Sills, To Fill Or Not To Fill? And "retaining Nut Brackets"...

I've heard that some early mini's had their sills filled with expanding foam. Has anyone done this to their min and is it effective at stopping the dreaded tin-worm?

Also a question regarding the retaining nut brackets that are found on the inner sill. When replacing the outer sills there are holes either end which line up with these brackets but I've not seen any minis that actually have nuts fitted. From reading project threads it appears a lot of people don't bother replacing these brackets when re-doing their sills. But if you have, should nuts be put in to help stop water getting in? Or should these holes in the outer sill just be blanked off?

Somerford Minis website has this to say regarding the retaining brackets, so thought I might replace mine:

"Slinging shoes were used to move bodies around the factory, prior to fitment of wheels and running gear. Each shoe fitted into a bracket under the floor, and was secured by a nut in the sill, into which a bolt on the shoe was threaded. The nut brackets also act as reinforcements between the outer and inner sills, so they should be retained or replaced if work is done in that area."

why would you want to fill them with expanding foam? Idve thought it would just hold the moisture in, and It wont be nice for whoever has to replace the sills next, as it is flammable, if you want to stop them rusting spray waxoil inside the sills.

closed cell foam doesn't absorb water

closed cell foam doesn't absorb water

Maybe not, but I'm sure that it would hinder it from escaping as effectively and therefore contribute to corrosion. Surely the best way to avoid rotting sills is regular maintenance? (i.e waxoyl them regularly, particularly the inside using a pressure sprayer & a box section extension probe, clean salt deposits off regularly through the winter and make sure that the drain holes are not blocked so that moisture can escape)

I know someone who filled the new sills on his Triumph 2000 with expanding foam. When it cured ane expanded it split the seams and the whole job had to be re-done whilst wearing breathing gear as cutting off the foam-filled sills gave off noxious fumes and vapour. In fact, the reason why foam filling was discontinued in early 1960 was because of this risk. I believe someone was injured or killed when repairing a sill using oxy-aceteline welding gear.

Thanks folks. Did wonder why they stopped doing if it was supposedly a rust preventative.

Any suggestions regarding the slinging shoe retaining nuts?

bin them, there not needed, ive cut mine off of my estate

Ok cheers. Did u then close off the holes for the bolts in the outer sill? Or leave them open?

welded them up, ground them down and painted them