the stock class with obvious mods. ;)

I didn't replace the TA bushings. I'm doing these upgrades/repairs on a very tight budget. So if something isn't obviously bad, I leave it be. They don't seem to be too loose so far.