Drilling into trailer frame.

[Silverbullet555]

OK, a little bit about my trailer and rig.

Boat is 2002 Cobalt 226 with BBC, tower, 2 group 31 batteries and associated crap on board.

Trailer is Performance Trailer, tandem 3500 lb axle, electric brakes on both axles.

Upgraded coupler to 12K coupler.

I need to drill a hole or two holes near the tongue for wiring to come through and go into the toolbox where all the connections are being made.

The trailer is made of painted steel. The front part of the trailer looks like a peace symbol with an additional cross bar in the "Y" of the symbol. I hope that explains the style of trailer. It is a bunk trailer with 4 bunks.

The trailer frame is 3X4" rectangular tubing with 1/8" wall thickness.

As stated earlier, I need to have my wires come out under the toolbox and go into the toolbox.

I have 2 choices on how I drill the holes.

1.) 2 holes, 1 on each side, 3/4" in diameter in each of the frame rails 1-2" away from where the frame rails are welded to the tongue tube.
2.) 1 hole on top of the center section, right in between where the 2 frame rails meet with the tongue, 1 1/4" in diameter.

I would take pics, but it is dark right now.

 

[Bondo]

Re: Drilling into trailer frame.

Ayuh,... those are some pretty Big holes,...
It'd probably work just fine, but that's also nearly 3/4ters of the size of the tube...
Can't ya fit the wires through a 1/2" hole,..??

 

[wellsc1]

Re: Drilling into trailer frame.

Drilling holes in structural members doesn't reduce it load bearing capacity to any extent. Keep your preception open around you as you look at structures and you'll begin to realize the practice is prevalent. What can affect frame is crushing due to too much tightening of u-bolts or welding improperly.

Half-inch holes? That makes me go "hmmm." Maybe your accounting for rubber gromments or something to avoid chafing. Do paint the bare metal inside the hole from drilling.

imho...wellsc1

 

[robert graham]

Re: Drilling into trailer frame.

Maybe tie-wrap the wires to the inside or underneath the frame rails?

 

[Silverbullet555]

Re: Drilling into trailer frame.

The reason for the larger holes is that I added a couple extra runs for wiring for halo lights and backup lights and larger wire for trailer brakes. I also have extra grounds built in and chose to limit the connections and splicing back in the trailer. A bit more complicated, but I believe it will be more reliable in the long run.

I did take into account some extra space for grommet or loom and all holes I have drilled have been painted.

I do think I will be drilling into the sides of the rails a bit further away from the welds and on the inside of the "box" created by the Y and the second cross member. This should limit any potential negative effects. The wires will exit the trailer tubes and go into the toolbox for the final connections in a junction box.

This is a bit of overkill, but I decided to go the extra mile now and prevent any future problems or questions.

 

[bruceb58]

Re: Drilling into trailer frame.

I do think I will be drilling into the sides of the rails a bit further away from the welds.

I agree that I would do this further away from the welds.

 

[jeeperman]

Re: Drilling into trailer frame.

I would instead drill no holes and run pvc conduit along the outside of tongue from the coupler back to the toolbox and up into it.

 

[Silverbullet555]

Re: Drilling into trailer frame.

I would instead drill no holes and run pvc conduit along the outside of tongue from the coupler back to the toolbox and up into it.

Can't. The new coupler covers the end of trailer tongue tube keeping wires from coming out there. The only way I could do that is to drill a hole in the bottom of the tongue and run it out that way.

 

[Silverbullet555]

Re: Drilling into trailer frame.

Thought I would add some pics after sitting and staring at my trailer.

Here is a shot of the tongue area of my trailer. Sorry about the shadows, but after a crappy summer we are finally having nice weather.

The hole you see is where the brake line used to go into the frame rail before I removed the hydraulic brakes and went to electric.

That hole gets covered by the new coupler.

Just out of the pic is the cross member I spoke of earlier.

Here you can see the cross member.

This gives you an idea of the tool box. The trailer plug wire will be entering the front of the toolbox on the lower corner on the port side.

Inside the toolbox will be the brake-away battery and the junction box for all the wiring.

In an ideal world, this is where I would bring the wires up. It would take a 1 1/4" to 1 3/8" hole to bring the wires up right through the bottom of the toolbox and into the junction box. Everything is protected, no hanging wires and it is a clean install.

This is the second favorite location. Just in front of the weld where the side rails join the tongue tube. 1 hole on each side, 3/4" in diameter.

Third favorite spot would be just to the left of the welds, about 4" back from where the outer part of the tube is welded to the tongue tube. The wires would come out and go right up into the toolbox.

