Thinking of cutting my lowered steel floorpan off and replacing with bonded and riveted aluminium panels. Reasons being I'm a shortarse so don't need/want to sit that inch lower. Would get a little more ground clearance and maybe save a few kg as well.

Question is how thick should an aluminium floor be and how close should the spacing be on the rivets. Seen it done before but still feel a bit uneasy riveting something that takes my full weight...

[Edited on 16/12/16 by luke2152]

My J15 floor is 1.5mm thick, riveted at 40mm spacings.

1.5mm for the floor. Use large head rivets and think the spacing on mine are about 50mm. A lot use PU to bond it as well though mine just has silicone to keep moisture out. Not been a problem despite a lot of miles and the seat being mounted direct to it (no chassis cross mounting bar like some cars have).

I wouldn't want my seats bolted through a alloy floor TBH.

Why don't you just space your seats higher rather than removing the floor?

If you do go to a alloy floor do the job properly and weld in some steel cross braces for the seats!

I'd guess (with no scientific knowledge) that the floor material (ali, or steel) will not make much difference in an impact, as long as the driver has a decent seatbelt on. The main problem I've heard about with a too-thin floor is intrusion by stuff on the road - branches, bits of metal, etc.

I agree that removing a lowered floor seems a huge amount of effort for little gain. Is the floor the lowest part under the car? On mine the end of the bellhousing is lowest. Will you save weight? Not as much as you think.

I'd also be concerned about damaging the chassis members while removing the old floor...

[Edited on 17/12/16 by David Jenkins]