25 replies to this topic

[stuart bowes]

depends what you mean by 'significantly more work'

if you cut out the whole floor you'll have to brace up the shell internally, also when you clamp up the new floor before welding, check your measurements and make sure the rear subframe fits and is in the right place

there's a fair bit of strip down required, also as Sonik pointed out, once you're at that point, consider the boot floor as well because by then you might as well. There is bound to be more rot in and around the seam with the base of back seat as well, doubtless also around the rear wheel arches and rear corners of boot floor

Hire a spot welder and go round all the seams, at least that bit is 'easier' than all the MIG welding

but neither option is an 'easy' job obviously

I think just looking at pics I'd probably lean towards the whole new floor in your case, but that's just one opinion and not necessarily the right one for you

Edited by stuart bowes, 19 March 2025 - 01:48 PM.

[stuart bowes]

Don't forget as well spot welder will need a type C breaker in your distribution board or it'll keep tripping.

Actually for outdoor use (and any other circuits where you have sockets and running leads outside) it should be an RCBO to meet regs

mig you can do from a normal supply with those sort of sheet thicknesses so maybe the option is to plug weld. But that's a lot of tidying up afterwards. Swings and roundabouts

Edited by stuart bowes, 19 March 2025 - 01:52 PM.

[s2ulk]

Thanks Stuart, very helpful. Would bracing not be required if just replacing inner and outer sills (given reference above to removing the cross-member to make it an easier job)?  I would need to use a mig welder and so I think I would then be in for the plug welding..... 

[stuart bowes]

I can't answer that with 100% certainty but my gut feeling is, if you cut a whole inner sill off, and the end of the toe board as well, I'd probably want to do a bit of bracing yeah. Depending how and where you place jack stands the shell might settle into a different position when you cut out a section that large

Also as sonik rightly pointed out make a jig to locate the toe board end repair piece to ensure correct alignment

Take advice from someone who's done it though these are just my thoughts. I did mine in small repair sections working my way along. But my inner sills were not that bad

Edited by stuart bowes, 19 March 2025 - 05:37 PM.

[sonscar]

I have put floors in other classics but not a mini on which I replaced floor to first groove and outer sills.If you can cover the cost then put a full floor in it.It will look better and not be as difficult as it appears.Brace it well and use the bracing to pick up datums like subframe mounts,seatbelt holes,gear lever mounts and have at it.Steve..

[Cooperman]

I have used the MMachine inner and outer sill sub-assemblies which have around 5” of floor. The come with jacking points and are very accurate.
I usually tip the car onto its side and don’t add braces so long as the door frame, cross member and rear quarter panels are fairly ok.
Changing a complete floor is a massive job and bracing is necessary.

[coopertaz]

for small amount of time i would still brace b post to a post and across car too just to be safe, also as i said previously if you remove the comapnion boxes this makes the job far easier and are pretty easy to get out but does leave the b post less stable hence the bracing.

[s2ulk]

cooperman when you say it’s a massive job, is that due to all the prep required to ensure it lines up correctly? Sounds like the welding side of things may be easier than localised repairs based on what others have said.

Coopertaz, if the companion bin comes out, does it generally need to be replaced with a new one? Or are they salvageable?

[Cooperman]

I have never, ever done a complete floor change.
Huge amount of cutting and prep. Alignment may be difficult and accurate alignment is vital.
It’s rare that the centre tunnel is corroded so why cut it out. I see it as the ‘backbone’ of the body structure.
I do like the M-Machine inner/outer sill sub-assembly as you get quite a lot of floor with it.

[s2ulk]

I have never, ever done a complete floor change.
Huge amount of cutting and prep. Alignment may be difficult and accurate alignment is vital.
It’s rare that the centre tunnel is corroded so why cut it out. I see it as the ‘backbone’ of the body structure.
I do like the M-Machine inner/outer sill sub-assembly as you get quite a lot of floor with it.

Thanks Cooperman - is the M-Machine panel you are referring to numbered 11.33.01.37 / 38 in the diagram below which is about £160?

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[Cooperman]

The 37 & 38 are the sills and wide sub-assembly with a floor which goes right to the tunnel.
I have only ever used the one with less floor width which goes in about 5” from the inner sill.
It depends on how corroded your floor which ones you need.