Single Axle Car Trailer

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morrisman1, Aug 12, 9:24am
We need to sort a transport solution for the track car, we have a single axle salvage trailer there which needs rebuilt and before we start doing that I want to make sure that it is going to be a suitable solution.

Framework on it is pretty good, no concerns there. its in good condition but could do with a paint. The issue with it though is the design. Its bloody terrible to be honest. The axle is well back and its about 30kg tongue load with nothing on it! Once you get our car on there I calculated it to be about 160kg on the tongue! eek, would need a freaking humvee to handle that!

So what I have considered is moving the axle. It currently sits 2860 from the hitch, which is 230mm rearward of deck centre (deck is 3030mm long). Calculations work out that excluding natural balance of empty trailer, the car would place a tongue load of 126kg on the tow vehicle. By moving the axle forwards 300mm, bringing it slightly forward of centre I can reduce this tongue load of the loaded trailer to about 30kg with option to increase that by parking car further forwards. Without weight data for empty trailer I don't think I can calculate the empty tongue load.

Any thoughts on this!

Step two: the ride height of the trailer. I dont have any data on how high it is currently sitting but I would estimate it at about 400mm above the road surface (13" wheels and about 100mm clearance between deck and axle). We want to have the trailer as low as practical so that the centre of gravity is lower and hence the trailer will be nicer to tow. What is a good way of achieving this!

I thought potentially reposition the spring mounts, so that they are maybe raised 50-100mm relative to the rest of the deck, this would achieve the lowering. Another way would be to raise the stub axles relative to the main connecting axle. We have to replace the sub axles and hubs anyway so the options are there. Can anyone in the know please offer suggestions and practical advice!

This is not going to be a fancy trailer, just a safe and reliable way of getting the car A-B and be able to be towed short distance by a 2L sedan, and longer distances by a SUV

morrisman1, Aug 12, 9:28am
And can anyone around who has Unideck's email please ask him to contact me in my classified listing! That is, of course, if he is willing to offer help. It's a shame not to have him on the board anymore

unclejake, Aug 12, 9:31am
IMHO you are doing too much thinking and not enough putting the track car on the trailer.

Changing the ride height can massively change the tongue load as you can go from tilting one way to tilting the other (I know that sounds hard to believe but it is true).

Get the car on that trailer and then work out what to do. Perhaps all you have to do is park the track car 45mm further back. That just happens to be a bit of 4x2.

morrisman1, Aug 12, 9:35am
I cant park the car any further backwards, those figures were based on most rearward position which was safe (centre of rear tyre 200mm in from rear edge of trailer)

Unfortunately the trailer is not in a condition to park even me on it, theres no deck! I can tell from just looking at the trailer that its not going to work. Looks like its designed for a mini to be parked backwards on!

When I lower the trailer, I will subsequently raise the coupling to ensure the trailer sits level when on a standard height towbar.

NZTools, Aug 12, 9:36am
Park the car on the trailer then roll it back till the tongue load becomes optimal. Bolt a couple of wheel stops to the deck at that point. Job done.

morrisman1, Aug 12, 9:38am
I did the sums for parking car on backwards and thats not happening either, would be tail heavy resulting in a tongue lift of 82kg

h.e, Aug 12, 9:52am
dont move the axle forward 300mm even if it weighs up great loaded,cause unloaded it will be a mare.2'' rear of the centre is fairly standard

msigg, Aug 12, 9:52am
Well if you put the car on backwards then the weight of the engine at the back will take some load of the front, are the springs mounted under the axel or on top. Might be cheaper to just bolt on another axel as well if your going to move it, just a thought. But yea move the axel is easy. Just lots of grinding and some more welding.A good trailer is worth its weight in gold, done well you shouldn't loose money on it anyway.

morrisman1, Aug 12, 9:59am
just did sums. 2" rear of deck centre results in 106kg on tongue, excluding trailer's empty balance.

cjdnzl, Aug 12, 10:03am
If you move the axle forward you will probably find the trailer will fishtail uncontrollably.
A better idea might be to fins another axle and convert to a dual axle.

h.e, Aug 12, 10:04am
you really dont want to be forward of centre.its quite a large trailer to be single axle.tandem with no springs to keep it cheap prehaps!

flashgordon_nz, Aug 12, 11:35am
yeah, was thinking that. get rid of the springs. if towing long distance empty, let the tyres down to 10psi, then top up before loading. Anchor the car by its wheels, not the body. that way the natural suspension of the car doesnt make the trailer ride as harsh. true, but its exactly how ours works, and works well. will have a measure up next weekend for you when the car is back here. and let ya know some measurements. cause we sure know it works for a car identical to yours, as well as a vr4, and a cg8 imprezza. all tried loaded front, and rear facing.

the-lada-dude, Aug 12, 7:31pm
what about a towing dolly !

thejazzpianoma, Aug 12, 10:12pm
+1 for no springs.
Just check on the speed limit for an unsprung trailer, it used to be less but I don't know if it is anymore since they changed the trailer speed limit rules. With an unsprung trailer you want the trailer itself to be as light as humanly possible, so if this is some heavy old behemoth don't do it without some modification to lighten it as the shock load on your axles when you hit bumps etc will be severe. The weight of the car on the trailer is less important as the car is sprung.

With regard to safe towing, distance means nothing, its the speed you are towing at and the weight/capabilities of the tow vehicle (assuming the trailer is set up properly).

So being "safe" to tow short distance with a 2L sedan is a nonsense statement. Its either safe to tow with that car at the particular speed you intend or not. The trailer won't wait a certain number of km's before it decides to throw you off the road.

