Well, I broke it.

[pugslyyy]

Hi Pugslyyy,

What's getting welded? Not riveted?

Regards John?

The crossmembers are going to be weldments. The crossmembers and frame rails get riveted/bolted together into the final frame assembly. (A656 steel has excellent weldability/formability)

Here's an example of one of the crossmembers. The channels are stitch welded together, and then the gussets are welded on.

 

[whatcharterboat]

Looks great.

 

[pugslyyy]

I'm at the point in the project where I keep having nightmares that I got a dimension wrong somewhere.

 

[Maninga]

I'm at the point in the project where I keep having nightmares that I got a dimension wrong somewhere.

I feel your pain. I've only seen my truck for a total of 20 minutes since buying it, done the entire design process without being able to verify the measurements and working through any issues that're coming up with the people building my frame & camper via phone. I'm basically trusting that it'll work out and they're experienced enough to do so. Has kept me up at night.

 

[pugslyyy]

I feel your pain. I've only seen my truck for a total of 20 minutes since buying it, done the entire design process without being able to verify the measurements and working through any issues that're coming up with the people building my frame & camper via phone. I'm basically trusting that it'll work out and they're experienced enough to do so. Has kept me up at night.

I've been trying to sync up the new design with the original Fuso drawings, the work Doug Hackney did, etc.

The thing that gives me the most confidence is that I did the drawings using a solid modeling package with sheet metal support (Autodesk Inventor). Except for the elongation coefficients (which I SWAGged) the model works - everything fits, everything unfolds flat, etc.

The thing I'm most concerned about is mating the new frame section up to the forward frame, since the new section get's sleeved by the forward section.

It's nice to be able to pass a STEP file on to the fabricator - that way you get all the details transferred the way you want (all the corners radiused, etc)

 

[pugslyyy]

Photos of the new frame next to the old frame...

 

[haven]

Looks like a bridge truss! Much stronger than the original.

 

[gait]

has to be a win if it looks that good

 

[pugslyyy]

I had it powdercoated. I'm sure it won't look quite that good once we're done installing it, but the idea is to protect it (especially the insides and on top of the crossmembers) where it will be hard to inspect/clean.

 

[SkiFreak]

Shiny....

 

[blackduck]

Shiny....

at least its not beige

 

[pugslyyy]

Test fit of the frame today - it mates up to the front section as intended. Now drilling the 24 9/16" holes (12 per frame rail) that are used to mate the front and rear frame sections.

 

[gait]

first time I've noticed (but still a bit difficult from the photos) - for some reason in Aus the regs (of which we have many and often don't know why) have the main sub-frame beams at least partly over the chassis rails. I also notice that the three (?) sub-frame mounts seem to be at the extremities. Its quite possible that the original unconstrained chassis rails were oscillating (bending) more than with most designs, resonating even, which may have led to the fatigue cracking of the chassis rails.

From reading so far the new chassis rails are of different thickness and will resonate differently (a bit like the bass notes on a piano are thicker heavier (and longer) than the high notes).

One possible suggestion could be the addition of extra flexible mounts. Simply springs which are rated to support their load when compressed a bit and long enough that they don't change much over the limited range of compression/expansion. Extra support for the sub-frame, but also some damping for the chassis rails. There's "lots" of other possibilities.

Very difficult without being there so treat this as possible ramblings of deranged mind .....

 

[pugslyyy]

first time I've noticed (but still a bit difficult from the photos) - for some reason in Aus the regs (of which we have many and often don't know why) have the main sub-frame beams at least partly over the chassis rails. I also notice that the three (?) sub-frame mounts seem to be at the extremities. Its quite possible that the original unconstrained chassis rails were oscillating (bending) more than with most designs, resonating even, which may have led to the fatigue cracking of the chassis rails.

From reading so far the new chassis rails are of different thickness and will resonate differently (a bit like the bass notes on a piano are thicker heavier (and longer) than the high notes).

One possible suggestion could be the addition of extra flexible mounts. Simply springs which are rated to support their load when compressed a bit and long enough that they don't change much over the limited range of compression/expansion. Extra support for the sub-frame, but also some damping for the chassis rails. There's "lots" of other possibilities.

Very difficult without being there so treat this as possible ramblings of deranged mind .....

We are changing the sub frame mounting method - you just don't see it yet. The rear mounting pin is going to be removed and I'm going to add in square tube between the sub frame and top of the frame rails, along with spring body mounts.

 

[pappawheely]

We are changing the sub frame mounting method - you just don't see it yet. The rear mounting pin is going to be removed and I'm going to add in square tube between the sub frame and top of the frame rails, along with spring body mounts.

So the subframe will rest on the truck frame but is able to drop away when it needs to due to the spring mounts?