Bolting versus welding on frame

[BobA]

I have a 2020 rPod 176 with 2" x 4" (thin metal and cheaply made) Lippert frame.

rPods of this vintage and older have sagging side walls because;
- the side walls sit ~6" outside of the frame rails
- the floor material is not rigid enough to support the weight of the side walls
- there are too few (or no) outriggers to support the floor from front to back

Many rPod owners have fixed their sagging floor issue by either;
- welding custom-made outriggers to the frame, or
- drilling holes through and bolting outriggers to the frame

I realize that drilling holes or welding on the frame will void the Lippert frame warranty.

That aside, I would like to understand the pros and cons of welding versus drilling & bolting, and any advice.

Thanks in advance.

Bob
Grand Rapids, MI

[Aussieguy]

welding or drilling holes in a frame can BOTH be bad ideas.
you almost need a degree in engineering to modify a frame

welding ... small welds are probably better than drilling
but don't put LONG HOT welds ... keep them small.

divide a span into 3 equal lengths... ............|................|.............
try and stay away from modifying the middle of the 3 lengths ( red section)
black section OK to slightly modify drill etc


divide the HEIGHT of the frame by 3
example frame is 6 inches high ...
the first 2 inches and the last 2 inches avoid holes or modifying ....
middle 2 inches can have holes EVEN IN THE RED part of a span

[NMWildcat]

Take it to a professional frame shop/welder and express your concerns and goals. No worries.

[moose074]

Originally Posted by NMWildcat

Take it to a professional frame shop/welder and express your concerns and goals. No worries.

X2

[wildcatter]

Originally Posted by NMWildcat

Take it to a professional frame shop/welder and express your concerns and goals. No worries.

X3, o would have a welder weld it, poking holes in your frame can cause it to crack if not done right.

[aircommuter]

I have repaired unibody frames since the sixties on Ford econoline trucks when they would tear out a spring mount completely. If you are comfortable welding that thin material then you should make some plates thicker than the frame and the height of the frame so you can install them by welding horizontally on the top and bottom corners of the frame, no vertical welding on the frame, then attach your outriggers to the plate where you can now weld vertical. Making a vertical weld makes a rigid line on the frame where you want it to flex.
I have lengthened and shortened frames on class 8 truck by cutting and welding the frame at a 45 degree angle allowing the frame to flex then adding a fish plate over that attaching with horizontal welds only.

[BobA]

Thanks to everyone that responded to this post.

Frankly, I was really hoping to see more support for bolting, but I guess drilling holes through the frame is not the best idea.

Again, thanks.

Bob
Grand Rapids, MI

[Ballistic]

Why is drilling holes in the frame a bad thing?

[Aussieguy]

Originally Posted by Ballistic

Why is drilling holes in the frame a bad thing?

frames are designed to carry loads.
some parts of the frame are under more load/stress than other parts
removing metal (drilling) in a high stress area can cause cracks or bending of the frame.


You can drill a frame

Knowing where you can drill is the important part.

[BobA]

I guess I was reading into the other comments that bolting was the riskier method of attachment.

My plan is to mount eight outriggers, four per side, to the vertical aspect of the 2" x 4" thin-walled frame. If I drill and bolt, each outrigger will require two 3/8" bolt holes centered on the vertical aspect of the frame, and will be about 4" apart. Since there are four outriggers per side, there will be four sets of two holes (4 inches apart) spaced evenly along the 16 foot frame rail of our rPod 176.

I am concerned that drilling that many holes (16 in total) might significantly impact the structural integrity of the frame.....

This is WAY out of my area of expertise, so just trying to get some understanding. I done so many stupid things in my life, just trying to prevent one more.

[jimmarako]

Originally Posted by BobA

My plan is to mount eight outriggers, four per side, to the vertical aspect of the 2" x 4" thin-walled frame. If I drill and bolt, each outrigger will require two 3/8" bolt holes centered on the vertical aspect of the frame, and will be about 4" apart. Since there are four outriggers per side, there will be four sets of two holes (4 inches apart) spaced evenly along the 16 foot frame rail of our rPod 176.
:

I don't know how much of a match this is. I have the wooden I beams in my house. They point out that there is little stress/deflection in the center of the I so you are suppose to drill all your holes there for wires, pipes,.....

I would think its similar on a trailer frame. loading the trailer the frame will want to sag/bend in the middle. The top of the frame will be in compression. The bottom of the frame will be stretched. The center should be little deflection. Then you are also filling the hole with a solid bolt so that will add back a little bit of strength.

So I'm not a mechanical engineer (electrical) but this sounds reasonable. At least for wanting to drill a few small holes in a trailer frame. Perhaps if this was a fighter jet or rocket I'd be more concerned about stresses.

Jim M.

[aircommuter]

Originally Posted by BobA

Thanks to everyone that responded to this post.

