70 windshield wiper door assembly

[Warren L.]

Thanks for your thoughts on cleaning threads in the windshield wiper door.

Would like to know about the finish on the windshield iper door assembly. From what I can see this has been painted flat black, either it came that way or when the car was repainted they got paint on it then blacked out the overspray.

Is it painted flat black at the factory and if so is it painted before it is aseembled so the white nylon washers get paint on them. This one has the black paint chipped off on half the white nylon washers and there is a fine amount of rust showing up around some of them. I was going to put it back maybe it should be sandblasted and painted first?

I noticed on the windshield wiper door underside that there are two areas that are threaded and in the GM parts book they show a bumper and screw that fasten to them, this is not on either of the doors I have, should there be a bumper on these two threaded areas?

Do most people find the height of the grill in front of the windshield wiper door sits flush with the profile windshield wiper door? or is normal for this part to sit low?

Thanks,

Warren

[Chuck S.]

Re: 70 windshield wiper door assembly

Warren, my first thought about your question on wiper door underside being painted was that they wouldn't even prime it, leaving it bare aluminum since it isn't visible. However, after checking my wiper door to confirm my thoughts, I found that it was painted with a very light coat of flat black paint BEFORE the top side was painted body color.

I am as surprised as you, and it's definitely original...the flat black is uniform in areas that would be under the molding clips, and trust me, these clips would almost certainly not be removed by any painter. I would not epoxy prime the underside if it were me; that will tend to fill and level the aluminum texture, giving you additional gloss on the underside finish. Just use flat black right on the aluminum just like the factory did it, if you want authenticity.

As for the bumpers, my late 70 didn't have them, and the AIM doesn't show them either (UPC 1, Sheet D5), but the un-tapped holes are there. If the AIM didn't show them as an assembly item, then the bumpers would needed to have been supplied already assembled to the door. It is possible the bumpers were used in 68, 69, maybe even earlier in 70, then discarded as un-necessary in an engineering change.

[Warren L.]

70 windshield wiper door assembly

Thanks Chuck for your response, I hadn't thought about the underside of the door itself. I can put on a light coat of epoxy and it won't change anything, just spray on the dry side, it you spray wet on wet and not sand the epoxy it will not change the texture. Will black it out as you have said your original door is.

Was asking specifically about the assembly itself, you know the assembly that fits under the windshield wiper door and raises and lowers it. I either put it back on as it is which would be fine but I know they do rust so it makes more sense, I noticed it is painted flat black, that is over all the nylon washers, some of the paint has fallen off the washers. I can blast and prime light and paint this flat if that is the case, I can't tell if it came painted flat black or if someone else blacked it out after painting the car as it was repainted one time in it's life to a different colour.

Warren

[Chuck S.]

Re: 70 windshield wiper door assembly

Warren, the linkage I am not sure about...I have seen many with the black paint flaking off the white nylon washers. Although I want to believe they painted the mechanism parts, then put it together, the evidence doesn't support that. It is possible that what we see flaking off is "black out" paint that may have been applied AFTER the linkage was installed in the wiper plenum.

BTW, what I meant on the epoxy primer is that whenever you apply more coats of any paint, be it primer or whatever, you will get a smoothing effect with the increased film build, which reduces the surface texture. Been there, done that...the voice of experience come too late.

Also, if you are sanding epoxy primer, you are absolutely wasting your time and effort. I don't know which product you are using, but if PPG's DPLF is top-coated within a week, no additional surface prep is required. In fact, if you wait more than a week, PPG will tell you to sand with 400, then apply ANOTHER COAT of DPLF because nothing else will stick to it. Personally, I try to top coat DPLF the same day.

[Warren L.]

70 windshield wiper door assembly

Thanks Chuck,

I just checked with a guy up here and he said he had restored one and after it was cleaned and blasted it was epoxied and painted with black satin urathane as per the customers request on a 71, he didn't remember the nylon washers but because he didn't remember that means he painted the assembly as a whole, dissassembly would be difficult.

