Can the tork cause cracking in the paint

[Kevin71]

I was thinking of just welding in the subframe connectors I have.  The bolt in the front and rear and to the bottom of the floor plan in one place.  It's got a inch wide strap running across the connectors that is bent toward the floor pan behind the front seat.  So it would weld in three places.  And then add the torque boxes.  It seems like a cross brace along the top of the front fenders from side to side would do alot also. 
Doesn't seem like it launches hard.  It will just spin the tires like hell.  It's hard to get grip.

[70chall440]

If you are easing into spinning the tires that is one thing, however if you are reving it up and dumping it or in the case of an AT just slamming the pedal to the floor; then even though the tires are spinning, the car is transferring any grip it is getting into the car which causes the twisting you are asking about. sub frame connectors will reduce or stop (depending what they are and how they are installed) this twisting which forces the torque to propel the vehicle forward (verses wasting some of the energy in twisting the body).

[rhamson]

As with any polyester resin based product such as Bondo or even fiberglass, the mixture between hardener and filler is important. the problem is that they never stop curing and in some cases can shrink to failure. I have been told by my boater friends that a boat over twenty years old that is fiberglass is a risky investment as the crazing and cracking that occurs could make the boat unsafe and expensive to repair. I think in this case that maybe the hardener had some "hot" mixes and eventually shrank to reveal these cracks. I have used fiberglass resin and hot mixed it so bad the wax paper cups I mixed it in caught fire. Just my 

[Kevin71]

And this is why I don't do body work.  Guy that painted this car was 75 years old and been doing body work since he was kid.  I must have gotten Alzheimer's right before he did my car.  Was retired worked out of a shop in his back yard.  Wasn't even a shade tree in sight. 

[rhamson]

And this is why I don't do body work.  Guy that painted this car was 75 years old and been doing body work since he was kid.  I must have gotten Alzheimer's right before he did my car.  Was retired worked out of a shop in his back yard.  Wasn't even a shade tree in sight.

The newer mixes of Bondo have shrinking inhibitors in them with some have fiberglass strands in the filler to help this not happen. It also depends how thick it is applied. I use lead if I feel the area being faired out is a little thick. There are problems with that too as bondo won't stick to it. I have to prime the leaded areas before I apply any bondo over it. Your old guy maybe did all the right things and the torque caused too much flexing in these areas as well. I am an "Old Guy" in my sixties and have been restoring cars for at least forty years and am still learning new things all the time.

[Kevin71]

I was thinking that because it did this before in the exact same spots that it might be the torque of the car,  but I kept thinking (as Wild Rt said) it couldn't on the roof because of the rear glass would break or prevent the metal from flexing as the glass is ridged.  But the other one I could see might flex.  Now I am trying to decide if I should  get a weld in subframe connector the butts up against the floor board from front to the rear would be significantly better than just welding in the connectors I now have.  I will get a pic of them and post it when I get home.

[rhamson]

I have the US Cartool type that conform to the floor and they are welded in solidly. I also use the rest of their frame strengthening kit on the front end core support, torque box and tower supports. I also will be triangulating the cowl to the towers with support for the engine compartment. This is in anticipation of around a 600+ HP 440 I will install up front. I looked at the bolt in type that Hotchkis sells but I feel the torque will be too much for the bar to plate welds that that type has.

[Kevin71]

Here is a picture of the ones I have.  I just don't think they will be nearly as effective as the full weld in, but I don't know. Don't have to spend more if I don't have to.

[msbaugh]

I'm willing to bet it's bondo or bad paint prep. I have the same thing but in different spots on the car

[AARTA340]

The crack appears to be below the factory seam joint. If it was higher, my first thought was, it is/was a vinyl roof car that had it removed. Most vinyl roof cars got fiber filler, hardtops got lead seams. The only way to find out for sure will be to grind the filler out and then it may not disclose the entire story. Let us know what you find. 

[Kevin71]

It will be awhile.  I am trying to find someone to take this car to in NW florida, south alabama or south georgia.  Just about everything else on this car is new.  I should have had it rotisseried before I did all the work to it, but I never thought I would end up putting so much money into it.  At this point if I am going to paint it I have it sand blasted. I would bet it did have a vinyl top at some point.  It was a 318 car with AC, power steering, and a automatic. 

[TelisSE440]

I believe it has more to do about the paint and body prep rather than the twisting, although in a sleeper like this, the welding of frame connectors should be mandatory.

[msbaugh]

It will be awhile.  I am trying to find someone to take this car to in NW florida, south alabama or south georgia.  Just about everything else on this car is new.  I should have had it rotisseried before I did all the work to it, but I never thought I would end up putting so much money into it.  At this point if I am going to paint it I have it sand blasted. I would bet it did have a vinyl top at some point.  It was a 318 car with AC, power steering, and a automatic.

I say weld your sub frame connectors and torque boxes in and let it go for a little while with some touch up paint, it's not anything that can't be fixed!  Enjoy the hard work and money you have spent already by driving the car and enjoying it as is.  Stripping and re-painting a car is a long process, especially if you've got a bondo car!

Once you've had your fun with it and you're happy, then tear it down and begin the whole process. 

 

[Kevin71]

Good advice.

[jimynick]

I say weld your sub frame connectors and torque boxes in and let it go for a little while with some touch up paint, it's not anything that can't be fixed!  Enjoy the hard work and money you have spent already by driving the car and enjoying it as is.  Stripping and re-painting a car is a long process, especially if you've got a bondo car!

Once you've had your fun with it and you're happy, then tear it down and begin the whole process. 

 

Yep, that's damn good advice. As for the connectors, I've got mine in and can take some pics if it'll help you. As for flexing, keep in mind that the body flexed enough to crack the seam and didn't break any glass there, either. It's mounted in rubber, remember? You also don't need to see much movement for a marginally prepared top coat to break loose. I'm not saying that's the case here, it's just one of several possibilities. Take a good narrow-holed blow gun to that spot and see if you can blow off some more; that'll tell a tale or not. Other than that, enjoy!