Towing/Towball height/Rear Rideheight

[Mark Stanton]

he'll be too busy in the new toy......

And that's no good for towing either          

[Al Yupright]

Still here, been thinking about the problem, whats the best solution etc.

I can now see exactly why the problem occurs. I stood the jockeywheel on a set of bathroom scales today, and took measurements of the 'noseweight' at various hitch heights, by winding the jockey down a bit each time.

This was with the westy on the trailer, and the trailer not hitched to the tow-car.

Towball height          Noseweight

26cm                      0kgs

27cm                      19kgs

28cm                      37kgs

29cm                      45kgs

30cm                      60kgs

31cm                      65kgs

32cm                      78kgs

33cm                      85kgs

34cm                      98kgs

35cm                     102kgs

36cm                     106kgs

37cm                     121kgs

38cm                     127kgs

So, obviously, the higher you lift the nose of the trailer, the heavier the noseweight becomes, because the more you lift it, the less weight is being supported by the front axle.

The tow-ball on my Pug is at 45cm, but at this height, the noseweight of the trailer would be ridiculously high (200kgs?) and the suspension couldnt handle that. So the suspension sinks, and the more it sinks, the lower the noise weight becomes until it reaches a point where the suspension can sustain that noseweight. This is probably about 30cm (=60kgs) for my car.

This was measuring the weight at the jockeywheel, the actual hitch is about a foot further forward than this. Does this mean the weight will be even heavier at the hitch?

I'm slowly gearing up to fit spacers to the front axle. Got some 10mm thick bits of stainless cut, and got some longer bolts. Just got to measure/and drill them. 10mm spacers equate to a 40mm lift of the nose. I've checked this actually works in reality by fitting CCC backissues under the tyres. I _think_ that this means that the weights column above will effectively shift down 4 places. So instead of 60kgs at 30cms, I'll have 60kgs at 34cm.

I do tend to wonder if I may not just end up with the nose at the same height, and the rear axle lifted up a bit though!

Hope this is of interest to someone!!

Cheers,

Al.

[Mark Stanton]

If your Pug tow ball height is 45cm then its like everyone has been saying all along - its too high      

45cm = 17.72 inch  

See previous postings suggesting tow ball height at something more like 16.5 inch = 41.91cm to suit your tow hitch

This will reduce nose weight      Not sure if that would be sufficient to suit the specifics of towing with your Pug though    

Just as an aside - I checked my mobile tent (cos they tend to ride high as standard much like 4x4 stuff) last week which is also set at 16.5 inch as suggested by PRG - It has been fitted with a drop plate which has an "Approved" stamp on it    

[Al Yupright]

And as I've been saying all along, I cannot change the height of the tow-ball on the Pug!

Not without breaking the law/invalidating my insurance, anyway.

EU Type Approval states that tow-balls must be between 41 and 45cms from the ground. And also states that I cannot use a drop plate, unless my tow bar was type approved with on in place (for which Witter say they dont do for anything other than 4*4s)

So, I cant lower the tow-bar.

Spect your mobile tent is pre 1998. Its only post 1998 cars that the EU stuff applies to.

Cheers,

Al.

[Mark Stanton]

Nope my mobile tent is a 2000 model    and it carries a full Approval stamp on the drop plate      The thing with mobile tent tow bars is that 99.9% are an insitu custom made item for mobile tents rather than a standard bolt on item

My other tow barge Vectra Estate has a Witter tow bracket fitted by Indespension with the tow ball set at 16.5 inch without the use of a drop plate  

A quick scout around the paddock at SS events shows that most tow bars are set at about 16.5 inch give or take half inch either way      With BJ Minnos, A series and PRG trailers being favourites    

[Al Yupright]

Nope my mobile tent is a 2000 model    and it carries a full Approval stamp on the drop plate      

Hmmm,

The stamp on the drop plate doesnt actually mean anything other than the drop-plate is made out of good quality steel.

It doesnt mean that it is legal for use with your tow-bar.

It is only legal if the tow-bar manufacturer submitted it for type approval with one of these plates present.

You may or may not want to check with the tow-bar manufacturer!

Cheers,

Al.

[Mark Stanton]

It is only legal if the tow-bar manufacturer submitted it for type approval with one of these plates present.

It has the stamp on stating grade, thickness, spec etc and Approved Tow-Bar drop plate clearly noted      

Can't remember manufacturers name - I'll have a look next time I use it    

It suits me just fine     all confirmed with insurance and everything.

