As you can see in the photos, I have a few very good size dents in the roof of my cab. I was really not wanting to cover the whole roof in bondo. I have tried hitting the dents with a body hammer and it showed little result. What would be the best way to remove these dents?

 

More patience and some knowledge from the master:

 

The WRONG way is to hit the dents in the center with a body hammer or try to fill them with bondo! The Key to Metal Bumping is an old book, but it is one of the best (and inexpensive). If you are working alone, a porta power would be a worthwhile investment.
A roof as dented as yours is going to be a very difficult repair. It can be done, but would take a skilled body man about 2 weeks to do. What tools and equipment do you have besides the body hammer? (and what hammer(s), brand and style, and dollys do you have?) Do you have access to another cab with a good roof that you can take templates off of? Do you have an Oxy-Ac torch, gas shielded mig welder? If you can weld, it might be better to replace the whole roof with a straight one off a parts cab. What is the condition of the rest of the cab?

 

The condition of the rest of the cab is very important. if it's a rusted out mess that will need a bunch of patch panels, it's not worth messing with. But if it's totally rust free and in awesome shape, and the only thing wrong is a dented roof, it's certainly worth the effort of fixing it right. Seek out help from a local professional if you don't feel comfortable doing it yourself. You might visit an auto body paint and supply store and see if they know of someone credible that is looking to do some side work cheap. There's always guys out there that do that, and they know who the good ones are, as well as the bad ones.

 

I actually have a mig welder, and a parts cab. Would it be easier to cut the whole roof, pillars and all, and completely replace? Or cut what I need just out of the top of the roof and weld the piece in?

 

I would scrape the filler out of the gutter on the good roof with a heat gun and made to fit scraper (make from a cheap wood chisel, lightly round the corners), drill out the spot welds with a spot weld cutter so you don't drill thru the bottom of the gutter and along the inside rear seam and remove the roof panel. (note the gutter consists of 3 layers, study the construction before starting) You could then cut the damaged skin even with the bottom of the gutter with a small cutoff wheel. Set the good roof panel in place clamp into the gutter and plug weld thru the drilled out spot welds, alternating side to side, front to back keeping the welds as far apart as possible. Use a self leveling gutter sealer and a seam sealer (NOT bondo!) to seal.

 

The roof on my 49 had similar but a deeper dent (tree fell on it 20 years ago).I have a spare cab with a nearly perfect roof. I considered a complete change out as AX suggested but decided that I would attempt to straighten it since if I was not happy with my efforts at straightening, I could go to plan B. I used a jack arrangement (homemade porta power) and then worked the edges of the dent. Can be challenging as you try to work the very center of the roof if the dent goes in that far. It did in my case. I can not tell you that it is filler free. I am just not that good! However there are no spots more than about 1/16 inch thick.

 

From what you have done so far you have demonstrated that you do not currently have the skills to finish the job. You are not seeing success because you are not moving the metal in such a manner as to let the panel restore itself to its original shape. You should be working the EDGES of the dents, not the centers. The edges are the areas that are stretched and need to be massaged back down...as soon as that happens the centers will pop back into place. Any more dents that you make trying to force the centers up will only make the situation worse.

 

I replaced the roof skin on a cab. Not sure I'd do it again. It was a lot of work. I found a solid cab with a bad roof which is why I did the swap. I used automotive panel adhesive to glue the roof skin on. I did this in a hobbyist auto body class at my local community college. Here's a photo set showing some of the steps I took.



Roof skin swap

 

That roof can be straightened if you haven't done too much additional damage hammering on it. Trying to beat the dents out results in a a lot of stretched metal and what is commonly referred to as a bag of walnuts appearance. If the rest of the cab is solid, you think you have the patience (LOTS of patience), are willing to invest in the right tools and want to learn how to do it right, I can help you with the process