Sills; has anyone built their own?

[TomMull]

I've been considering building my own sills for several reasons. These, as far as I know, are not available here in the US. Shipping has gotten very pricey and I've not even been able to get a quote from a British supplier.

What is left in the car is mostly rust and I made this sketch from what I could glean from the rust pile. Comments and corrections are welcome.

I'm also guessing that the material is 18ga. Perhaps someone can correct that assumption too.

I'm also leaning toward cold rolled steel sheet metal. I've investigated stainless but so far prohibitively expensive. I could I suppose use a tube section similar to Spydercar's but perhaps safer to stay with the box.

Galvanizing is available in my area but I wonder if some of the new coatings would do as well.

Cheers,

Tom

[Bud English]

I had a pair made up by a local sheet metal shop back when I lived in CA. They did a really nice job of forming and spot welding them at a reasonable price. That some time back and IIRC both came in at under $100.00.

I gave him the best one of the pair that I took off and had him make two new ones in 16 GA, one a mirror image of the other. I had him leave them un-drilled. I added the jacking points, clamped them in place and marked the seat belt mounting points and the holes across the bottom. I drilled the holes, added the captive nuts for the seat belt mounting plates. I didn't make any drawings for mine but if you have enough left of your sills to make that drawing, I think you'll do fine.

[TomMull]

Thanks, Bud. More than a little guess work in the sketch but not all that complicated so I think I can make it work and hopefully make it right.
What did you do about finish and rustproofing?
The plan is to mark the flat side for drilling before I spot weld the box section onto it.
Also appreciate the 16 gauge material. Better to be too heavy than too light (Sorry Colin, I'll go without pudding for a few days to compensate).
Tom

[mbell]

I haven't built one but the rear wheel arch liner decided to fall off my car a couple of weeks ago. So will try take some measurements in the near future. Mine appear to be galvanized replacement ones.

[Bud English]

I just degreased them well and painted them with the Rustoleum Red Oxide metal primer that they sell at the local farm supply for painting tractors and implements. The sills don't show so I brush painted the outside surfaces then hung them vertically and poured the primer down through the folded channel. I just caught it in a container and poured it back through until it was totally coated on the inside as well. I let them drain and wiped the drips off at the bottom end before they totally dried. Hi-tech method and not nearly as messy as it sounds. Probably not as bad as trying to spray the inside.

Some of holes for the seat belt plates went through the weld flanges of the box section. It would probably depend how wide you make the flanges.

My original sills were 16 GA. They weren't totally rusted out except at the jacking points.

[alan.barker]

My first choice would be stainless even if expensive, do once and do it right.
Or minimum is galvanised.
You don't want to do a second time and if you sell the car it is a +point
Alan

[mbell]

Attached image of my measurements. Taken via access from the rear wheel well which gets in the way but the seem to be nice round numbers so probably right.

They are a bit smaller than your measurements. I think my sill members might be a different design as the upper bolts mount into the top flange but I think they fit in side the box section on you diagram.

[JJ66]

Hi There, I agree with Alan, Stainless if you can, but use 316 grade Stainless Steel, not 304 grade. 304 is cheaper but it doesn't have the chromium content and rusts - Any stainless steel that is slightly magnetic will rust. If you use mild steel then Galvanising (Galvanizing with a Z for you ) will be the best option down from SS. If you get them made in SS then it is easy to spot weld SS and if you want to add jacking tubes yourself then it is easy to weld if you have a MiG wleder, you just need a roll of 316 wire and gas with 20% argon. Hope it goes well, Jonathan

[TomMull]

Attached image of my measurements. Taken via access from the rear wheel well which gets in the way but the seem to be nice round numbers so probably right.

They are a bit smaller than your measurements. I think my sill members might be a different design as the upper bolts mount into the top flange but I think they fit in side the box section on you diagram.

Thanks, exactly why I posted my sketch. I had the box section too tall and since the inner plates are intact, I couldn't get the holes to line up outside. I see that the remnants of mine are on top like yours. I would probably have discovered the error when I tried to fit a short mock up section to one end but it is far better to know this in advance.
Many thanks,
Tom

[Bud English]

Tom, also note that the bottom edge of the rails aren't straight across. At least mine weren't. There is a slight curve, downwards and back up. Check the bottom of the body between the wheel arches with a straightedge.

[TomMull]

Tom, also note that the bottom edge of the rails aren't straight across. At least mine weren't. There is a slight curve, downwards and back up. Check the bottom of the body between the wheel arches with a straightedge.

Yes, I noticed the same on mine. I thought that was from having essentially no sill reinforcements for many years and had planned to try and straighten it. Perhaps a bad idea?

Tom

[Bud English]

I hope someone else chimes in here so you're not relying on a sample size of one, but the vertical portion of my original sills were totally intact when removed. The top edge was straight and the bottom edge was cut in a shallow arc. The car was eight years old at that point in time. It's not sag. It's design.

[mbell]

My car has an arc.

[Greg Foster]

If you go with mild steel, do all of your welding on non galvanized steel first and then send the sill members out to have them hot dipped. Any good welding shop will have someone who would dip them as it will coat the welds also.
best
Greg