Frame specifications of the boxed HD frame

Hendrickson360 · June 15, 2013

Hello,

since i've read that GM will use the 2011 boxed HD frame a little while longer i think about getting one and i really like to compare it to some other frames i owned or know about.

As far as i know the Dodge HD frame is around 190mm in height, 70 mm in witdh and the metal is 4mm thick.

Ford uses a similiar boxed part front but sadly remains using an open c in the rear, which is also 190mm in height and 70mm in withd but of course a lot thicker, around 7.6mm to my knowledge.

So how about the silverade HD frame? It looks pretty tough, got some nice slid crosmmembers, which seems to be welded more carefully trough both the inner and outer part of the boxed frame than the ram cross members, but how about the sheere frame height ans especially thickness??

Greetings

newdude · June 25, 2013

2500hd:

Width: 3.49in. (8.86cm)

Depth: 8.46in (21.49cm)

Thickness: 0.181in (0.46cm)

Section Modulus: 6.811in

Yield Strength: 60,000psi (413,700kPa)

RBM: 408,660

All from GM: http://www.gmfleetorderguide.com/NASApp/domestic/graytabcontroller.jsp?graytabtype=7&rpoid=36178&vehicleid=12791&section=oi_def

For comparison purposes I wrote this up about three years ago on a different forum:

2008-2010 F-450/F-550: Frame uses 36,000psi steel

2008-2010 Ram 4500/5500: Frame uses 50,000 psi steel.

2011 2500hd/3500hd: Frame uses 60,000psi steel.

Modulus is 6.811 cu.in. and RBM is 408,660.

That would put the GM's RBM over the F-350 (313,200) and over F-450/F-550 140.8 and 164.8 in. wheelbase regular cabs, 161.8 in wheelbase super cabs, and 176.2 and 200.2 in wheelbase crew cabs (modulus of 10.1, RBM of 363,600).

So, as far as I could see, at the time, the 2500hd and 3500hd(non-chassis cab) frames are very very stout.

3500hd chassis cabs are an entirely different beast:

http://www.gmfleetorderguide.com/NASApp/domestic/graytabcontroller.jsp?graytabtype=7&rpoid=36178&vehicleid=12793&section=oi_def

That RBM is near Kodiak numbers when they were out on the market.

Edited June 25, 2013 by newdude

Hendrickson360 · July 6, 2013

Hello,

thank you very much for this quite detailed answer!

It is very interesting that compared to that, the Dodge boxed Frame looks pretty weak! Less height (depht in gm's words), little less width and little less material strengh.

I guess this height(depht) is measured at the biggest part between the two axles, becaise normally at the end and front point it's much lesser in size.

Well the chassis cap is of course pretty different, since i guess it is an open c from the first door to the rear?

Sadly i do not have the data from the Dodge 3500, but it is definetly bigger than the Ford f-350 chassis cap, (which is only 195mm in height and 77mm in width, so a little more width but far less height) but how the **** did they rech 12mm thikness??? this has to be some sort of double layer! The only truck i know with this kind of frame is the ford f-550 in the 19500lbs version which has to layers , both the same dimensions (195height, 77mm width) and with 7+8mm thickness adding up to around 13mm.

But why using an even bigger c-profile of that insane thickness for a 3500 truck? this frame, if the data is correct, would be strong enough for 19500lbs at the least, if it is not combined with the normal boxed 3500 front end, which would be a weak point conidering the overdimensioning of the rear part...

Greetings

Hendrickson360 · July 6, 2013

oh and what's rbm?

C/K Man · July 7, 2013

_{RBM is Resistance Bending Moment. It's a bid complicated, but here's a good explanation:}

_{http://en.wikipedia.org/wiki/Bending_moment}

_{It's basically at what load the frame bends.}

_{Looking at the specs. of the 3500HD cab and chassis models, it is very surprising GM does not offer 4500 and 5500 models yet. Seems that with that kind of frame strength and the new front suspension, all they would need are higher capacity rear springs and axles.}

Hendrickson360 · July 7, 2013

Well yeah ok but that's a quite theoretical number, when it comes to offroading bending and torsional stress is quite important and at this point the crossmembers are as important as the main rails.

