Gooseneck hitch fab question

[CarolinaHD]

Put a gooseneck hitch on an old C50 2 ton and wanted some input on the design and strength of it.. Has a wooden bed on it that is in fantastic shape so the brackets had to be tall enough to reach the bottom of the bed floor.

Using a drawtite hitch bracket from Ebay
3/8" plate, 11" wide by 14" tall
2.5" by 3/8" angle
Grade 8- 5/8" hardware

Theres 6 bolts holding the angle to the gooseneck plate,4 bolts for the angle to the side brackets, and 8 bolts to the truck frame.

Questions are:
Should I weld in a piece to stiffen the 3/8" plate to help with side to side load? 2.5" wide and tall as the side plate. Red line in pic

Should I add more bolts between the angle bracket and plate? Thinking of putting in a small piece of angle in the corner, welding it to the plate and bolting it through the angle.
Weld where its blue and bolt through where its red
In the pic.

Hope this all makes sense

 

[CarolinaHD]

..Also chopped 2 feet off the bed/frame. best comparison pics I have.

Last 3 pics are the draw tite ball sitting too low and the Curt Puck ball from a 2017 2500hd sitting just right

 

[shawn]

Not a structural question, but how far is it from the ball to the edges of the bed? Might want to tack it up and hitch up your trailer before you put too much time into it. Make sure you can turn without hitting the headboard of the trailer with the truck's bed. This is why a lot of factory-built flatbeds have the rear corners chamfered off.

 

[Fabrik8]

Adding a couple of bolts higher on the plate will help with side loads and plate bending/buckling, and with stiffness in shear (less unsupported plate length). Probably not a problem with 3/8" plate. Obviously, most of the loads are vertical and horizontal (longitudinal), with only some component of the load in the lateral direction when turning.
The hitch ball is a pivot, and it's hard to introduce lateral loads through a pivot when the trailer wheels are far behind the pivot. I would be more concerned with buckling of the plates from vertical load, or bending of the angle bracket from vertical load. I have no clue if either of those are an issue at all, I'm just saying I wouldn't be concerned with lateral load compared to vertical or longitudinal load.

If you look at most of the commercial gooseneck brackets, they have a longer vertical leg/flange on the angle channel than what you have, which increases vertical load (like a truss). Not sure you need that, I'm just noticing things off-the-cuff.
Again, 3/8" channel can likely forgive a few sins.

 

[CarolinaHD]

Not a structural question, but how far is it from the ball to the edges of the bed? Might want to tack it up and hitch up your trailer before you put too much time into it. Make sure you can turn without hitting the headboard of the trailer with the truck's bed. This is why a lot of factory-built flatbeds have the rear corners chamfered off.

57" from ball to rear of bed and 72" to the corner. My other flatbed is 56" to the rear and the corners are angled but its wider than this one. It clears with plenty of space so should be good.

 

[CarolinaHD]

Adding a couple of bolts higher on the plate will help with side loads and plate bending/buckling, and with stiffness in shear (less unsupported plate length). Probably not a problem with 3/8" plate. Obviously, most of the loads are vertical and horizontal (longitudinal), with only some component of the load in the lateral direction when turning.
The hitch ball is a pivot, and it's hard to introduce lateral loads through a pivot when the trailer wheels are far behind the pivot. I would be more concerned with buckling of the plates from vertical load, or bending of the angle bracket from vertical load. I have no clue if either of those are an issue at all, I'm just saying I wouldn't be concerned with lateral load compared to vertical or longitudinal load.

If you look at most of the commercial gooseneck brackets, they have a longer vertical leg/flange on the angle channel than what you have, which increases vertical load (like a truss). Not sure you need that, I'm just noticing things off-the-cuff.
Again, 3/8" channel can likely forgive a few sins.

Yea that's what I stepped up to 3/8" everywhere but my main concern is the plate bending/buckling. The only way to bolt it higher is through the wood frame and I'm not sure if that would actually make a difference? Thought about putting a sandwich plate on the backside of the wood and tacking it to the truck frame..

 

[Fabrik8]

Yea that's what I stepped up to 3/8" everywhere but my main concern is the plate bending/buckling. The only way to bolt it higher is through the wood frame and I'm not sure if that would actually make a difference? Thought about putting a sandwich plate on the backside of the wood and tacking it to the truck frame..

If that's wood above the frame rail, don't worry about adding extra bolts there. Too much compliance to add much benefit in stiffness to a 3/8 plate.

 

[WARRIORWELDING]

Add bar stock to outer edges of plate. Place just inside 3/8 angle leg. Would give area to weld both sides of plate. Basically makes plate into a channel. Weld another on the top just like the sides to bridge the top (twisting load).

