Monday, September 2, 2013

Disassemble!

Today I was able to drop the rear sub-frame from the car. It was a lot easier than I had anticipated, but I suspect the copious amounts of PB Blaster I applied the week previous did its work on those old bolts.

I also suspect this wasn't the first time the sub-frame was removed since the car left the factory since one of the trunions was held in by an additional nut due to the factory, welded in nuts were stripped.

Anyway, here's what the sub-frame looked shortly after its removal from the car.

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That's the last time that board will ever be so clean.

In the process of removing all the things that had to come out before the sub-frame would I did some serious examination of the nooks and cranny's of the boot. Thankfully, it's mostly in good shape, but I do not escape without some cursed rust.

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One good sized hole on the left-side, behind rear wheel arch.

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Another on the right-size, although not as bad. The black stuff is bituminous tar that they used for water proofing, it was fairly effective I guess. I still plan on removing all of this and using some of the more modern waterproof coatings.

One good bit of news was that the sub-frame mounting points on the car body were completely rust-free. I had heard that this was a particularly bad area for rust to form because of how much junk gets trapped in these places. Luckily, while there was a copious amount a road debris up there, there was no rust.

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All four points look this good, which is quite the relief.

The sub-frame wasn't so lucky and it suffers some rot on one of the main support beams. If I were to guess, the water got between two pieces of metal and started rusting internally. What I'm seeing the picture below is just the surface expression of that rust.

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Toward the middle of the image you can see the two different layers of metal. That line you see shouldn't be visible, but instead tacked down by two little welds. As an added bonus, you can see the remains of the two bolts I snapped off trying to remove the swing arm bracket. Evidently I didn't get enough PB Blaster applied to these.

To properly fix this all the rust would have to be completely removed or rendered inert. Then it would have to be re-welded and probably gusseted. Given the way this is rusting I don't think that it's possible to get to all of it so that may mean I have to get another sub-frame which isn't exactly inexpensive. It will also be a bummer because I think this part is original.

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Here's another shot showing the rust peeking through.

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So after a couple hours work I managed to get all the parts off the sub-frame. Had I not encountered the rust I would immediately begin stripping this and making some small repairs, but for now I'll wait for some advice and decide how to proceed.

Up next:
  • Decide on the fate of the sub-frame.
  • Purchase new brake assemblies and drums.
  • Clean up and re-coat all the small brackets that came off.
  • Buy new bolts.
  • Reassemble!
One more thing; I've arrived at the inescapable conclusion that I need to learn how to weld. Progress will be painful without that ability.

3 comments:

  1. Awesome stuff....I need to check out your blog more, but I also know that with owning a Mini - things do take time. I had exact same situation - my rear sub was bad like yours and by the sheer grace of god, I saw this ad on MiniMania for a brand new BMH Mki4 subframe (full unit with all the fixings) and was located in a city that I was visiting for business. What a coincidence and before you knew it, I got it for a steal. Keep plugging away!

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