hey guys, i've got a 1968 chevelle with new quarter panels from year one, its been in primer for two years, because i've had a problem with a crack in the body fill over and over, ive sanded down to metal and weld which looks good. I've replaced with minimal fill and yet it still cracks. this is not a over built engine with alot of fram flex but a very hyper small block. I have used a body fill with fiberglass for a base and a finish fill on top, any ideas would help........ Thanks Tim

Heres what I would do.

#1 clean area with ppg acryliclean dx-330.
#2 sand by hand with some 36 grit paper, you don't have to put a lot of pressure on it, but you want the heavier grit to get in around the welds and also a little on the surrounding bare metal right next to the weld.
#3 reclean with dx-330, and when you wipe it don't scrub it, wipe one way then turn your rag over, then wipe the other way.
#4 if you don't have to put a lot a lot of filler on it, I would skip the fiberglass filler and go directly with rage body filler.
#5 then sand the rage with whatever your comfortable with, but don't put excess pressure when you sand, use good sharp sandpaper that will cut the filler.
#6 before you add more filler, reclean with dx-330, I use a 409 bottle with some dx-330 in it, spray it but don't let it soak in, just wet it quick and wipe it off quick.
#7 after the second application of rage you could use a skim coat of some 2k filler for finishing, but I wouldn't necessarily keep cleaning it everytime as you get it down good and flat.

knead the hardner good before you add it to the filler, make sure the hardner is not old from age, get some fresh hardner.

Make sure the tempeature of your panel is not cold and your garage or shop temperature is plenty warm, I keep mine around 76 for filler or paint work.

You don't have to use 36 grit, sometimes this is hard to cover the scratches, so you could go with something less aggresive.

The last thing, some epoxy sprayed or brushed on the welds and bare metal might keep it from rusting out years down the road, but thats up to you.

If you use epoxy, this would be put on right after the bare metal sanding and cleaning, but don't go above 80 grit on the bare metal if your going to epoxy it, maybe a 60 grit.

Rob

this is not a quick reply , but I realize I dont think I ever said thank you for the info, so Thank You , i did try your advice and yes it helped but I still have a small crack developing. I will bring it to a "professional" and see what they have to say.... tim

this is not a quick reply , but I realize I dont think I ever said thank you for the info, so Thank You , i did try your advice and yes it helped but I still have a small crack developing. I will bring it to a "professional" and see what they have to say.... tim

Your welcome tim. Are your quarters welded solid, body bushings okay or are they original and hardened, maybe something is moving causing that crack.

We have some pro's on here if they see this they will know what to do, just give it a couple of days until they see it.

You know I have never thought about body bushings, I know they are orginal, I am the third owner and I know that they have not been changed. I did sand down to original metal on the quarter panels, all welds look good, it is a high compression sb, but in my opinion not enough to break body panels, I am putting a big block in and if neccessary sub frams but i cant belief thats neccesary. Do you think sub frams would stop the cracking in the body panel, or I am I missing something very basic, besides bushings, anyway thanks again.... Tim

The thing that comes to my mind, the panels are welded together in a certain order up there in the seam. The rear quarter panel was welded to the inner roof structure, then the roof was welded over the top of those two panels. Could be that you didn't get any penetration into the inner structure to quarter panel, and it's allowing the roof to flex on the quarters.....

The thing that comes to my mind, the panels are welded together in a certain order up there in the seam. The rear quarter panel was welded to the inner roof structure, then the roof was welded over the top of those two panels. Could be that you didn't get any penetration into the inner structure to quarter panel, and it's allowing the roof to flex on the quarters.....

I am with Dave on this one. Filler just doesnt crack at free will unless it is subjected to movement.

Thanks again for the good info, and i agree something must be moving, so i think i'll take it back down to metal and see what the local body shop thinks, I am a do it yourself kinda paint and body guy, but this one has me guessing.......So maybe a "pro" can tell me if the welds are correct....... Tim

Thanks again for the good info, and i agree something must be moving, so i think i'll take it back down to metal and see what the local body shop thinks, I am a do it yourself kinda paint and body guy, but this one has me guessing.......So maybe a "pro" can tell me if the welds are correct....... Tim

Tim, if you could get some real clear pictures, Dave and eric could tell you if the welds are okay.:yes:

Tim, is the metal cracking or is it the body filler over the weld?

It's not the metal cracking, it's the filler, I made a point of taking it down to metal checking the welds and building up from there with as little filler as possible, starting with fiber fill and then body fill, now the crack is alot smaller than before, only 1.5 inch's were it was easy 5 inch's. I'm no welder, and maybe what looks good to me is'nt, so maybe the welds are bad, I would love to try and fix it myself, and after doing alot more learning I honestly think I'll try...... however, I plan on asking lots of questions, so your help would truely be appreciated. Thanks again for all the help..... Tim P.S. If I can figure out how to post pictures , I will.........

Tim, what part of the country do you live in? What is the temp there?

Tim,post some pictures.In the past,have you had a problem with a broken lower door pin ? I have seen the spring in the lower door hindge crack the quarter panel.The side window about 2/3 of the way down from the door opening,a crack runing vertical,is this what your dealing with?

what about using something like All Metal first?

Where exactly is this problem happening?

I am with Dave on this one. Filler just doesnt crack at free will unless it is subjected to movement.

what about using something like All Metal first?

Yup, there is an underlying structural weakness. All Metal will provide no structural integrity; it too will crack. It's also a cleverly marketed product that people are led to believe it being a panacea. They can keep it.

The problem is directly above the passengers side back tire, where the new quarter panel meets the roof pillar, the crack is about 1.5 inch's and runs vertical up the side, not horizontel, exactly where the two parts come together. The car is pushed to the corner of the shop, because i'm helping my son with his 89 IROC right now, When I can get good pic's I will post them. I live in the upper Northwest, 3 weeks ago it was zero and today it's 37 F. Thanks again for the help, I know that pic's would help a ton so i will get them up very soon.... Tim

Tim, I have seen this kind of problem before in cold climates. If there is plastic filler in an area that can flex an if you drive the car and it is zero degrees out. The plastic filler can crack. If you take a piece of plastic filler that is frozen and try to bend it ,it will snap in two. If the filler is warm it will bend some. I have used the Eastwood lead free body solder for areas like that. It is not that hard to use.

Thank you for the help, I dont usually drive it in the cold , however the crack developed in the summer temps which are around 70's to 80's , I think there must be a problem with the welds, and I will look to it as soon as i finish with a hundred other projects that the wife and kids throw at me , but its winter and thats what its for.... Tim

Tim, if you can't figure out how to post pics, feel free to email them to me and I'll put them up for you :thumbsup:

Thanks for the offer, I havent even tried to post pic's yet, the car is parked in the corner of the shop with that side closest to the wall. I am in the process of pulling the small block and putting a built 454 in with a 400 tranny. So when I get the chance to do it, I will push it out in the open and get some pic's and try to post them, I run my business out of my shop, so I dont always have easy access to the car like I would like to... Someday when I'm rich and famous I'll have just a car shop ( yeah right ).........Tim