GREGGPENN

I asked a similar question in the body section but didn't get an answer. Tonight, I was watching (MotorTrend) "Garage Squad" and was reminded that early C1 Corvettes have exhaust traveling THROUGH the body panels. I SHOULD ASK YOU GUYS!!!!

I actually have a C4, but I have aftermarket sidepipes. My question stems from my plan to increase/replace the piping using 3" pipe. The outlets are bigger than 3" and more like 4" oval. I'd like to keep the same powder-coated trim rings but (as stated) run 3" from the headers then 3" oval from the center tunnel to the outlets. The original aftermarket piping is 1.5"x3" rectangular steel tubing that runs out, up to the front wheel, and does a 180-deg turn before coming down the side -- and out the outlets.

In thinking of ways to route 3" pipe STRAIGHT to the outlets (from the tunnel), I'm mostly clueless on how to mount pipe THROUGH the side covers WITHOUT having them tilt/vibrate and hit the outlets.

THIS IS THE SAME ISSUE I SEE WITH EXHAUST PROTRUDING THROUGH YOUR BODY PANELS!!!

I'm looking for feedback on how much your exhaust pipes rattle around and IF they hit the body panels? If not, are there any steps to prevent it? Rubber donut? Anything?

If it helps, here are the covers (and outlets), that I'm looking to replumb...


There's probably 1/8" to 3/16" space between the silver ring and the outlet hole, so not a lot of room for movement.

The system I'm replacing only has two mounting points (with rubber isolators) and AFAIK, it really doesn't move. At least I've never seen evidence (sound or damage to the outlets) to indicate that. With piping traveling straight to the outlets, I'm a bit concerned about movement with engine torque (rotation). There is a body point I can run a rubber-isolated rod and weld to the 3" pipe. So, that SHOULD minimize torsional movement.

If there's some type of rubber isolator that stands up to exhaust tip heat, I'd be curious to hear it. Or...another means to prevent body panel damage?

Thanks!!!

67:72

The C2 (& C3) exhausts have mounting points at the exhaust manifolds, the mid-frame cross member, and the rear of the mufflers just before exiting the rear valance panel. There isn't much flexing happening from the engine back through the cross member because these are cast iron and solid steel connections with clamps. The rear muffler hanger is a rubber/canvas loop that allows for just a small bit of movement up and down (if you hit the pipes under the differential on a speed bump or the like); the movement isn't much - maybe 1/2". Vibrations are absorbed by the rubber. Overall, there's not much movement in the system and what's there is minimal. The openings in the rear panel are pretty big compared to the exhaust tips - probably at least 1" free-space all around the tip. I'd bet any torque movement is just absorbed by the pipes flexing a bit along their lengths.




From memory of my mom's '58, the C1 system isn't much different though the pipes are supported by the rubber/canvas hangers at midpoints of the system and exit holes in the rear bumpers. The hole has cushion material in it to keep the pipes centered.

GREGGPENN

THANKS!!! Very helpful. The supports don't look exactly like something I'd imagine BUT they do appear to serve the function you describe. The first one is very interesting -- going under the assumption it kind of clamps to the pipe, has an insulating layer, then the mounting bracket.

The fact you said there's a larger space "buffer" around the pipe (than mine), adds to my skepticism of accomplishing the same type of pipe-thru-panel configuration.

67:72

The hanger above is bolted to the rear of the frame and directly to the muffler. You can see it on this '69 (C2s and C3s are much the same).



Here's a closeup of the rear panel exit on a C2 that shows how much room there is around the exhaust tip:

DZAUTO

Just as an added comment.
Back in the late 70s, I bought a COMPLETE stainless system from Zierden (anyone remember them???) for the 56. Since I had 2 1/2in manifolds on the engine, I got their system which had 2 1/2in pipe at the manifold end, and the rest was the normal 2in size.
After extended driving, when the system was TOTALLY heated up, that stainless system expanded and and extended nearly 1in from the exhaust bezels. I fought and fought adjusting the clamps/hangers as a result. I adjusted them cold, then adjusted them hot several times trying to find a NO rattle position. Finally, after a few years I removed the complete stainless system and gave it away to someone, and had my local muffler shop fabricate a FULL aluminized 2 1/2in system ZERO issues now!
I did fabricate some stainless hangers/clamps to fit the 2 1/2in pipe