Can someone please explain, as i dont understand. Or im just confusing myself more and more.
Im making a 4000x1950mm tandem axle car trailer using 75x50x5 RHS for frame and 100x50x5 RHS A-frame tilt drawbar.
My questions are on axle placement - every writeup ive read says 60/40 front/rear of DECK length for centre of tandem springs rocker. Eg 2400/1600mm.
Does draw bar weight not come in to the equation? Eg 100x50x5 RHS weighs approx 10kgs per metre - 2x 3m lengths = 60kgs extra forward of the "60/40 DECK" measurement.
Also when loading a V8 onto the trailer you then have all the weight of the motor forward of that DECK centreline too. Which then places more weight on the towbar tongue.
I have centred the frame and drawbar on some round stock, just to find the pivot point for shits and giggles. And this point is well forward(550mm) of just the deck only 50/50 point.
Am i just throwing too much maths at this and should i just go with the flow and do the Deck 60/40? Or 60/40 of deck AND drawbar?
AARRGGHHHHH
muzz67,
Aug 17, 4:06am
need some weight on towball, or it'll rattle. meybe 15-20 kilo? Too much and it gets too heavy to lift off without jockey wheel.
mrcat1,
Aug 17, 4:08am
You have to back them on as you don't want any more than 80-100 kgs on the tow vehicle.
mrfxit,
Aug 17, 4:20am
The only time drawbar weight is of any real concern is when the trailer is empty & you have to lift it. Calculate on DECK only
I have always set std 6x4 trailer axles at 50mm rearward of the center & it's worked pretty good.
How a trailer settles with different weights can be a little tricky at times. Balance will shift a little as the increasing weight goes on & is very evident when loading gravel & sand but pretty stable with a car etc on board because you can adjust the weight balance to suit.
mrfxit,
Aug 17, 4:24am
I think the ideal tongue /ball weight is around 40 to 50kg for heavy full loads. Physically, if you struggle with a 2 handed lift, then it's too heavy, (or you're a weakling/woman/ girl/ kid . take your pick)
mrfxit,
Aug 17, 4:27am
Just as an example of what NOT to do. >
1 trailer I purchased a few years ago was a 5' x 7' with the single axle set back 6" back from center. It was a heavy 2 handed lift . empty
pierced1,
Aug 17, 4:28am
Thanks for responses.
When researching axle placement, i looked at lots of trailers - online and in the real world haha. So many vehicle tandems have the wheels set toward the back of centre and cars loaded normally(driven on forward) surely this puts undue load on the tongue.
I know there has to be some weight on the tongue, but surely the trailer should be mostly balanced so to be able to lift it off the towbar and not destroy the jockey wheel.
mrcat1,
Aug 17, 4:32am
Exactly or the tail tries to wag the dog and with that much weight it gets all out of shape very quickly. You don't want any more than 80-100 kg on a tow coupling ever so that's why you back them on.
Hopefully the link will work - my brain says use the 60/40 Deck and drawbar setup but it will 'look' wrong, wheels too far forward. But engine and front of car weight will still put weight on drawbar, but nowhere as much as if the wheels were further to the rear.
Hyd unit looks cool! But maybe not for towing behind a coon station wagon haha
morrisman1,
Aug 17, 5:56am
when I build the trailer I put the axle half way. That way as an empty trailer it has the drawbar weight putting about 30kg on the tow ball. With a car it puts about 60kg on the ball, which it tows real good with.
I think the 60/40 (or 50mm rear of centre) is more applicable to trailers which have an even load, eg load of gravel.
do you know your weight distribution of the car? I used math to calculate the exact weight on the drawbar before I mounted the axle. Not hard, just a weight x arm = moment calculation.
because my trailer is a tipper, I know that once the trailer tips forwards then I have load on the drawbar and Ill then drive forwards 15cm and thats where I park. Every 10cm is about another 25kg on the drawbar with the car weighing about 830kg
red97,
Aug 17, 1:33pm
that's pretty heavy steel for a car trailer in my opinion, lot of "extra" weight and dollars there, have you considered using 3mm? except for the axles of course
pierced1,
Aug 17, 1:48pm
Steel was cheap deal - plus i build solid to future proof myself, just incase i buy a tank. ;-)
mrcat1,
Aug 17, 2:20pm
I'd be looking at the GTM of the car your going to use to tow this trailer and car, I have a feeling your going to be over the towbar or GCM rating for this vehicle.
tweake,
Aug 17, 6:27pm
the bit about the trailer being to heavy to lift off by hand is BS. its better to have to much forward weight than not enough. while your v8 may have a heavy engine you will probably find that it does not center on the trailer. especially long wheel base. the rear will hang out a lot further. catch is that because trailer acts as a pivot, weight further out has more effect on the handling.
mrfxit,
Aug 18, 1:13am
LMAO you blimin think WHAT >. "the bit about the trailer being to heavy to lift off by hand is BS."
If the draw bar is THAT heavy, then your steering is going to be pretty light with stuff all tyre contact or traction on the road.
Been there done it once, never again, scary driving like that.
thats because your grossly overloaded, probably using the wrong tow vehicle for the job. it may have been a bad drive, but at least you made it. if it was tail heavy you most likely would have never made it.
mrcat1,
Aug 18, 1:54am
I have yet to see a transporter trailer without to much weight forward, hence why I have said in this thread to back a V8 vehicle onto a transporter trailer, that's just as bad as not having enough weight forward, as I have said numerous times on this thread, no more than 80-100 kg on the draw bar otherwise the tail will try and wag the dog.
tweake,
Aug 18, 3:05am
that total BS. sounds like your trolling and will get some poor bugger killed.
trailers wag the dog because of lack of weight on the draw bar. if you put a vehicle on back woulds it will wag so bad it WILL throw them off the road.
its very difficult to get to much weight on the drawbar and easily corrected by moving the load back a fraction. the official method is use a scale and weigh it. however i've never seen anyone do that. most just judge it by eye and how much the tow vehicle rear drops. if your an idiot and go towing a 1400kg car on a 500kg trailer, with a lightweight car with soft rear suspension, then its always going to be marginal at best.
what tow ball weight you can use is dependent on the tow vehicle. i see a mention of the 10% rule. so for a 2000kg load you have 200kg towball weight. car can't handle that towball weight? get a better tow vehicle.
stevo2,
Aug 18, 3:12am
I've done some pretty serious towing over the years and the tail can wag the dog with either the trailer having to much weight at the rear or to much on the tow ball. The latter takes to much weight off the front wheels and you lose all "feel" of the steering. Nek minute you have the speed wobbles. Around 60kg is recommended on the tow ball. I have built all my trailers with the axle placed 100mm behind the centre of the tray.
mrcat1,
Aug 18, 3:15am
Considering I have 8 custom made trailers with some carrying up to 3500kg I do have some idea, if you cared to look at most tow bars they have stamped on them the maximum downward pressure on them, they will wag with to little or TOO MUCH on the tow bar, I have spent a lot of time getting one trailer to tow right as it has 6 meter lengths of 148mm seamless tube up high on a rack with a heap of heavy drilling gear, as I have said before and will say again, a trailer only wants to have 80-100 kg of down load on the tow vehicle. The hammer sitting on this trailer weighs over 2 tonne, and travels very well, and the mast on the hammer is over 6 meters long. https://trademe.tmcdn.co.nz/photoserver/full/404516847.jpg
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