If that is a single rail frame as it looks.....add plate to inside twice as wide as the out side. Bolt at outer edges and through 4 bolt pattern. Radius corners of said plate to reduce stress at channel. Utilize the holes in the center section to add 4 more bolts in the angle to plate. Too much space between what is their to fight twist the ball mount and angle.

The design present is woefully weaker than most factory B&W hitches. Your biggest weak points are the angle attachment, height of bracket (Load point above the frame and shear plane), and the lack of spreading the load out on the frame rail.

 

[CarolinaHD]

Add bar stock to outer edges of plate. Place just inside 3/8 angle leg. Would give area to weld both sides of plate. Basically makes plate into a channel. Weld another on the top just like the sides to bridge the top (twisting load).

If that is a single rail frame as it looks.....add plate to inside twice as wide as the out side. Bolt at outer edges and through 4 bolt pattern. Radius corners of said plate to reduce stress at channel. Utilize the holes in the center section to add 4 more bolts in the angle to plate. Too much space between what is their to fight twist the ball mount and angle.

The design present is woefully weaker than most factory B&W hitches. Your biggest weak points are the angle attachment, height of bracket (Load point above the frame and shear plane), and the lack of spreading the load out on the frame rail.

Ok, I think I'm pickin up what you’re puttin down. I must not be as well versed in the science of metals as i thought

How about welding 2 triangles on the side of the 3/8” plate And extend it out to 20-24”, Double bevel and weld both sides, grind the back side smooth and leave the weld on the face? Box in the side and top as you said.
Then, put 1/4”x5.5”x24” plate inside the truck frame rail with 4 extra bolts like you described.
Still need input on another mounting point between the angle and truck frame plate?

Also a little confused on this part:

...Utilize the holes in the center section to add 4 more bolts in the angle to plate. Too much space between what is their to fight twist the ball mount and angle...

Theres already 6 bolts between the ball mount and angle which is how it comes from the factory. The holes grouped together are for ubolts for the safety chain and the other 2 (4) circled in red are extra. Unless you meant use 10 bolts total between the ball mount and angle.

Edit: there’s 2 bolts inline with the ball, you can kind of see one sticking out in the last pic.
Thanks for your input

 

[WARRIORWELDING]

Ok, I think I'm pickin up what you’re puttin down. I must not be as well versed in the science of metals as i thought

How about welding 2 triangles on the side of the 3/8” plate And extend it out to 20-24”, Double bevel and weld both sides, grind the back side smooth and leave the weld on the face? Box in the side and top as you said.
Then, put 1/4”x5.5”x24” plate inside the truck frame rail with 4 extra bolts like you described.
Still need input on another mounting point between the angle and truck frame plate?

Also a little confused on this part:



Theres already 6 bolts between the ball mount and angle which is how it comes from the factory. The holes grouped together are for ubolts for the safety chain and the other 2 (4) circled in red are extra. Unless you meant use 10 bolts total between the ball mount and angle.

Edit: there’s 2 bolts inline with the ball, you can kind of see one sticking out in the last pic.
Thanks for your input



View attachment 325079 View attachment 325080
View attachment 325078

Yes add the bolts in the mout you have high lighter on the underside of angle. Yes add interior plate on frame. As for the outside wings will spread it out, but you want to fight the twisting or buckling load because of the height. Bars on the edge perpendicular to the plate and one joining the top together will create a box or channel to fight it.

 

[WARRIORWELDING]

The above hitch has the same number of angle to insert bolts....but the member inside is made different and stiffer. The flanges do not step down and the ball box is reinforced differently. The extra bolts won't hurt. The biggest difference is the ball height to frame mount relationship.

All things aside Your assembling a kit. No harm in over kill. I'm sure B and W and the like have better paid lawyers.

 

[jeepinmatt]

In my opinion, everything looks fine except the side plates. I'd weld some more of that 3/8" angle down each side of the plate and call it a day.

That will properly stiffen up the plate for lateral loads. Even if you have to notch around the bolts or narrow the washers it wont matter because the strength comes primarily from the leg that is sticking out.

Then the next issue is going to be the moment (push and pull) loads on the side brackets with such a long extension and not much bolt separation. The plate will handle it fine, but you have about 6" of bolt separation fighting a foot tall moment arm. Doing something like you indicated here would be better...

But honestly its overkill. I assume the truck doesn't have the juice to rip it off, and old drum brakes aren't known for their massive stopping power...

Burn some angle on the sides and let er rip.

 

[CarolinaHD]

Guess who's back? Finally got a house with a shop and can work on the fun projects. Ended up taking a section of channel, cutting it to fit around the plate, and welding it back up. 2x2x1/4"" tube for vertical stiffners and 2x6x3/8" tube to fit inside the frame. Gonna run it as is, unless someone thinks it needs some more triangulation to save a bus load of puppies in the future.