I understand about film build with primers etc yeah from mistakes. Epoxy I use is old style DP-40, don't know if you can get it in the states but an expert has done tests and he prefers that so that is what I use. Re coat on that is 72 hours, I do it in two or three. Understand about the recoat window and sanding or not sanding, I don't I just thought that was part of what you were saying in loosing texture. Have been told in the past that adhesion may be better to do it wet on wet as well, so that matches what you were told.

Will clean the assembly today and see if there are any more posts on this.

Thanks,

Chuck

[Wayne P.]

Re: 70 windshield wiper door assembly

The bottom side of the wiper door is NOT black!!

[Chuck S.]

Re: 70 windshield wiper door assembly

Well, Wayne, I didn't think so either, but if you want to make a positive contribution, tell us what color you have seen on the underside of wiper doors, and on which years you have made these observations. I can only offer what I see on a single 70 wiper door, and I believe it to be original. I might be misled, but I'm not making this up. More input is what we need here.

[kelly theaker]

Re: 70 windshield wiper door assembly

an early 69 door i recently stripped did have the 2 grommet holes for a #10 or 8 screww but as far as primer i believe it was green - probably vynl wash for adhesion and a sparse amount of body colour on the back side accumulated on the raised portions/ hope it helps, as for the wiper linkage assembly i also found all or most of the nylon to have black paint flaking / as if a blackout treatment was used , hope this info helps ,

[Chuck S.]

Re: 70 windshield wiper door assembly

Kelly, green overspray (zinc chromate) around the edges and bare aluminum in the center is what I EXPECTED to see...What I SEE is flat black uniformly over the underside of the wiper door. This observation is unchanged after a thorough wipe-down with mineral spirits. It is clear from close examination of the edges that the flat black went on before ANY body color. I have documented that the car was re-painted poorly one time, so complete disassembly, stripping and painting of the door is unlikely.

Whatever the flat black is, it is soluble in lacquer thinner and transfers when wiped. I also see very, very slight overspray of body color on the ribs and raised areas as you decribed. There are bosses that I assume for mounting bumpers located about 25-30% of the length from each end, and on closer examination, they ARE threaded. I didn't remove any bumpers at these locations, but it's possible they were removed earlier. There are no threaded bosses on the ends of the door that could be used for that purpose.

That's my story, and I'm sticking to it. It may not be "correct" for every C3 or even every 70, but I am convinced its original to my late 70.

[Warren L.]

70 windshield wiper door assembly

Thanks for your thoughts on that. I have two wiper arm assemblies. I sandblasted one last night, then epoxy primered it and painted it with Glasurit with flattening paste to lower the sheen. Turned out great but it looks like it should be on a Mercedes. Not sure if I will do the second one the same this one seems too fancy.

Right now it seems that it had a green vynil wash primer orginally, then I can see overspray from a second paint job in a different colour and that was blacked out. And the black is flaking off most of the nylon washers with some rusting around those pivot points.

Does anyone know how the wiper aseembly was painted orginally? before, after assembly etc?

Thanks,

Warren

[John H.]

Re: 70 windshield wiper door assembly

I can't speak to the C3 specifics, but typical GM practice in those days was to have hardware assemblies that were installed on the Trim Line painted semi-gloss black by the supplier, and die-cast parts that were to be painted body color arrived in the plant already in prime from their suppliers.

[Warren L.]

70 windshield wiper door assembly

I recieved an e-mail from a member who said the assembly was painted then assembled hence the still white nylon washers.

If so then maybe these two assemblies I have with the black paint flaking off and Kelly's assembly is the same, is paint from that area being blacked out at a later date, on my two assemblies it may be because each of the cars had been repainted.

Only brought this up cause in many cases it doesn't take much longer to do it as it was rather than just do it. There are still parts on this car with original factory paint so in those cases it is easy to duplicate what was there.

Thanks for your responses,

Warren