Bobbed M925

[wehring]

Hey Folks,

The M925 has not sold so I have decided to put it under the fire knife during my Christmas vacation. Will, Soni, Joe and other big truck gurus please chime in for some questions. This is my first bobbed truck with air brakes so I do not really know what I should expect to find.

Question 1: Will I need a proportioning valve when I use a single rear axle or is the supply to the tandems split in a way that I will not need one?

Question 2: What is the groups opinion on an optimal wheel base? I am going to use a deuce (12') bed so I figured I would get an approach angle from the front (remember the winch) and match it on the rear.

Ideas to incorporate. I am going to:
1. Replace the drop down pintle with a deuce pintle and add one of my drop down double receiver hitches.
2. The rear suspension will be the Freightliner airbag system
3. Don't know if I am going to run 1400s or 1600s. Got 1400s in the tire room but the 1600s would look great.
4. Going 686 tan (got some deuce tan cargo covers that need a purpose)

What say ye? I am sure the purists are locking my Lat/Long in their GPS machines to hand deliver me a good beating.

Justin Wehring
979 997 3112

 

[gimpyrobb]

Sounds cool, make sure we get progress pics.

 

[steelsoldiers]

First thing to do, go here and download the SOMARPI manual. It will show all of the air brake valves and lines in great detail. https://premiernorth.com/m939/DesktopDefault.aspx?tabindex=1&tabid=9

Then, go here and download the P2P program: https://www.themotorpool.org/forum1/uploads/p2p/

The supply to the rears is split. There are relay valves over each rear axle. The first rear gets a supply line from tank #2 I believe. That line has a T in it, which goes to the rear-rear axle relay valve. The brake pedal treadle valve sends an air signal to each of the rear relay valves. It is split in a similar fashion. You should be able to remove one of the rear axles and cap the T's to keep the brakes working. The front axle has a limiting valve to bias the brakes properly to the rear. It may be a trial and error thing after you get it running and driving. Good luck and take plenty of pics.

 

[wehring]

Thanks Chris

Thanks Chris. That is the input I was looking for. The links are a big help.

This morning I ordered more paint, tan cab cover and air suspension kit. I also put my driveshaft guru on the hook for a TBD fab job. This project is underway!

Justin Wehring
979 997 3112

 

[Derrickl112]

Make it like the experiment 4x4. thats what i want to do.

 

[wehring]

Yup that is it...

That is what I am shooting for.

I have not confirmed but I believe that truck has a 12' bed on it. It is big enough to still be useful but smaller than the big 5 ton bed.

Justin Wehring
979 997 3112

 

[Alredneck]

Wow that rig is pretty sweet! Where were the pics taken? Those tires look a lil small to be 14s or 16s. Maybe 12s or 14.5s.

Its been awhile since I have messed with 900 series, but was thinking along the same line as Chris about how the brakes work or are layed out!

THe pics above look like a deuce bed and seem proportionate for the size vehicle, needs bigger tires!

If you need a deuce bed I have a pretty good straight one, paint flakes off but no rot for $300.00. I could bring it to you latter in the month when I get some other running arounds done!

 

[wehring]

tires

The tires on that truck are 1400s. I too think bigger tires will look good. I have several beds from deuces I have bobbed but thank you for the offer.

The best I can estimate I will be shortening the truck almost 4' to copy the truck in the pics. 2' from the bed (14 to 12) and ~2' from removing the spare tire carrier assy. The more I kick this around the more I like the idea. The M939 series trucks are great but I do not need the capacity of the rear tandems. The ride will be exponentially better and I will not wear out tires as quickly. I know it will not park as easily as a bobbed deuce but I bet it will get close.

Justin Wehring
979 997 3112

 

[XanRa]

my friend lol

 

[Maxwell1815]

Can't wait to see pics of your progress! It will look sweet!

 

[Alredneck]

WOnt park easier than a deuce? What? 900s have power steering! Size wise, if your asthetically challenged and cant fit things where they belong then you should be driving or doing whatever you might be doing ( or wanting to be doing ) anyway!

 

[wehring]

huh?

I am talking about wheelbase. I can park a bobbed deuce in a standard parking slot at walmart. No two point turn needed. Hopefully this truck will be similar. The comment had nothing to do with driver competence.

Justin Wehring
979 997 3112

 

[Derrickl112]

just dont use a trailer bed when bobbing a 939....

 

[bigjuice69]

i dont like the trailer bed either but i do like the bobbed 939.

 

[wehring]

Thanks for the pics...

I have been looking for pics of an M939 with a trailer bed. It looks just as bad as I imagined. Thanks.

Just my opinion but the deuce bed is the way to go with this series of truck.

Justin Wehring
979 997 3112

 

[Derrickl112]

i found the pictures in one of the rally threads. i think the GA rally? not sure. and from what i have been told its a 101 bed, not a 105.

 

[wehring]

1600s...

Those 1600s do look nice...

Justin Wehring
979 997 3112

 

[nofearnohope]

Are you going to try and have this done for the March rally up here in Bryan?

 

[wehring]

New Years

It will be done for a New Years Day machine gun shoot. It is a carrot-on-a-stick for a friend that wants to buy a tow vehicle for his ferret. I expect to sell it around the camp fire that evening.

Justin Wehring
979 997 3112

 

[nofearnohope]

Wacha got in mind for the March Rally?