Quarter panel seams

[442_Mustang]

Ok, I have been working on my 72 Cutlass S for a while and last fall I ramped up my progress. I put aftermarket quarters on it although I maybe should have patched the area around the wheel lip. that's the only area that really needed attention. there was a little bubbling in a couple areas and my fear was if I fixed those areas, 6 inches away would be bubblinga couple years after i painted it.I put the whole panels on.
Ok, I painted it black3 weeks ago. No problems. after a few days I wet sanded it and a week later I cleared it. it looks absolutely frigging awesome. Saturday I flat sanded it and buffed it. Looks perfect. No ripples or waves. I'm impressed with myself. Sunday I pushed the thing outside and within a half hour, the welded seam had shrunk and showed most of the whole length of the quarter. Later when I pushed the car back in the garage and looked at it, it had flattened out again. no trace of the line. Perfect again. I welded them solid. after welding and grinding and cleaning up the seam, I spread a coat of everglass and sanded that before i used Rage body filler.I then primed with DP 90 and then 3 coats of PPG K36 primer surfacer and I did all of this last spring. Last fall I blocked the whole car with 240 grit and reprimed the whole thing. It then sat in a friends booth all winter (He no longer uses his shop) and this spring I blocked it with 320. In my opinion I did not skimp on procedure or materials. I am a bodyman by trade and I have put on at least 40 sets of aftermarket quarters and I have never had a problem using the above procedure. It's very strange that the seam will show up in the sun but will go completely away when it is back in the garage. Has anybody ever came across this before? Sorry I'm kinda long winded but I wanted to give as much information as possible. I'm really devastated with this thing
Thanks.

[joe_padavano]

Originally Posted by 442_Mustang

...Sunday I pushed the thing outside and within a half hour, the welded seam had shrunk and showed most of the whole length of the quarter...

It really sounds like a thermal expansion problem, which is exacerbated by the black paint. Did you lap the seam or butt weld?

[442_Mustang]

It is lap welded. The thing is, I've done many replacements like this before and other body techs I've spoken to do the same or quite similar techniques. I wonder if I may have gotten a bad batch of that fiber reinforced filler. The lap weld should be stronger than a butt weld because of the double thickness of metal overlapping. It's only like 1/2 inch overlap but this is a big kick in the stomach and I'm not ready to get up off the mat and commence swinging again...

[gearheads78]

There is a post about this very subject in the fabrication section of Pro-touring.com right now

http://www.pro-touring.com/forum/sho...highlight=weld

[scrappie]

I did a job similar to yours a few years ago. 71 cutlass with aftermarket 1/4's. I flanged the seam and the lap was about 1/2 inch about an in from the body line. I used a combination of body panel adhesive and welding. I then used marglass on both sides of the joint and sanded then body filler. After the body filler came polyester primer and then sanded again. Everything came out nice and flat. This was all done in about a 4 week time frame. The main difference I see between what you did and what I did is the type of seam and the time. Maybe while the car was sitting, moisture or air got into the seam and expands or contracts after being heated by the sun? Sounds like you did a good job so I am only guessing and I am not a body man by trade.

[442_Mustang]

Wow, I guess it has happened to some others. I put quarters on a 67 Camaro basically the same way and painted it dark green/almost black and that never came back after almost 10 years. I had a 78 Camaro as more of a street rat(I hate Camaros). On that one I really didn't care about the thing so I just glued and screwed the panel on. I then mudded the seam with duraglas and quickly shaped it with 36 grit on a paint roller to get the curve right. the rest of the job was just a quick butch and I painted it almost 10 years ago. My bro in law has it now and you can't see any trace of it. How come on stuff I really don't care about it stays perfect but on my baby that I took the time to really make perfect, something like this happens? Stupid Murphy!

[Lady72nRob71]

Different expannsion rates between the original metal and the aftermarket metal??? Do you know what gauge metal the aftermarket panel was? With all the concerns now days to cut costs, maybe the newer ones are thinner...

