Trailer Hitch fab - threaded rods and nuts

may be usefull if someone needs to fab up a small little trailer to tow some tires and a cooler to an autocross event.

@ cyclehead

Here's your man .... blewis87 from spyderchat

https://www.spyderchat.com/threads/where-to-buy-m22x2-0-threaded-rod-rare-pitch-for-the-factory-tow-points.154487/#post-2122258

Thanks Phat!   Thanks BLewis!

Making a little bolt on beer cooler would be awesome. Maybe a lightweight deatchable BBQ grill. Or just a small no-wheel trailer to throw some chairs, beer boxes, and such to strap down for BBQs. Oh man, so many ideas.

So, my understanding is that the nuts in the back (inside) of the crash bar are only tack-welded to the bar, and are not even full welds.

However, am I wrong to think that if you put a nut and fender washer on the threaded rod, on the outside of the crash bar and tighten it down, wouldn't that transfer a lot of stress to that interface and relieve it from the tack welds themselves? IOW, you will change the mechanical forces and now the two nuts on each side of the crash bar are pinching the crash bar, instead of all the torque being applied to just those puny welds.

Could it be that Mr. T actually intended us to use them that way, and the tack welds are just there to make it easier to hold the back nut in place while the tow platform is installed?

A few fuzzy photosukit pics here.   https://www.spyderchat.com/threads/fs-rods-for-trailer-hitch-or-bike-rack.47354/post-785637

My theory of loading is...

the tow hook nuts are tack welded to the frame. The trailer hitch rods should be a close fit in the pass-through hole in the steel bumper.  Any vertical loads will cause the rods to bear against the steel bumper.   The nuts will only see a moderate vertical reaction.  If you prefer you can weld the nuts up 100%.   I have not, and I’ve used my hitch to pull trailers, carry a platform, and to carry a bicycle rack - all with no issues.

So, does downward force on the rods result in compression or tension force on the welds? What about lateral forces... I am thinking about that 120qt cooler sliding from one side of your "basket" and banging against the opposite side. Could create some substantial shearing force on those welds.

I am not bickering, just discussing. I haven't even laid eyes on The Frog's nuts, while you've actually used them thar nuts in your own car.

We have a member that tried putting a transmission on a hitch rack on a spyder and I think the welds broke.  I don't think I would put over 100lbs of weight on a carrier style hitch rack, definitely so if it's a bumpy drive.

Huh huh .   I forgot about that, pretty scary!   I think he welded it up solid after that.

Hello all!  Yes, I found the sacred bolt lol. 

I also found where you can buy a perfectly sized collar for the threaded rod to ease the stress on the nut that is welded to the frame.

Google search the size below to find it (speedy metals)

1-1/4" OD {A} x 0.874" ID {B} x .188" Wall

Sorry, blewis87.  Your post had to be approved since it had an image and you had fewer posts than the threshold requires.  It's approved and visible now though.  🙂

Posted by: @nottamiata

So, does downward force on the rods result in compression or tension force on the welds? What about lateral forces... I am thinking about that 120qt cooler sliding from one side of your "basket" and banging against the opposite side. Could create some substantial shearing force on those welds.

I am not bickering, just discussing. I haven't even laid eyes on The Frog's nuts, while you've actually used them thar nuts in your own car.

Here it is...

Wanna talk about tow bolt weld failure?

First picture shows beautifully painted storage rack prior to loading:

Second picture shows what a broken tow nut weld looks like:

Next pictures show loaded storage rack....dragging on the ground after both tow nut welds failed catastrophically:

Granted the storage rack was heavily loaded.  One Euro 6 speed M/T crated; lots of spares and liquids for full engine and transmission swap.

BTW, failure occurred within 5 mins of local"Around Town" driving time.  Luckily not during 12 hour Interstate trip to get swap done.

P.S. Also slightly bent the bolts holding the trailer hitch to the tow nuts.

P.P.S. Ending up carrying everything inside the car .... after removing passenger seat, 😆 

Paul