Thursday, February 6, 2020

[M3] Fire extinguisher mounting

[note: this post, like an air-cooled 911, is back-dated to when these events occurred] 

The next item of business was something that I've been meaning to do with all of my classics for a while - a proper mounted fire extinguisher. BMW makes a bracket that bolts up to E30 sport seats without any modifications. It's not available in the US but I found it in Germany - the part number is 72601906501 and you can find it here at Walloth & Nesch. I rounded up some locals and bought a handful of them to save on shipping.



The bracket comes with the required mounting hardware. I pulled out my seat to have a real good look at the mounting situation. The two fixing holes are already there on the front face of the seat frame, you just clip in the nuts and off you go.







The bracket also 'wings' out to grab two additional fixing points. My seats have been recovered and I didn't want to unravel anything so I just left these free. With just those two other fixing points the bracket is study and does not rock around on the seat.





Unfortunately this bracket is only half of the story. It's the hard half, but it's only half. BMW offered a fire extinguisher kit that was designed to work perfectly with this bracket (and in newer cars as well). Of course, like all useful things it went NLA in the United States a few years ago. If you're keen you can buy one with no extinguishing agent in it for $500 on eBay. Tempting! Frustratingly it's still available in the UK, sold on eBay by BMW themselves, but shipping across the pond is expressly verboten. The part number is 72600000335 and the eBay listing is here. It looks cool and comes with its own little cute seatbelt and everything. The part number cross-references with a Porsche part number so I think they shared this extinguisher, but the Porsche version went off the market at the same time the BMW one did. The important part of the story here is the bracket that HOLDS the fire extinguisher... the bracket on the bracket. I started looking for something to mount the Home Depot dry chemical extinguisher I have in the garage.



These extinguishers are not particularly well-marked with part numbers, this white one is a Kidde brand and I think it's a 2-2.5lbs size. I found that Home Depot carries a Kidde extinguisher bracket that works well. The Kidde part number is 21010541 and the Home Depot product page is here. While I was buying the bracket I went for the slightly smaller Kidde automotive fire extinguisher they offer, since the one in the photo above looked pretty big. The part number for that extinguisher is Kidde 21006287MTL.



It's not 100% plug and play but it's an easy modification. The Kidde bracket and the weld nuts on the BMW bracket do not line up, and the stiffening darts create a small interference that prevents the Kidde bracket from sitting flat. I fixed one end and match-drilled a hole in the BMW bracket using the Kidde bracket as a template. I put two small washers between the brackets to clear the interference with the BMW bracket darts. Please forgive my crusty seat tracks in these photos.











And there you have it! The last photo shows how nicely the extinguisher is tucked out of the way. I really did NOT want something huge and pronounced and as you can see it's barely noticeable from the driver's door approach. I hope that I never have to touch it again, but it's nice to know that it's there.

There are different types of fire extinguishers, each with different benefits and drawbacks for an automotive application. I will be honest and concede that I got excited about an OE BMW mounting bracket and just ordered away, assuming that a cylindrical fire extinguisher is a cylindrical fire extinguisher. As I did my homework, I found good resources like this one that provided more detail about the differences in extinguisher technologies (dry powder versus halotron, both in that link) as well as newer options like Element extinguishers, which look like a great option in terms of shelf life, form factor, and discharge time. Coming from Japan, my GT-R already has a flare mounted in the passenger footwell so I will probably purchase two Element extinguishers, and find a home for one in the M3 to supplement the dry chemical unit. Belt and suspenders.

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