A point to discuss, while I have said the only tow ball weight you need to worry about is that written on the tow bar compliance plate, I must mention what I was told by two people. One was an ARB tow bar fitter, fitting tow bars at my once place of work, and the other was the supplier of the tow bar fitted to our vehicle.
That the tow ball weight, and I think the towing allowance only applies provided you use the bar and tongue as supplied with the tow bar, i.e. all testing was done with that configuration. Changing the bar in anyway changes the limits on the compliance plate.
I'd like to see your advisors present a verifiable link supporting their claim, iana. Every auto parts store sells replacement components to fit towbars, many produced by respectable manufacturers like Hayman Reese and I haven't heard about transport authority raids yet. I can imagine each separate component is rated not the complete towbat just as a vehicle or trailed unit is comprised of many individually rated components.
The trouble arises when the standard fitted towbar and hitch may bey rated to 3500kk with a ball weight of 300kg, the manufacturer has worked all that on the vehicle specs and TBO, now replace the hitch with one with the coupler another 100mm extended you have now changed the dynamics of the towbar and hitch
cheers
blaze
Blaze, exactly, also by raising or lowering the ball, you have changed the rotational moments (shear), its all about the length of a lever about a pivot point, i.e. one of the bolts supporting the tow bar assembly (pivot point) to the tow ball. Now to be honest, I have just put this up for a bit of fun, it is true about being told about this, and I believe what they say, but its only an interest discussion, I wouldn't panic about it.
-- Edited by iana on Friday 19th of July 2019 08:24:27 AM
Further to Hayman Reese, after my gvm upgrade my towball height was a bit high, so had to purchase a longer drop shank to gain(ie lower) the connection height. The offering from H R means that I have a surplus on the drop side of the casting. I asked if I could cut it off, save a little weight and less chance of snagging on a driveway etc.
" NO WAY " they reply, it is an engineered solution as a whole, dont modify or it may create stress issues. Cannnot comment about the pivot point, but the height is reversible
according to a number of OEM vehicles.
The trouble arises when the standard fitted towbar and hitch may bey rated to 3500kk with a ball weight of 300kg, the manufacturer has worked all that on the vehicle specs and TBO, now replace the hitch with one with the coupler another 100mm extended you have now changed the dynamics of the towbar and hitch cheers blaze
I think this is the key issue. Just remember all this towing gear had an additional safety margin designed into it. About double i think.
Hayman Reese, and any other supplier of shanks, drawbars etc. will of course tested their gear to withstand the loads stamped on their equipment. But they are not concerned about what its mounted into. The compliance plate is mounted on the tow bar assembly which in turn is attached to the vehicle, its that part that effected by any changes in the tow ball position.
A point to discuss, while I have said the only tow ball weight you need to worry about is that written on the tow bar compliance plate, I must mention what I was told by two people. One was an ARB tow bar fitter, fitting tow bars at my once place of work, and the other was the supplier of the tow bar fitted to our vehicle.
That the tow ball weight, and I think the towing allowance only applies provided you use the bar and tongue as supplied with the tow bar, i.e. all testing was done with that configuration. Changing the bar in anyway changes the limits on the compliance plate.
For the record I am using the original set up.
Close but not necessarily correct. First off, not many towbars come standard with a hitch, tongue, ball, etc. from the same manufacturer, even if they are supplied at the time of fitting. ARB for instance don't make towballs. They buy them in, as they do with many things carrying their label. The more normal requirement is for a standards compliant hitch, etc., as approved by the towbar manufacturer. That's quite a distinctive difference. Even that wording is mainly to give them an out when things go wrong. Personally I never hesitate to use any suitable hitch with any towbar, including ones I've made myself. I currently have three hitches for our tug so that I can just change hitches instead of balls or coupling pins. The heaviest duty one is used for towing the camper, which is our heaviest load.
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'In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual.' - Galileo Galilei
