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MG MGA - Transmission tunnel hole

On the each side of the rear transmission tunnel, near the floor and towards the rear flange, is a small hole. On the inside of the tunnel are welded small, channel-formed sheet-metal baffles extending below the level of the tunnel flange, which allow these holes to communicate with the underside of the car. What function does this arrangement serve? It must not have been so important that blocking off the hole with the carpeting led to adverse results. Could some optional wiring have been routed through here?

Ken
Ken Korey

I believe the factory put them in to allow drainage. Not sure how effective they ever were with carpeting and all. But kudos for the effoft.

Cheers.

Larry
York, Maine
Lmazoway

I reckon the backward pointing baffles are there to create a negative pressure, when the car is travelling forward, at the drainage holes so as to suck out any water that collects on the car floor. If the car got caught in a heavy rain storm with the hood down there could be a half inch or more of water on the floor in no time.

The holes seem to be the only means of draining if the floorboards are fitted with mastik and the tunnels are well sealed. If the baffles weren't there there could be a positive pressure at the drainage holes making them only effective when the car is stationary.
Also as there is a slightly raised crossmember above floor level across the car to the rear of the gearbox there are two more drainage holes with baffles in the gearbox tunnel, a few inches from the front, to drain this half of the car...................Mike
m.j. moore

Thank you both, Mike and Larry. I suppose in a deluge rainwater might well up a bit, but I'm guessing that the layers of carpet and mat resist perfusion to this covered drain (even with negative pressure at speed), enough that direct evaporation is all that effectively dries the floor. This detail seems rather like the fins on Buck Roger's rocket ship.

Ken
Ken Korey

This thread was discussed between 28/08/2010 and 29/08/2010

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