Datsun Roadster Forum-311s.org

What is the fastest way to remove bondo. The car that was given to me was coated in 1/4 inch of bondo all over the body. I used a wire brush on a drill to do one door, but the whole body? Surely there is something to melt that junk away. Thanks for your help.

If you don't want to use sand or bead blasting then a heat gun and a putty knife works pretty good. Creates a very nasty smell though so I'd definitely recommend a mask and of course eye protection is always a good idea too.

Hope it helps

Jon

I recommend having someone else do it. Sounds like to much fun

As for me, I would do as Jon suggest. There is no "easy way" to do it. The questonis why did the PO use all that Bondo? I guess you will find out. Good luck, and have patience.

Fastest (and messiest) is to use a 7" angle grinder with a 36 grit disc and go crazy. You will have bondo dust everywhere (wear a good dust mask!), but it will be over pretty fast. The cleaner you want it, the longer it will take.

Mark

The FASTEST would be to take the body to a place that does chemical dipping. Unless I am mistaken, they have one that takes off EVERYTHING that is not steel. Not cheap though...

That would be interesting to find out what that chemical is and if it is available to the general public (probably not). I have tried to use different types of paint stripper, from environmentaly friendly to really nasty proffesional strength, and nothing I have tried would take off more than a thin coat of bondo at a time, even letting it sit on there for hours! The fastest way is always letting someone else do the dirty work!

Mark

Fastest and easiest: Chemical Dipping as Sid mentioned. Not cheap though, and while it is fast it may take a couple weeks depending on backlog at the shop that does it.

Fastest and cheapest: Grinding it off as Mark mentioned. Not easy and can be both very messy and not the fastest. Then don't forget having to be careful of the base metal. That bondo may be on there for a reason, or it may just be someone's cheap fast fix like they do on the TV shows... slather it on, sand the whole thing down... it's bound to be smooth then.

Easiest and cheapest: Aircraft Paint Stripper, but decidedly not fast; again Mark. And be very careful of the residue as it can give some nasty chemical burns... and even though it won't curdle paint or bondo it can STILL burn you.

Fast / Easy / Cheap === Pick two.

Yet another method is to pull out your D/A sander and use some 60 grit or lower and go to town. Don't forget to step the grit back up as you get to the metal so you don't scratch it deeply.

FWIW
E

Thanks guys, your input is very much appreciated.

Just had one chemically stripped and I don't know what type of chemical they use but it removes everything except the lead. They let it soak for about 10 days and the good thing about this process is they dip it into a neutralizer / rust inhibiter afterwards so no more rushing to get the primer on. The only down side to it is the cost. (A little over $2000.00) The streaks you see in the pictures are from the inhibiter.

Jon

Awesome. So what project is that one Jon? You're a busy guy.

Kyle

Excellent shots of the dipped body.

Hopefully the anti-rust properties of the neutralizing/rust proofing agent are long lasting.

There are two very critical sleeping rust bombs in the car body's design.
The rocker panels and the front box frame members.

These are enclosed volumes with no previous rust-proofing compounds added. There are no built in access points to insert a rust-proofing material into those plenums. The sheet metal used to manufacture the body had only minor rust-proofing and as such, these areas can be sleeping bombs just waiting to go off.

The front box frame is the square component of the inner fender metal. Typically this is where battery acid rust will eat a hole into, which is part of what had happened to my car, except that it had also allowed water to accumulate within and hence the lower portion of the box frame, back towards the firewalll, had also rusted through. The box frame ends at the firewall and at the radiator support. The lower edge bends up and over the A-Frame for the front end. There are no access holes into it, except for the corners of the frame at the front and back ends.... where water can seep in. Additionally the seam to the inner fender metal isn't well caulked.

When I worked on my car, I cut a pair of access holes to the interior of this plenum through the firewall from inside the passenger compartment. Once that was done, I was able to insert a venturi style spray to coat the inner surface with POR. The location of the end of the frame is clearly discernible from the inside due to the spot-welds.

The rocker panels have only two access holes, neither of which allows for the insertion of any kind of rust-proofing material. The access holes are the ones that surround the Jacking Point Support. In order to rust-proof this area, I cut a series of 3/4" holes into the plenum from inside the passenger compartment just above the floor and just below the door sill. I inserted the venturi tip sprayer and coated the complete interior of the rockers with POR. I closed the holes with plastic hole plugs.

Take note that there are weep hole drains on the lower edge of the rocker that allow for water drainage... but where did they expect the water to come in from?

FWIW
E

Skyman wrote:Awesome. So what project is that one Jon? You're a busy guy.

Kyle

This is SRL-00003 and the deeper I go with this car the more amazed I am at how well preserved it was. The previous owner (Don Mackinley) had this car since 1971 and told me it had around 80,000 miles on it since new. Don is definitely an honest guy because we are going to be using all of the original metal and the engine just went through an overhaul where it didn't even require an over bore. (Thanks Don!)

EScanlon wrote:There are two very critical sleeping rust bombs in the car body's design.
The rocker panels and the front box frame members.

Definitely good points and we had to deal with some body work in those areas anyway so we got to dress them down while we were there. One side was super clean but the other side still had surface rust which means the chemical stripper didn't get inside. Tight enough to keep out everything but the moisture.

Jon

Is it possible to cut two holes, say 1.5" in diameter into the back of the rocker panels, dip the whole body or treat the inside of the rocker panels, and then plug with 1.5" plastic plugs? Or is drilling ANY holes in the rocker panels dangerous from a structural standpoint.

There should be no ill effect from what you are proposing...