[chequenman]

.
Ok, I painted it black3 weeks ago. No problems. after a few days I wet sanded it and a week later I cleared it. it looks absolutely frigging awesome. Saturday I flat sanded it and buffed it. Looks perfect. No ripples or waves. I'm impressed with myself. Sunday I pushed the thing outside and within a half hour, the welded seam had shrunk and showed most of the whole length of the quarter. Later when I pushed the car back in the garage and looked at it, it had flattened out again. no trace of the line. Perfect again. I welded them solid. after welding and grinding and cleaning up the seam, I spread a coat of everglass and sanded that before i used Rage body filler.I then primed with DP 90 and then 3 coats of PPG K36 primer surfacer and I did all of this last spring.


Hi there; I read the steps you took in preparing your Paint work, and I haven't read anywhere about sanding your Base Color prior to Clearing the car. Now sanding the Color with most Paint manufacturers such as ICI, PPG., Sikkens states that a recoat of Color should be applied if sanded prior to Clearing the Car within a "24" Hr. Window. So you "HAVE" to Clear the Car within 24 Hrs. of applying Color. When you sanded the Color maybe the Paint Color is so thin at the body seam joint that you're seeing a line of distortion over the seam when you have the car outside in the sun light. I'm not trying to Rain on your Parade but to offer some insite on your situation....

[joe_padavano]

Originally Posted by 442_Mustang

The lap weld should be stronger than a butt weld because of the double thickness of metal overlapping. .

It is also stiffer, which is why it moves differently from the rest of the sheet metal when the panel expands in the sun. Butt welding is much more difficult to do, but solves this problem. The only factory lap weld, at the top of the C pillar, was purposely put in a high crown area where it was stiff and wouldn't show.

[J-(Chicago)]

My quarter panel is made out of great stuff. I welcomed the expansion.

This is not constructive, but I thought you could use a joke.

[442_Mustang]

[quote

Hi there; I read the steps you took in preparing your Paint work, and I haven't read anywhere about sanding your Base Color prior to Clearing the car. Now sanding the Color with most Paint manufacturers such as ICI, PPG., Sikkens states that a recoat of Color should be applied if sanded prior to Clearing the Car within a "24" Hr. Window. So you "HAVE" to Clear the Car within 24 Hrs. of applying Color. When you sanded the Color maybe the Paint Color is so thin at the body seam joint that you're seeing a line of distortion over the seam when you have the car outside in the sun light. I'm not trying to Rain on your Parade but to offer some insite on your situation....[/quote]


Actually I painted it single stage black urethane. A few days later I wet sanded the paint with 1000 grit. Then I cleared it after a few more days. It gives the black a depth that's hard to describe next to a regular BC/CC job. I'm formulating a plan of attack now. I am going to keep building the car and this fall i will clean it out and use a different product. A guy I know had the exact same problem on a GTX and he told me how he managed to solve it. Apparently there's some kind of marine filler that is ungodly ridgid and will not move at all. Rated for over 800 degrees F. I'd hate to have to put a stinking vinyl roof over it because I already replaced the roof skin with a used one. Another long story.

[442_Mustang]

Also, I've seen those 1/2 quarters installed on Dusters and Novas that are only half way down barely above the wheel opening and they don't usually come back. I'm still researching and I will post my findings and hopefully save a few others this headache.

[chequenman]

442 Mustang; Your aftermarket 1/4's do they have door jams or are they the type that just come up to the rear of the door opening and weld flush about 3/4" short of the door opening?

