Rear subframe mounting bolt stuck

[rickyb916]

1991 318. The mounting holes for the rear subrframe still had the 'foam' in it, so I'm assuming these are the stock bushings and never taken out mounting bolt.

I got the SIR tools bmw bushing kit (rented from bmwm42, highly recommended)

Jacked up the rear driver side and I took off the mounting plate nut off, I've heated up the bolt (the top, the top bottom (under the car where you see the bolt go up into the body) and tried hitting it with a dead blow hammer (2 and 4lb, hard to really get good leverage with the car on a stock jack and stands) with no luck. (I didn't heat it until glowing red, but for at least a good 1-1:30(min) and tried.
I used some teflon chain lube and even some mx shock oil(all I had, going to get pb blaster tomorrow) and put it on the top bolt and it dripped down right away (So the foam isn't holding it back), didn't work.

I used a bigger c clamp and got it to hook onto the subframe and the bolt didn't move up, but the subframe lowered more.

Also with the car jacked up, used another jack with a big bolt (grade 8) and put it on the base of the second jack and lowered the first jack to try and ghetto press it out, didn't work either.

My next step I guess is to drill it? I tried using a drill set (not even sure what material it was) and couldn't get it to go past more then 1~mm, battery was dying on the cordless, going to try the corded one tomorrow.

Also note, when I lowered the car back down after all of my attempts and the mounting bolt isn't going all the way through the bushing? bent?
I have a good amount of tools, lacking air and power tools though, neighbor has most common air and power tools though.


1. How else can I go about this?
Getting pb blaster tommorrow along with a heavier metal sledge (was using a 2/4 composite).
Neighbor has an air hammer, but his compressor is a huge one that would be a PITA to go across the street with it.
Can possibly move my car close to their house but don't want to block their driveway while I work on my car.

2. What kind of drill bit (material) would work good on this alum. bolt?
And how far do I go down?

3.Is only jacking up one side a good/bad idea? any other tips are greatly appreciated.

Thanks! Only have 6 more days with this tool and only have the next two days off.

[matthugie]

Are you trying to get the entire subframe out? If you only have one side of your subframe loose it isn't going to go anywhere. The bolts on the sides are very long, and they both need to be off (as well as the diff mount and driveshaft) before dropping it.

[rickyb916]

No I'm using the bushing kit that doesn't need the subframe to be completely off/down.

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[jlevie]

Use a bigger hammer, something in the 14-16lb range.

[catalyst.]

are you using a breaker bar? You can try to tighten it a tiny bit before you loosen it to help free up the threads.

Also you can hit the head of the bolt to free up corrosion in the threads

[e30_302]

So you've got the nut off and you're now trying to pop the bolt up through the body? If you're only jacking one side you may be putting it in a bind. Just guessing at that though. Try a metal sledge vs the dead blow. If you can't see the tip of the bolt still it's probably because the subframe is still pulled down a little (after you put the c-clamp on it). You may need to jack on the subframe to raise it back up and expose the bolt.

[rickyb916]

So you've got the nut off and you're now trying to pop the bolt up through the body? If you're only jacking one side you may be putting it in a bind. Just guessing at that though. Try a metal sledge vs the dead blow. If you can't see the tip of the bolt still it's probably because the subframe is still pulled down a little (after you put the c-clamp on it). You may need to jack on the subframe to raise it back up and expose the bolt.

I think you're right, I was literally brainstorming and should have caught it last night but Yeah I think the bolt is binding in the sleeve of the bushing with only one side raised. Going to get good wheel chocks, pb blaster, BFH and some red bull.

Use a bigger hammer, something in the 14-16lb range.

Not sure if one that heavy and big would fit or would I be able to get sufficient leverage.

are you using a breaker bar? You can try to tighten it a tiny bit before you loosen it to help free up the threads.

Also you can hit the head of the bolt to free up corrosion in the threads

Breaker bar? I have the nut off and the top doesn't have anything. I gave it some light taps, maybe i'll try harder ones.

bolt looks like this:




Thanks e30_202 and everyone else who has responded with tips.
Going to give it a go in about a hour when I'm back from my bike ride to the hardware store!

[jlevie]

To use the bigger hammer the rear of the car needs to be 3' or more in the air. A lift works (obviously), but 6-ton jack stands on a couple of 4x8x8 concrete pavers also works.

[rickyb916]

So I got them both out and installed my akg in the driver side but now the pass side bushing and top plate are corroded or stuck to the mounting hole/body(drilled inside the actual bushing itself, read somewhere it helped removeing the bolt ) so now it's like pictured , tried using a flat head and sledge to hit the top of the top plate/washer for the bushing down but it doesn't budge. Any tips on this? Thanks !

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[KVF]

Two tried and true methods...

Get a lag bolt that's a bit larger than the bolt you removed, and screw it up into the hole where old bolt poked out. Screw it in tight and use a big mallet and rod to hammer down through hole inside car.
Or
Drill a hole directly through the sleeve, between the big washer and top of subframe in your picture. Slide a bolt or rod through the hole you drilled. Use big mallet and rod to hammer down through hole inside car.

There's posts in this section explaining a bit better, but can't find on my phone right now....

[rickyb916]

Two tried and true methods...

Get a lag bolt that's a bit larger than the bolt you removed, and screw it up into the hole where old bolt poked out. Screw it in tight and use a big mallet and rod to hammer down through hole inside car.
Or
Drill a hole directly through the sleeve, between the big washer and top of subframe in your picture. Slide a bolt or rod through the hole you drilled. Use big mallet and rod to hammer down through hole inside car.

There's posts in this section explaining a bit better, but can't find on my phone right now....

Thanks! Drilled a 3/8 hole through the sleeve and stuck a fat Allen key in there used the stock old mount bolt and gave a few good hits and boom. Now the washer isn't coming off lol


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[rickyb916]

Done. Used an angle grinder to get a groove and used a flat head to jimmy it out. Now to wait for my two new mounting bolts from ecs :) thanks to everyone in this thread

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[dullrot]

I was just looking to post a thread on this problem. I removed my driveshaft, diff mount, and the subframe mounting bolts (hint for future, dig out the foam before hitting bolt into cabin). Even the half shafts, and the driver side trailing arm (replacing lots of things). But my subframe won't drop.

Today I tried the method of tapping the stock bushing's inner aluminum tube with a 16mm tap, then threading in a 16mm bolt. Then I put an extra long 3/8" socket extension into the subframe bolt hole in the cabin, and whacked at the extension, which in turn was pushing on the 16mm bolt.

But the damn thing still will not drop. I have a motorcycle jack supporting the diff, and have tried holding that at a bunch of different angles to change the force the subframe arms exert on the subframe bushing, then thwacking at the extension again. But no joy.

I think I'm in the same boat as above with the "top hat" washer stuck, and the subframe arms falling below that an inch or two. I've seen the frankenpuller design for pulling the bushing out of the subframe in place, but hope to avoid spending yet more money on another method.

[dullrot]

when I lever the subframe downwards with a pry bar, it lowers 1/4 to 1/2 inch, but when a release the subframe just gets sucked back up, by the bushing I presume.

I also tried putting a jack where the spring goes on the passenger side control arm, and opened it up as far as I dared. No dice.

[mr2peak]

Do you have a friend to help you? It's a very difficult thing to do by yourself. It would really help to have a hand so you can remove both bolts at the same time.

It also helps to have a jack underneath the diff to hold the subframe in place. Remove both bolts, then lower the jack, best way to do it.