Proper routing of rear exhaust of 71-76 GM full-size wagon

I took my '72 Kingswood Estate wagon back in the summer to have a completely new exhaust system installed and thought all was fine.

I took my car to my mechanic last week to have an oil leak checked and when on the lift we heard something thump. We got to looking and one of the muffler brackets had snapped and got to looking and the rear axle had pulled the muffler down. He got mad and said they routed this incorrectly and that it was supposed to run ABOVE the rear axle. I honestly don't remember how it was before, but he said I needed to take it back and tell them I wanted this done correctly.

So, it this ran incorrectly (below the axle), or should it run above the axle like he said? He said someone got lazy and didn't want to bend the pipe.

Thanks!

 

It's been a few years now since I sold my clamshell, but I'm pretty sure it's supposed to run above the axle.

 

I think it should be over the axle. Here's a pic off the 'net of a Pontiac clam:

 

NEWS FLASH!


It is supposed to run BELOW the axle NOT above it! IT was done correctly.

I don't care how you guys have it now from when it was replaced after the fact, but they are below from the factory.


Mine are run correctly and under if you load the car to full capacity and would hook a trailer to it you would crush the pipe.

By the looks of your Photo they did not put the full bend DOWN when it comes under the rear end. It should just barley touch the pipe when lifted like that.

 

Thanks for the replies. I wasn't sure. I thought it was strange though that when the car was on the lift during the installation of the new exhaust, the axle should have been as low as it was when my mechanic had it on his lift when it (bracket) popped.

I guess I will just take it back and see what they need to do.

 

If it crushes the pipe under full load, the exhaust is NOT bent correctly.
Please show me any car that has factory exhaust below the axle.
Running the pipe below the axle is a quick, cheap and lazy way to build the exhaust.

This is why it won't crush the pipe if bent correctly.

 

I have never heard of a properly done tail pipe running UNDER the axle. Even a Model T with lots of ground clearance ran above the axle.
As far as I know anyone who bought any vehicle with the exhaust under the axle got a lazy cheap job. Think about it, the axle bounces over bumps and pot holes.

But I could be wrong. I was once before. Maybe!

So they were done wrong from the factory!
Mine are run correctly and under if you load the car to full capacity and would hook a trailer to it you would crush the pipe.

 

Look at the floor above the rear axle on a clam and you'll understand. That's why they did it that way. We have state inspection in PA and I took my single factory exhausted Clam in for inspection. The mechanic said "hey that won't pass it runs under the "scrub" line". He had to look it up and it took a while.


Still want to argue a moot point?

And FYI na that won't crush the pipe bent like that! It'll just screw up all your pretty new paint it's running against or beside. Unless of course you Podunk it with some heat wrap.

 

Yea that bend behind the muffler going under the rear end needs to be a bit lower. Possibly they put the pipes on with the car raised and the rear NOT hanging to check for clearance? That's how they should do it for exactly the reason your having a prob.

 

05 magnum under the rear from the factory

 

It's amazing the cars built today even have room for an exhaust. Then they add cats and resonators along with it. Of course they are built for flat smooth highways and not off roading or living in the boonies.

 

Wagonkiller is correct. Official docs for 71 Fullsize Chevy. BOP should be same/similar:

Wagon:



Wagon and Coupe/Sedan:


Except wagon:


Make note of all the stuff that gives spaces, clearances, and how much suspension should droop, etc. Also look at the crimped/flattened portion by the axle. This is where yours in the pics need help.

Best,
Tom

 

I did forget about the factory slight flattening under the rear. also notice how heavy duty those hangers are in front of and behind the rear.

I also think running it this way may have been for rear 3rd seat passenger comfort? or fire safety? who knows lol

 

I noted looking thru everything in the manual (and some is shown above) that there is only a single exhaust shown for all small block V8 Chevy engine-d full size coupes, sedans, and wagons, but a dual exhaust is only shown for big blockV8 Chevy engine-d full size coupes and sedans, no duals are shown for big block wagons.

I imagine for a BB dual wagon the straight-back pipes after the muffler would be the same on drivers as passengers side, with a shorter turnout to the left. Back when these were plentiful in the yards I never looked, but I know I have seen 454 equipped wagons, and cannot imagine that these monster motor wagons were single exhaust in 71. By 73-74, maybe...

And the hangers may have been a little more stout for a wagon, but the illustration looks much like what I have seen on Chevelles and Monte Carlos, which, in good condition, are pretty tough.

Tom

 

Thank you. I stand corrected.