M809 M54 M35 Cab Roll Cage, Roll Bar

[Superthermal]

Anyone out there ever put a Roll Cage into an M809 M54 M35? These models share the same cab. Anyone ever done it in cab? Behind the cab roll bar? Frame mounted? What DOM tubing would anyone suggest to handle a full tumble roll with a 5 ton?
I am leaning to be more practical to just mount a frame mounted Roll bar behind the cab between the bed and cab.
If anyone has any pics of one done I am interested.

 

[SCM35A2]

Anyone out there ever put a Roll Cage into an M809 M54 M35? These models share the same cab. Anyone ever done it in cab? Behind the cab roll bar? Frame mounted? What DOM tubing would anyone suggest to handle a full tumble roll with a 5 ton?
I am leaning to be more practical to just mount a frame mounted Roll bar behind the cab between the bed and cab.
If anyone has any pics of one done I am interested.

I myself have thought about this as well too.

 

[Superthermal]

For my M813 that has the stock bed, which I see as amazingly tuff, i.e. no drop sides, with fully welded gussets in all the right places, could be used to mount at least to the front of it a hoop like roll bar similar to what an 80's pick up truck might have had.
Concept:
If I made a hoop that shared strength with the bed frame and then a pair of backward bars still keeping with the bed sides and a pair of cross bars to take side impact, I think this would be the strongest setup aside from moving the bed back however far and just going directly to the frame. This option of using the bed may be the easy route, but could the bed detach in a roll over? I don't have a dump bed or anything like that and the bed is bolted in the rear in the stock 4? locations and the front has the articulation springs in the front with what looks like 4ea 9/16" bolts. Made this drawing with what would my first thoughts of connection points. I am thinking 2" or 2.5" DOM .250 wall tube would land on 6 total mounting plates with bolts and welds. The overall height would be tastefully over the cab. Maybe I would even attach my double 16.00 XZLs to the rear down-bars

Picture below is borrowed from https://militarytruckdepot.com/product/1971-kaiser-carbo-bed/

 

[G744]

The aftermath I saw with a fatal downhill rollover in an M52 leads me to believe the defenestration of the windshield frame & glass, ragtop supports, and door glass is what got the poor soldier. Those parts looked to have turned into knives and daggers.

The residue was at a guard base, some months after the accident. A part of the cab was torch cut away as well, I suppose to allow access.

It happened on a 6% grade, pulling a lowboy with an M113 APC aboard. The story was too much speed on turns, went off into large boulders.

A 4-point in-cab 4130 cage would be the best idea to keep the interior from collapsing, even it was ripped off the frame.

One at the rear outside would be better than nothing.

 

[US6x4]

I've given this idea just a little consideration and haven't gotten beyond the front-of-bed configuration. Anchored to the bed with a frame-to-bed mount on the bottom side of the bed floor in the same location. Personally, I need a 16.00R20s storage rack & crane in my bed so maybe a cage or hoop could be integrated. While not as ideal as an inside-the-cab cage I think it could keep the ground from touching the tops of the seats.

Since these trucks don't really care about added weight i would think about something big like 4" DOM with 0.5" wall.

Babenhausen 1974. Looks like a rollover.

 

[matt444]

The cab is to small to put the cage inside the cab without hitting your your head.
There is barely enough room to put a 2" hoop behind the cab on a m35 but on mine I had to trim the bed because it's slightly bent.
Tubing size depends on what you want the cage to do low speed rollover or hi speed crash.

Sent from my SM-S906U using Tapatalk

 

[sreng]

I have considered this and things get complicated because of the overall weight. The risk with larger diameter thick wall tube is that rescue teams will have a hard time cutting it out of the way quickly if they need to. To be most effective I would say even a rear roll bar needs at least 6 points to be strong enough. and should be braced directly off mounts on the frame if possible. Adding frame mounted pads to get as wide as the cab is the way to go. It would be a tight fit in the name of safety. For an M35 I would guess that 3.0 x 0.375 tube or square would do. Forward bar would have to go through the cab in the space where you don't step much anyway. You lose a little bit of bed space in the process, it's for safety. Added a basic drawing of an M35. The more small tube bracing added the better it will resist twisting. (original image: https://shopequipment.tpub.com/TB-9-4940-331-30/TB-9-4940-331-300011im.jpg)

For a 5 ton, I wouldn't consider anything less than a sturdy piece from the front spring mount to the forward most rear spring mount area. Managing over 20,000 lbs in a rollover is not easy and it wouldn't really look like the original truck much with an entire custom cab. Less than that, I think anything you add will just be another thing that breaks and squishes you. All just my opinions based on building race cars and off road trucks over the years. Rolling over at 5 mph is a lot less stress than rolling over at 30 mph.

