M939 Exhaust Mod as in 800 Series.

[99nouns]

Hello every one,

I am planing to relocate the exhaust to front by passenger side fender and support it with brackets like the mirrors. Just as close to hood so that it will not interfere with opening of the hood.

Now you might ask WHY???!!!

Well I am removing the spare tire and using the space to build a box extended from the bed in its place 3" away from the cab.

And out of all of my very little experience of building things I am worried that I will have problem supporting a muffler which is very heavy on-and-through that fender none of the less I haven't measured gauge of it, which seems less than .125 steel bent in all different directions to make it amazingly stronger than if it was flat. Kudos for the engineer. (sorry I had to read that twice to be able to understand my self)

Also because of the difference in movement between cab and chassis I am planing to use exhaust flex pipe after 1' or 2' out of turbo where pipe drops down just before or around front wall of the cab, turn about 100 degree towards out an reach to fender and turn up possibly with an elbow and reach for the sky.

Because of the above mentioned problem I want to delete the muffler and use flex pipe.

So my actual questions are 2.

1- Will I have problem with local law for removing muffler if sound is too loud? Does it become too loud? Will I be making new enemies in the neighborhood? Because I am planing to drive it often.

2- How durable is steel flex pipe? The ones made for exhaust systems, will it be able to successfully compensate the movement between chassis and fender and will it last while doing that?

I would like to thank all in advance who shares their thoughts on this subject.

 

[Floridianson]

I like my ears working. I vote for muffler.

 

[jasonjc]

There is a good reason its behind the cab with a muffler. Just saying.

 

[patracy]

I can say that my SEMTT project has completely changed my thoughts on MV noise. It's kinda strange. All the noise is behind me. It's still loud, but completely different. It's been a while since I drove my deuce. But that stack right there gets old...

BTW I just put a stack on the HMMWV too. Again, that completely changed the noise inside the cab.

 

[JohnnyBM931A2]

I can say that my SEMTT project has completely changed my thoughts on MV noise. It's kinda strange. All the noise is behind me. It's still loud, but completely different. It's been a while since I drove my deuce. But that stack right there gets old...

BTW I just put a stack on the HMMWV too. Again, that completely changed the noise inside the cab.

Yup. Nice to have it father back. Not to mention the exhaust gas that inevitably makes it into the passenger compartment if the exhaust is forward of the cab.

 

[Tornadogt]

I did this
http://www.steelsoldiers.com/showth...uot-Miss-Ava-Lynn-quot-Mods-and-Repairs/page4
Post #36 It clears well, just warn the passenger to watch out for the hot pipe..

 

[99nouns]

TornadoGT I envy your measuring skills on round pipes, that exhaust fits like a glove, but my project is bit more complicated than that, and hopefully I will try to post a pic on details of what I am building soon.. But I need to bring that pipe forward of cab even if I have to go around the front bumper...

 

[JohnnyBM931A2]

TornadoGT I envy your measuring skills on round pipes, that exhaust fits like a glove, but my project is bit more complicated than that, and hopefully I will try to post a pic on details of what I am building soon.. But I need to bring that pipe forward of cab even if I have to go around the front bumper...

Why are you so intent on having the exhaust at the front of the truck?? I understand if you're building a box on the back, but that does not automatically mean that the exhaust needs to go up front. I can think of 2 solutions right off the bat, unless you plan on driving through deep water.

First idea, is to cut the exhaust right under the passenger side of the cab, where the passengers feet would be resting on the floor. Add a round muffle there, then put a 90 degree exit pipe right before the end of the cab, so the exhaust exits out of the gap between the base of the passenger side of the cab, and the top of the passenger side toolbox.

The other option that comes to mind, is running the exhaust along the frame rail of the truck, and having it dump out the back. That is what Acme66 did on one of his 5 tons>

https://www.youtube.com/watch?v=Ti4sryZ2oDE

Like I said, the only issue with that is if you plan on going through deep water. But if you don't plan on doing that, both of those ideas will work.

 

[Floridianson]

I would not want the end of the exhaust pipe low and near the cab. When at stop lights or real slow driving you are looking at maybe exhaust coming back into the cab.

 

[74M35A2]

Yes, the stock muffler is very heavy. Use of a stainless in-line aftermarket muffler will greatly reduce your bracketry. Flex tube for exhaust is junk, regular steel is rotten in a year or so. Stainless flex will last longer, but also not forever. It has to be thin to flex, and each grove holds a pool of moisture to sit and degrade it. Exhaust gas is hot, acidic, and mostly CO2 and water vapor. Even the factory stainless flex joints on todays cars have a limited life and need replacing. I think you are wanting to replicate an M35A2 exhaust system from a looks and functionality perspective. A pipe support flange to fender could be made easily, say for example from an all steel toilet closet flange (one sized for 4" pipe). Weld it on where needed, bolt to fender. M939 front fender supports a persons weight, so it should be able to do a lightweight exhaust system. I would venture it to eventually crack if expected to hold the weight of the stock muffler over time and vibration though.

 

[JohnnyBM931A2]

I would not want the end of the exhaust pipe low and near the cab. When at stop lights or real slow driving you are looking at maybe exhaust coming back into the cab.

