M939 Frame Extensions

[Swamp Donkey]

Yep, please send me whatever you have. I want to put these extensions on as well and it seems to be a chore to find them for the M900 series...especially with the connector rails.

Also, I would be curious to know how much the fab shop is going to charge you to make the connector rails for the extensions.

PM sent.

 

[juanprado]

see if these help?

 

[Swamp Donkey]

That's perfect. You just saved me a lot of guess work there. Thanks!

I'll ask you a question since you plan on installing these. Is there a difference in the hood crossbar or brackets between trucks with a winch and without one? This would be the bar that the trunnion mounts on. I assume the there is, since the inner rail goes past this and there needs to be room for it.

 

[juanprado]

That's perfect. You just saved me a lot of guess work there. Thanks!

I'll ask you a question since you plan on installing these. Is there a difference in the hood crossbar or brackets between trucks with a winch and without one? This would be the bar that the trunnion mounts on. I assume the there is, since the inner rail goes past this and there needs to be room for it.

Not to my knowledge. The crossbar is the same You have to loosen it and remove 2 bolts but keep 2 hooked up and it slips in as 2 holes are used with a longer bolt. A Little foggy since it was July but that is what I recall. In 2 weeks, I will be installing the extensions and winch and can advise what I might not remember.

The inner extensions also have 1/2 fine lock nuts welded inside to hold the bolts fyi. My pics does not show it well as the winch was cut off with a torch and removed previous to my removal of the extensions that were still in place. I had stubs left that I could not grip and it was easier just to beat the remaining stub and nut out than to try to unscrew. I believe the nuts are prewelded as there is little room to work and grip the fasteners with the winch in place.

 

[Oldworldtenacity]

Me and swampdonkey just discussed this issue again tonight since he just got the inner channel rails and I will be getting them next week for my truck.

The brackets underneath the crossbar that bolt to the frame are flush against the frame and there does not appear to be room to slide the inner channel rails past those brackets as seen in this pic below.

That's what we are trying to figure out is if there are special modified brackets available to allow the channel rails to slide past the two bolts for the hood cross member brackets on winch trucks because there is no space between the brackets and frame where the 2 bolt holes are on each side, however there is space between the actual cross member to fit the channel rails. The brackets on our trucks fill the space unfortunately.

Perhaps you have installed your winch at this point and can advise us further?

 

[Artisan]

There would be a small fortune to collect for the guy who duplicates
these extensions for 5Tons and other trucks like the M915 Series of trucks.
Every m923 guy would love a winch, well a lot would...

I would LOVE a winch on the front on my M915 series M916 truck.
A bolt on solution, engineering all done. It would sell unless the
designer was greedy...

 

[MyothersanM1]

I did a little research for you in the -24P-1 (Fig. 31) and -24P-2 (Fig. 46). The cross member (pictured above) carries two different part numbers for winch (12302674-2) and non-winch (12302674-1) trucks. I would fathom a guess that the -2 cross member is slightly narrower to compensate for the additional thickness of the frame extension inner channel. Being that your truck is non-winch equipped, as built, you are going to have to swap out or modify that cross member as part of your upgrade.

BTW...All the parts, cross member and the inner extension channels, are on eBay, but come at a cost. I can get the links if you want them.

 

[goldneagle]

We are having a machinist look at the extensions for the M939 series trucks. I will get back to all of you with costs as soon as I get them.

 

[Oldworldtenacity]

I did a little research for you in the -24P-1 (Fig. 31) and -24P-2 (Fig. 46). The cross member (pictured above) carries two different part numbers for winch (12302674-2) and non-winch (12302674-1) trucks. I would fathom a guess that the -2 cross member is slightly narrower to compensate for the additional thickness of the frame extension inner channel. Being that your truck is non-winch equipped, as built, you are going to have to swap out or modify that cross member as part of your upgrade.

BTW...All the parts, cross member and the inner extension channels, are on eBay, but come at a cost. I can get the links if you want them.

Thanks for looking that up. At this point it doesn't appear that the problem is the cross member...you can't tell in the picture I posted, but there is enough room for channel extensions to fit in between the cross member already. The problem is the brackets attaching the cross member to the frame. Maybe there is a shorter bracket available to allow for the channel extensions to fit through because the bracket is a separate piece from the cross member on my truck.

I dunno...I probably just need to see a pic of the cross member and bracket on a truck with a winch.

Ebay is where me and Swampdonkey both got our frame extension parts.

 

[juanprado]

We did remove one angle bracket which it no big deal to remove just a few bolts and then drilled/elongated 2 holes to the crossmember and bolted it in. I think the side holes to the frame did not need tweaking. There is enough room to slip the extensions in.

I was not aware there were 2 different crossmembers as I could have scooped those off the scrapper donor

 

[goldneagle]

I have 2 of the cross-members here that were leftover from the 2 winces we sold. I will check to see if the holes in the brackets are already elongated. I know that on the passenger side the bracket moved enough to allow the extension to slide in. Modifying the bracket was as easy as drilling 2 holes next to existing ones and connecting them to the original holes with a file. (make an elongated hole)

 

[Swamp Donkey]

There would be a small fortune to collect for the guy who duplicates
these extensions for 5Tons and other trucks like the M915 Series of trucks.
Every m923 guy would love a winch, well a lot would...

