I am in the process of fitting an Eazlift wdh to my van. I have been told by the Jayco man that I need 430mm centre of ball to ground! Does that sound right. Mine is about 490-500 at the moment and the Jayco spares guy has told me to drop a few holes to get it lower, but it sits pretty level at this height. (mazda BT50 standard height and normal 16-49-4) Did not want to steal post but I had a search and it came up.
Cheers Geoff
I've also been told by different Jayco dealers different heights for the towballs/coupling height on the draw bar when asking to have the coupling raised at the factory. The dealer I purchased from, said that Jayco manufacture to the Australian standard for tow ball heights and will not put in a spacer or weld the plate to the top of the draw bar at the factory...
So… I looked up AS4177 - Caravan and Light Trailer Towing Components.
I have attached a diagram from AS.4177.1 - it shows the centre of tow ball height between 350 – 460mm from ground level when the vehicle is laden. Therefore, I gather the hitch will be in this height region out of the factory to comply with the standard.

I think is may also have something to do to with the angle of movement required for trailer couplings (AS4177.2) which is as follows for angle of movement: The coupling body, when coupled to a towball complying with AS 4177.2, shall be capable of being tilted to an angle of 20 degrees in any direction from that required for straight forward and level movement.
My assumption is that there is the potential for restricting coupling movement when you raise or lower the towball height out of this region (to extreme variations) BUT you do NOT alter the van hitch to be on the same height or level (or when you go to hitch up to a trailer set at the standard height….).
I.e. Towball way too low - the hitch/draw bar is angled down towards the tug thus coupling strikes on the front edge of the towball tongue not allowing full 20 degrees of upward travel at the van
vs. Towball way too high the hitch/draw bar is angled up towards the tug thus coupling strikes on the rear edge of the towball tongue not allowing full 20 degreess of downward travel at the van
I'm in the process of purchasing a Eazlift WDH for when my van arrives and I tend agree with the latest replies that a level van and tow ball height to suit is the best option. Thus, my second assumption - that if you raise the towball height, just raise the hitch so it’s at the same level for no dramas… this is what I will be doing to maximise ground clearance with the WDH fitted.
The reason I have been looking into this is because I have a rather steep drive to back the van up (starting at road level across the kerb then up) so I don’t want the WDH to catch, and a Hyland hitch may provide better articulation in my case since it offers better that the standard movement.