It occurred to me the other day that although there was a few previous threads giving some coverage to the subject, there was no 'one stop shop' for information on oversills.
Oversills, or 'cover sills' are a sadly regular bodywork phenomenon. I have in fact never owned a mini without them, most people fit them for the sake of 12 months MOT, some fit them in error and a few people fit them thinking the problem is water getting into the sills, whereas in fact the sills are vented for the purpose of moisture being able to exit the sill.
Oversills block the venting, thus moisture builds up and rots the structural parts of your car from the inside out. I bought a project car recently and it came with oversills. I'd already fitted proper narrow heritage sills onto a different Mini so i used this opportunity to demonstrate to other mini owners what the difference is. (For those not super clued up on minis, this is a bodyshell on its side.)
Not a lot of difference to the untrained eye. Just as a comparison, here are the before shots. The car was fitted with oversills, the original sills were just handfuls of rust sliding about inside the sills and crossmember.
As a result of what was probably a two hour quick repair bodge job, ive had to replace a full length inner sill, the entire doorstep, rear bin strengthener, a section of the rear heelboard, the flitch panel, reinstate the jacking point and finally put the correct outer sill back on.
I just wanted to put this pictorial together to educate people out there as buyers and budding bodyworkers because oversills either mean the car has, or will have, hidden horrors. A quick repair it may be but down the line it will significantly damage the structure of a car, as well as its value, especially when you have to sell it needing all the welding ive just had to carry out.
I hope this helps at least one person in future anyway, if it stops at least one car from the peril of sill bodges then i've succeeded. Feel free to share it out and ask any questions if you should so desire.