Trailer Tongue Weight

[winston66]

Another aspect that may ,or may not be relevant , is the height of the tow ball in respect to the axle height of the Mc.  If the tow attachment height is much higher than the axle height it might be found that when under hard acceleration the forces en counted might tend to act as an excessive  downward vector on the bikes  rear suspension and frame  and thereby tend to greatly unload, and contribute to lifting the front wheel excessively.
I think that the type and style of motorcycle being used would have quite an influence on how this would manifest itself in any particular set of circumstances.
From your measurements of the trailer in question I would carefully consider lengthing the tow bar at least a couple of hundred millimeters from what you have now. After all that would be very easy to do and of minimal expense and might just improve the trailers handling so that you will be comfortable using it.
Cheers, Winston66

[alans1100]

The single axle light trailer specs I have seen over time specify that the length from the axle centre to the rear of the trailer must be shorter than the draw bar length from axle centre (excluding coupling). If you look at single axle full size caravans the axle centre is about 1/3 of the whole length from the rear to coupling.

The rough measurements I took from my trailer put the axle centre from the rear at about 30% of the total length of 2350mm. I also checked the Classic site and found out my hitch is load rated at 230kg and I'm clueless as to if that's the ball weight (not likely) or the load I can tow with the bike.

Hitch attachment height.

The most common info I have seen to date is to be as close as possible to the rear wheel axle centre as you can get. The instructions I got with Classic weren't to specific as to whether it meant the height of the tow ball or where the ball mounts into the hitch so I took it to mean the latter.

This is mine hitched up before the new rear shock was installed and before I lowered the hitch height to suit. The coupling is still the original OEM from when trailer was new in 1988.

[Williamson]

This similar to way I had the Classic tow hitch initially fitted to the CB1300.   

.....

A friend pointed out to me that a slight bend movement was starting show around where the blue arrow is pointing on this pic.

I re-positioned the mounting point of the vertical stay (double headed purple arrow) to the hole at the point of the red arrow head.  Just saying what worked for me .......

I'm not a fan of Classic tow hitches (since the one that I paid $395.00, plus $25.00 delivery, or thereabouts, was faulty, and Classic showed no interest in fixing), so I was rapt with the US made tow hitch I purchased from jwm (John from near Nowra).  It's much more sturdy and of far better quality, with not any sideways movement and thus less possibility of inducing any sway.

A couple of the colleagues had a look and commented on it at Blackwood - I think they were complimentary.

PS. Alan, hope you don't mind me re-using your pic, if you do I'll delete it.

[alans1100]

PS. Alan, hope you don't mind me re-using your pic, if you do I'll delete it.

It's ok.......it may help some one if they have a similar issue. 

[Down Under]

Sorry Tony - work got in the way as usual.
I tow an elite camper trailer. The markings are as follows:-

Max tow bar weight - 28kg - I used fish scales to get it right
Max laden weight - 230kg - I put over a weigh bridge to check this out
Recommended tyre pressure is 22 PSI

Its the model with nose cone and has brakes fitted so has extra weight.
Have you adjusted the suspension to counter the extra weight the same as you would for having a pillion on board?
When I have a pillion on or towing the trailer I adjust the suspension up 5 turns of the wheel.

 

No worries at all Tony.  Thanks for going to the trouble mate!  Suspension is good.....I've fitted a heavier spring for the purpose with preload/rebound  adjusted accordingly.  Thanks also winston66, some words of towing wisdom there!  I've got leaf springs on my trailer and I'm running 20 PSI, the manufacturer recommends 20 to 25PSI.....does that sound OK?

Some interesting observations with the tow hitch Williamson.   I've also got a Classic hitch and from the start I've been concerned about the amount of movement in it, especially lateral movement.  In particular, I don't like the mounting points they selected on the motorcycle.  They could have bolted directly into the frame with the 2 lower arms but instead they chose to use the pillion peg hanger which is part of the much weaker sub-frame.  It's a similar case with the upper arms which also bolt into the sub-frame.  Putting that aside the hitch itself isn't the sturdiest of construction. 

One thing I found off putting when towing the trailer was slight flexing in the sub-frame which could be felt through the seat.  Perhaps hitch issues could be another factor causing problems with handling in my case.  Unfortunately this problem would be difficult to isolate unless I could use another style of hitch which is just too cost prohibitive.  The more I get into the trouble shooting side the more I'm convinced that the bike just isn't suitable.

A lot of good information coming out of this thread which is very useful for trailer newbies like me! 

Cheers,

Tony

[atoyot]

Hey Michael, thanks for the info about the Classic towbar, as I have to drop mine to the lowest holes to get the bar level with the trailer which is about 350mm from memory, so I might have to fabricate some longer mounts, with maybe a bend in them. I look forward to checking your towbar out at Ballarat then maybe?

[Williamson]

Hey Michael, thanks for the info about the Classic towbar, as I have to drop mine to the lowest holes to get the bar level with the trailer which is about 350mm from memory, so I might have to fabricate some longer mounts, with maybe a bend in them. I look forward to checking your towbar out at Ballarat then maybe?

I'll be there, the ST13 and the camper too (at the Big 4), so I suppose the tow hitch as well.  Your are welcome to have a look.

[Sicman]

One thing I found off putting when towing the trailer was slight flexing in the sub-frame which could be felt through the seat.  Perhaps hitch issues could be another factor causing problems with handling in my case.  Unfortunately this problem would be difficult to isolate unless I could use another style of hitch which is just too cost prohibitive.  The more I get into the trouble shooting side the more I'm convinced that the bike just isn't suitable.

Thats interesting Tony and a bit concerning about the flex. When I got the Classic towbar I thought how is this ever gunna be strong enough to tow a trailer, but once it was bolted to the ST it was solid and strong as, with no flex at all. maybe yours needs extra bracing to solve that problem.

 

[atoyot]

I weighed my trailer today, and empty, it has 40kg per wheel, and 5kg on the drawbar. Yet to carpet it, but will re-weigh it then, I'll put it over a weighbridge. So far, the items I'll be carrying in it totals 28kg, with a bit more to come, but not too much.