All the sevens I've seen the last years have no drain holes for water to get out, and I've seen a lot of rusty floor tubes.

Have anyone ever made a attempt to use a wheeling machine to make the floor plates stiffer, and adding some drain holes? Maybe with a rubber button that could be removed when needed.

How would it affect the airflow under the car? Their had to be made in longitudinal direction, that's for sure.

After a very eventful trip out to Goodwood many years ago I had what seemed like 2" of water in the floor and in the seats for the rest of the journey
Got the drill out and made some strategic holes in the seats and floor when I got home

Floor tubes on mine are surface rusty and the alloy has gone a bit fluffy where I cannot get to it properly...but then it lives outside and I am coastal
I have rubbed back and painted the tubes I can get to a few times, but rust/corrosion always finds a way

I have not bothered putting bungs in the holes I made (they are only 4 or 5mm or so..) and don't bother me - or the MOT examiner and could come in handy again


Floor on my MK is quite thin alloy and I don't have any "oil canning" ...but can see where it has bowed slightly from the years of a chubby fella getting in and out when viewed from underneath
Not sure if wheeling lines into it would make that situation better or worse

I've got drain holes in my Fury floor. Think they're 12mm and in the inner corners. Only issue is in heavy rain spray came up through them and wet the back of my legs/trousers. In very heavy rain and standing water, I had fountains! I made little covers underneath with channels that exit is to the rear. No issue since.

I think the issue putting stiffening ribs in would be achieving it without distorting the rest of the panel.

I have one home in each corner of each floor well, holes are only about 4mm. When I had GRP seats they didn't have holes IIRC, grp would not like a hole at the bottom, especially as I stand on the seat to get in. It will crack very quickly.

Regarding the stiffening ribs, they will offer little gain. The sheet metal, when tiger bonded and rivetted is like a stretched fabric. It offers a lot of strength to the chassis in tension, like canvas to a tent. The ribs may reduce this strength. The floors don't say much when you stand on them so I really see little benefit.

The MK Indy I built didn't have any drain holes in the alloy floor. Got caught out in the rain once, but didn't really acquire any water as I was moving the whole time.

Another time the car was sat out in the rain at my parents house and acquired some water. Dried it out with towels and no harm done. My chassis rails were well painted and I didn't incur any corrosion from it.

If adding drain holes I'd probably have whacked a centre punch through in a few places. Personally, I'm not greatly concerned about effects of under car airflow from doing so.

MK indy with small 3-4mm drain holes... All good when the cooling system lets go and fills up the footwells

Not sure I would bother strengthening the floor pan at least on my indy as the seats are attached to steel plates and don't use the floor for strength.

I wouldn't worry about the airflow in general these cars have the aero of a small brick - the main gain in this regard is the small frontal area rather than anything else

[Edited on 13/10/23 by Bluemoon]