[442_Mustang]

They come up short of the door jamb and maybe 4 or 5 inches above that hip curve on the quarter, they do not have the window opening or the area that the trunk meets up to

[442_Mustang]

By the way, on solid color cars the reason that you get the depth by flat sanding the color before clearing is the color pigment is totally flat and the light reflects and is absorbed evenly before the clear brings shine back to it. Try it... :-)

[chequenman]

Originally Posted by 442_Mustang

By the way, on solid color cars the reason that you get the depth by flat sanding the color before clearing is the color pigment is totally flat and the light reflects and is absorbed evenly before the clear brings shine back to it. Try it... :-)

The reason I wouldn't put Clear over top of Urethane is it's an Enamel Based Paint and the Base Color of BC/CC is Thinners based stock. The Clear Coat has really strong Activators that quite often attack Enamel Based Urethane Top coats after you break through the hardened surface by sanding it out. Now maybe I'm missing something here and you're using a non base/coat Clear but I had heard that type of material had been discontinued and was obsolete.

[chequenman]

442; I have a good friend with a '68 442 Conv. and it had lap welded aftermarket 1/4's and they were a mess after a couple of Years so the car has been taken off the frame and the old aftermarket 1/4's were painstakingly removed with aftermarket Inner and Outer Wheel Wells installed and the Old/New previously removed 1/4's reinstalled and are Butt Welded by Mig spotting and then Tig Welding comletely from end to end. Now this car hasn't yet been painted so I guess all we can hope for is it not to have a similar problem. The 1/4's are in Primer Surfacer and have been blocked and Guide Coated so they feel & look really straight. Hey cross your fingers....

[442_Mustang]

I blocked mine and it is very straight. In my garage right now there is no line or trace of the work done underneath. only when it sits in the sun does it show.i guess as long as i never put it in the sun it looks great. I just can't believe that they can not be used without that line showing. Like I said, I've put many sets of them on. This is the first time I've had anything show up.
The products I used are recommended by the reps at Finishmasters to get a show car finish and I believe it is not a paint problem. The body work was done over a year ago and the car was final primed last september. I blocked it out with 320 a couple months ago and have been prepping it when I had the chance and I painted it 2 1/2 weeks ago. Everything should be well cured. Something strange is happening.

[joe_padavano]

Originally Posted by 442_Mustang

Also, I've seen those 1/2 quarters installed on Dusters and Novas that are only half way down barely above the wheel opening and they don't usually come back. I'm still researching and I will post my findings and hopefully save a few others this headache.

Unfortunately, none of that applies because the problem is very dependent on the shape of the specific panels and the location of the joint in relation to other features. All sheet metal expands and contracts with temperature. The thickness of the metal and the shape (and location of ridges or other features that change stiffness) all have an affect on how the panel moves.

[chequenman]

Hi Joe; In reference to welding two sheet metal panels together whether it's lap or butt, the most critical factor is to weld where the overall panel has a lot of Memory, such as close to the top corner edge of a'68/'69 Cutlas or waffling will happen even from the most skilled Hammer Welder, but thats where Dollying comes into play...

[joe_padavano]

Originally Posted by chequenman

Hi Joe; In reference to welding two sheet metal panels together whether it's lap or butt, the most critical factor is to weld where the overall panel has a lot of Memory, such as close to the top corner edge of a'68/'69 Cutlas or waffling will happen even from the most skilled Hammer Welder, but thats where Dollying comes into play...

Agreed. That's why I noted that nearby ridges or feature lines play a role. The typical Chinesium partial quarter panels are thinner than stock sheet metal and are designed to be welded in place in the middle of the quarter. They usually don't go all the way to the fender peak and certainly don't wrap over or incorporate the trunk gutter.

[442_Mustang]

Yup,Mr.Padavano.Those are the ones, Although the sheetmetal is the same thickness or very close anyways. Maybe I will run a torch over the area around the metal surrounding the weld to relax the metal molecules. I do know that those panels can be used with satisfactory results. I've seen it before and I've done it before. They are not as nice as factory panels by any means but until I can get factory style quarters like you can for the Cutlass Supreme, I will have to deal with this. I found one NOS quarter a couple years ago but they wanted 2000.00 for it. Heck, I will keep trying with what i have. I'd go a grand per quarter but the one i found before was a lot of money and had damage from laying around for all these years and I still would have had to find the other one. I don't believe that every aftermarket chinesium quarter panel will have this problem.