Frankly, I was really hoping to see more support for bolting, but I guess drilling holes through the frame is not the best idea.

Again, thanks.

Bob
Grand Rapids, MI

I should have clarified my welding method was because I thought the frame was tubing and bolting would possibly squeeze the frame out of shape. If it is open channel let me know and I can suggest a bolting alternative if you want.

[BobA]

Yes, aircommuter, you are correct. The frame is a rectangular thin-walled tube. I would guess the metal is 1/8" in thickness.

I agree that the frame will likely compress in the center if too much torque is applied. I have read in other posts that people use Loctite on the nuts because the frame will eventually compress and the bolts will loosen up.

[Aussieguy]

Use jacks and blocking to get floor and wall level again

I would make up some triangular gussets plates out of some nice thick steel
may have to add some angle iron to floor so you can drill and screw into the floor.
then weld the angle iron to the gussets

weld the gusset to the frame and to floor
using small tack welds no bigger than 1/2 inch long

if in doubt ... add some 4 inch long flat bar to the frame where the brackets will be added



weld the flat bar to the top and bottom of the frame tube




Edit additional.
don't forget to paint any welds or drill holes
make sure gussets don't interfere with tires / suspension movement

[aircommuter]

Originally Posted by BobA

Yes, aircommuter, you are correct. The frame is a rectangular thin-walled tube. I would guess the metal is 1/8" in thickness.

I agree that the frame will likely compress in the center if too much torque is applied. I have read in other posts that people use Loctite on the nuts because the frame will eventually compress and the bolts will loosen up.

You could find or have made some c-shaped metal to go over the frame at least 1/2” return on the top and bottom and using some large grade 8 washers and bolts in the middle, 5x16” grade 8 bolts with all metal prevailing torque nuts would be sufficient. Clamping from both sides and tightening with caution.

[BobA]

I've already had the outriggers fabricated at a local shop. Yes, they are over-engineered and I would likely make them out of thinner stock next time.

I've thought about adding a plate to the back side of the frame to eliminate some of the deflection of the frame that is bound to occur......if I go with the bolting method of attachment.

[Aussieguy]

assuming that the cardboard is the frame side....

if the bracket is the same height as the frame height
I would be comfortable using the bracket. I would weld it to the frame

[NMWildcat]

Originally Posted by BobA

I've already had the outriggers fabricated at a local shop. Yes, they are over-engineered and I would likely make them out of thinner stock next time.

I've thought about adding a plate to the back side of the frame to eliminate some of the deflection of the frame that is bound to occur......if I go with the bolting method of attachment.

Ah, the rest of the story. Since you already have the supports built, and are looking for support for bolting them, go for it. Evidently others have done so.
You can also use lock nuts to prevent loosening.
If it were myself, I would at least talk to a frame shop and a certified welder for advice. Then I would probably just trade the RV in Those ultra light frames just aren't made for much modification, especially for DIY mods.

[Ballistic]

Originally Posted by Aussieguy

frames are designed to carry loads.
some parts of the frame are under more load/stress than other parts
removing metal (drilling) in a high stress area can cause cracks or bending of the frame.


You can drill a frame

Knowing where you can drill is the important part.

Have you seen all the holes and welds on these trailers? What about all of the self drilling screws the factory arbitrarily adds when securing braces, brackets, etc? These aren't rockets. Since the objective is to add support to the walls of the RV, when holes are drilled there be a brace/brackets added which will support the frame where the holes are. It's pretty simple really.

To the OP- if the frame is I-beam, then template out your brackets and stitch weld them in place. If it's a tubular frame, then throughholes can be drilled, sleaved with a steel tubing and then weld the sleave to the frame. The sleave tubing will eliminate the frame tube from being crushed. No wheels are being invented here, just standard fabrication practices.

[Aussieguy]

Originally Posted by Ballistic

Have you seen all the holes and welds on these trailers? What about all of the self drilling screws the factory arbitrarily adds when securing braces, brackets, etc? These aren't rockets. Since the objective is to add support to the walls of the RV, when holes are drilled there be a brace/brackets added which will support the frame where the holes are. It's pretty simple really.

To the OP- if the frame is I-beam, then template out your brackets and stitch weld them in place. If it's a tubular frame, then throughholes can be drilled, sleaved with a steel tubing and then weld the sleave to the frame. The sleave tubing will eliminate the frame tube from being crushed. No wheels are being invented here, just standard fabrication practices.

He has a tubular frame... No one said he can't drill holes

just have to know where it is safe to drill holes
Manufactures should know where it can be drilled and welded!



he can use the brackets as long as they go to the bottom of the frame
welding them on easier than drilling sleeving and bolting.


There was a pic on another thread that showed a buckled engineered tube frame and it was not user welded or bolted shows how easily they can get damaged!