When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Question about plastic trim along top of door panels
I am in the process of restoring the interior of my 91 Z28 vert to showroom new and have come up with a question.
With the black plastic top piece of the door panels, is it supposed to bend or is that some type of heat warp.
I have noticed almost everyone's is tearing out of the cardboard of the door panel and becoming loose at the rear of the piece. That lead to me assume they are supposed to be flat and are becoming heat warped.
BUT, just now I was over in the appearance and detailing forum and saw this picture of a members beautiful car with what appears to be an immaculate interior and his is bent too.
Re: Question about plastic trim along top of door panels
They are supposed to be straight, most of the ones I pulled were straight because the cars up here don't see as much sun or heat.
You can straighten it with clamps and a heat gun.
Re: Question about plastic trim along top of door panels
I would guess that they bend over time when they weren't attached to type door panel.
Maybe they start to warp as soon as they pull them from the mold and they bend them back straight when they mount them?
Clearly they are supposed to be straight as the piece they are mounted to is straight.
Re: Question about plastic trim along top of door panels
always remember make sure all of the holding clips/tongues are in the slots in the doors upper rim. this holds the door panel in place, if they are installed on top of the slots it hold them up..out of place.
Re: Question about plastic trim along top of door panels
I've never seen a pair that was "straight"; I've installed dozens of pairs into cars over the years and have maybe 7 pairs of them around here tight now and they all have a curve to them.
Re: Question about plastic trim along top of door panels
Can't really tell on the drivers side - but your pass side clearly has bend in it...... it sits much higher in the back than it does in the front.
Put a straight-edge (that extends past the trim at each end) on the top - and then again on the side - of those upper trims panels then take the some more pics and post them up.
Last edited by John in RI; 01-12-2014 at 05:59 PM.
Reason: spelling
Re: Question about plastic trim along top of door panels
I have never noticed a bend in mine however, both cracked near the dash..leads me to believe there is stress somewhere on this trim piece that causes it to bend/crack..just my thoughts.
Re: Question about plastic trim along top of door panels
The crack near the front is caused by improper panel removal. Mine were both cracked when I bought my car with 6k miles on it. I replaced them both with brand new GM and they had a slight curve to them. Look at the pic below and you'll see that the rear of the door is higher than the front of the door when using a level reference point.
Re: Question about plastic trim along top of door panels
Ok, so that shows they would be tapered, but still straight.
The holes along the top of the door card are in a straight line. The lines on the upholstery are straight. It's very possible that every one of the top caps is slightly bent but they are obviously supposed to be straight to line up with the holes when installed.
Either the part is very low quality and warps as soon as it pops out of the mold or warps over time. They were able to assemble them straight enough (maybe by forcing the bend into place when installed on the STRAIGHT card) for gm standards.
They were either straight originally or were forced straight by the card. Then the battle between card and top cap raged for 30 years, sometimes the card held it straight, sometimes the cap stretched the holes or the mounting pins broke.
Remember what we are dealing with here, I love the 80s style of the firebird cockpit, but the materials and assembly of third gen interiors is a disgrace, absolute junk. It's this era of gm that gave them such a poor rep for quality.
Re: Question about plastic trim along top of door panels
Not sure if you understand the fact that the plastic can't warp lengthwise when it has multiple angles and contours built into it. The only warping that can happen to these pieces is a twist. The fact that there are vertical sides to these top pieces are what restrict the lengthwise movement. You can think of this like a shelf on a bookcase. A shelf by itself can warp or sag with weight, but once a front decorative trim is added to the shelf, it prevents the warping.
I went to camarosource.ca and looked at brochures of the cars starting in 1983 and every picture of the door showed a slight curve in the top piece. These pictures were taken when the cars were new, so that disproves heat or age as a possible reason for the "warpage". This was the design in the 80's.
Also, the door panel card does not have a row of perfectly straight circular holes. It does have a row of oval holes to allow for movement. I tightened each of the speed nuts as tight as I could without breaking the stud and then ran a long run of duct tape over the door panel and top plastic to keep it tight and restrict any movement.
Re: Question about plastic trim along top of door panels
I Checked Mine And Get The Same Reading mantaguy, About A 1/2" Taper From Front To Rear,Maybe That Gives The Illusion Of Them Being Bent/Curved In Some Pics.
Re: Question about plastic trim along top of door panels
ok, checked some parts out in the garage .
first an old door card:
theres a crease in it from the bottom edge of the plastic trim cap. it does slant upward as you go back in a STRAIGHT line. in might be hard in the pics, but you can see where the middle bowing downwards (over time?) pushed down the fabric. the holes on this card are pretty beat, but IIRC the holes are ovalled side to side, not up down.