I would LOVE a winch on the front on my M915 series M916 truck.
A bolt on solution, engineering all done. It would sell unless the
designer was greedy...

I have actually considered this since all my parts are new and have never been installed, they would be perfect for making copies. I can handle getting the fab shop to do the work but justifying the time to handle the rest (shipping, etc) would be a little overwhelming for me right now. I agree though, there is money to be made...

 

[Swamp Donkey]

I did a little research for you in the -24P-1 (Fig. 31) and -24P-2 (Fig. 46). The cross member (pictured above) carries two different part numbers for winch (12302674-2) and non-winch (12302674-1) trucks. I would fathom a guess that the -2 cross member is slightly narrower to compensate for the additional thickness of the frame extension inner channel. Being that your truck is non-winch equipped, as built, you are going to have to swap out or modify that cross member as part of your upgrade.

BTW...All the parts, cross member and the inner extension channels, are on eBay, but come at a cost. I can get the links if you want them.

This is what I suspected but couldn't find in the TM. I knew it had to he there but I could only find the NSN for the winch cross bar. Basically, the bar on the M923 is fine as it is. It doesn't go all the way to the frame rails so there is clearance for the inserts. I plan to move the bolt holes that go through the crossbar on the brackets in the picture by 1/4" to compensate for the thickness of the inserts. I'll do an updated write up next week sometime after I get finished.

 

[Swamp Donkey]

We are having a machinist look at the extensions for the M939 series trucks. I will get back to all of you with costs as soon as I get them.

I'll pass this along as this has been one of the snags I had to gamble on. It was hard to compare with pictures on the bolt patterns to get a definitive answer.

Basically the extension rails will work either side. All holes are symmetrical, which is why there is only one NSN in the TM. Juanprado eluded to the fact that the inner rails were slightly different and the TM confirmed it as there are 2 NSNs for the inner rails. Basically the only difference is the 2 holes on the very end of the notched end are offset. All other holes are symmetrical. This was causing problems since the inner rails we were looking to purchase were only available in right side. So basically, if you want to use one side for the other, you just need to drill 2 holes. Everything else will bolt up as is for either side.

 

[Swamp Donkey]

We did remove one angle bracket which it no big deal to remove just a few bolts and then drilled/elongated 2 holes to the crossmember and bolted it in. I think the side holes to the frame did not need tweaking. There is enough room to slip the extensions in.

I was not aware there were 2 different crossmembers as I could have scooped those off the scrapper donor

I have 2 of the cross-members here that were leftover from the 2 winces we sold. I will check to see if the holes in the brackets are already elongated. I know that on the passenger side the bracket moved enough to allow the extension to slide in. Modifying the bracket was as easy as drilling 2 holes next to existing ones and connecting them to the original holes with a file. (make an elongated hole)

This is the route I'm going to take, redrill and slot the holes. At this point I'm tired of sourcing correct parts, lol.

Juanprado, your pictures are what kept this ball rolling for sure. They are much appreciated!

 

[Swamp Donkey]

Time for a break so I'll post a teaser shot...

"Operation Pinocchio" is well under way. Ended up with the house to myself tonight so I'll be finished by morning. Gonna be a long day at work tomorrow...



Slotted the hood trunnion bar brackets...

 

[Oldworldtenacity]

Well that was quick! It's a good thing I ordered the inner channel rails today so I won't be far behind you. I will definitely be using that second pic to make the holes in the bracket...I really don't feel like ordering more parts right now either lol.

 

[Swamp Donkey]

The details...

My whole plan here was to install extensions for a bumper project. I need the room for the hood to open with the bumper installed. A toolbox will be placed in between the rails. A winch might be added later but is secondary to the bumper and box at this time.

The problem I ran into was that everybody selling frame extensions wanted to sell the winch too. Without getting into a electric vs. hydraulic winch debate, I don't want the factory winch. So I found a source that had the extensions for cheap and they were new. They also had the inner rails that were new...but were not so cheap...and were only for one side. I started this thread to find out what the difference was between the left and right inner rails and to shed some light on the the whole process. This addition is common but finding specific information about dimensions and such is difficult.

In the pictures below you can see the only 2 holes that need to be drilled to make an inner rail work for either side. There is the original hole on either side with an offset and the new holes with an opposite offset.





The brackets on the end of the hood trunnion support bar had to be notched so the inner rail had room to slide in. This was done by drilling a second hole that slightly overlapped the original, then using a double cut file to open it up.

 

[Swamp Donkey]

I had mentioned before that I considered having the inner rails made. I'm glad I didn't because we would have never been able to achieve the snug fit of the factory rails without already having a sample to copy.

The holes along the top and bottom are threaded via a nut welded on the inside. Those take 1/2" fine thread bolts. The rest of the holes are open and are 1/2". The only bolts that are not 1/2" are the ones for the shackle mounts. Those are 5/8" but you can reuse them.





Since these were new I figured it would be best to assemble one piece at a time. This turned out to be correct as i had to use a porta-power to line some of the holes up. A line-up bar can't be used for the top and bottom holes without the risk of damaging the threads. I figure my issue was the fact that i was bolting new to old. In the end i got them all in. I would assume used rails would be easier to have already assembled and installed as one piece.

 

[Swamp Donkey]

A sequence of events...

STOCK

























FINAL PAINT









THE END.