Just some super basic stuff abut frames. When looking at a frame on a rail your going to buy look for things like Cracks in the frame, quality of welds, pretty doesn’t mean good metal penetration.  Scratches on roof are a BAD sign Name brand is pretty good. Home built frames you should take a real good hard look at it with somebody that knows frames and fabrication. Look for triangulation to absorb shock from suspension and high stress area’s. If it’s a rear engine, check horns, engine mounts and chassis stress points. Cracked paint around a weld doesn’t ALWAYS mean there is a crack there. Paint can be either very soft and pliable or it can be brittle as in some of the epoxy based paints. Some people also use Bondo to smooth out the welded area. Loosened Bondo can cause paint to chip or crack. But with the sellers permission chip some the cracked or chipped away it’s worth looking further to determine if a crack is present.

                                                               

If there Is a crack present you CAN reweld it. If the chassis is chromemoly, it’s a sign that too much stress was placed at that weld or joint. When re-welding, it’s wise to add a gusset. Gussets at stress points and suspension points may save a weekend. Mild steel is much easier to work with as it usually bends before it cracks. While you have the welder out, or in my case the frame at the welders, have them add gussets. In general, tubes should never intersect other tubes mid-span. In other words. wherever a tube comes into another tube perpendicularly there should generally be a tube on the other side supporting it. Plate gussets, technically, should be used at every intersection, but this is never done.

From a joint standpoint you can not over do it on gussets From a practicality and weight standpoint, of course, you can over do it. Adding huge gussets to support a tachometer or GPS. IS over kill.


                                                                              

Another thing to do while at the welder is to beef up the shock mounts. Although our rails aren’t as heavy as other LT cars with big V8s it’s never a bad thing to have double shear shock mounts.

                                                                                  

An alphabetical pillar is just as it is in an automobile. The A pillar is the roof support closest to the windshield, the B pillar is the next support towards the rear of the car and the C pillar is closest to the rear windshield Convertible cars for the most part only have an A pillar (windshield support) A car with a roof will have an A and C pillar and if the manufacturer feels that the roof isn’t supported enough, will add a B pillar. Some cars like early Chevy’s had what was called a hard top, wherein no B pillar was present.
In a sand car, and based solely on my opinion, if the distance between the A and C pillars exceeds 36 inches then a B pillar should be present. Some LT high horse power cars have D pillars.

                                                

                                                                       

  When picking out the type of tubing to build your frame out of Light chassis design big car but trying to hold down the weigh I recommend Chromoly, otherwise, mild steel is perfectly acceptable. 4130 MUST be welded by an experienced individual as it will become brittle if welded incorrectly. All metals will become brittle if welded improperly, but 4130 is much stiffer to begin with so the problem can be exaggerated. Inch and a half Outer Diameter (O.D.) tubing with .120 wall thickness is recommended for the main hoop. Smaller diameter for cross members.  An off road racer may use thicker tubing for strength where as a sand car may use a thinner tubing to reduce weight.

                                                                                                               

    This by all means does NOT cover everything when it comes to frames if you have anything to add or have questions PLEASE click here for this topic.