This a cage in a Dakar rally truck for reference. They weight about 9,000 lbs.

 

[Superthermal]

I have considered this and things get complicated because of the overall weight. The risk with larger diameter thick wall tube is that rescue teams will have a hard time cutting it out of the way quickly if they need to. To be most effective I would say even a rear roll bar needs at least 6 points to be strong enough. and should be braced directly off mounts on the frame if possible. Adding frame mounted pads to get as wide as the cab is the way to go. It would be a tight fit in the name of safety. For an M35 I would guess that 3.0 x 0.375 tube or square would do. Forward bar would have to go through the cab in the space where you don't step much anyway. You lose a little bit of bed space in the process, it's for safety. Added a basic drawing of an M35. The more small tube bracing added the better it will resist twisting. (original image: https://shopequipment.tpub.com/TB-9-4940-331-30/TB-9-4940-331-300011im.jpg)
View attachment 878324
For a 5 ton, I wouldn't consider anything less than a sturdy piece from the front spring mount to the forward most rear spring mount area. Managing over 20,000 lbs in a rollover is not easy and it wouldn't really look like the original truck much with an entire custom cab. Less than that, I think anything you add will just be another thing that breaks and squishes you. All just my opinions based on building race cars and off road trucks over the years. Rolling over at 5 mph is a lot less stress than rolling over at 30 mph.

This a cage in a Dakar rally truck for reference. They weight about 9,000 lbs.
View attachment 878326

I read through the Dakar spec sheet and they only have some basic minimums seen here. They did have an extensive structural build list which since they are building race rides are all full cages with gussets, bolted and plated to body parts etc... as I believe we are all in agreement would be best practice.

Spreng, you bring up a good note of what is the build criteria. High speed roll over or 5mph tumble. I was thinking whatever I want it needs to hold up to two full rolls from a hill climb or off camber roll over and be able to hold the weight of the truck in the event that the truck ends up on its lid at the end. In my mind all the 4 wheeling I did where a roll could happen my rig would have done 2 tumbles. I cant even imagine with no cage that someone would live in a 5 ton without something. My rig of the past was an FJ40. Full cage 4 top bars full front hoop, double rear hoop roll bar with drop bars a cross bar in the back and the seats mounted on a saddle that straps from the bottom bottom of the front hoop to the back first roll bar and then had two horizontal bars that the seats sat on. 5 point seat harnesses too. So I felt safe wheeling around. But in the 5 ton... not so much. Amazingly enough my FJ40 had more cab room than the M813 cab LOL!
With as much flex as I anticipate from the frame/bed on this 5Ton I cannot see any attachment from something in the cab to be connected to anything in the bed due to flex.
This is not an easy choice or fab job.

I've given this idea just a little consideration and haven't gotten beyond the front-of-bed configuration. Anchored to the bed with a frame-to-bed mount on the bottom side of the bed floor in the same location. Personally, I need a 16.00R20s storage rack & crane in my bed so maybe a cage or hoop could be integrated. While not as ideal as an inside-the-cab cage I think it could keep the ground from touching the tops of the seats.

Since these trucks don't really care about added weight i would think about something big like 4" DOM with 0.5" wall.

Babenhausen 1974. Looks like a rollover.
View attachment 878296

View attachment 878297

WOW you can see the body just "peeled" back from forward movement. RUFF!



Build designs as per FIA, referenced by Drakar specs and requirements:

https://www.fia.com/sites/default/files/283_2020_chap_8_wmsc_2020.10.09.pdf

https://storage-aso.lequipe.fr/ASO/motorSports_dak/reg-dk21-cst-asc-provisional-210720.pdf

 

[sreng]

I had to start looking. It can go bad pretty quickly. This guy was pretty lucky and probably he has done this kind of thing many times before without trouble.

