1980:Exhaust inside frame??

Joined
Dec 11, 2006
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449
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Rockwall, TX
How can the exhaust be ran inside the frame like earlier models. Does the gas tank have to be relocated? I can run the exhaust up under the skid plate beside the trans, but then I run into the gas tank behind it. What are my options?
 
Joined
Mar 4, 2007
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Honolulu
Three options:
1) go back to the stock gas tank and run the exhaust.
2) have the exhaust exit just in front of the rear tire. This depends greatly on your set-up. May not be street legal in all 50 states. If you have body lift run between the frame and the tub with appropriate heat shielding. If not and your springs are flipped, could exit between the front spring hanger and the rear tire. Must take into account suspension travel.
3) Place the muffler ahead of the rear axle. Route the tail pipe over the rear axle out board of the shock. Run the pipe next to the fuel tank. A heat shield would be appropriate. The exhaust tip can exit in one of two places: if springs are reversed straight out the back. If in a more stock config. exit between the rear tire and the rear shackle.

Needless to say, if the vehicle is primarily stock with an auxiliary tank, slung under the tub, behind the rear axle then your options are limited and careful measuring will be required.
 

3_puppies

SILVER Star
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Helena MT
It's awful tight in there with the gas tank. even if you moved the tank to behind the rear axle, where would the muffler go?

Do you need the cat. conv?? where would that go?
 
Joined
Jan 11, 2006
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2,380
Location
Melbourne
Option 4

I can get a 3" pipe through here too. Never below the frame muffler in the rear. Requires custom extractors though see last pic.

100_4238.jpg


Old system was 2.5"

000_0038.jpg



Pacemakers shortened to go above the gearbox cross-member. To suit 2.5" system for sale too and ceramic coated

100_4159.jpg


Easier with a pre 79 I would think as the gas tank is under the seat.

Matt
 
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65swb45

Elder Statesman
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The thing you've forgotten to include in your query is whether or not the vehicle needs to remain emissions compliant. VERY, very relevant to discussion, as your model year ALSO REQUIRES A CATALYTIC CONVERTER!

:hmm:
 
Joined
Jan 11, 2006
Messages
2,380
Location
Melbourne
No issues with heat clearance it's actually quite good even for the 3" but leave as much space as you can between the gas tank and the exhaust.
Just a note though the 3" is mandrel bent stainless and painstakingly fabricated together to follow the same route as 2.5" and came in at $950Aus 2.5" in steel is way way cheaper.

DSC00119.jpg


New system is complete now.

Never damaged this set up even at comp
 
Last edited:
Joined
Jun 23, 2006
Messages
687
Location
Del Boca Vista, FL
I haven't had any issues with the exhaust run inside the frame all the way back. It was a concern at first though. I guess the heat isn't enough and the fuel tank has a little insulation.
 

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