The only factor relating to distance is wear/cooling abilities of the vehicle.

You havn't mentioned what you are going to do about brakes!

If you get in an accident with no brakes on the trailer and a car on the back the Po Po are going to be all over you for dangerous driving, your insurance may choose to abandon you too. Aside from that given you are going to try and tow this with the Primera or similarbrakes are going to be essential as even stripped out the combined trailer/car weight I would expect to still be over 700KG, possibly well over.

Lastly, don't go too light on the tongue weight. I would be going for close to the maximum permissible for the lightest car you will tow with. That's often around 45KG with a lighter car, so 40KG might be about right (when loaded).

This much weight shouldn't take the weight off your front wheels too much, while cushioning you as much as possible from the likelihood of the trailer trying to sway. Swaying out of control is your worst enemy, especially with a light tow vehicle. Even at 40KM/h it can take over and flip you, especially on old vehicles with no trailer stability program.

dave653, Aug 12, 10:36pm
Bugger!

thejazzpianoma, Aug 12, 10:37pm
Yip, still. another Hilux off the road is never a bad thing, especially when it's replaced with an Audi as this one was.

morrisman1, Aug 13, 12:12am
ouch! A hilux would have rolled even without a trailer and on a straight road.

I've priced up tandem setup too, its an extra $500 so most likely worth the expense in order to get the trailer more versatile.

we would like to have springs if we could, as it will mean the trailer can be used as a general purpose if required rather than only be able to use for a car. You can fit a lot of firewood on a salvage trailer!

When I say short distance, I mean the straight and flat piece of road, several KM long from my place to the track, rather than taking it on the bump and windy high speed state highway one. 90% of the time its going to be towed by a izuzu bighorn or landcruiser. I am quite happy with the braking performance of a light car, I had the pulsar on the dolly behind my sentra and it was good as gold with braking. I certainly wouldn't go towing an unbraked/loaded to christchurch behind a small vehicle.

Im going to price up brakes to see how much more they will cost.

morrisman1, Aug 13, 12:18am
brakes would be an extra grand or thereabouts, for the coupling and calipers/disc assembly.

fryan1962, Aug 13, 12:30am
What cost safety hey, I have classic car no seat belts, I fitted them was told I was mad, I said it was not my driving I was concerned about, about two years latter I had high speed head on accident,The guy in the other car passed out,He had medical condition 5 cars involved, some times it is worth the cost

dave653, Aug 13, 12:44am
Old work van, CF Jumbo, was used to drag a large tandem around, sometimes with a coupla ton of windows/doors. No brakes on the trailer. stand on 'em and wait. With brakes. stopped as if there was no load, let alone a trailer. Highly recommended! Cheap insurance!

thejazzpianoma, Aug 13, 12:49am
To put it bluntly, if you do it without brakes your an idiot.
It dosn't matter if you are travelling on a straight road or not, the Hilux in question flipped 3 times towing on a straight at about 60km/h.

As I mentioned before, if something happens you will be charged with dangerous driving and chances are your insurance will bail out on you as well. This alone could set you back tens of thousands and if you are really unlucky cost you your life. The Police and insurance have every right to do this because you are towing around twice the unbraked load that your car is rated for.

Towing it with an SUV dosn't make it O.K either.

You have been told, now its up to you. I just hope you don't take out an innocent party if it goes pear shaped.

thejazzpianoma, Aug 13, 12:58am
BTW, given you are replacing the stub axles anyway, adding brakes should cost you around $600 if you are using all new gear

To spend about that on a tandem setup yet still not add brakes is even more absurd.

morrisman1, Aug 13, 1:19am
I hear you Jazz, and I didn't need such a rant as I already understand the value of brakes. The kitty is pretty empty unfortunately due to the costs of this car piling up so a trailer needs to be cheap. In the mean time Ill probably consider hiring one to get me started. Theres a single axle on here with brakes, might be worth a look. I've asked for the measurements so I can do some sums on it and see if I can safely load the car on it.

mm12345, Aug 13, 1:22am
Put tandem wheels and brakes on it. It's not worth the risk.You can do what's needed with a stick welder in the right hands,plus you'll need a brake hose flaring tool (~$50!).
http://www.transitengineering.co.nz/
I think the above company also sells some stuff on Trademe.
They make some nice 2 pot machined alloy calipers with SS pistons.These fit on the same "ears" as Trojan (you need to be a bit careful to centre them when they're fitted - welding the "ears" on to the stub in the correct position, but once set up, they are excellent. (pre-assemble the hub/disk, pump up the caliper tight on the disk and centred, tack-weld the "ears", disassemble and weld the ears on properly)
There are brake "kit" prices etc on that site. I have a sneaking suspicion that you might be able to negotiate price if you're wearing overalls and ask nicely.You can also save a bit if you don't need marine anodised calipers (TBH, I've got non-anodised plain ones which have been on my boat trailer for 5 years, and there's no corrosion on the alloy anyway.

thejazzpianoma, Aug 13, 1:26am
Starting fresh like that may well be an economical course of action. If hiring take special care to check the trailer out thoroughly every time and take it really easy for the first few km.

The incident in the picture was with a hired trailer with brakes. Everything appeared visually fine on the trailer but the accident was apparently caused by a fault with the trailer.

I have hired many "hairy" trailers that have tried to sway etc in past. They are generally far heavier than required (due to people abusing them) and not very well kept.

I understand about a limited budget, its just a case of somethings not being worth compromising on. Plus your budget will be a lot more limited if you are wearing a fine and no insurance in an accident.