The Black Rat

bruce · Postby **bruce** » Mon Mar 30, 2020 12:50 pm

I think he means tha metal on the back edge under the softtop. The tank is still covered up by the body and the silver cover.

The American · Postby **The American** » Mon Mar 30, 2020 2:09 pm

greenMachine wrote:
The American wrote:. More of the unneeded steel around the back of the fuel tank hump will also go.

Will that affect the sealing of the fuel tank from the cockpit? Or will it be replaced with something lighter?

Good question. Given that none of the material was ever providing a seal as such, I am not sure. The tank is still underneath the hump with the cover plate which will not be removed. This was always exposed but for carpet. Anyone know how the rules apply to MX5s?

RS2000 · Postby **RS2000** » Mon Mar 30, 2020 2:33 pm

If you're talking about Cams rules, they are the same for all cars:

"be fitted with a bulkhead constructed from a flame - and liquid-proof material. If the material is constructed from polycarbonate it shall be a minimum of 6mm thick. This bulkhead shall effectively seal the cockpit from the fuel tank and re-fueling system."

I'd say the hump & cover does this, but keeping all the tin plate (that the carpet sat on) adds good extra flame protection in my opinion.

The American · Postby **The American** » Mon Mar 30, 2020 2:57 pm

bruce wrote:I think he means tha metal on the back edge under the softtop. The tank is still covered up by the body and the silver cover.

Yes, the complete hump and cover stays

greenMachine · Postby **greenMachine** » Mon Mar 30, 2020 8:43 pm

If the boot interior is to be exposed, that will also expose the (I think) fuel tank itself, but certainly the fuel filler piping and rubber hoses. I doubt that will get through your logbook scrutineering, I am pretty sure you will have to close it off somehow.

:mrgreen:

RS2000 · Postby **RS2000** » Mon Mar 30, 2020 10:53 pm

I think the fuel filler piping is exposed to the cabin in all NAs & NBs (don't know about NC/ND) via the gap between the wheel arch & fuel tank hump.
The tin plate cover that curves down behind the seats certainly doesn't seal the cabin from the boot. It doesn't seem to effect getting log books though.

greenMachine · Postby **greenMachine** » Mon Mar 30, 2020 11:17 pm

RS, you are correct as far as you go.

My car was built as a 2F car, and also ran as a sports sedan (amongst other classes). I, and all the local MX5s that I know of, kept the stock tinware sealing the cabin from the boot/fuel tank. Many (most? all?) also sealed the multitude of holes in that tinware. In addition, either the channel between the boot and the cab was sealed with a welded plate at the seat belt tower (racecar), or a blanking plate at the boot end (registered logbooked car). Purpose was to ensure that fire or fuel could not directly enter the cabin.

If you can see an entry point for fuel or a fuel fire from a damaged tank or fuel piping/lines, I believe it will have to be sealed one way or another. I'd have to check, but if in fact the fuel tank hump covers it within the boot, the vulnerability is limited to the refueling piping and rubber connectors etc which are exposed to the boot space, so that has to be sealed off, hence the need for the horizontal panel and its holes being sealed.

The holes in the horizontal panel behind the tank are a source of inconsistent treatment. I was told to plug them, others have them ignored.

I would not be totally surprised if the interpretation/enforcement of this varied between States though.

FWIW I have seen kits retailing in the US that comprise the aluminium components to replace the tin panel - exchange rate would probably make that prohibitive these days.

RS2000 · Postby **RS2000** » Tue Mar 31, 2020 7:56 am

Thanks gM, the complete sealing is what I thought would be required according to the Cams wording.

My race car, logged booked before my ownership, obviously slipped thru' without all the sealing of the 2 side channels & horizontal tin plate.
I only do speed events, but the same rules apply, & extra sealing from fuel is a good thing. Another job for my list!

The American · Postby **The American** » Tue Mar 31, 2020 9:57 am

I think the tank is sealed front and back from the cabin, except for the pipe work. Perhaps a box around these?

greenMachine · Postby **greenMachine** » Tue Mar 31, 2020 12:04 pm

Probably.

Have got someone lined up to do the logbook scrutineering, they would be best to talk to, and discuss that method and what they would look for, and then weigh up that and the alternative (horizontal panel/side plates).

:mrgreen:

RS2000 · Postby **RS2000** » Tue Mar 31, 2020 12:14 pm

Yes the tank itself is fully enclosed. I think it would be much easier & more practical to seal the boot ends of the 2 passageways, rather than build a sealed box around the filler piping.

greenMachine · Postby **greenMachine** » Tue Mar 31, 2020 1:15 pm

So do I, but that also means keeping (or replacing) the horizontal panel.

:mrgreen:

RS2000 · Postby **RS2000** » Tue Mar 31, 2020 1:50 pm

The Cams manual says "bulkhead shall effectively seal the cockpit from the fuel tank and re-fueling system"

With the seat belt towers in place, I think the OE tin plate 'effectively' (but not totally) seals the cabin from boot flame.
Sealing from fluid fuel would be almost impossible, but perhaps the above statement doesn't require that?

Tim_cyc03 · Postby **Tim_cyc03** » Tue Mar 31, 2020 8:17 pm

I just made a box up that goes over the hump, then sealed the sides with more metal.

RS2000 · Postby **RS2000** » Tue Mar 31, 2020 10:07 pm

I don't understand Tim.
Why has the hump got to be in a box, when the hump is the box that the fuel tank is sealed in? It's the filler hoses that aren't sealed from the cabin. Maybe I'm missing something?