Minno Shuttle - have dropped hitch height by 50mm - request for informed comments please

[anthonym]

Minno Shuttle - have dropped hitch height by 50mm so now a bit nervous. Having previously lost wheels with the Seven aboard and replacing wheels that then fell off, the whole thing has had my attention, especially with a 2,000km trek due tomorrow or the next day.

 

I worked out that every inch off the hitch height, by changing the jockey wheel height while the rear wheels were the on a weigh bridge, reduces the weight on the rear axle my 70 kilograms per inch of drop.

 

The nose weight was 280kg when it should be no more than 75kg.

I don't know how much this procedure reduces the nose weight, but it should be a lot, which I know is not very scientfic.

 

So dropping the hook by 50mm (which is 2 inches) should reduce the rear axle weight by 140kg

 

BJT say to use 17" as a rule of thumb, but that doesn't work for my set up, I suspect because I have harder than average suspension.

 

This 140kg reduaction reduces the rear axle weight from 820kg (which also exceeds the wheel capacity as I understand it) to 680kg which is within it.

 

Clearly this reduction is transferring weight to the front axle, which is what I want. How much of that weight is comiing off the nose weight I would love to know, but have to await an opportunity (no bathroom scales on tour) for another weighbridge, the previous one being a thousand miles plus away, somewhere in Norway.

 

Must say that within seconds of settiing off with the new setup and without being conscious of the changes I was feeling that everything felt "better". However caution took over and nerves are a little on edge about the whole thing.

 

The height reduction has been achieved (key question) by use of a 6 level height adjustment plate (a proper one for the job), fixed to the old fixing place with the pair of holes three from the top and the hook bolted on to the pair of holes immediately below that. All actually looks professional to my pleasant surprise. The plate is a very solid affair indeed, weighs a ton (so to speak). Fitted with two pairs of 8.8 24mm dia 50mm bolts using Nyloc nuts and two extremely powerfu guys using pipes to extend the spanners... have to admit I thought torque settings were for that, but they used a force similar to what it took to remove the original. Me? I stood well clear.

 

So. Hopefully no more wheels will fall off - though those problems are said to have had other causes, but this issue cannot have helped.

 

from MacD net as usual, East Jutland, Denmark.

 

I suppose I am writing in case anyone has any caveats to suggest, preferably not suppositions as I am about to "hit the road" across Germany.

 

I'll check back here before I leave. Hopefully.

 

Anthony

 

edits to fix typing errors.

 

Edited by - anthonym on 28 Aug 2010 18:40:45

 

Edited by - anthonym on 28 Aug 2010 18:41:51

[Clousta]

Anthony,

pop into a caravan dealer and purchase a nose weight gauge.

 

e.g. nose weight gauge

 

They are cheap and easy to use. It takes the guessing out of the equation. You can play around with the weight distribution as much as you like. Also useful if you put different vehicles on the trailer/different orientation. etc.

 

I use one for my glider trailer or if I have to tow some one else's trailer and need to shift stuff around to get teh weight distribution correct.

 

BTW the tow hitch max load for my Range Rover is 100Kg so at 280Kg you are seriously overloading your tow vehicle.

 

Gavin

1988 1700 Supersprint (LA, long cockpit)

[rj]

The max load of Anthonys tow car is 75 kg.

 

 

[The Pikey]

280kg 😳 you will be able to go a bit higher than 75kg without any problems but at 280 kg I'm supprised your front wheels are on the ground.. You really want to be towing at 16.5"-17" this is a standard height for a level load which will put equal weight on both axles. Can't you simply have the car 6" further back on the trailer?

 

BTW 210nm is the torque setting for the towball bolts..

 

jason

 

 

 

 

 

Edited by - Jason Fletcher on 28 Aug 2010 22:14:13

[anthonym]

Thanks chaps, so nothing dramatic to fear in so far as I am fixing the problem rather than making it worse.

 

I will give my weigh bridge results below. The catch 22 is that the trailer rear axle has too much weight on it to the extent that aiui it is over max capacity and so is the nose weight, so moving the car inside the trailer makes one or the other even worse.

