Question about lower rocker panel gap....

[bs46488]

I'm new to doing paint and bodywork.

I'm currently working on my other project a 1970 Nova. What am I supposed to do with the area between the lower quarter panel where it meets the rocker?

Here is a photo of the area I'm talking about that I found on the internet (not my photo, copied off another forum)

[MP&C]

Originally Posted by bs46488

I'm new to doing paint and bodywork...…...What am I supposed to do with the area between the lower quarter panel where it meets the rocker?

Can you define a bit more what you're asking? What are you supposed to do as far as welding one in, paint prep, seam sealer, media blasting or rust removal????

[bs46488]

I guess my question is to prep for paint.

Do I do nothing? Fill it with seam sealer? Other?

[mongocanfly]

That pic looks to be full of rust thru holes...if so...then itll need cutout and replaced...clean to bare metal...epoxy prime..bodywork ....highbuild...paint

[Foot Stomper]

Originally Posted by bs46488

I guess my question is to prep for paint.

Do I do nothing? Fill it with seam sealer? Other?

No seam sealer. Make sure it's clean with a wire brush or similar. Epoxy prime and paint. If you get some high build in it, fold a piece of sandpaper and put the crease back in.

[MP&C]

The inside of that area typically has a flange at the bottom of the quarter that is spot welded to the top of the rocker. Looking at the downward slope you can see that this area is prone to water/dirt collection and thus rust generation.


Option 1: If the area is still solid, clean and abrade from the inside, remove any seam sealer from the outstide and abrade from that side as well, and then once ready for primer... my preference is to paint the area from the inside with epoxy primer using a brush. By using a "wiping" action downward against the top edge of the flange inside, the epoxy will wick into any gap between the rocker and flange. Any paint that runs through to the outside should be wiped to remove runs. Allow flash time/dry time, and repeat "brush wicking" application and drying process until no more paint runs through to the outside (you're not done until no more paint flows through). Depending on what the dried epoxy looks like on the inside (ie: is there still a gap to capture moisture or was the flange good and snug to the rocker) I would either leave alone or if there is a gap showing at the edge despite epoxy having "sealed the passage" from inside to outside, if warranted I would add some seam sealer to fill any voids.

The premise here is that any seam sealing in this area is ONLY DONE AFTER all parts are covered/flooded in epoxy, as any water intrusion that gets in between and can't get out is only going to start the rust process again. Now I'd go on the outside as Footstomper suggests and sand the outside joint, to include any runs or excess, so there is a slight recess. If there is any bare steel after your sanding efforts, re-apply epoxy. Depending on what your seam looks like, (ie: is it tight or a wide gap) if it looks like the epoxy has bridged the gap from side to side, it should be ready for further paint process of the entire area. If the gap looks excessively wide, I would add a slight skim of seam sealer. AGAIN, any seam sealer on the outside is a trap. If your efforts from the inside have not totally covered any bare spots from the wiping/wicking process, then don't make a dam to hold in the water. If your epoxy has totally filled in the gap for no possibility of water intrusion, then seam sealer on the outside can be used as a cosmetic fill to lessen the appearance (width and depth) of the gap.

Disclaimer: The suggestions I have written above are all an anal retentive attempt to eliminate water intrusion into an area that by design is a water trap and rust generator. Any priming needs to coat all surfaces from the inside out, using the paint running out the seam at the bottom (outside) as your indicator of paint flow/panel coverage. If you don't have evidence of full paint coverage, don't use seam sealer on the outside and create a water trap.


Option 2 (rust present), if this area shows any rust/scale at all, your abrading efforts need to include media blasting to remove scale, my preference is to use a garnet abrasive in about 80 grit or finer. If you have any rust through the outer panel or through to the inside of the rocker, or deep pitting, I would cut away the bottom of the quarter, to include the flange, and repair the rocker first and foremost. At this point an application of epoxy primer is in order to protect this area before the flange is added back in. At the end of all sheet metal replacement/welding, abrade any welds, and wipe/wick epoxy primer into the seam from inside and follow process as laid out above in Option 1..


Yes, this rust prevention is time consuming, tedious work. But we're trying to rust proof an area that by design is prone to rusting. The rust proofing should start from the inside and work it's way outward. No room for shortcuts here or you will see a repeat appearance of the rust issues. Repairs are cheap before the paint goes on.


If I've missed anything in my ramblings here, feel free to add other thoughts..

[bs46488]

Thank you.

This is extremely helpful!

I'm going to try option one. The interior of the car is missing so I can easily see the flange on the bottom of the quarter and will do some "wicking" with epoxy.

[MP&C]

Do you see any rust in the area?

[bs46488]

I believe it is clear of rust.

I had some rust hole about 1" above the gap. I cut it out and welded in some patches on the lower quarter.

[mongocanfly]

A sandblaster will tell you in a second or 2 if you've got rust thru....if youve got access to one....I had a spot full of holes on mine I didn't even know was there til it came back from the blaster...
Do you have any pics of your actual car?

[MP&C]

Originally Posted by bs46488

I believe it is clear of rust.

I had some rust hole about 1" above the gap. I cut it out and welded in some patches on the lower quarter.

