fitting new sills

[Deleted]

I'm after a bit of advice, family all packed away for a week and I'm about to replace the outer sill and spacer sills on my coupe. Are there Any pitfalls doing this do i need brace the door ways to prevent body twist?

Also a friend reckons that after the sills are on to fill them with expanding foam to prevent water ingress and stop the sill rusting. I never heard of anyone doing this and think it will work but am i missing something really obvious?

Any advice greatly appreciated.

[p5tgc]

Bracing the door aperture is strongly advised to avoid a banana shaped car!

Filling a box section with foam would work if the foam was closed cell, otherwise you would have a sponge in there, exactly the opposite to what you want. I think the P4 had a foam filled crossmember, this is known to absorb water and rot out.

[Phil Nottingham]

Use SEARCH set for 900 days - whatever way you use its essential you brace the shell, via the door frames and stand car level

Do one side at a time and remove the doors. Even the smallest sag, which may have already occured will leave uneven door gaps particularly at the front bottom and the doors will stick. Get it straight before removing the doors

Try the doors again before welding it all up fully as well - the outers are not structural. Do not forget there is a piece at the bottom of the B/C post that attchaces to the outside of the middle sill.

Take plenty of photo's especially of the ends as these are the givaways if fitted wrongly and the bottom sill strips will not fit properly either.

You may find you need other repairs eg jacking points D pots A post wing bottoms

Good luck

[Smallfry]

I can't see that you will not end up doing the inners as well. If the spacers are gone, then the inners will be well on their way too. Seems a bit pointless to me going that far and not doing it all properly.

Dont know about the foam. Seems a good idea............they use it to fill big mooring buoys............Will rust still burrow under it like it does with paint though ? If it does, then you can't spray in any product, or do any welding. On balance however, I think I would do it as long as ALL the metal it contacts is new. I used it many years ago on my old "stealth" Bedford HA van, to fill the rotten sills. Couple of coats of underseal and it lasted for another two years !

I don't know what the product is offhand, but its a two pack material that has to be quickly mixed together and poured in. The downside of any of these fillers is that the expansion is really powerful. In a sealed space it could easily deform your bodywork. Its important to start filling in the middle, and let the foam find the vented ends. Its also important not to use too much either.............it will end up looking like a scene from "Shampoo"

Don't use the stuff they sell in aerosol cans................its not long term waterproof, whereas the two pack stuff is OK for constant immersion. If you have ever used the aerosol stuff and think it sticks well, it can't hold a candle to two pack. You have extreme difficulty getting it off your hands, let alone anything rigid and porous. I still have some stuck to my drive that has been there twenty years.

[Phil Nottingham]

Early Minis had their sills foam filled to waterproof them - they gave stiffness as well but did not stop corrosion.

As to replacing the inners, localised repairs may be all thats needed if you are very lucky. The centres are very thin anyway and have loads of cutouts which the replacements do not. These may add strength.

Rover never recommended patch repairing the inner sills as did a lot of restorers, I have done both and it really depends on how bad they have gone which is needed.

[Warwick (Ozcoupe)]

smallfry said:

Dont know about the foam. Seems a good idea............they use it to fill big mooring buoys............Will rust still burrow under it like it does with paint though ? If it does, then you can't spray in any product, or do any welding. On balance however, I think I would do it as long as ALL the metal it contacts is new.
I don't know what the product is offhand, but its a two pack material that has to be quickly mixed together and poured in. The downside of any of these fillers is that the expansion is really powerful. In a sealed space it could easily deform your bodywork. Its important to start filling in the middle, and let the foam find the vented ends. Its also important not to use too much either.............
Don't use the stuff they sell in aerosol cans................its not long term waterproof, whereas the two pack stuff is OK for constant immersion. If you have ever used the aerosol stuff and think it sticks well, it can't hold a candle to two pack. You have extreme difficulty getting it off your hands, let alone anything rigid and porous. I still have some stuck to my drive that has been there twenty years.

Wise words indeed.
I'd be very very cautious. Once done it can't be undone. Not all 2-pack is closed cell either. We used 2-pack polyurethane foam pressure-injected into the space between the outer jacket and inner tube when fabricating cryogenic pipelines for liquid nitrogen and argon (also for CO2). If the outer jacket didn't have a perfect moisture seal the foam can become waterlogged.

So as Smallfry says......It will have to completely fill the cavity and stick completely to clean surfaces, with no voids at the surface. You need to be certain that it is a closed cell foam. You need to do it exactly right the first time as you don't get a second chance and you can't undo it. If you overdo it, it makes an extreme mess. If you under do it, you can't redo it to top it up.

Personally, having used it and seen it used in industrial applications for many years by people with experience (who still stuffed up occasionally), I'd steer clear of it.

Just one exception.....If you want to stiffen a rally car. A lightweight tube or box-section filled with foam is unbelieveably strong. Just look at how bones are structured.

[PatMcCoy]

When i had my car resprayed last year
I had the front scuttle repaired
The front scuttle had foam in it and the rear
I had it all ripped out,It was like a sponge