25 touring rear tack strip: straight or curved?

[NY John T]

Hi all,
I'm doing a new interior and top for my 25 Touring. On the back panel, there is a break in the center of the panel (see photo)

I have since welded the crack but I'm not sure if the back panel should be completely flat where the tack strip goes, or should it have a slight curve. I feel that the back panel of these cars is not exactly flat, thereby requiring the tack strip to curve as well. I'm using the white trim material, plastic?, from the big box store, and will be heating it and curving some pieces.
So, should the tack strip be perfectly straight on this panel or curved? I can make it either way.
Thanks for your suggestions. I've looked at many photos, but can't make a final decision.
John

[DanTreace]

The wood tack strip should be straight. The back panel on the touring is mostly straight on top, then has gentle slope inward to the lower wood member.

IMG_2983 copy.jpeg (33.55 KiB) Viewed 2348 times

I've used the plastic strip and works good. A heat gun bends it just fine, use clamps and mount stove bolts as you go.

These photos are a '24 runabout, likely slight difference from the touring rear seat panel.

Final note: The original wood strip is shaped like this drawing, that gives a relief for the seat upholstery, when you later add the top rear curtain over the upholstery, keeps the trim all in line with the bodywork. Have found the plastic is narrow enough to provide that shape and keep the look right.

[big2bird]

Dan,
Could you post a link to that material?

[DanTreace]

Dan,
Could you post a link to that material?

Lang’s has that plastic strip. Works well.

[Jerry VanOoteghem]

I have heard it said that '25 Touring bodies had a very slight arch across the back panel. All I can say, is that my '25 Touring has that slight arch.

[NY John T]

Hi Jerry,
After a lot of searching of pictures of 23, 24, and 25 touring cars, and studying mine, I was convinced that there should be a curved rear panel. The cars that show a completely flat rear don't look as nice to me. Mine is clearly slightly curved.

Thanks for your confirming my suspicions. A curve belongs there. Here's the line for my rear. You can clearly see a slight bend. I'm so glad I got that issue resolved.
Thanks all,
John

[Allan]

John, the crack in your rear panel is the result of flexing and the deterioration of the wooden tack strip. Using a maleable plastic strip will be easy, but it will not support the panel like a timber strip will. Cutting a timber lath and shaping it to fit requires some effort, But I feel it is worthwhile. On my Canadian built 1915 tourer there was a corresponding strip on the inside of the panel too. If you can fit the same you will have the best job.

Allan from down under.

[Jerry VanOoteghem]

Hi Jerry,
After a lot of searching of pictures of 23, 24, and 25 touring cars, and studying mine, I was convinced that there should be a curved rear panel. The cars that show a completely flat rear don't look as nice to me. Mine is clearly slightly curved. curve back tack strip.jpgThanks for your confirming my suspicions. A curve belongs there. Here's the line for my rear. You can clearly see a slight bend. I'm so glad I got that issue resolved.
Thanks all,
John

John,

That appears to be the same curvature that my '25 has. As Allan suggests, a wood tack strip here will be best for proper support of the rear panel.

EDIT: I deleted my comment about not needing to steam bend the wood. I was thinking only about the slight curved section and forgot about the curves at each corner of the body.

[NY John T]

Thanks guys. I have a piece of white trim board from the big box stores or from a lumber yard. It was leftover scrap. The welding job I did seems to hold the back stiffly. I think shaping the plastic might be enough. The oak suggestion is great, but oak is such a hard wood; I wonder if something like ash or hickory might be easier. I'll have to look into it.
John

[John kuehn]

I used the plastic material as Dan showed on the back and side panels of my 21 Touring. It worked well and formed as you need to with a heat gun. Pretty good improvement if you ask me. Maybe not so much for a purist. I don’t know if a show car for judging guide lines would make any difference. My 21 Touring has a straight across back. If I would have tweaked here and there it could have had a very slight curve. The curve may have been the way some cars were assembled by the body builders and maybe not all bodies were exactly alike. Ford wasn’t building a precise body every time as shown by examples of the Model T’s over the years. MHO of course.

[DanTreace]

While ash or maple or oak wood tack strip is strong, it is hard to form, have to use steam to get the curve shape, tried that on my '26 and took a long time to get the wood pieces in place. Same with the '24 runabout.

So in my last body trims, have used the black plastic, IMO, much better than wood, is very strong, holds tacks super well, and can never split or rot. Superior in my hands.

(Left) New oak straight piece I made using neighbors router, shaped to original, Black plastic strips (Center) , new oak curved vendor wood strip (Right, original rotted Ford wood strip (on body)

Difficult in using the new straight home made, as the body isn't straight, you need curved wood, tried the curved vendor wood, but in my lack of skills fitting that pre-curved piece to the body didn't work well. The wood curves wouldn't meet with the body curves, as the body side sweeps up and then curves as it sweeps, really impossible without wet steamed wood and then clamping to try to fit.

Ended up with black plastic, sure easy with a hot air gun, no shaving, sawing, steaming, or fretting involved.


Fitting the plastic tack strip.

[Allan]

John, I was not aware that you had to go around the corners of the body as well as across the back. The maleable plastic does make the corners easy, but i would still use timber for the straight/slightly curved centre section. The panel is already weakened at that point by the bolt securing the centre upright for the seat. That centre upright also means any load exerted by back seat passengers is concentrated at that point.

Allan from down under.

[OlGeezer]

I’ve worked on a few interiors, and I’d say the tack strip should definitely have a slight curve. The back panel often isn’t perfectly flat, so a little curve will help it fit better and look more natural. It’ll also help the trim material sit nicely without any bulges.

[NY John T]

So what I plan to do is to weld an additional piece of metal under the lip of the back panel. I already welded the crack and feel pretty secure that it is strong by itself. But additional metal support is always more insurance. I will still use the white plastic board from big box store. When this section is done I will post pictures.
Thanks again,
John

[RVA23T]

Take into consideration that the expansion and contraction of your chosen substrate might be significant enough to cause you issues down the road.
If you "white plastic" is a PVC item it moves much more than a solid HDPE or UHMW type strip the vendors sell. Even covered, they all will experience heating and cooling cycles. Fasteners could work lose.

[Allan]

Good solution John. i was going to suggest an additional piece of wood under that lip. Your fix is better. No extra holes to be drilled to fix it in place.
I had done the extra wood trick behind the back panel on the front seat of an Australian bodied T tourer damaged in an accident.

Allan from down under