Corolla Exhaust Reroute – Making Room for a Panhard Bar

By: Bob Goodson
September 15, 2020

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Author: Michael Yount

I decided to pull the exhaust system off from the header back.  It had been welded on while on a lift — so I had to make a Versa-saw cut to remove it.  But cuts need to be made to modify it anyway.  Where the tailpipe turns up to go over the rear axle — they left it way too close – only about a 1/4″ clearance between the front of the axle tube and the upward riser.  And, where it turns down behind the axle – it sits in a place where it will interfere with me fabbing up a Panhard rod the way I’d like to.  So, off it comes for modifications.  Disconnected from the header below.

The gasket separated – not a surprise.  Fasteners came apart easily but are quite corroded.  For about $5 total, new fasteners, washers and a 3-bolt/2.5″ flat gasket

Disconnected the bolt-on hangers in front of and behind the rear axle and un-did the rubber “loop” hangers at the back of the muffler.

Then, with one cut by the Versa-saw — out she came.

I removed the over-the-axle bit from the muffler — and then made a clean cut, also cleaning up that end of the muffler for welding.  

I also noticed that there were some leaks from the muffler seams.  So I did a bit of hammering on the seams to tighten them up.  Wire brushed the problem areas and applied hight temp RTV.  The heat this far back on the system isn’t extreme – I think the sealer will work fine.   And of course, a bit of satin black paint will cover everything up.
I think I’m gonna reroute the over-the-axle piece to under-the-axle.  I’ve had dual 2.5″ tailpipes on my Volvo 242 (LS3 powered) running under the axle for almost 25 years.  Never a problem and never any contact between the axle and tailpipes.  The OEM Volvo set up runs the tail pipe under the axle.  The nice thing about an under-axle set up is that it makes removing the system a piece of cake.  So as I continue to work on things, dial things in – if I need to remove the system, I can — without CUTTING anything.
Made a bunch of cuts to square up the bits that will go back on the car – makes welding a bit easier.  Also removed the hangers on the muffler and the chrome tip.  Not a fan of chrome — and, doing this will allow me to rotate the muffler 180 degrees.  This will place the inlet closer to the centerline of the car — it’ll line up better with the run under the axle.
Playing with muffler positioning and pipe routing.  The offset piece coming out of the front of the muffler was left over from fabricating the duals on my V8 Volvo.  It’s about the right offset to clear the axle underneath – certainly good enough to help me do the head scratching part of this exercise.  It would be better if it were 2.25″, rather than 2.5″, to match the pipe coming back from the header – may have the local muffler shop see if they can replicate it 2.25″, and expand one end for a tight fit into the muffler opening (2.5″ ID on muffler/OD on the pipe.
After spending a lot of time under the car looking and thinking – decided I’ll stick with the 2.5″ offset piece I already have.  Tacked it into the muffler, and tacked the ‘tail pipe’ (all 11″ of it) into the muffler just to help with fab.  Located the hanger and tacked it into place.  
Looks like muffler alignment and tailpipe length/angle is gonna work out fine.
Picked up a couple of pieces of new pipe in 2.5″ and 2.25″ to finish up.  The final exhaust tip.  Nice, tight fit – just needed a couple of tacks to keep it in place.  Also reconfigured the hanger and welded it to the muffler.  The rubber donuts attach to a bracket on the car – had to remove it and slot the mounting holes to center the tip in the body opening.  The mid-pipe hanger was shot – so I modified a new one to weld to the mid-pipe — used the same chassis mounting point.  Also made a “pie cut” in the mid pipe to slightly modify the angle that it takes towards the rear angle — that will be welded up.
Took a 15″ piece of 2″ cardboard tubing — and put 2 angle cuts on each end.  By rotating each cut end independently, you can create a piece that creates offsets in more than one plane.  This was my first guess at what the piece might need to be shaped like.  It needed to accommodate about a 1.5″ horizontal offset and about a .75″ vertical offset.  So I guessed and taped stuff together.

And danged if it wasn’t pretty close on the first try.

With that proof of concept, I mimicked my cuts on a 15″ piece of 2.25″ pipe that I bought for this purpose.  I’ll tape them  together and start to test fit. 

Test fit the taped up pipe – fit just great – so I tacked it up and another test fit.
Beautiful.  Pulled it off – welded it up and painted.  The connection to the mid-pipe is a really snug slip fit about 2″ deep.  It would be nice to be able to remove the system (if need be) in two pieces – so I put some high temp RTV in that slip joint and tightened a stainless steel clamp around it.  Hopefully it will seal.  But if not – I can easily put a good tack weld on it under the car, pull it off and weld that joint too.

All of that so that I can fab a Panhard rod that will go about where you see the 1/2″ wooden dowel.


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