Topic: how does water get into inner sills on convertible?

[2V8s]

Just wondering (sorry didnt know the best place for this thread), how and why my inner sills towards the rear seem to have suffered from corrosion where everything else is in good condition.

I am assuming, from looking at sheet metal parts, that the extra inner sill strengtheing on a convertible is a reverse C-section and open to the main closed sills found on all cars, or is it also closed it'self? Has anyone a photo or diagram of the cross section of a convertible sill arrangment?

I cant understand how water would get into this section to rust it out from the inside, whilst the outer sills, which im 99% sure have never been replaced, are all very solid, and so are the floors etc.

It seems to have affected the area just rear of the front seat belt anchor bolts and forward of the rear seats. will attach some photos shortly.

[T Lea]

First of all outer sills are galvanized inners are not. Verts are prone to leaking at the rear of the top at the back of the rear window. From there it travels down the back of the inner 1/4 and the area behind the back of the front seat. Thats why a lot of otherwise rust free verts have weak back floors and rockers

[2V8s]

Thanks, that explains it a bit - and I never knew any parts were gavanised (other than the 4 floor plate covers). were the sills the only structural places on the body that were galvanized?

[J_Speegle]

Thanks, that explains it a bit - and I never knew any parts were gavanised (other than the 4 floor plate covers). were the sills the only structural places on the body that were galvanized?

Nope  - thing most if not all of the "frame" (frame rails, trans, front and rear cross members)  was

[2V8s]

Thanks thats  very interesting - you learn something knew everyday!

Im still going to inject Dinitrol wax protection in all those areas though.

Here's some pics of the areas in question......