The boxed 2500/3500 frame (i guess it is the same frame there?) has those nice pipe-shaped crossmembers which are weldet trough both the inner and outer metal of the boxed frame, this is the way to go. This method is used by the mercedes g-wagon, the mercedes unimog (some models do have a boxed frame for the military), the Mowag Duro, the MAn Kat and so on etc.

But the chassis cab, sadly, is using those pretty simple boltet crossmembers which are shaped like pretty simple sheets of metal, ford and dodge do the same thing with their chassis cabs.

Does anyone here own a 3500 chassis cab of the new generation and can take a picture or two where this insame material thickness is? are there layers? Is the height only in the topkick area and how is the boxed front part added to the open c-rear?

Greetings

5Alive · July 7, 2013

Hendrickson360...

Your user name may or may not be different, but I think I recognize your writing... and believe you are from somewhere in Scandanavia, Norway, or Belgium (forgot which) and have posted similar type of frame questions on a Ford truck enthusiast website about a year or two ago concerning the strength of Ford chassis cabs frames. I'm curious what you are ultimately looking for?

C/K Man · July 7, 2013

The C-section frame rails aft of the cab are used on chassis-cab models to facilitate mounting of vocational bodies. Mounting vocational bodies to boxed frame rails would require bracketry specific to the particular truck, and in the U.S. the industry has standardized on C-channel rails with 34" outside width.

Hendrickson360 · July 9, 2013

Well as you can see i am collecting Datas about these trucks from each major brand. Why? Because it is very hard to get your hands on one of these trucks over here, so i can not measure for myself and this kind of information is pretty hard to get.

Since i am planning to use the truck offroad and it might get pretty tough, the frame is a very important part and as you can see, it differs more than one would expect it to do in this close competion market. Data about the axles, the transmission and the suspension is much easier to get and most of those parts are quite easy to upgrade, but you're not allowed to tuch the frame.

Of course you can not just compare the outer measurements, as i described above, the entire design is important. From the sheere numbers the Chassis Cap frame is much stronger, but since i have no picture of the part where the rear and front frame is combined, it's hard to tell what#s really going on. If the hydrformed front part is exactly the same the entire frame is not really stronger offroad, because it will twist at the front then and if the thickness is generatet by using 2 layers, it is not as strong as one solid piece of metal.

In case of the F-550 the boxed front part is also much stronger as the front part of the lighter trucks, so ford designed an entirely stronger frame, but this is of course a class 5 truck, so it's uncertain weather or not chevy did the same. So since the normale fully boxed frame is already really strong and features those nice pipe-crosmembers, it may be the better way to go.

Greetings

Hendrickson360 · February 15, 2018

Does anyone know if the rear end of the 3500 chassis cab is still this extreme huge piece of metal?

The number on the link above:

http://www.gmfleetorderguide.com/NASApp/domestic/graytabcontroller.jsp?graytabtype=7&rpoid=36178&vehicleid=12793&section=oi_def

are no longer there, so maybe something changed.

I guess with this massive rear end and the solid front end, the Chassis Cab frame is probably as strong as a HMMWV-Frame. The rear axle would probably be stronger than the IRS on the Humvee, which leaves only the front suspension as a weakpoint, so maybe with some front upgrades you could built a narrower offroad vehicle from that beast, that could rival a humvee in strenght....

Gary Goodloff · April 2, 2020

Would anyone know the steel/frame dimensions of a 2007 1500 LT extended Cab Silverado.

My son just bought one and everything on it is great - EXCEPT the entire drivers side frame is rusted through - (salt)

I'm looking to buy the steel then have a shop fabricate it in.

Any help is great.

davester · April 7, 2020

That sounds like a train wreck waiting to happen (patching up a frame rail that has rusted through from end to end). It'll be cheaper/faster/better to get a used frame from a junkyard, a truck being parted out, or a used part place...