[PairOf69's]

I was wondering what the maximum "acceptable" thickness was for body fillers? Because I got some pretty thick sections on my 69 Camaro

[MARTINSR]

This is a common question, the answer "as little as possible". Doesn't give you much does it. Well, the most accepted answer by manufacturers is 1/8". Most people who use the stuff are likely to say the same, probably because we were "told" by the manufacturers.

But I think they are a bad guage to use. I mean, the jewelery industry is who taught us "Three months of our wages is what an engagment ring should cost" Yeah RIGHT!

How about the shampoo manufacturer, "Wet, lather, rinse and repeat" REPEAT, yeah use twice as much shampoo as you need.

No, I think a 1/16" is MAX.

Now, there is another way to look at, how BIG is this area we are talking about? If you have a 3 foot by 2 foot 1/8" application of plastic filler, you have WAY TOO MUCH filler. However, if you had a 3 foot by 2 foot 1/64-1/16" of filler over 99% if it and in one 2" round area that you couldn't get up any better you had 1/8" that really isn't a big deal.

Those two examples are MILES apart.

Basically, if you can't see thru a majority of your filler, yeah, that's right, see thru it, you are building up too much. Or, you are probably going to have high and low spots that you will be asking primer to fill. A 4" round dent should have an 8" or more filler around it with the majority being litterally transparent. This will insure that you havn't sanded the filler too low. But it all will be very thin.

By the way, if you do a search on users John Kelly or Randy Fergison you will find a lot of info on not using fillers at all! Realistically we do, 99.9 % of pros use it so don't worry about that. But using none or even seriously reducing the amount you do is within your grasp.

I personally have been trying to eliminate as much as possible just as a challenge (I do this stuff every day as a living) and I have found that I am using WAY less than I was a short time ago.

Brian

[PairOf69's]

I figured you would be the first to answer MARTINSR, thats the info I was looking for by the way..thanks! Wow I didn't know the manufacturers say 1/8 should be maximum that seems like alot. Thanks again

[steve t]

bike builders mold their frames and tanks with it, a lot thicker than 1/8in, but that is not a side pandel on a car

[oldred]

First let me say I am NOT saying this is ok but I have been helping a fellow install q-panels on a 1968 Mustang and this thing was loaded with filler which was the reason for the change. Whoever did the job before got it straight and it looked pretty good on the outside but when viewed from inside of the trunk it was obvious that the welding from the q-panel patch installations had warped badly and the guy never made any effort to straighten it he just smoothed it with filler which was over a 1/2" thick in places, in some places WELL over 1/2" This stuff has been in there for over 15 years and still looked straight with no cracking so if this mess will hold up that long I would not think 1/8" will hurt a thing and certainly 1/16" will be fine. Again I don't mean it is ok to use a 1/2" of filler I just thought you might be interested in what I found.

[kenseth17]

Filler has been abused and used a bit thicker then 1/8 inch without problems, I use to work at a used car dealer that rebuilt wrecks, and lets just say filler was often thicker then 1/8" and entire quarters full of mud sometimes. Seen some of em around and didn't see any fall out or cracked anywhere. It was quite the change going from that shop to my next job in a bodyshop where all metal work had to be worked out so hardly any filler was used and wetsanding everything before paint. Your better off starting with fiberglass filler if you have a bit of fill to do. On one of my old cars I still have the filler is kinda thick on the door because it warped some when welding new metal in the bottom of it. It is an old car and not really worth much so I didn't try real hard getting the warp out. The whole thing had rust outs everywhere to fix and knew I had a lot of work to do, so I just put fiberglass filler in the door, followed by plastic filler. The car was driven for a couple of years, and the door hasn't cracked anywhere or anything. After doing that car I've been pretty good on not getting warpage, guess you live and learn. But like Brian said, the less filler you use the better. There was a guy back when I still worked for the used car dealer that drove around in an old roadrunner. A huge chunk of filler fell out of the quarter panel and looks like the filler was at least an inch thick. Sure looked crappy. Don't know if it was hit in that spot or it just plain fell out.

