'77 Excella 500 31' Off Road Build

[Mikebrady62]

That will certainly be a stable floor!
I can't wait to see how the rest will be finished in a completely overkill way.

Keep up the great work and the pictures!

[GPurcell]

Originally Posted by Mikebrady62

That will certainly be a stable floor!
I can't wait to see how the rest will be finished in a completely overkill way.

Keep up the great work and the pictures!

Thanks! Today I will be leveling out the trailer and starting the prep work. Updates this evening.

[truckasaurus]

Just curious as I'm ordering my holding tanks today but are you going with above floor tanks? Anything within the frame cavity at all?

[GPurcell]

Originally Posted by truckasaurus

Just curious as I'm ordering my holding tanks today but are you going with above floor tanks? Anything within the frame cavity at all?

I'll be going with above floor tanks. Frame cavity will be as bare as possible.

[GPurcell]

This should work I think. I'll be adding them to all the edges.



That hurt... grinding away all that fresh paint... however I did find that stuff is STRONG. It did not want to let go.

[GPurcell]

All tacked in to place.





Lined up all the edges.





Doubled for the doorway.



Very happy I'm taking the time to do this.

[GPurcell]

Got a good amount of welding done!



My welds are getting pretty decent

[Iansk]

Nice!
I can smell the sizzling bacon...

Always look foreword to your posts.
You added these to address the subfloor joints, yeah?

I really appreciate the time you take to post your progress.

Ian

[kidjedi]

Originally Posted by GPurcell

kidjedi - I will be cutting down the boards like you suggested so the joints land on a crossmember.

However - I still will take the time to weld in some more supports. Just feels like the right thing to do.

Cool. I know it hurts to trim and "throw away" that Coosa, but i think it's the right thing to do.

And as far as welding in more supports... I wouldn't expect any less. I'm actually surprised you went with Coosa instead of sheet steel.

[kidjedi]

Originally Posted by truckasaurus

Just curious as I'm ordering my holding tanks today but are you going with above floor tanks? Anything within the frame cavity at all?

Originally Posted by GPurcell

I'll be going with above floor tanks. Frame cavity will be as bare as possible.

But... aren't you worried about your center of gravity being too high when your tanks are full and above the deck?

(I'm making a really funny joke, considering the weight of your frame).

[kidjedi]

Originally Posted by tbashin

Interesting. I see this mentioned often but I don't get it though. I can't figure out how the monocoque structure needs to have flex or it pops rivets or could buckle.
I would think that being more structurally rigid, it would prevent the flex that causes these issues.
It seems every time I've seen a post of an AS buckling or rivets popping it was because of too much flex or a hard jolt. Rivets were popped by hitting rough roads or trailer twisting, or due to too much WD force, etc.
Buckling of panels, I would think, can only be caused by displacement of the supporting structure in some way, such as when a wrecker tries to pick up by the rear or extreme tail drag situation, etc.
I can't wrap my brain around how more rigid frame would not help maintain the overall integrity of the structure. A properly cushioning suspension being part of the build.

Yeah... this seems to be one of those things that "they" say, but I have yet to see any scientific evidence (even though I hear/read it a LOT). Part of the reason I started following this thread was just to see how a super-rigid frame would fare in the real world (now I just enjoy the thread and everything GPurcell is posting). Truckasaurus also has a crazy rigid frame, and his panels seem to be holding up fine (though... from what I remember in the pics, I think his trailer only has two reaaaaally long panels).

I agree with what you are saying... if the flex in the frame was absorbing any kind of energy, it would actually *cause* problems for the monocoque shell. Because the shell is fastened all around, any movement in the frame would cause the shell to flex and thus pop rivets or crease.

I would love it if someone would chime in and really explain why a rigid frame could be a bad thing (other than crazy amounts of weight).

[Bubba L]

kidjedi, to build rigid or not to build rigid. That was the question we asked while renovation the 55. I never understood why the horizontal stringers were “floating” and not attached to the ribs. I spoke with Colin Hyde about it and he recommended attaching to the ribs. This built more rigidity. On our frame, I added a 4’x4”x3/16” Steel plate and puddle welded to the main frames from the axle toward the rear to transfer some rigidity toward the rear. I didn’t like the amount of flexion. I understand semi-monocoque construction, but just a gut feeling to add a little more structure. A couple of decades ago I built a beach house. I discussed with the engineer if I needed to build to allow the structure to sway a bit with storm winds or build rigid to withstand the winds. Don’t remember what he said now, but we built very rigid. It withstood a hurricane whereas the surrounding beach houses didn’t. I know it’s a different animal, but we haven’t popped a rivet in two years in or on the 55. That’s not to say we won’t in the future. GPurcell’s frame is rigid, but a heck of a job.

[Bubba L]

Also, good shocks and axles play a big role in ride performance.

[Iansk]

My Avion (28’) has three 6” main rails that are box tube and from just in front of the axle to the bumper there is three 7” c-channels under that. This is factory built and how I’ve seen other Avions. It is muy rigid...

When I pulled the shell off my 31’ AS I was amazed at how much the frame flexed.

I like the idea of the frame supporting the shell and not the other way around.

Ian

[GPurcell]

Originally Posted by kidjedi

Cool. I know it hurts to trim and "throw away" that Coosa, but i think it's the right thing to do.

And as far as welding in more supports... I wouldn't expect any less. I'm actually surprised you went with Coosa instead of sheet steel.

It does hurt Going to see how the floor feels now that the new supports are in. My Dad seems to think it'll be rigid enough not to trim the Coosa but we'll see.

As for sheet steel... that would be overkill

[GPurcell]

Thanks for all the posts guys lmao.

Finished adding the new outriggers and it's ready to be prepped and have the paint touched up.

Floor will be going back on for the final time tomorrow!





This picture kinda scared me because I leveled it out before welding the new supports. Definitely looks like the frame is not level lmao. Just the sloped driveway compared to the barn floor.

[Krek]

Originally Posted by GPurcell

...that would be overkill

I have a good friend who is a professional rollcage fabricator and one of his favorite sayings is "Overkill is underrated".

[Foiled Again]

FLEXIBLE FRAME BENEFITS?

Ever see the bottom side of an AVION?

Massive 6 inch beams.

Flex? Not so much.

[GPurcell]

Originally Posted by Krek

I have a good friend who is a professional rollcage fabricator and one of his favorite sayings is "Overkill is underrated".

I would definitely ask to use your good friend if I ever need a rollcage fabbed up

[GPurcell]

Big moves today. The floor is down for good!

Started by finishing painting.



Then moved on to the floor itself.





Burned the last of the old floor



These fastenal screws were amazing. They bit in to the floor supports HARD. I love them.





Keeping it square all the way down.



Last of the screws going in.



A finished floor. WAY more solid than what we took off. Adding the extra supports was the right thing to do. I'm glad I took the time to add those.