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Old 06-21-2023, 12:57 PM   #1
mrobvious34
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Join Date: Sep 2014
Location: USA
Posts: 23
Exhaust under rear axle?

Does anyone have any pictures of their exhaust routed under their rear axle? I did a search and read several threads where people have done it but have not seen pictures. I have a 67 swb that is on air bags with a rear mounted gas tank. My current exhaust is tucked inside the frame and runs thru the trailing arm crossmember, over the trailing arms and dumps right before the real axle. I would really like to have it run all the way out the back of the truck, however i do not have enough room to run my pipes (2-1/2") over the axle. I also do not want to cut a hole in the frame and run it on the outside of the frame because I have my air compressor & tank mounted to the frame on the passenger side, and my fuel pump and filters mounted on the outside of the frame on the drivers side. Just curious to know from the people who have done it, if the exhaust would hang to low, or have problems hitting when the rear suspension unloads. Thank you
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Old 06-21-2023, 04:59 PM   #2
Rufas
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Location: Fort Mohave, AZ
Posts: 369
Re: Exhaust under rear axle?

I have my 70 GMC C2500, now a C1500, air bagged front and rear. Because of my 6" drop, I also did not have the room to have my exhaust travel over the rear axle. I mounted my air pump and tank on the drive's side outer frame near the cab and the bed. For ground clearance I used shorty headers to keep the exhaust pipes close the the floor of the cab. This is not ideal for heat in the cab, but I use exhaust wrap from the collectors to the just forward of where the exhaust exits over the frame. The wrap works very good to keep the heat out of the cab.

I'm using the Ride Tech Rear StrongArm System and Rear HQ Shockwaves air bags. I used this system to replace the 3/4 ton 7 leaf rear springs on my GMC.
https://ridetech.com/product/60-64-g...le-adjustable/
https://ridetech.com/product/1963-19...stem_11337199/

My exhaust pipes (2.5 inches) go through the tubular cross over from Ride Tech. The next two photos are of the passenger side where the exhaust pipe crosses over the frame and follows the frame over the rear axle. No holes were drilled in the frame to do this. Doing this does not allow enough room for mufflers to be mounted before the rear axle. I did not want to mount the mufflers under the cab because of heat concerns. My muffles are mounted in the rear near my aluminum rear gas tank. Sorry don't have a picture of those. I do not have any interference problems with the tires and exhaust.



This is looking forward from the rear on the passenger's side. Look in the upper left corner and you will see the edge of my Flowmaster muffler. The pipe exits the muffler and is tucked nicely under the rear bumper.


You can see how the exhaust exits the rear bumper. The mufflers are mounted high so they are not visible from the side of the truck. The exhaust sounds good, loud enough to have a presence but not annoying and NO exhaust rumble. I don't remember the Flowmaster number. They are not the smallest ones nor the largest. But they do a good job of sound control.
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1970 GMC 2500
700R Trans, RideTech 4 link rear suspension, air bagged on all four corners, factory upper/lower A-Arms, 2 inch drop spindles.
350 SBC 300hp
Weiand Supercharger
FiTech 30004 EFI

Last edited by Rufas; 06-21-2023 at 05:09 PM.
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