w123 rear subframe bolts won't go in..

[sceh]

I have replaced one side of the rear subframe front mount. No problem. I removed the other side, removed the mount, replaced it only to find that the subframe seems to have moved relative to the body so the bolt goes through the mount but will not engage in the chassis.
I have tried crowbars, jacks, wedges - you name it - to realign things. I have tried jacking the vehicle up and then jacking the subframe up and vice versa. It simply will not bite the thread. The threads are OK since it screws in with the mount removed.
I am tempted to give it some Barnsley screwdriver treatment but guess this will knacker the thread.
Anyone had the same problem and know the fix? Since the bolt is tapered, is it designed to be hammered in? Should the body be jacked up and the subframe jacked up or does it not matter?
Needless the say, the car is totally undriveable with a loose subframe.

Any ideas or advise welcomed! I am at my wits end...

 

[sceh]

towing the car

Do you think it is feasible to tow the car with one of the front subframe bushings missing? I am thinking of taking it to a garage to see if they can do it - followed by the scrapyard if not..
thanks

 

[grober]

TRY THIS from a US thread. Subframe Mount install SOS - Mercedes-Benz Forum

So heres the deal..

When one side is being stubborn and wont align,

1. Jack up the car and support both sides by jack stands (under jacking points)
2. Place a floor jack under the diff.
3. Release both sides of the subframe, this allows the entire thing to move into position.
4. Choose the toughest side....mine was the troublesome side which had damaged threads (these were re-chased).
5. Align both sides by lowering and moving the jack under the Diff.
6. Give preference to "Tough side" and then attach this side first.
7. Now do the same on the other side...
8 Torque all the bolts up and take it for a drive.

 

[sceh]

Sounds good!
When you say jack it up you mean the wheels off the ground (stupid question I know)?
When you say 'release' both sides you mean remove the bolts or just loosen them? I am terrified I will end up with two sides misaligned...
For the jack stands, the jacking points points are right beside the subframe mounts so Some pretty big blocks of wood should do the trick. Can I assume that the chassis along the side of the car under the doors will take the weight?

I am being a bit cautious here since these things are heavy!

Do you think it would be possible to do this by jacking up one side, loosening the other and then using a large crowbar to move the subframe or is the weight too much? I could always try I suppose

 

[grober]

This might help a bit? http://mb.bolinko.org/wis/w123/CD02/Chassis/35-410.pdf

There should be jacking tubes/pads towards the rear of the sill strong enough to take the entire weight of the car on each side . Its pretty important to jack it up symetrically so there is no tendancy for the body to distort under its own weight. Thats why it should be adequately and equally supported at both sides at the same height. Its vital you have the correct kit for this sort of job- good axle stands and heavy duty trolley jack/s on a smooth level surface. I would suggest at least one strong assistant not afraid to get their hands dirty- most garages will have two guys on this job for certain parts of the operation- one to move the assembly and one to check alignment at the same time.
If you jack the car up on one side only your chances of problems of misalignment are going to go up and on your own your probably on a hiding to nothing. Whatever you do don't take risks- its all to easy if you are tired and frustrated to take short cuts under a poorly supported car-- many people have died that way.

 

[sceh]

Thanks very much for the advice and the diagrams - really helpful. I haven't tackled it since yes, I am tired and frustrated after two day of fruitless effort!
Tomorrow I hope to post the good news and a beer for you!

thanks

 

[sceh]

Couldn't do it so I took it to the local garage who managed in 15 minutes....
Done though. It has not solved the dead-body in the boot noise so it must be something else though what I do not know. Any clues?

 

[grober]

Large thumps from the rear can result from a poor located exhaust hitting the underside of the car when going over bumps . Try bouncing the car on its rear suspension with a friend to see if you can elicit the sound. On some cars there is a small rubber bump stop on the exhaust mounting purely to prevent this