Allison M916 + Mk48 Cab = 6x6 "FEMTT"

[Northern Mexican]

Wow Sony, very clean looking truck, beautiful work. This thread is quite the inspiration for a project of my own.

 

[mendo]

Nice work and you better get your A$$ in gear before it starts to get cold!!

 

[M920]

We just picked up a bunch of M939's and if can find a good deal on one of those cabs...

How much do those go for?

Anywhere from $2500 to $4500.....I have an extra one for sale for $2500 if you need one.

Soni

 

[M920]

A Small Setback......

So I feel really stupid this eve.....I spent most of the day re-doing all the hydraulic lines and pipes in the control console, just to discover while picking up my tools, that I did not put any pipe-sealant on the threads of the VERY FIRST thread joint coming out of the hydraulic tank!
This is pretty devastating, since I now have to take EVERYTHING inside of the control console BACK APPART!!!!

I guess the only thing that makes me feel a tiny little better, is the fact that it would have been even worse if I had filled the system with hydraulic fluid already!

Well....I sure hope that tomorrow will be more productive.....


The first pic shows the new and improved suction hoses running from the tank to the pumps. They are also equiped with threaded disconnect couplers, for ease of maintenance.

The second pics show the completed new plumbing in the console....unfortunately the joint that is missing the pipe sealant is behind the elbow just above the hydraulic filter.



Soni

 

[jesusgatos]

Ah, bummer. But that kind of stuff is bound to happen, right?

 

[turbosniper1]

I have to ask this.... Soni, have you ever thought about making a 4-door?? I love the design of this cab, and know there would be major surgery required to move the engine, and/or building around it.... But that would just be SICK!!!!
I'm turning my M813 into a 4-door in order to fit my whole family.... But I've always wondered about making a 4-door HEMTT!!! Your thoughts??
- Matt

 

[goldneagle]

So I feel really stupid this eve.....I spent most of the day re-doing all the hydraulic lines and pipes in the control console, just to discover while picking up my tools, that I did not put any pipe-sealant on the threads of the VERY FIRST thread joint coming out of the hydraulic tank!


This is pretty devastating, since I now have to take EVERYTHING inside of the control console BACK APPART!!!!

I guess the only thing that makes me feel a tiny little better, is the fact that it would have been even worse if I had filled the system with hydraulic fluid already!

Well....I sure hope that tomorrow will be more productive.....


The first pic shows the new and improved suction hoses running from the tank to the pumps. They are also equiped with threaded disconnect couplers, for ease of maintenance.

The second pics show the completed new plumbing in the console....unfortunately the joint that is missing the pipe sealant is behind the elbow just above the hydraulic filter.



Soni

I got a suggestion. Cut the horizontal pipe below the filter and either put a quick disconnect there or a UNION fitting. That way you don't have to redo all the plumbing.

 

[M920]

I have to ask this.... Soni, have you ever thought about making a 4-door?? I love the design of this cab, and know there would be major surgery required to move the engine, and/or building around it.... But that would just be SICK!!!!
I'm turning my M813 into a 4-door in order to fit my whole family.... But I've always wondered about making a 4-door HEMTT!!! Your thoughts??
- Matt

Matt,
Justin and I have been kicking that idea around for a while....problem is that the way the cab is sitting down over the front of the tire makes it very difficult to turn it in to a four door. The second cab would have to be all the way behind the front tire with a considerable spacer added between the two cabs....just not sure what that would look like. Photo shop anybody....

Soni

 

[M920]

I got a suggestion. Cut the horizontal pipe below the filter and either put a quick disconnect there or a UNION fitting. That way you don't have to redo all the plumbing.

Excellent idea goldeneagle! I already went and bought a pipe union and will fix it as you suggested....thanks a bunch!!!!

Soni

 

[goldneagle]

Excellent idea goldeneagle! I already went and bought a pipe union and will fix it as you suggested....thanks a bunch!!!!

Soni

I am glad I got to you on time. I have done a bunch of gas piping in my past so i know the importance of using unions in threaded pipe work. Do you cut and thread your own pipe or do you buy pre-threaded only?

BTW I think your welding skills are top notch. I love the detail you put into the project.

 

[M920]

Top Radiator Mount

Thanks to a great idea from 'goldeneagle', I do not have to take all the piping inside the control console back apart. So I was able to make the top radiator mounts, rivet on the hood latches and install the air compressor intake kit from Cummins.

I used parts from the original top radiator mount and modified them to work inside the ROPS / engine enclosure.

I also moved the air intake for the air compressor to receive drier pre-charged air from the coolant to air intercooler. This makes the air compressor more efficient!

The parts to re-route the air compressor intake hose from the air cleaner tube to the bottom of the intercooler housing are available from Cummins. I can post the Cummins part numbers here if anyone is interested.