Please don't pick option 1 because it sounds easier, pick the option that matches the condition of your car. Next, It's difficult to dance around any question regarding paint jobs and bodywork without pictures of YOUR car, not something from the net. A picture of your exact situation helps to tailor the response to address your course of action. Body shops don't give estimates over the phone for the same reason.

Looking at the picture in your Nova thread, this area shows a couple patches down by this seam. It also appears in these spots that the outside panel has been repaired but the original flange left intact. It has been my experience that rust does not come through an inch up from the bottom of a panel without affecting the very bottom of the panel. If this area became a swimming pool for rust to come through an inch up, then the bottom is due for inspection as well. Not saying rust HAS TO BE there, but unless one can explain the floating rust spot, don't waste time, materials, and money putting paint on this panel just yet.


Next, welds shrink. Multiple vertical welds (I count 5) and horizontal welds (3) are each going to shrink and cause deformity at each weld and surrounding HAZ (heat affected zone, that which is blue). The slight bit of metal at the bottom (under middle and right patch), once the lower weld shrinks, is going to open up that seam, making it near impossible to keep straight. Please pause here and read this linked thread, pay attention how the multiple vertical welds pulled at the edge and deformed/opened up the fender to door gaps..


http://www.67-72chevytrucks.com/vboa...d.php?t=571177


You can't readily fix that fender gap in that thread with bondo, and likely by the time all welds are done on yours, I fear there will be enough panel deformity and likely rust issues remaining under the flange that the entire width should be replaced, including new flange at the bottom. This would give you one horizontal weld across the top and plug welds through the bottom flange, which should result in much less deformity to address and the opportunity to see what's under the flange to fix other rust issues. Perhaps I'm wrong, but I'd advise checking into this further. Do you detect any swelling between the lower flange and rocker, or is it still perfectly flat? Can you post up some pictures of this inside area?

[bs46488]

Robert,

That's an impressive write up and repair!

I've made a lot of small patch panels on the lower quarter and the corner of the doors too. For the passenger fender I used a full patch panel for the one horizontal weld to rebuild the lower section. The drivers fender looks to be an aftermarket replacement fender.

Makes me wonder how much deformity I've caused with the quarters and the door repairs.

I'll see if I can get the doors hung and get some more photos of the gaps. I'll also try to stick my phone inside the lower quarter and see if I can get a pic of the flange area.

Thanks for the replies. This was a lot of helpful information.

[MP&C]

I didn't have time the other day to add details pertinent to your repair area, let me add them now. You likely already have this complete, but even so this would be good food for thought as to how the panel will react after exposure to heat (weld)


On the picture below, Looking at all the weld seams close to edges (yellow arrows) the smaller an area next to a weld, the more susceptible it is to movement. When welding the seams on the lower door corner, the two lower seams are not accessible from the back side due to multiple layers, and thus will not be able to planish using hammer and dolly to stretch things back out where the weld has caused shrinkage. The down side to this is that any shrinkage that occurs is more permanent, and will thus pull at the side more susceptible to movement (not anchored). That would be the edge of the door, causing door gaps to widen, and in the case of the weld patches in the qtr, it would tend to pull at the slight bit of metal at the gap, possibly opening up the gap with little recourse.


Additionally, the rust through that you cut out of the door is likely due to debris held by the inner door. Without cutting all the way to the edge you'll never know if you removed all the rust (although if it tends to blow holes in this area during welding, that's a good clue the metal is rusting from the inside) If you can make a patch that includes the flanges (as shown in the previous link) this gives a good inspection of the area that had rust through in the vicinity, cuts your welds, and thus shrinkage, down to two seams vs four, and allows you to put the two seams in a location where they can be planished by accessing the rear side with dolly.



The larger patch toward the rear has a good amount of length of weld, and since the weld shrinks circumferentially, it will actually decrease also in length (red arrows), absent any planishing. For a shape typical of a quarter panel, there is an outward crown if you were looking from the rear toward the front. On 99.9% of quarter panels with vertical seams, this shrinkage will cause the weld seam to pull inward, forming a valley. This equates to a given length of an arc (the crown) decreasing in length, so it tends to form a lesser arc or more closely to a straight line. That is why the panel pulls inward at that weld seam, you may notice this especially between the blue arrows. This is SHRINKAGE, and must be planished to restore the original size to the arc/crown.



For proposed "seam location", many times a given crease in the panel will help to control weld distortion. It won't eliminate it, but will help control.. On your particular panel, a seam at the purple line, which has a slight crown outward (vertical) and is either flat or ever so slight crown in horizontal (front to back direction). Any shrinkage is going to pull this inward, no two ways about it. Looking at the green line for a seam, this area has a slight concave or inward crown in vertical, and flat or slight outward in horizontal. So this area may have a better chance of the shrinking forces cancelling each other out, if horizontal and vertical crowns go opposite directions. My first choice would be a seam in the area of the green line, but either should be readily accessible from the back for planishing to remove any deformity. So this would align with what you actually did on the top seam of the door patch.



Hopefully this isn't too much info at one time, but it also explains why it's nice to actually see YOUR car to make better recommendation..

[bs46488]

Here are some pics of my actual car from last night. The exterior has already been epoxy primed, body worked, more epoxy, and the first coats of high build ready for block sanding.



Inside of drivers side. Safe to say its not 100% rust free. I vacuumed it out before the pic but there is evidence of some old seam sealer in there also.