True. The same would happen with a deuce style exhaust, though perhaps to a lesser degree.

 

[Csm Davis]

Just copy the 809 series exhaust

 

[99nouns]

Exciting Part

Thank you for all the replies, I was able to put some illustrations as of now so all who participate can get an idea of what I am trying to do;


This picture shows different colors of the same set up, so you can see different components.
RED Is regular 4" straight either stainless steel or aluminized steel pipe.
PURPLE Is the original pipe coming from turbo.
YELLOW Is the Flex pipe.
GREEN Is the elbows one is 45 and another is 90.
CYAN Is the Muffler which is smallest I could find, P/N 3871 Inlet 4" Outlet 4" Shell Dia 7" Shell Length 22" Overall Length 28" which I have no idea how well will that perform.

Closer view from above the passenger side front wheel.


Explanation of why Flex pipes are used;
One of the two reasons why I want to use a Flex pipe is to be able to compensate the stress that would be generated between the cab and engine as they are separate moving sections.
Second reason is to be able to compensate the separate movement between the cab and box as shown at below picture.



My drawings are as close as to real sizes, so if you want measurements of any area I can provide.

Another perspective;
This is best I could do without interfering with opening of hood.



Box will be covered with aluminium sheet, how much space do I need for muffler to be away from the box so it will not laminate the sheet because of heat up and cool down process deforms the sheet?
^^^^^^^^^^^^^^^^^^^^^^^^^
Unless you can suggest a better location.

Answers to few questions;

JohnnyBM931A2
Asked Why are you so intent on having the exhaust at the front of the truck??
Because I have an entire platform built at the back and there are side compartments, as far I know I have to sacrifice substantial amount of storage space to be able to run a 4" pipe next to frame all the way back. Not only that, heat is concerned because of a fuel tank on driver side and propane tank and it's pipe lines at passenger side.

About deep water fording;
I am driven by the mentality of "better to have it and not needed than need it and not have it", I dont want get stuck crossing a creek because my presence somehow caused water to pool above my exhaust line. so that's my point of view about deep fording.
Not everything in life of-course.

And I cannot come out from side of the behind passenger door because over-head extension is going to be on top if the pipe and if I move out my width will be wider than legal limits, box is intended to be 102" wide.



I appreciate the suggestion 74M35A2 made at his post #10, I would truly appreciate some solution where expanding reliability and life span instead of using Flex pipe without getting into space technology or price of a space craft, however location of the flex pipes are not at terribly difficult to reach location so I don't mind changing them if I can get minimum of 5 years life span before holes appearing. Unlike underneath a car where it is tucked in space where you have to remove entire system to be able to replace a 4 inch long flex pipe to be able to pass an emissions test.

Thank you for reading all, looking forward to replies.

 

[99nouns]

Just copy the 809 series exhaust

That's exactly what I am trying to do with a twist.

 

[Csm Davis]

Okay big problem I see is you can't, even with flexible tubing, attach the muffler to the camper box it will rip off from the box moving, I have seen movement of 4-6 inches between box and cab at that area, sideways mainly.

 

[Csm Davis]

I think you need to run it underneath the truck with a turndown or turnout at the front of the rear tires. You can cross the creek just keep you foot in the gas, it won't flow uphill against pressure. The rear box will be fairly air tight if you are making a camper out of it and the air flow under and around a 5 ton is huge, as long as you aren't parked with the engine running for an hour you should not have a problem.

 

[Jakelc15]

You could recreate the m809 style exhaust through the mirror brackets and use a muffler that goes in the stack.
https://www.iowa80.com/DirectionsWEB/webcart_productDisplay.php?itemid=185086

 

[99nouns]

So far I have changed the title of my posting and I have been working on this project.

Just 2 days ago I had the parts come in mail;



Then I removed the stickers off them...



Then I made my first mistake and painted them I should have practiced fitting them first and paint them just before installing, unfortunately they are all scratched up now, but that ok I can paint again later...



In a meanwhile Mr. Socks was making sure I was doing everything safe according to CATS standards. (Civilian Automotive Technician Safety)

(He is very polite, he will act as if he is not looking...)

Later I made the hole where the exhaust will be going through...



And practices how I would install it in its place... (don't mind the turnout, that's just the to see if it sits straight)



My next planned step is to fit a heat shield around the 90 Deg Elbow and some of the flex pipe...

Well it is not complete yet, no brackets, no clamps it is basically hanging in the air and I asked my dad if we can please go to test drive to see if all works short of ok, and I didn't like his counter offer after a short inspection, he said he would drive and I have to walk behind the tuck and pickup fallen parts. So no go...

So far it looks good I did put a galvanized flex pipe knowingly being advised that it will not last, but I have no problem changing it to Stainless when I need to, because it was so cheap locally, I could not refuse it...

So my current question is where I made hole on the fender where pipe goes through is tight fit, will that be ok or do I need to make the hole wider then insulate the pipe with some kind of Exhaust Wrap so I don't lose the fender?



I would appreciate any advise.

Thank you,

 

[Csm Davis]

Don't sweat the heat it wasn't a problem on the 809 series

 

[gimpyrobb]

Is that fender fiberglass or metal? Might worry if its glass.