Re: Question about plastic trim along top of door panels
and some door trim caps:
left 2 are a LH RH pair, two rh on the right
you can see they are banana shaped.
they can easily warp into this position, or flex back into this position if that is how they came out originally. they have no reinforcement ribs except the bottom edge. you can see me easily flex it with 2 fingers. as i press one place in the center, it goes straight and all mounts line up straight.
Ill stick by my original statement, they either all came out of the mold bent and they straightened them to the card as they installed, or they all warp over time, pulling themselves out of the card.
I'm pretty sure the pair i have pictured was straighter when i pulled them, even the weatherstrips in good shape, but did they warp since or return to original shape when freed from the card?
I'm going to try a heat gun on one tomorrow and see if i can straighten it without the card.
Re: Question about plastic trim along top of door panels
I have no pics because I checked with a laser on a black panel and it was hard to see let alone get a pic of. These pieces are far from straight. They belly down in the center and are up almost 3/16 on the ends. Manta, if you look where you measured the front of the trim, it bulges up on top of the trim over 1/4", making that measurement off. There is an optical illusion going on, but it has a bow to it no doubt.
Re: Question about plastic trim along top of door panels
Yup, yours are bananaed just like everyone else's, but it isn't SUPPOSED TO BE LIKE THAT.
If you hold the center tightly and push down on the foward lower corner of the trim cap, you'll see it twist back into place. The edge will be tighter to the card and the little rise at the front will level out with the weatherstrip.
Here's a pic someone just posted of their newly redone door panels https://www.thirdgen.org/forums/atta...52161_n-1-.jpg
You can see how nice the upholstery is, but they did not straighten the cap when they installed it on the card. It clearly looks wrong. You can see how the front and back ends curls up when they should be straight. See how the inner and outer weatherstrip are parallel except at the ends?
Re: Question about plastic trim along top of door panels
You say they aren't supposed to be like that, yet they are all like that, even when new. Here is a brochure pic of a 1989 Camaro. You can see the curvature of the trim piece when new. The curve did not happen due to age.
Re: Question about plastic trim along top of door panels
I might see the slightest curve in those panels, but we can't see the ends to be sure. The definitely do SLANT.
In post #14 above, those look pretty straight, no curling at the ends, weather strips are level , top flat edge is flat. It may have the slightest curve to the bottom edge.
I don't believe this slight curve (if not an optical illusion) is intentional. I think it is more evidence they all came out of the mold curling and twisting, then were tacked down straight as they could.
Curved just doesn't make any sense. All the other lines involved , door panel, door panel inserts, top edge of door, holes in card, weatherstrip are all straight. The whole theme of the interior is square and angular. It's easier to make straight molds than curved ones. The curve is just a materials error that needs to be corrected.
Scott- you have to admit that the pic you showed the cap is straighter than most others pictured, so doesn't it make sense that it's a flaw that appears in time?
I think you may be right they didn't curl over time. I think the door card looses its ability to hold it straight over time.
I guess this is as far as I can go with the argument until I can reassemble my door panels and show you how it should look.
The only other thing I can say is if anyone has a bare door and a bare top cap handy , pop it on the door (without card). I'm sure that without the card to pull it into place, I will look like a canoe sitting on a table. I might be able to try that today if I can get to my doors.
Re: Question about plastic trim along top of door panels
ok, had some time to look at this some more. Im interested in these issues as I've started making fiberglass interior parts to replace these horrible plastic parts in our cars. I might try and make some of these trim parts, but they will be a challenge.
I was right and wrong on some things.
difficult to get pics that illustrates this but ill try.
First, yes, they are supposed to be straight by design, however also yes, they are all warped from the factory.
I removed the window felts, which are straight BTW, and experimented with clamping it to a jig and heating with a heatgun to get it to go straight. This has worked well for me before in straightening similar warped plastic parts such as the door sills.
In this case, I couldn't get the plastic to reform straight, just kept going back to bent shape as soon as released from the jig. this tells me it took that shape during the manufacturing process, not warping with age or sun.
If you examine the back side of the cap, you can see the tabs that attach the cap to the window channel were added after the main part was molded. You can see where these tabs were attached by either some sort of hot welding process or molded in a second stage to the first. This is what caused the warping. They pulled it from the female side of the mold before the plastic had stabilized, hence they all warped.
They were mostly straightened out when attached firmly to the flat, straight door card. it takes quite a bit force to straighten it, so they immediately started pulling on the card to resume their warped shape. this is why some new ones look straight, some show some curving, and finally completely banana when the card totally lets go.
i was incorrect about one aspect of the shape, there is supposed to be a curved "ramp" on the top edge of the cap where it mates to the dash. it is supposed to be dead straight after that to the trailing edge.the bottom edge of the cap along the card is also supposed to be straight, not curved.