 

[matt444]

The truck racing here in the US use 2" .120 DOM cages
Which some weigh up to 13,000 lbs going 100MPH
So far the cages have held up well just slightly bent
But in your truck there won't be enough room in the cab to be practical

Sent from my SM-S906U using Tapatalk

 

[G744]

That's why I said to make a suitable cage just in the cab. Kinda like spacecraft with a capsule; don't try and save the whole rocket

If the cab sheared off partially or completely, the occupants would still be in a hardened safety zone.

I've seen how older 5-ton tacticals look after a rollover: tin and glass frames just turn into hazards. Their architecture is nothing like a modern unibody design.

Rather doubtful a 5-ton cargo rig will even get close to Paris-Dakar velocities.

The fact that they are designed to flex far more than an on-road semi rig obviates the use of frame mounted cages.

D

 

[sreng]

The truck racing here in the US use 2" .120 DOM cages
Which some weigh up to 13,000 lbs going 100MPH
So far the cages have held up well just slightly bent
But in your truck there won't be enough room in the cab to be practical

Sent from my SM-S906U using Tapatalk

2" .120 DOM is a great size material. I have used it alot and I have seen it keep 3,000 lb cars survive rollovers ar 200+ MPH (salt flats). The weight of a 5 ton on 2" .120 would likely help to some extent on low speed rollovers if designed properly. Rolling a 5 ton at 50 MPH, it's mostly just time to pray for the best. A cage should bend a bit and even buying you 1-3 seconds of time to maneuver in the cab is a lot of time in my experience. I tend to keep thing on the slow side and be cautious.

 

[sreng]

There is the ROPS cab. Maybe that is an example to go from.

A “Frankenstein” M939A2

by Silvio Iacuone During 2014, some odd-looking M939A2 trucks came up for sale on the Government Liquidation auction site. All of the vehicles released were A2

www.militarytrader.com

 

[TacticalTruck]

I put a cage in a M925.

 

[runk]

Some pictures of the Norwegian / UN / Canadian bed mounted roll bars-

What did you do to your deuce this week?

Hey fellas, been away far to long, looking to put a full roll cage in a deuce cad, anyone ever do it, thanks

www.steelsoldiers.com

And a dismounted picture (from @cranetruck I think)-

 

[G744]

Not much new under the sun...

 

[Superthermal]

For my M813 I would need to move the prime pressure gauge.. maybe... and the hand throttle on the drivers side and the air cleaner "your doing it wrong" gauge on the passenger side. I would also need to move my parking brake pull handle from the drivers left floor to another location.
Unlike the M35 flat floor cage set up posted above, I would need to allow any cross bar setup to be removable from the cage to allow trans and t-case access. I would also need front to rear lower bars and quad upper bars like I had in my FJ40.
I do like the cargo-roll bar as well. When I get to this I think it would be best to be doing both, Cab cage, and Cargo roll bar for added safety. I'll start gathering measurements to see how much 2" I would need for each project part. I'll post that later.
t

 

[Superthermal]

There is the ROPS cab. Maybe that is an example to go from.
View attachment 878452

A “Frankenstein” M939A2

by Silvio Iacuone During 2014, some odd-looking M939A2 trucks came up for sale on the Government Liquidation auction site. All of the vehicles released were A2

www.militarytrader.com

I like it.
Any idea what tubing size they used? 2" and some 1 3/4? x .120 or .250?

 

[sreng]

I like it.
Any idea what tubing size they used? 2" and some 1 3/4? x .120 or .250?

No idea. Looks like 2.5". I read they only made 600 of these cabs. Not sure if that is true though.

 

[ToddJK]

That's gonna take one heck of a roll cage to stop that truck from turning it's occupants into a pancake. A simple roll over is one thing, it merely just needs to support the weight,but any kind of roll over with speed, there's no real way of ever knowing that would hold up.

I thought about just replacing the bows with heavy duty steel. The idea was to never hold the trucks weight, but if it was to tip over, that steel would be enough to keep it on it's side. A light duty roll cage inside the cab can't hurt, but also, you don't need something that becomes a trap either if it was to collapse.

That was my idea anyway.