I was wondering if anyone knows the wall thickness of the frame. In this instance a 1976 coupe. Also, is it a hollow tube or are there any baffles or other obstructions within. I have looked at a lot of reference material but cant find this one. I have got a hare brained scheme that just might work. Thanks for all the great input this forum contains.

 

I beleive it is a hollow tube with two ribs on each side - one at the rear kickup and one at the front body mount (the area where the frame bends in). I'm not sure how thick the stock 76 frames were, but I just used 1/8'' sheet metal on my frame walls...it worked just fine.

 

Thanks for that. I'm thinking of maybe incorporating the frame as part of the exhaust system. Trying to think outside the box.

 

What exacly are you planning on doing...sounds interesting to say the least.

 

A few problems, none insurmountable if you want to do this badly enough.

1. Hope you are moving your fuel and brake lines
2. Anything else plastic/damageable by heat
3. The frame rails are only "stitch welded" so you would have to weld up the whole length to prevent leakage. You have to close off every other hole in them of course so that's just another thing to add to the list. I don't know the thickness but I believe the frame is basically two C-channel pieces welded together to make a box shape.
4. Any fastener that connects to the frame will have to be sealed in some way to prevent leakage or replaced with a weld-on tab.
5. Where are you going to have the exhaust enter the frame? The choice of this will significantly affect the engine's performance.
6. Heat and exhaust gasses will adversely affect your frame's tendancy to rust into a million pieces. Does JetHot coat frames??
7. Hope this is an otherwise wildly modified car or else the next owner is going to call you "bubba"!

So in conclusion, why don't you just buy some oval tubing if you want to save ground clearance? You could also modify the trans crossmember as needed. You've probably already eliminated sidepipes as an option but if not, that's also worth consideration. Any of these choices would be immensely cheaper, easier, and more tasteful than repurposing the frame. No offense intended, just words of caution...

 

Get back in the box.

I'm just busting your chops but seriously the rust issue is really something to think about.

 

You can locate where the ribs mentioned above (box frame braces) are located by the welds along the locations mentiond. There was a slot in the frame where the braces were welded in place. One is located about 3 inches ahead of the rail end cap. The frame material is slightly thicker than 1/8, maybe 5/32. Liveandlet covered the negatives well, forgetabout an exhaust through the frame rail. In addition to comments made, carbon monoxide in a leaky exhaust can kill.