If you get one of these in your hands and straighten it, this all becomes very clear. you can even see that the warps match up with the hot weld? spots on the underside. if you leave it in its natural state and look a from different angles you can clearly see they would not have made the mold in that shape. besides the fact that curves wouldn't fit on straight lines, you can see the shape would have been unnecessarily complex for a mold.
I think i will try and make some fiberglass replacements at some point, but this part will be a challenge to mold so won't be soon.
the important points to take from this are:
1)don't bother buying new caps to replace banana ones, they are all like that new
2)when restoring door panels its important to make sure the mounting holes at top are not distorted and the cap is firmly secured by them in its designed strait position.
prob best to replace the card with something more durable that will do a better job holding the cap straight.
Last edited by stealtht/a; 04-01-2014 at 08:08 AM.
Re: Question about plastic trim along top of door panels
huh... I've had 3 3rd gen birds ('83 Ta, '87 Formula, '87 TA) and all of mine are straight (well, not exactly, the front end has a different shape to it to sort of meet up to the dash pad, but there is no bow in the middle), and I don't think that it's the door card pulling them straight, on any of them- I'm currently fixing the broken front pieces on my '87 TA (PO broke both of them, the other 2 weren't even broken, even though I've pulled the door panels on the '83 dozens of times), and there is room to wiggle the studs around in the door card the length of the piece suggesting that they're in the same row as the holes in the card, and the holes are not egged or anything. None of my 'birds have had the door card pull free either, there is no tension on any of them.
To be quite honest, I haven't seen this on any of the 3rd gens that I've dealt with, but I haven't looked (but I'm also pretty **** retentive so I'd expect I would have noticed if it was the case). I'm wondering if they came from multiple plants and only one of them was bad or that all the replacements are warped. OTOH, I don't know that I believe that you couldn't bend it back with heat suggests that they were made that way, since that could just be a result of them sagging and changing basic shape. They're ABS plastic (I chemically welded the front of my broken pieces and heat welded the back, then added an fiberglass reinforcement from the back using ABS resin), so you should be able to do at least a minor reshape with heat...
Re: Question about plastic trim along top of door panels
Originally Posted by 83 Crossfire TA
huh... I've had 3 3rd gen birds ('83 Ta, '87 Formula, '87 TA) and all of mine are straight (well, not exactly, the front end has a different shape to it to sort of meet up to the dash pad, but there is no bow in the middle), and I don't think that it's the door card pulling them straight, on any of them- I'm currently fixing the broken front pieces on my '87 TA (PO broke both of them, the other 2 weren't even broken, even though I've pulled the door panels on the '83 dozens of times), and there is room to wiggle the studs around in the door card the length of the piece suggesting that they're in the same row as the holes in the card, and the holes are not egged or anything. None of my 'birds have had the door card pull free either, there is no tension on any of them.
To be quite honest, I haven't seen this on any of the 3rd gens that I've dealt with, but I haven't looked (but I'm also pretty **** retentive so I'd expect I would have noticed if it was the case). I'm wondering if they came from multiple plants and only one of them was bad or that all the replacements are warped. OTOH, I don't know that I believe that you couldn't bend it back with heat suggests that they were made that way, since that could just be a result of them sagging and changing basic shape. They're ABS plastic (I chemically welded the front of my broken pieces and heat welded the back, then added an fiberglass reinforcement from the back using ABS resin), so you should be able to do at least a minor reshape with heat...
Yes, before someone brought this up I hadn't realized how bent the ones I had were, yours might be bent to if you see them off the door card. I think the broken parts are also an indication of the warpage being pulled out by the door card. It would normally take a really good blow to break that abs plastic, but being held in a stressed position makes it prone to cracking.
It's very possible the molding problem was corrected at some point or that only some were pulled from the mold too early, so there may be some straight ones out there, but on the sample we polled in this thread I can only see one where it could possibly be completely straight.
Last edited by stealtht/a; 04-01-2014 at 08:11 AM.
Re: Question about plastic trim along top of door panels
Well, I was going to post a picture but I'm finding it next to impossible to do from the phone and don't feel like going through the get it to something else, re-size, post.... process, so you'll have to imagine but I checked all 4 of them on my '87's, and found that the one that I have taken apart is perfectly straight (had a pic of it with all the fasteners on the back taken off and the studs are sticking through the middle of the holes in the door panel without any pulling...), and all the others, with the exception of one of the passenger side ones are perfectly straight too. The one passenger side one is just curved up at the back edge (honestly, you'd never notice if you weren't looking, with the door closed it's behind the passenger and the driver's view is blocked with the passenger seat), and from the looks of it, and the fact that all the pictures are slightly different I'm next to positive that it's from heat, not how it was manufactured.
