Mounting Coupler, holes, bolts ect

[Section 8]

I have a coupler with 1/2 inch holes, that will be mounted to a tube section.

I didn't think ahead on this part of the build so the tongue is already mounted to the trailer, which means I will be using a hand drill.

Can I drill 3/8 holes and use 3/8 hardware to insure everything lines up?

This is a stupid problem to have, especially since the tube section is ~18 inches long and would have been so simple to do with 1/2 inch holes and hardware before I welded it to the frame. Ugh.

[emiller]

You can use a step drill bit to go up to 1/2". I find it easier to use a step drill bit rather than trying to go with 1/2" drill bit. Or you can just weld the coupler on. Put the coupler on mark your holes and then drill them.

[bobhenry]

awe just break out they wrist snapping arm brading 780 rpm 3/4 inch drill and chuck in a good 1/2 bit like I did last week.

Seriously my wrist still hurts ! I was drilling the centertube on the barn for a draw bar to pull the chuckwagon. It was no fun !

I don't see any problem with using 3/8 grade #8 Hardware and double nutting the bolt Maybe a small hole drilled thru and a safety cotter pin would make everyone feel better about the substitution.

My big concern now is how / where to connect my safety chains !

[asianflava]

A step bit (aka. Christmas tree bit) will do the trick. They are designed for thin walled metal. I got a set from Harbor Freight, not the highest quality, but they got the job done.

[proformance]

For a tear drop trailer you will have more than adequate strength using 3/8" Grade -5, -8 bolts in a double sheer application. But, there is more to it than just placing two bolts in the holes.

You need to insure the holes are on center to the mating holes in the hitch, insuring equal load around the circumference of the bolts. I recommend using a 1/2" transfer punch, then create an 1/8 to 3/16 pilot hole using the punch mark for your center prior to drilling to final size.

In addition, you will need to purchase/MFG 4ea 3/8 ID x 1/2 OD (on size) washers/shim (using the same thickness (or a few thou smaller) of the hitch material thickness) and install 2ea (one left and one right) per 3/8 bolt to take up the clearance difference between the 3/8 and 1/2 inch hole. Also, be sure to use Grade -8, thick, precision washers with an OD larger than 1/2 inch under the head of the bolt and the nut to insure these washers do not distort in shape, maintaining pressure on the hitch and not the space/shim..

Note: The problem you may experience is the hitch sliding fore and aft and/or up and down on the trailer tongue as a result of the excessive clearance between the 3/8 bolt and the 1/2 inch hole. This sliding will increase load on the bolts and has potential of causing catastrophic failure. For this reason, I recommend using the 3/8 ID x 1/2 OD washer/shims and the grade-8 thick washers under the head and nut to eliminate the potential movement.

[Larry C]

Does anyone put a bolt spacer tube inside the square tubing where the bolts go through? I think it would be a good idea so the bolt/nut holding the coupler don't crush the tube, and are allowed to be torqued properly.

Larry C

[Sonoma ZR2]

I've always had good luck just welding the hitch on. In two minutes I can have a new hitch on.

[aggie79]

A step bit (aka. Christmas tree bit) will do the trick. They are designed for thin walled metal. I got a set from Harbor Freight, not the highest quality, but they got the job done.

That's what I did to attach my safety chains. (Texas does not allow welded chains.) I applied "blue" tape and located of the hole center. Then I used a punch to mark the center and to keep the drill bit from wondering. Then I drilled a 1/4" hole with the drill bit and reamed the hole to 1/2" with the HF step bit.

Does anyone put a bolt spacer tube inside the square tubing where the bolts go through? I think it would be a good idea so the bolt/nut holding the coupler don't crush the tube, and are allowed to be torqued properly.

Larry C

I didn't use an internal spacer, but I did use 1/4" thick by 2"x2" washers to keep from crushing the a-frame tubes.



For a coupler, this type of washer is probably not necessary since the coupler will spread out the load, but I would use washers or fender washers.

Take care,
Tom

[dh]

So, why can't you drill a 1/2'' hole? I do it in 1/4'' steel with a hand drill all the time without a step bit. Take the 1/2'' bit, put the coupler where you want it, and start to drill through the coupler hole, just a bit, and stop, now you have a nice center mark. Start with a 1/4'' bit, and work your way up in sizes to a 1/2'' bit. Drill all r holes seperately from the outside in.