Tow ball sizes

[Specialized29er]

Just wondering what sizes do tow balls come in, its because we purchased a 7 x 4 box trailer and when connected to the Commodore the hitch seems loose compared to our other 7 x 4 box trailer.

I'm also wondering what does that threaded thingy with the nut do that's on top of the hitch because when I poked at the inside of the ball area not only did I get a greasy finger I also felt that the threaded part doesn't protrude into the tow ball cupped area and just to make sure this is normal our older trailer hitch is the same but the hitch is a firm fit when connected to the ball.

[duggie]

Most tow balls/hitches are 50mm.

That threaded thingy with the nut do that's on top of the hitch, is so you can adjust some of the play/slop out of the hitch/ball when coupled, once adjusted leave it alone.

[Spada]

The threaded thingy with the locknut is an adjustment so the coupling locks onto the ball properly.
Sounds like it might need adjustment if it came off the ball.

Sit the trailer on the ball leaving the handle of the coupling in the up (unlatched) position, loosen the locknut, then use a screw driver to adjust the threaded thingy until the coupling is firm enough to just be able to lift off the ball, then tighten the locknut back up. With the coupling still on the ball, now drop the handle down into it's latched position, and test that it cant be lifted off.

Another method is to lock it all into place, then tighten the screw up until everything is snug (but not tight), then back the screw off about a 1/4 turn. Be careful to hold the screw in place while tightening the locknut.

PS- I'm not qualified to offer professional advice, and I'm happy to be learned more proper if someone knowledgeable offers better advice. 

[RebsWA]

Check the diameter of the ball and what is cast (written) on the hitch, if anything.
As said, nowadays they are 50mm diameter but years ago 1 7/8" was commom.
Maybe your trailer has the smaller hitch and the commodore has a ball to suit and that could explain the new trailer being loose on the ball.
Most newer hitches have the ball size on them so check to see you have a matching set.

[Beachman]

I was going to say the same as RebsWA  as I know my Fathers old boat trailer had an imperial hitch and his work trailer had a metric hitch. So that meant we also need to keep the 50mm metric and the imperial towballs and swap them around depending on what trailer we used.

Another theory is it’s a well-used towball and its worn or a  new cheap import which isn’t quiet 50mm.

[Specialized29er]

Thanks for the help guys and this trailer is a Hans and only 2 years old. Somethings wrong here because when I screw in the threaded part up until it touches the ball there's no thread left to do up the nut.
Hitches are inexpensive so I'll go buy a quality new one and a matching tow ball to suit and scrap this one.
Better safe than sorry.

[muzza01]

Thanks for the help guys and this trailer is a Hans and only 2 years old. Somethings not right here because when I screw in the threaded part up until it touches the ball there's no thread left to do up the nut.
Hitches are inexpensive so I'll go buy a quality new one and a matching tow ball to suit and scrap this one.
Better safe than sorry.

No, your must be doing something wrong unless it is a 1 7/8 ball. Ask a mate or handy neighbour for some help before you shell out the $$$$$.

[Specialized29er]

We took the whole trailer down to the caravan sales and reprs place and was told the hitch is a 50mm to suit our 50mm ball.
The problem was the shackles were stuffed and the hitch has been given a flogging so we had the shackle bushes replaced along with a new hitch and the trailer now tows perfectly.
$270 spent on the trailer repairs and $600 for the trailer so were still way in front.