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N62 Z3 Part 15: Fabrication (Chassis)

First up with chassis fabrication was to get the heater core valve in place. I cut the bracket off the firewall ages ago and had it saved so I just trimmed it to fit the location I chose. There was not a lot of room to find a spot that seemed like it would allow clearance around the engine once installed but I managed to find a spot under the expansion tank that I thought would work quite well. This space was previously occupied in part by the ABS module

The next day I corrected the hose routing as the heater core valve does indicate directionality and also deleted some extraneous brackets in the area. I also used a 90 degree elbow quick connect for the expansion tank to make the supply line to the the heater core a little nicer

Mocked up a hose for the heater core outlet as well and then one for the engine supply

Then I went to work on the passenger side framerail - the idea here was pretty simple, to just cut out a little piece and invert it to give me the clearance I needed. It worked and was a lot more drama-free than I was expecting. I will likely end up modifying the driver's side framerail as well, since I had such a positive result working on this today. It's not pretty, but I am using flux core so it's not usually destined to be pretty. I do have confidence in it being structural though. I am starting to think I should get some gas and start practicing on getting my welds to look a little better

This was a pretty nerve wracking moment as I have never done this to a car before... I have been practicing a ton with welding frame rails and shock towers on my parts cars in order to get comfortable with it though

Flipped around and tacked in place - the surrounding metal was simply hammered to sit flush, it wasn't exactly ideal but it worked well

It will get some more grinding to get a little neater looking but this is where it ended up for the day. You can note how the body line "inverts" here, I thought of a method to avoid that after I finished though I definitely will not be re-doing this on this car, in part because I feel the least amount of welding possible is best for the integrity of the frame

The below angle is much better at showing the clearance that this is adding. The timing chain tensioner was just barely hitting in this area when the engine was sagging so it didn't need a lot of clearance, but I did want to address it as I still currently intend to use rubber engine mounts so need to account for the engine sinking as the mounts wear

I realized I was going to have the engine back in place with quite a bit to finish up before I planned on painting and I want to test the engine next time it's in so I got the DME box back together while also verifying all the wires I thought were grounds were indeed grounds since it's been months now since I worked on the wiring

I also have another idea for the engine mounts, though I am not entirely committed to it. My thinking was that since the issue with these engine mounts is that they were just a little too wide for the frame rails, if I simply hacked some off the tips of them, that maybe they could be made to work... I am not sure though. I have a feeling the engine mount will interfere with the framerail even if these fit and I am also not sure I love the loss of structure... so may just go custom mounts like I was originally intending. I want to see how they look when installed at the very least

Before I got started on the driver's side framerail I decided to weld these strut towers together a bit more, for structure or whatever

And this too...

Did the other shock tower as well

And then there was no more avoiding cutting a giant hole in my frame rail

Which revealed that there were two layers in this area so I decided to weld this inner structure to the metal below it for structure or whatever

I was never a big fan of framerails anyways

The original CAD

I worked very slowly and let it cool down to the touch in between welds, to try to prevent anything from warping

I am not done at this point but am very happy with how it is coming along, at this point it is completely welded up

Some of the clean-up is done. I need some better finishing tools...

I primered it and then hated how it looked so bought some flap discs to knock the welds down a bit more... I will likely finish it off with just a little seam sealer

Before I did that though, I did think it would be wise to test fit the engine as the build continues in Part 16



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