They’re typically a self-tapping screw that’s run in with an impact driver. Good for speed in manufacturing, bad for maintenance many years down the line. Once they’re in and have some added moisture to the mix, they’re in to stay unfortunately. At that point, it’s hammer and cold chisel time to shear them off.

 

I've had a lot of problems with hardware I've bought recently. I got some flat head wood screws for a restoration project and about every fourth screw broke right where the threads stop. I even pre-drilled and countersunk the holes. I've seen a lot of trailer mfgrs using this same Chinese crap, it rusts badly and the metal is cheesy and brittle, had to do some work on my 7 year old 5th wheel and I found I had some of the same crappy hardware. I took a center punch & hammer and gave each screw a good sharp rap. They seemed to come out a lot easier and it didn't take much of a hit to break the corrosion. Also, I had to use only a hand screwdriver with a lot of downward pressure, one slip and the driver cams out of the slots and messes them up. It's tedious but trying to drill out the broken ones is even worse.

 

A great little tip I discovered is to dip screwdriver in coarse valve lapping compound. I've done this on screws that I could not get to grip to screwdriver and removed with ease. I keep a small can in my toolbox.

 

Take a robertson screwdriver and it should fit in the slot. Then use self tapping screws to reinstall everything

 

Take a punch and hammer and give them a couple of hits and then unscrew them... also before that soak them down with a penatrant oil.....

 

It is always tough to get the screws out on the top of these trailers. You should be able to get the right bit and i would use an impact but most likely many of them will break off, but try penetrating oil and you might have better luck.

 

Thanks for all the replies guys. It sounds as if I am on the right track judging from all the input. I'm just going to have to deal with the difficulty of these little buggers. I do have another idea that I will be trying as well using a tool from my old aircraft days. Nut sure if it will work since it was primarily designed for aluminum rivets but I will let you all know.

 

On the trailer we just traded in I did some preventative maint with the screws and will do the same with the new trailer (it is new).

Stainless screws are not that expensive, especially if you think you might need to work on something again. I replaced all the screws with stainless, and put a little silicone caulk on each one to seal the holes. I spent less than 10 or 15 dollars to do an entire 28 ft bumper pull.

Plus they just flat out look nicer.

 

last enclosed trailer I did had what looked like torx but they turned out to use a #2 square drive bit.