Hi,

I agree with our UK friend that they just pop on. Anything easy and fast for assembly line work is the mind set you have to remember.

For the most part I have only messed with those trim pieces in junkyards
As I remember the trim pieces have a tiny one spot area that has a notched opening along the length of the trim. It allows for the insertion of plastic clips that Derek speaks of.
You slide them down and space them apart from end to end above each hole in the body part.
Those pop in.

Now this is where it get tricky with the type clips, if they decided to use during production, or whatever a body shop used for replacement?
I suggest looking into the trunk along the side behind the spare tire to start with. You need to see what kind of protrusions from the clips are coming through.
If you have an door card off one of your doors you can peek in there also.
This is called acquiring INSIGHT.
(:-) It’s a big help when the other two are not working. Foresight and Hindsight.

Some clips are plain prongs that pop through to engage the hole there. Some will have a pin in the center and be sticking out slightly that spreads the tip.

As far as taking them off Never try to pull straight out with the rest of the trim being help up close by.
If you bend the trim you will never get it straight like the factory again. Junkyards say that all the time and they try to sell it by the foot, nice shape or not. Buy the whole fender and doors on sale is far better.
Those come with clips that should be cheap as popcorn in the first place.

If you have slack from a loose one then you can slip a thin blade behind and up to the next one and gently work the clip out or hope it breaks off. Sliding the trim “a little” is also possible being mindful of which way the tips go.

If you can access the back side of the body, door or fenders, you can thump them out.
Once you get some loose it all gets easier to slide the trim and hopefully spot the notch that lets you put the new clips into the trim.
Be careful with the tips of the trim while doing this.
They are plastic and are brittle.
I have had one trim piece slip sideways over the door seams.
It can catch the fender or other door from there.
You know when the trim is getting too loose or you duct tape along side the trim. (:)
I got one car where the PO put a screw through the plastic. Luckily it was in far corner and she had a new replacement in a box but never put it on. They were expensive she said and I don’t know if you can get them. That’s why I have four complete doors stashed away. Not the right color but hey!

Additional information.
On the very bottom of the car there’s a black narrow trim rail attaches to rocker panel.
These clips are installed on the body first.
The trim pops over the edges and up inside the trim along the whole length.
I have found out that their almost too narrow to get a good grip on the trim is why they come loose.
You only get one shot to press the trim back on.
You try to engage one side and bump the other over the clip. Using a wide plastic face firm faced hammer or a combination dead blow (leaded shot) hammer works really well.
A Rubber can work but the lead helps more directly with a less tapping technique.
A small piece of soft flat wood will work too.
If you are nimble enough with your fingers to push on and hold the trim in place while at the same time able to hit the trim properly.
(:) I didn’t have that much trim to put back on acquire that skill.
I use a dead blow or even “real” lead hammers to set parts in a vise before machining.
No OHSA in my house.

Additional information.
On the cars with the flat plastic trim, above that rocker, on the doors, I have resorted to using 3M VHB tape from a hardware store.
It comes wider and I trim the stuff more narrow so it’s a lot cheaper, square inch wise, that the Auo Parts stores.
I build up layers inside the void to make trim fit up out to the cars body. I think it’s two thicknesses or three in places. It’s a judgment call. (:)
It’s similar to what Volvo used but a lot stronger or better quality IMO.

Hope all these ideas helps you be like the “cable guy” and “Getter Done”.
(:-)

Phil