Soni

 

[jesusgatos]

Nice work, as usual, and that's an interesting idea (routing the air compressor to the intake). Does the air consumed by the air compressor have any measurable affect on boost pressure or engine performance? Seems like it would be 'diluting' the charge a little bit, no?

 

[M920]

Nice work, as usual, and that's an interesting idea (routing the air compressor to the intake). Does the air consumed by the air compressor have any measurable affect on boost pressure or engine performance? Seems like it would be 'diluting' the charge a little bit, no?

A valid question and strictly theoretically speaking, yes. But in reality, the tiny amount of air that the air compressor uses, in comparison to the huge 'appetite' for air from the 855 engine, is totally neglectable and can not be noticed at all.

To do the math:

Air compressor air consumption @ 2100 rpm engine speed and 0 psi pressure = 12 cfm

Engine air consumption @ 0 psi boost and 2100 rpm:

855 cid x 2100 rpm = 1,795,500 cipm : 1728 = 1039.06 cfm

So the engine uses 86.6 times more air then the air compressor at zero load, wich is the worst scenario. Since the air compressor output drops to 4.5 cfm @ the 120 psi system pressure maitained by the governor, this number will almost triple to 230.90 times more air for the engine over the compressor!

So this is why Cummins does all their later 855 engines like that.

Soni

 

[turbosniper1]

Matt,
Justin and I have been kicking that idea around for a while....problem is that the way the cab is sitting down over the front of the tire makes it very difficult to turn it in to a four door. The second cab would have to be all the way behind the front tire with a considerable spacer added between the two cabs....just not sure what that would look like. Photo shop anybody....

Soni

That's exactly what I've been thinking about when it comes to making a 4-door.... It would probably be easier if you just use the door portion of the cab an got the whole thing, like you do when making a 4-door Out of a 2 1/2 or 5 ton!! I'll do the photoshop tomorrow for you! Here's the photoshop for my winter project!! I'll be turning Into this.... So I can carry the whole family while towing my baby.....

sorry for for the thread jack Soni!! Just wanted to share my design as a possible inspiration for someone! My work is nothing like Soni's... But maybe it will help someone!! Please enjoy the pics for a minute, then back to Soni's Kick @$$ build!!! Keep up the good work Soni! I'm still loving this build!!
-Matt K.

 

[goldneagle]

That's exactly what I've been thinking about when it comes to making a 4-door.... It would probably be easier if you just use the door portion of the cab an got the whole thing, like you do when making a 4-door Out of a 2 1/2 or 5 ton!! I'll do the photoshop tomorrow for you! Here's the photoshop for my winter project!! I'll be turning View attachment 456682 Into this....View attachment 456681 So I can carry the whole family while towing my baby.....View attachment 456683

sorry for for the thread jack Soni!! Just wanted to share my design as a possible inspiration for someone! My work is nothing like Soni's... But maybe it will help someone!! Please enjoy the pics for a minute, then back to Soni's Kick @$$ build!!! Keep up the good work Soni! I'm still loving this build!!
-Matt K.

I think he was talking about a HMMTT cab not a M939 cab.

 

[M920]

First snow already.....yuck!!!

Well, the first snow has hit us yesterday, so I had to spend most of today 'winterizing' the yard.
Finally though, just for the sunset, the clouds parted and illuminated the hills behind my compound with the most beautyful fall colors!

Anyway, despite the cold I did get the throttle linkage done and the air drier fixed and installed back on the truck.....

I'm getting pretty close to firing it up but in hindsight, my 10 day estimate was apparently a little over enthusiastic......

 

[turbosniper1]

I think he was talking about a HMMTT cab not a M939 cab.

I understand that... That's why I said in my first paragraph about using a portion of a cab.... Meaning a portion of a HEMTT cab...
- Matt

 

[59apache]

 

[wreckerman893]

Ref the crew cab HEMMT...if anyone could do it Soni would be the man. Having driven many a mile in a HEMMT I can say that the ride is rough no matter where you sit. My thought would be to use a civilian cab over cab and convert the sleeper area into seats but then you lose the low profile if that was your intention in the first place.

 

[M920]

So close!!!!

So I made pretty good progress on the FEMTT this past week, mostly working on the wiring and air system. I fired it up a couple of days ago and it still runs nice and smooth. I've been hooking up the remaining vitals for the Allison and installed the touch button pad in the cab. As I mentioned earlier, the wiring harness between it and the control box was to short and I had to extend it. There are about 20 wires to deal with and I was worried that I would accidently cross a couple of them and 'fry' the TCU.

I have been changing out senders on the engine to match the new VDO gauges on the dash, but I'm still trying to figure out how to change out the trans. temp. sender, at the bottom of the tranny, without loosing all the fluid....I really do not want to drain it right now....

So I'm thinking TEST DRIVE TOMORROW!!!!