[chadsbodyshop49119]

question I have is what about the bike tanks.. i just did one and the only way to make it straight was to mold the whole tank... most custom tanks are this way, sometimes I just dont think there is a option

[Festive57]

I had the same experience with my 57 Chevy, 210 Sedan. When my dad and I bought the car over 15 years ago, the car came with the whole quarter panel filled with over 1/2" thick filler. We as amateur's did not know any better, when we bought the car it was at night and it was freshly painted gray primer. We soon found out about the true condition of the car and opted to have both quarters cut out and replace... even the body shop we took the car to at the time commented on the amount of filler used. They even stated they were very impressed with who ever did the body work, due to it being undetectable. Irony of it is, they replaced the quarters.... crooked! Over these years we still have not completed the car. I told myself at that time, I will do what it takes to get the tools I need and learn the proper way to do the car. I am now on the right track.... I will get it done eventually. I just thought I would chime in. I have some old body shop pictures somewhere of the filler in a box. If I can find them I will try to scan them and post them...

PS. It is my continuous reading of this site that is giving me (just a hobbyist) the understanding of how to do it right.

[steve t]

Originally Posted by chadsbodyshop49119

question I have is what about the bike tanks.. i just did one and the only way to make it straight was to mold the whole tank... most custom tanks are this way, sometimes I just dont think there is a option

i had a harley chopper, the tank was molded, i had to chisel the 2in bondo off to change tanks, it never cracked over the years,but i would hate to use that much on a car

[MARTINSR]

Guys, I win, not only can I tell you about the thickest bondo job you will likely ever hear, but I am the guy who did it! For those of you who have not heard this you will get a kick for sure.

When I chopped the top on my 48 Chevy truck (I was 16) when I split the top to lengthen it I warped it real bad. I filled it..........with two, count them two gallons of PPG 999 plastic filler before I even sanded! I checked with a "micrometer" (my 18" vice grip c clamp) and found it to be an inch and a half! (1 1/2")

It didn't look good for long, at about five years it started showing some micro cracks. At fifteen years when I sold that cab, it was cracked all over. They weren't open cracks, very thin, but they were a few inches long and quite a few of them.

But unless you looked up there,no one was the wiser. The truck was well detailed and to the unsuspecting, it was a perfect chop.

I wonder where that cab is today?

Brian

[kenseth17]

I was told about a suburban that the whole side was wiped out on years ago. Apparantly they used a two by four and spread a whole bunch of filler on it to fix it. Not sure weather or not this is true, but it was the worst I've heard. What gets me even more then filler being a little too thick, is when someone fills big rust holes with it, That just won't last. Ran into that on a mustang I worked on, not small holes by any means. Wasn't fun finding all that when stripping it. One spot it just touched with the orbital and a huge chunk of filler fell out of a huge hole. I think everyone who does this work has used more filler then they should of at times. Kinda depends on what you are working on also. A 69 camaro thats worth something and you will probably own for a long time, finish it off right, or replace. Bring a magnet with you the next time you check out a car.

[chadsbodyshop49119]

I agree with you,, it seems to depend what your working on and the situation, but my point was that on some of the custom chopper tanks there is no option but to fill unless you want it to look like crap...

[mrcleanr6]

Originally Posted by chadsbodyshop49119

I agree with you,, it seems to depend what your working on and the situation, but my point was that on some of the custom chopper tanks there is no option but to fill unless you want it to look like crap...

yes your right on that. most of those aftermarket tanks that have extensions welded to them are crazy. dont dare grind down the weld either because if it fails, leaks or cracks down the road the repaint is on you. i've seen it happen. the good thing is that most of the tanks have very thick sheetmetal and dont flex or move at all like say a door skin on a car. i have had situations where the filler needs to be up to 1/2 thick. this is really common place on most custom bikes or tanks and unfortunately thats just the way it is. will you have problems...probably not, use a high quality filler and dont build it up heavier than needed. keep it to a minimum.

[chadsbodyshop49119]

Every time I put on a coat, i'll sand it till I go through in a few spots, that way i know I took off as much as possible.. but it still get's thick in the low spots....