 

The only thing that reduces the load on both is dropping the hitch height, because that transfers weight to the front trailer axle. How much of that weight comes off the hitch I do not know at this point.

 

Won't bathroom scales do? Assuming within load range.

 

thanks for your swift thoughts, I am a bit less nervous now.

 

Regarding the overload on the hitch, the front wheels have occasionally had trouble getting a grip, such as on a very steep hill covered in loose gravel, so really only problems in extreme circumstances. Five years of long distance travel (at least) with this car. The Stanvanger BJT agent observed that the rear suspension seems very hard (he was expecting me to say the tail tends to sway, but it does not) and all I can think is that this has compensated for the weight. The suspension was created/modified by Ford for the car to be a police patrol car demonstrator, so presumably much harder than usual (she drives and handles very well).

 

If this 2" drop does not work, there is one further 2" drop I might try.

 

The trailer has a fully loaded wheels and tyres rack as well as a front shelf in front of the car with things like oil supplies, then the A frame has a spare Mondeo tyre, water container and more oil. It all adds up. Then of course the Mondeo (Estate) is loaded to the gunnels.. plus me :-)

 

I now gather there is a weigh bridge about an hour South on my route home so I will see if I can spend some time there.

 

I was worried about using the drop plate to reduce the height of the hook, but it really does appear to be a very tough piece of work and to fit perfectly with the tow bar; though I have only done a few careful miles with it so far.

 

 

Anthony

 

[anthonym]

here are the BEFORE CHANGING HOOK HEIGHT weigh bridge numbers. I am assuming that it is valid to take the nose weight from the weight of the jockey wheel placed on the weigh bridge (alone) with it placed such that the hitch is at the height it is at when attached to the car.

 

All fully laden with all luggage and Seven ... and me where relevant.

 

TRAILER AXLES AND NOSE in Kilograms

_____UnHitched__Hitched__Diff

REAR ____380____820___+440

NOSE ___________280___+280

FRONT____1160___440____-720

TOTAL____1540__1540

 

CAR AXLES

REAR_____820__1020____+220

FRONT____940___880_____-60

TOTAL___1760__1900____+140

 

WEIGHT ON REAR TRAILER WHEELS

When hitch height is____then rear axle weight is___

16"___780kg

15"___710kg

14.5"_660kg

14"___640kg

 

which is 70kg reduction per inch of drop

 

so 2" drop is 140kg reduction from rear axle

 

So I have introduced a 2" drop to the height of the hitch.

This is intended to bring the rear axle wheel weight within operating capacity.

It is also intended to reduce the hitch weight, by how much remains to be seen.

 

The front of the car body is now raised by 1.5" when hitched, I do not know what it was before. Clearly I am hoping to have achieved a reduction in the negative 60kg over the front wheels.

 

The hook height is now 16" to top of ball, which seems odd as it was not 18" before-hand. Need to check this in case ground was not level (garage floor).

 

Regret gaps in these figures, but all I have for now and of course new results I will acquire as soon as possible (meaning when I find a weigh bridge I can use such as the one near the border an hour South).

 

 

 

Anthony

 

EDIT change 1760 to 1900

 

Edited by - anthonym on 28 Aug 2010 23:14:50

 

Edited by - anthonym on 28 Aug 2010 23:19:15

[anthonym]

p.s. how many gorillas is 210 nm ?

 

Anthony

 

[The Pikey]

God that seems complicated to me.. I'd say with the trailer off the tow car, loaded and level you should have 17" to the top on the inside of the hitch, if so then the weight on the hitch should be about 7% of the weight of the loaded trailer so about 100-110kg in your case. If you can't move the 7 or the trailer contents to acheive this then the wheels have been bolted in the wrong place on the trailer.

 

jason

 

 

 

Edited by - Jason Fletcher on 28 Aug 2010 23:29:55

[The Pikey]

p.s. how many gorillas is 210 nm ?

---

 

about two with pipes to extend the spanners so you are about there

 

 

[rj]

210Nm = 154.8878 lbf-ft

 

Your torque wrench x 2 or so :-p

[Clousta]

Anthony,

of course you can use kitchen scales. I didn't think that you would be travelling with a set but you seem to have everything _and the Kitchen sink with you! Nose weight scales are smaller and fit on/in the trailer for next time.