I would have liked to have been able to drill on the inside of the triangle on each aide, but I would have to drill pretty far back to get my right angle drill in there. My only option would be to cut rectangular hole with the dremel tool if that was a substantially better place to bring the wires through.

I hope that better explains what I need to do.

 

[bruceb58]

Re: Drilling into trailer frame.

Off subject but you probably could have used your old coupler. I switched to electric/hydraulic and just used a couple of large bolts to keep the coupler from sliding anymore.

 

[Big_Eddy]

Re: Drilling into trailer frame.

If you are going to make holes, round holes are WAAAAAAAAAY better than square. Square will lead to stress risers at the corners and eventually to cracks. Drill your holes and use the dremel to smooth any sharp edges.

The location on the tubes with the LEAST stress is the midpoint of the vertical sides. That's where I would drill my holes. Drill the smallest hole you can get away with.

I didn't design your trailer and I don't know what safety factor is built in, but I wouldn't hesitate to drill a 3/4" hole in the side of a 3x4" tube. You'd never get me cutting a 1 1/4" hole in the top.

 

[bigdee]

Re: Drilling into trailer frame.

I see no problem with an 1-1/4 hole in your "ideal" location.......ROUND holes in structural members,especially square tubing have little affect on integrity.....crawl under your truck and see how many holes are in that frame....and it is probably C channel too!

 

[Silverbullet555]

Re: Drilling into trailer frame.

If you are going to make holes, round holes are WAAAAAAAAAY better than square. Square will lead to stress risers at the corners and eventually to cracks. Drill your holes and use the dremel to smooth any sharp edges.

The location on the tubes with the LEAST stress is the midpoint of the vertical sides. That's where I would drill my holes. Drill the smallest hole you can get away with.

I didn't design your trailer and I don't know what safety factor is built in, but I wouldn't hesitate to drill a 3/4" hole in the side of a 3x4" tube. You'd never get me cutting a 1 1/4" hole in the top.

What about 1 1/4" hole in top. I have a hole saw that size and it would make short work of that part of the frame. Or are you referring to any hole?

 

[mxcobra]

Re: Drilling into trailer frame.

drill the holes already.
but dont forget to protect the wire's from the metals sharp edge.
I would persanaly get a nice rubber gromet then pick the right size hole to drill acording to gromet!
no protection and it will short out in no time?

 

[109jb]

Re: Drilling into trailer frame.

The tongue of the trailer is a beam and the predominant loads are vertical. Big_eddy has it right. Those that say drilling holes has no affect on structural integrity are obviously not engineers. Like Big_eddy said, drilling holes in the middle of the side is on the neutral axis of the beam considering a vertical load. A hole there, depending on the size will have little effect on the structural integrity of the tube. Holes in the top or bottom though would not be a good choice and would weaken the beam. Maybe the tube is over-designed for the application to take it, but how do you know???? In my opinion, the hole should go in the side for safety. Electricity can follow the bends in the wires without problem, but the trailer loads don't like to go around holes.

Edit. Oh yeah, the highest stresses in a beam like a rectangular tube are always on the top and bottom.

 

[Silverbullet555]

Re: Drilling into trailer frame.

drill the holes already.
but dont forget to protect the wire's from the metals sharp edge.
I would persanaly get a nice rubber gromet then pick the right size hole to drill acording to gromet!
no protection and it will short out in no time?

I've been doing other things which is why I have not drilled the holes yet. Most likely first thing in the morning. Wires are always protected in my builds and will be in this case as well.

 

[guy74]

Re: Drilling into trailer frame.

I wouldn't be a bit afraid of a 1 1/4" hole in the top, as long as it was in the middle of where the side rails are joined to the center part of the tounge.View attachment 115186

 

[Silverbullet555]

Re: Drilling into trailer frame.

It seems that everyone is ok drilling into the side and some are ok into the top.

For safety sake I think I am going to drill into the side of each of the side frame rails and run the wires up each side. Each hole will be in the centerline and 4-6" away from the welds and between 3/4" and 1" in diameter. I have some non-metallic flexible conduit sitting in my garage that I will use to run the wires from the trailer into the toolbox.

Should look clean and maintain the integrity of the trailer.

 

[Silverbullet555]

Just to end the discussion, the holes are drilled. Now just to clean them up and paint them and we are good to go.

 

[Pez Vela]

Re: Drilling into trailer frame.

Just to end the discussion, the holes are drilled. Now just to clean them up and paint them and we are good to go.

You don't get off that easy. We need pics.