Author Topic: Need help dropping rear subframe (Read 7706 times)

P. Kennedy · « **on:** August 30, 2008, 02:37:16 PM »

I have everything disconnected, but I'm trying to dislodge the subframe bushings themselves so I can drop the rear axle carrier and trailing arms.

Diff is out, axles are out, those 2 little plates (rear jacking points) that connect the bottom of the subframe bushing to the body are out.

There is a large bolt that runs through the center of the subframe bushing, with what appears to be a 24mm nut on the bottom, but this nut tapers to a larger diameter as it progresses upward into the bushing.

What am I missing?

Thanks

P. Kennedy · « **Reply #1 on:** August 30, 2008, 03:44:46 PM »

Just found out the bolts going through the rear subframe bushings are knurled at the top and pressed in at the rear seat metalwork. I will proceed to pound from underneath and see if that does it.

ak96ss · « **Reply #2 on:** August 30, 2008, 04:31:23 PM »

Prepare for some fun.

Have you already located the tops of the bolts? They are under the rear seat, right in front of the wheel well. There is some goo in there holding the bolt in place, IIRC I just scooped some of it out but not all - enough so that I could spray PB Blaster down in there and get it to soak through. That is an important step.

Loosen the nuts so they are flush with the end of the bolt, and knock the bolt out by striking upward. You'll probably want to put a towel or something over that hole, to keep the bolt from sailing up into the cab when it does finally break free.

If you are *very* lucky, your bushings have not welded themselves to the body of the car. In which case, it should just be a matter of pulling the subframe off.

That is probably not the case, and you will likely end up with something similar to this, maybe even on both sides.

P. Kennedy · « **Reply #3 on:** August 30, 2008, 04:33:39 PM »

OK...so...a few whacks with the 5 lb. maul freed up the bolts within the subframe bushings, but still no movement. What's holding it up, the old bushing material itself? Shall I just go in there and eradicate the old material until the subframe falls, using drill, Dremel et al?

Any suggestions?

P. Kennedy · « **Reply #4 on:** August 30, 2008, 04:38:17 PM »

ak96ss: You said to loosen the nuts until they are flush. Are you referring to the large, tapered 24mm nuts that appear to be integrated within the bushing itself, or the 21 or 22mm (can't remember) nuts that were below the little plate that is round one end and female hex-bolted to the body's rear jacking points? In which case I already removed those last night.

ak96ss · « **Reply #5 on:** August 30, 2008, 07:35:47 PM »

Well, if you got the bolts out, don't worry about loosening the nuts until they are flush - the concern was that you not mushroom the threaded part of the bolt when you were pounding them out with a hammer.

What is probably holding them in is the fact that there does not seem to have been any antisieze put on the metal nipple of the bushing when it was orginally installed in the body of the car. Dissimilar metals, water/salt/time, etc. - the two parts essentially fuse together, making it extremely difficult to remove the old bushing in one piece.

This is a comparison of a full bushing, and what was left when mine came out of the car:

The end that is left in the car has to be removed, and it is a bit of a pain.

I just used a long pry bar on the subframe to essentially snap the end of the bushing off, then Dremeled it out. Unfortunately, there is no access from the top to drive it out, unless you can somehow thread a bolt into the bushing material from the bottom and then smack it out with a drift from the top.

P. Kennedy · « **Reply #6 on:** August 30, 2008, 09:37:55 PM »

OK, thanks for your insight. Yeah, my bushings have been in there since 1/90, my production date. I will just begin attacking them.

P. Kennedy · « **Reply #7 on:** September 05, 2008, 09:01:04 PM »

So...John...my situation is identical to your 2nd photo in post #3 above, on both sides :rolleyes: snapped both them suckers right off after torching the crap out of the old bushing material. If I understand you correctly, you Dremeled those out? Did you grind them, cut them - how do you avoid excessive removal?

Thanks,
Pat Kennedy

monty23psk · « **Reply #8 on:** September 05, 2008, 11:54:57 PM »

When mine got stuck like the ones in the picture. i used a drill and chisel to get the stuck part out.

P. Kennedy · « **Reply #9 on:** September 06, 2008, 03:21:12 PM »

I am off to the hardware store to obtain a big honkin' drill bit. Thanks Monty.

'88 M5 eh? Now we're talking. Pics?

kowalski · « **Reply #10 on:** September 06, 2008, 05:12:55 PM »

i used a punch and i hit from the inside of the bushing out, moving around in a circle. after about 10 hits, the bushing just fell out.

P. Kennedy · « **Reply #11 on:** September 06, 2008, 07:17:47 PM »

Yeah, I actually have been pounding from the inside, using an 8" 1/2-inch ratchet extension. Mine are REALLY seized in there, but I am open to anything. I will try a small, flat-end punch in a circular fashion. I am prepared however, to go in there with a die grinder with about a 1" ball attachment.

Thus far, I've been using a 1/2" drill bit and working around in circles from below. Slow, but noticeable progress.

Thanks for the input.

ak96ss · « **Reply #12 on:** September 07, 2008, 06:53:29 PM »

Sorry, I've been camping, no Internet!

I used a cutoff wheel and sliced a chunk out of one side, then a punch to collapse the ring in on itself. Other methods will work - I've heard of folks tapping the hole, driving a bolt in there, then whacking it from the top, but I dunno bout that...

monty23psk · « **Reply #13 on:** September 07, 2008, 09:55:55 PM »

Here are pics after a wax, was dark at the time. That was about 5 years ago. Car has been sitting 3 years while working on interior after heater core spill. Got new dash and and cleaning up everything else. Working on it slowly due to budget. Now have the e30 as daily and will start on M5 at the end of the year. e30 takes time as its cheaper and more attention since it used daily.

http://www.bmwmregistry.com/detail.php?id=71

rhogg · « **Reply #14 on:** September 08, 2008, 07:46:11 AM »

I used an air hammer/chisel and chipped out the remaining metal after cutting off the bushings. Once I got to this stage it was pretty straight forward except for the abject fear that I would damage the the frame. I went slow and it came out all right. After cutting the bushing off the clean up (chip out) was only 10-15 minutes.