Tuesday, August 15, 2017

MGB - floor pans (Part 1)

Today's post is the first of a series dedicated to the removal and replacement of the floor pans in my MGB. This process would be the same for any car whose floors are not a critical part of the structure. I believe most cars fit that description, but I'm sure there are some unibody cars out there which have particular demands on the floors requiring a little more expertise. On that note, let's be very clear: I have zero prior welding experience. Nada. Zip. I've tried to play with a stick welder and was unable to strike a spark without getting the stick stuck to the target material. After a few hours of that frustration, I gave up, put the welder under my workbench and moved on. Until now.

The Patient
right side floor - before
I have posted quite a bit about the journey with this little British car since I acquired it late last Summer. After a spirited drive home with no seatbelts, no brake lights and little understanding of how it operated, I've made many improvements:
  • brakes (link)
  • fuse box (link)
  • master cylinder / pedal box removal (link)
  • engine mounts (link)
  • rebuilt the front suspension (link 1, 2, 3, 4) including front wheel bearings, etc
  • new seat belts, rear suspension rebound straps, fixed the brake lights (no links)
While working on the front suspension, I had a volunteer in K2 ask if he could help out. I wasn't in a spot where unskilled hands were really a help, so I asked him to start removing the interior. The carpets smelled bad and were pretty worn, so I'd intended on at least getting the smelly stuff out and putting in a temporary solution until I had the cash to do the interior well. That is where this story begins.

left side floor - before
With a 1/2" spanner and a small ratchet, K2 was able to remove the 4 bolts which hold in the passenger seat and pop them into a ziplock baggie. We pulled the seat, and set it on the floor. I left K2 to the carpet and I returned to the suspension. K2 did a great job pulling the carpet free from the floor, and the transmission tunnel. The floor looked fair, with surface rust, but half of it was covered by the original sound deadener. We split the task of hammering that out with a chisel so we could evaluate what lay beneath. There were some rusty spots as you can see in the upper picture, but only pin-holes through.
Prognosis: fair, but will require some work to have them sealed up. Replacement suggested.

With the limited space in the garage, K2 had to perform some gymnastics to get after the bolts holding the driver seat in, but once removed, he made quick work of the carpet and we cleared the sound deadener much faster as well. Unfortunately, as "okay-ish" as the passenger floor was, the driver floor was pretty bad. There were multiple small holes and the sound deadener came out so easily because of the heavy rust underneath it. Upon further examination, the floor around one of the nuts for the seat had cracks in it.
Prognosis: This floor was toast. Replacement required.

Decision made: we'll replace both pans, one at a time, and hopefully have the MG road-able before the next rainy season starts.

aftermarket pan
When it comes to the floor, there are OEM and aftermarket floor pans. The OEM cost about twice as much, but they have all of the little things that make them easier to work with. They have the nuts for the seat-bolts already installed, and the reinforcements to the floor around them. There are various little threaded studs on the underside that are on the OEM pans. Last, of course, they are heavy British steel. The aftermarket pans do not have most of the fasteners attached, are made with thinner (not British) steel and they reportedly have an extra lip around the edge that needs to be cut off. Based on the pictures, it looks like the aftermarket pans also lack the drains. neat. I chose the OEM pans, and ordered a set through my local MG specialty shop: British Auto Works in North Plains.

Weld or Glue
OEM pan
There is a whole religious war about using a structural glue to attach floors, or other "non-structural" panels. The glue argument goes "modern cars are glued together, and the new glues are far better than anything they had back then so the manufacturers would have used them if they'd had them". Sounds reasonable. The weld counter-argument goes "modern cars are CAD designed with things like cost of materials and time/effort factored into the engineering so the glue is part of the engineering work, the crash testing, etc so gluing anything that isn't purely cosmetic on a non-glue car is a bad idea". This also sounds reasonable. I decided that I'd err on the side of caution and learn how to MIG weld on these floors. I have always wanted to learn how and while floors may not be structural, my seat is bolted to it, so it feels a little more important than, say, a rear spoiler. With this in mind, I reached out to my wife's sister's boyfriend to borrow a welder, and some welding instruction. But, before we get too far down that path, we need to remove the old. We'll get to that next time.

That's it for today's appetizer of a post. More to come on this topic for sure. Thanks for following along.

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