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Old 08-10-2012, 12:29 AM   #301
Registered User
Join Date: Oct 2006
Location: Springfield OH
Posts: 740
My Ride: '00 323i + '75 2002
Thanks guys!

With the front mounts made up it was time to get the subframe square with the car and figure out how high I wanted to tuck it up into the body. Luckily I was able to talk my friend into helping me during the measuring and finessing the assembly into position. After about an hour of tweaking and adjusting I was happy with where it was sitting, and I tacked the front mounts in place. This then allowed me to figure out the correct placement of the rear cross member, which would hold the rear mounts for the diff cover.

Here's the front subframe mounts tacked in place. The bolts are a little long, but I don't think it will hurt anything. Worst case scenario I'll just trim them down a bit:

Here you can see the area cleaned up and ready for the new material to be welded in:

Next we cut and measured the cross member piece along with the extra side panel reinforcements. Here are both welded in place:

Close up of the driver side. The plate that the cross member is welded to is to help reinforce the inner wheel well. The weld-thru primer made my welds a bit crappier than I would have liked, but they will definitely hold.

With the cross member in we put the subframe back in place so we could measure for the diff ear mounts.

Front face of the mounts cut out:

Due to the way the bushings on the diff cover are, the ear mounts need to have a small, circular offset to them. So I TIG'd some washers onto the back of the ear mounts. This allows the inner portion of the bushing to be held rigid to the mount without rubbing on the outer portion of bushing and diff cover.

I then gusseted the ear mounts to add some rigidity and welded them in place on the cross member under the car. This let me remove the jack and see the subframe held in place on it's own for the first time.

Nother Diff Shot:

Here you can kind of see the gussets I added to the diff mounts. Essentially the cross section is a 'C' shape, except at the bottom where there isn't a worry of it flexing (it's lower than the bolt hole). I'm also going to add a gusset above where the ears sit once I take the subframe back out.

Last but not least here is a side view of the diff. You can see how it sits up against the body of the trunk floor. The cover has a clearance of about 1" between the top of it and the front of the cross member, which will be plenty of room.

Next up will be framing out the trunk floor and fit the fuel cell into postion. Then I can repair/brace the inner wheel wells and measure for my rear coilovers.
Tinker Engineering - 2014

Mica - 2000 BMW 323i - The one that started it all
Fiona - 1975 BMW 2002 - The Definition of Project Creep
Heidi - 1988 BMW M5 - The piece of BMW history
Silvia - 2013 Subaru WRX - Stock, for now
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