 

Gavin

1988 1700 Supersprint (LA, long cockpit)

[Bricol]

I'd be taking a close look at gross train weight with all that aboard.

 

Bri

[Graham Perry]

Perhaps I misunderstand the weights, but with 1540 kg total weight surely that is overloading the minno shuttle by nearly 200kg ? Could that be the heart of the problem ? Start getting towards 1.5 tonnes and the small wheels of a shuttle are going to struggle. Trailers at that weight and above are generally using 13 inch wheels.

 

I have towed dozens of trailers over the years and have typically found that if the trailer sits level when laden it will probably tow okay provided the tow car isn't at a stupid angle as a result. It sounds like lowering the tow hitch is the correct thing to do

 

Edited by - Graham Perry on 29 Aug 2010 22:08:15

[anthonym]

'morning all, I see you have been busy in my absence.. thanks

 

Using a Danish keyboard set to Danish so this post might prove interesting.

 

Somewhat relieved you concur Graham.

Regarding kitchen sink, I have now exchanged this for a collapsible one, more exactly I exchanged with the two Gorillas my plastic bucket for their collapsible one, quite chuffed really, the fulll size plastic one was a real nuisance, and they now have a proper size bucket.

 

Gross Train weight, yes ok, I have carefully not looked at this aspect as there is not much I can do about it. Having said that I am not carrying that much (in my view I suppose) by which I mean nothing looks overloaded when you look at it all, the car is only packed to the bottom of the windows, not the roof, for example. The trailer has 1 x 7 in it and two sets of wheels plus a few bits... just seems to me not so much.

 

Axles wrongly placed.. gee thanks ! :-)

 

Come to think of it I had observed the Gross Train weight is under 3.5 tonnes and figures that should be ok licence to drive wise... so not being a Range Rover becomes a good thing in this aspect only.

 

Wonder if anyone else has actually weighed their fullly loaded weights (gross train weight)?

 

see you later, have to take down a tent..

 

 

 

 

Anthony

 

[peterg]

Minno Shuttles capacities from Brian James website:

Gross capacity 1380 Kg

Load capacity 800 Kg

 

If we assume your R500 weighs 500kgs (Caterham site says 506 for latest Duratec version) plus 2 sets of wheel/tyres which should be no more than 120kgs all in... that makes a total load of 620 plus "a few bits" - by which I assume you mean trolley jack, toolbox and other stuff but surely that lots can't be more than another 130kgs bringing the total load to 750kgs meaning your trailer GVW is only 1330kgs rather than the 1540kgs you suggest

 

 

 

 

[anthonym]

With all its luggage on board my R500 weighs in at 560kg I think.. RJ may recall better, we weighed it at his place a few days ago. Bits are one race lift, not trolley jack, no tools except as included in the weight of the seven, one 12v impact wrench, 5 x 4 litres oil things.. some milk (!).. 8 wheels and tyres plus associated wheel nuts, a set of wheel studs, 5 litres of water in plastic container, one Mondeo 17" 45 series tyre...

 

I agree with your figures intuitively, I suppose the weigh bridge could have been over reading or some other fault with the way I did it. I weighed myself and it said 100kg whereas I weigh 94kg (again as per RJ's scales). IIRC.

 

I did have the wheels on the edge of the weigh bridge, not the centre.

 

Um. So, 1540 minus 560 for 7 is 980, less 240 for wheels tyres and bits is 740 and I always thought (just a belief) the trailer weighed 750kg.. ok, so now I am bemused as I agree with both your figures and my own.

 

 

 

Anthony

 

[anthonym]

seems like we are saying that gross capacity 1380 minus load capacity 800 equals trailer weight of 580kg ? Whereas I always thought it was 750kg.

 

I suspect these capacities do not include the tyre rack because it is an optional extra. Nor the spare wheel and carrier.

 

750-580=170kg

 

I'll check the plate on my trailer in the morning, see if that sheds any light with actual figures for my specific trailer, which mas made quite a long time ago and figures change over time.

 

Anthony