Door Sill Plate Installation

Home Page Forums Body Door Sill Plate Installation

Viewing 13 posts - 1 through 13 (of 13 total)
  • Author
  • #391774

    I just received my reproduction door sill plates for my 1928 Series 81 7 passenger sedan from Don Kuehn. They are excellent quality and look amazing. Now, I need to know how to install them since my vehicle didn’t have any sill plates when I purchased it. The new sills do not have any holes in them for mounting. My first question is: what type of fastener was used originally (screw or nail)? Secondly, where do the holes for mounting belong? Photos are very much appreciated. Thanks…



    I will send you photos later, but they are screwed in and if you cannot get oval-headed nickel screws, then get oval-headed stainless steel screws.

    Stainless, when polished is near identical to polished nickel.

    I will send you photos and sizes for the screws.

    I may even have a box of the little suckers kicking around the shop.



    Thanks Peter,

    Any information that I can get will help me to become a little bit more knowledgeable. Were the original screws a flat head or Phillips design?




    The screws are OVAL-headed, slot screws.

    Photos of the sill plate and screw info to follow later today.



    Too early for Phillips screws.


    Philips screws were developed/invented to speed the construction process for the war effort during World War II. If you see a Philips screw on anything prior to that time, it is not accurate. Nowadays, they change the heads periodically to (supposedly) improve the grip for power installation. In reality, it is so mechanics and construction folks have to go out and buy new tools and bits…


    Bob is correct and I learned from other PAS members at last years meet that Phillips head screws on my car were by definition not correct since they did not exist yet! It was interesting to find out that GM was one of the first customers for Phillips head screws on the assembly line for the 1936 Cadillacs. (



    I do hate smart people . Robert is right, it was invented earlier, but not widely used until the war. Good catch, doc!


    Henry Phillips developed the Phillips head screw in the early 1930s.


    Hi Phil, are there any witness holes in the wood sill plates in your car? I don’t remember that your car has new wood in it?

    I have some old sill plates somewhere around here, I’l try to find a few and take some photos for you.

    I believe that the oval headed, nickel plated brass screws were spaced roughly every 4-6″ down the center of the flat section of the aluminum sill plate. Avoid the nice engraved logo in the center of the plate.

    Greg Long



    The PAMCC apparently did not have concern for maintaining the integrity of the stamped logo on the sill plate, as my Series 80 (with original sill plates) has two rows of screws, each of which encroach on the logo.

    There are six screws across the top row and five across the bottom row.

    This number arrangement (6/5) is consistent for both the front and rear door sill plates.

    The logo is of such a grand scale that you cannot install the plate without encroaching on the logo.

    You may be able to strategically place the screws, but then they will likely not be evenly spaced.

    It is surprising to me that such a detail was not considered by the PAMCC.



    Hi Greg, You are correct, the original wood sills did have witness holes in them. Also, the new door sills from Don did come with the holes already drilled and countersunk. I just didn’t remember seeing these when I first looked at the pieces. It looks like the holes in the new door sill align with the holes in the wood sills so installation should be pretty easy. I will try to polish up some stainless steel screws this weekend and get the new sills installed.

    Thanks everyone for your input and help with this project….


    With the holes in your new sill plates aligning with the old holes in your wood sill, Pierce must have had s jig that they used to place and drill the holes. I guess it would make the job of installing the sill plates at the factory much faster, and very consistent.

    Greg Long

Viewing 13 posts - 1 through 13 (of 13 total)
  • You must be logged in to reply to this topic.