M900 series exhaust on M809 truck.

[KsM715]

M900 series exhaust on M809 truck. + a tool box

I'm thinking of putting the exhaust stack off a 900 on my M818. Anyone ever done it or seen it? It looks like it would pass thru where the batteries are now.I can relocate those easy enough. I know I would have to remove the second fuel tank, I was going to do that and put a tool box there anyways. I can mod the tool box to past the exhaust thru. Anyone forsee any other obstacles?

 

[M813A1]

It looks easy enough !! You could even add the M939 Battery box mod to your M818 battery box and it would fit the exhaust just fine ??

 

[KsM715]

Ive thought of that but I just dont like the look of that battery box on the side of the truck. I like the current step and boxes. I think I can place a driverside tool box on the pass side and just run the exhaust thru it and maybe put the batteries in the new tool box where the second tank goes. The only thing that I'm not sure about is that the 900 cab is (IIRC) 10 inches wider, that would be 5 inches extra width on the passenger side. I'm hoping that exhaust pipe will still be under the cab. Shouldn't be to hard to mod it if I have to.

While were here what is the diameter of 14.00 tires. Thats another mod I have in mind but the tool box I got is 36" long. It will extend farther towards the rear tires than the current fuel tank does. I suppose I could cut the tool box dow if I need to. It's the under bed tool box from a 5ton cargo truck.

 

[Sevin7]

Isn't the M939 series cab mounted higher (above the frame) than the M809 series? If that is the case, I think that there might be clearance issues running the pipe above the frame as it is in the picture.

 

[spicergear]

I know the 931A2's have the exhaust on the back of the cab. Oh, and yeah...cab looks to be mounted higher as the pipe can be pretty easily seen. Deuce is TIGHT.

 

[KsM715]

Hmmmm something to look into.

 

[Csm Davis]

Pretty sure fuel tank stays put but cab is higher and wider not sure about farther forward but makes sense because of bulge in fire wall. I am not sure but I think you might have enough room over the stock battery location to run the pipe through over the batteries sounds like a great idea you might have to get some different bends but I think it might be doable

 

[quickfarms]

how about making it a weed burner.

there is a field modification to do that to the 900 series

 

[KsM715]

I was out looking things over and it does look like there might be enough room under the cab but over the batts. I'll just have to wait till I get my hands on the complete exhaust to see if I need to make some cuts and custom bends to fit.

 

[KsM715]

Got the second tank removed and installed the tool box. Looks like it was made to fit there. It Might be a little tight with 14's on it though. I plan on getting a davit crane and spare tire holder off of a 900-a2 (should be wide enough for a 14.00 spare) and I'll probably lose the walk plate under the pass. side of the truck once I get to putting the exhaust on.

 

[sandcobra164]

Jeff, you're trying to re-invent the wheel. On an M809 base or A1, the muffler is under the hood right there on the exhaust manifold. If not,add or put a muffler in the stack behind the mirror. Losing a fuel tank of 40 gallons on an M818 limits your range greatly, ear muff's are cheap as are a simple in and out muffler and the needed supports. I like the toolbox though.

 

[KsM715]

The muffler is there I just want to get the sound behind the cab when going down the road. Besides I like fiddling with things.

I doubt I'll ever drive the truck far enough to worry about losing some range. It's nice to get out and stretch your legs every few hours and it gives people a chance to stop and ask "where'd you get that?"

 

[KsM715]

How wide is a 14.00 tire? Edit: found it, somewhere between 14-15 inches. I got a davit crane and the exhaust off a 923 yesterday. I got the complete set-up from side side but it's only 12" wide. I've been told the 923a2 davit set up is 15" wide. I'm pretty sure I can mod this to fit a 14.00 if I have to. (yep time to get the tape measure and welder out). I got the exhaust piping from the manifold back. Time to see if it works. (That is if I can get up off my butt today. You dont realize how heavy that stuff is till you start pulling it off and moving it around)

 

[KsM715]

Got alittle work done this past weekend. I think with just a little bit of cutting on the bottom lip of the cab and on the splash guard under the fender I can get the exhaust to work. It will take some custom exhaust work to get the piping from one end to the other but not much.

 

[MidnightDuramax]

I have dual stacks on my M818. Kept the fuel tank and batteries in the stock location. I was able to rune a 5" pipe from the engine under the cab and into the stacks. In my case I wanted dual so I lost the tire carier but pipe routing should have been the same for your single. I trimmed the same spots you mentioned and have had no problems. I have been running my set-up for 2 years. I will try to get some pics.

 

[timothy1]

Midnight did you keep the muffler or straight pipe to the stacks?

 

[MidnightDuramax]

Both kept the muffler at first then I straight piped it. It is straight piped as of now.

 

[KsM715]

How loud is it in the cab at highway speeds straight-piped?

 

[MidnightDuramax]

About the same or a little louder than a duece.

 

[timothy1]

I thought about doing that on our truck but keeping muffler and routing between battery cover and frame under cab, but didn't know how the bends would be with keeping the muffler stock.