I would bet that if you got it warm enough while pulling it a little past straight would bend it back once it cooled, and I doubt from what I'm seeing just clamping it straight and heating it would get all the bend out.
Re: Question about plastic trim along top of door panels
Well, you do agree at least they should be straight. Some here posted that they received NOS in the box that were bent so I still think at least some were warped in manufacturing.
I don't think you can be sure yours are straight until you get it completely off the door card. I thought mine were straight too.
I did more to try and straighten mine than the picture shows. I have straightened many warped plastic parts, couldn't get these to change shape at all. I had them hot enough to pop and creak, no change. I'm still pretty convinced these were warped out of the mold.
If you can get pics up I would still be interested in seeing them. Maybe there is a year where they figured out the molding problem. Then we would know to get caps from certain year cars.
Thanks for helping on figuring this out!
Re: Question about plastic trim along top of door panels
I just finished putting new window lift motor in. My question concerns the top plastic piece that attaches to the cardboard. You know it, it needs to be tighten up. Is using duct tape along the row of speed nuts the best thought? Anyone try contact cement? Any help would be great. Thanks!
Re: Question about plastic trim along top of door panels
Originally Posted by pfsteichen
I just finished putting new window lift motor in. My question concerns the top plastic piece that attaches to the cardboard. You know it, it needs to be tighten up. Is using duct tape along the row of speed nuts the best thought? Anyone try contact cement? Any help would be great. Thanks!
I used a very thin piece of roofing tin the length of the panel. Remove the speed nuts. Now mark the position of the studs coming through the cardboard on the tin. Then drill holes in the tin for those locations. On the back side of the tin use all purpose glue. Then place the sticky side down positioned over the studs on the panel. I then put a thin washer over each hole, then put the speed nuts on by screwing them down as far as you can without breaking the plastic studs. Once tight take duct tape and place over the strip to keep the speed nuts from unscrewing. This provides excellent support for the trim and cardboard material. I have done this way and very strong and very cheap. Hope that helps
Re: Question about plastic trim along top of door panels
So I was working on getting those speed nuts off. I can turn a few of the lose ones but they don't come up even with a little upward pressure applied with a small pry tool. Also I'll need to purchase a black plastic rail due to a previous owner butcher the old one. Any help greatly appreciated.
Re: Question about plastic trim along top of door panels
Originally Posted by 86FyrBrd
I am in the process of restoring the interior of my 91 Z28 vert to showroom new and have come up with a question.
With the black plastic top piece of the door panels, is it supposed to bend or is that some type of heat warp.
I have noticed almost everyone's is tearing out of the cardboard of the door panel and becoming loose at the rear of the piece. That lead to me assume they are supposed to be flat and are becoming heat warped.
BUT, just now I was over in the appearance and detailing forum and saw this picture of a members beautiful car with what appears to be an immaculate interior and his is bent too.
Straight or bent, what is correct?
I was wondering what to do about my tearing out of the cardboard. My card on one panel is in pretty rough shape. I'm very tempted to try to remove the fabric and cut a new card piece out of OSB board and re use the fabric, and buy new black plastic to piece. Thoughts?
Re: Question about plastic trim along top of door panels
Originally Posted by pfsteichen
I just finished putting new window lift motor in. My question concerns the top plastic piece that attaches to the cardboard. You know it, it needs to be tighten up. Is using duct tape along the row of speed nuts the best thought? Anyone try contact cement? Any help would be great. Thanks!
I actually don't like the idea of typical duct tape because of what happens to it over time, especially extremes of heat or cold.
Originally Posted by pfsteichen
I was wondering what to do about my tearing out of the cardboard. My card on one panel is in pretty rough shape. I'm very tempted to try to remove the fabric and cut a new card piece out of OSB board and re use the fabric, and buy new black plastic to piece. Thoughts?
As far as practicability goes, I've had door panels that were completely unattached from the upper rail, and it didn't make a bit of difference once it was installed. IIRC/IMO, it was done to make assembly easier/faster. That said, if I bought the new replacements, I might consider reinforcing it somehow.
As far as practicability goes, I've had door panels that were completely unattached from the upper rail, and it didn't make a bit of difference once it was installed. IIRC/IMO, it was done to make assembly easier/faster. That said, if I bought the new replacements, I might consider reinforcing it somehow.
Agreed, they really don't support themselves, but they kind of do. If I hadnt completed mine, I would get the board material. I looked for it all around but the cost was not enough to justify not buying a new set. Doing what were doing with temp fixing should last a few years at least if you have all your seals etc. Use new fasteners, seal and it should be good. Sure does beat 300 for a "good" set.
01-11-2014, 08:38 AM
and these are new replacements