On mobile tent tow bars drop plates seem to be either welded into position and thus being integral with tow bar or bolted in position    

They are fitted by such specialist mobile tent dealers as Brownhills, Hayes, Baldwin, Dudleys and Moran    but to name a few    and used extensively in the U.K and Europe  

Looking at the piccie of your pug is does seem that perhaps a longer wheel base car would be a better option although I understand this is not on your options list.

Hope you sort it - good luck and I admire your patience and perseverence          Keep it safe      

[John Fisher]

Mobile tents are exempt from towbar regs - at the moment.

Mine was manufactured and fitted by the supplier of said mobile tent. Drop plate was fitted to give 15.5" and 16.5" settings.

I can see only one option for you Al - buy another tow-car!  

Fish

[Al Yupright]

Its not necessarily the tow-car...

I've seen the same trailer, with a Westy on it, on two other cars. An Audi Quattro, and a Mondeo, and both of those suffered from saggy A*** too.

The problem is that tow-balls have to be at a minimum of 41cms, and because at that height the weight is being lifted off the front axle, it means that the nose weight is >130kgs.

Witter told me there is also a law/regulation that tow-balls must be above 35cm when the tow-car is fully laden, so even at this height, the noseweight would be 100kgs.

I'll sort it, I always do!

Just faff about deciding on the best way

[Bananaman]

Just out of interest (as I've just purchased a tow car) are all these height measurements from ground to TOP of the tow hitch 'ball'.

andy

[Al Yupright]

Guess what that is!? An adjustable height tow-coupling. I never knew such a thing existed, but it goes to show my problem is a real and common problem.

More Info Here

My trailer has full Bradley running gear, so I was just browsing their website for details on the hole spacing on the axle mounts etc. Tis very good, technical drawings of all the components etc.

But I get the impression they know their stuff, and will be able to recommend the best solution, so will drop them a mail. I've been put off shimming the axle a bit, because it has slotted mounts, and I dont want to unbolt it, then screw up the tracking/wheel alignment.

Cheers,

Al.

[Richard M Green]

A nice bit of engineering indeed, but what exactly is the difference (other than cost) between this arrangement and doing what Richard Brown did and spacing the entire hitch coupling upwards (still horizontal) by means of two bits of 40 x 40 RHS?

It looks to me as though the device in the picture is intended to allow a trailer to be connected to many different vehicles at different heights with the minimum of effort. In your case it's the same trailer to the same tow car at all times isn't it?

If you add spacers to one of your trailer axles the by-product will be to put an assymetric loading on the axles i.e. front pair will now take more of load than the rear pair. If you've got plenty of spare capacity then this won't be an issue. But if not.....

Just out of interest how much is this device?

Regards all

Richard

[Al Yupright]

A nice bit of engineering indeed, but what exactly is the difference (other than cost) between this arrangement and doing what Richard Brown did and spacing the entire hitch coupling upwards (still horizontal) by means of two bits of 40 x 40 RHS?

Indeed. Same effect, just quickly adjustable for different cars.

If you add spacers to one of your trailer axles the by-product will be to put an assymetric loading on the axles i.e. front pair will now take more of load than the rear pair. If you've got plenty of spare capacity then this won't be an issue. But if not.....

Will it? I'm not sure if its the same load, just making the deck slope upwards. I think having a stiff tow-car, that lifts the front of the trailer up from the horizontal, takes load off the front axle, hence putting more load on the rear axle. My car is so soft that the trailer forces it down until the trailer is pretty much balanced on its axles. I think the spacer will just mean the nose is higher up when at this balance point?

I dont think the axles normally take 50/50 because of where you put the car on the trailer, the length of the A-frame, and so on. My axles are rated 1300kgs each, so loads of capacity.

I did take heed of your first message about Richard's trailer, and eyeballed my trailer for this mod. The problem was that I've got a winch table, spare wheel and jerry can cage all mounted on the a-frame. And to lift the hitch by 40mm would mean having to lift those too, to avoid fouling. So I'd end up with two pieces of 1metre long RHS! Spacering the front axle seemed simpler!

Currently rethinking

I found some dead simple to fit spring-assisters, but they'll be taking weight off the front axle... and I'm dubious as to whether they'll turn my pug into an oversteering beast ( )

No idea on the price for that adjustable, but I'm sure its not cheap! I wasnt thinking of getting one, like you say, I'd be better codging up something fixed being as its same trailer, same tow-car all the time.

Cheers,

Al.