Maximum load on tow hitch - Autotrail Apache 634U

[Bernie Jones]

Hi all,
I've recently acquired a 2008 model of the above and wish to replace the current towbar with a carrier for a lightweight motorcycle. I've done all the calculations to work out what the resultant weights would be on the front and rear axles and am planning to get the vehicle uplifted to 3850kg with a 2240kg capacity on the rear axle with the help or air suspension and uprated tyres. That will ensure that I'm legal w.r.t the axle loads.

However, trying to determine the permitted safe load on the towing carrier - i.e. combined weight of bike plus carrier - is proving elusive. The Autotrail documentation doesn't mention it at all. The Fiat handbook gives figures for a number of variants of the basic vehicle but not of course for the conversion. I'm not even sure which chassis model the conversion is based on (the Fiat handbook refers to a standard and heavy version of the 3500kg model with max nose weights of 100kg and 120kg but I don't know which I have). Also, these figures refer to the SWB and MWB versions so I suspect might be reduced for the Autotrail with around 1400mm overhang from the rear axle to the towing hitch.

Any advice on how I can derive some figures to determine the maximum load would be hugely appreciated!

Many thanks,
Bernie

 

[pappajohn]

You can't.
If you know the towbar manufacturer try emailing and asking the max download.
Failing that I would take the lower of the two options....100kg.
Overhang should have no influence on noseweight other than imposed axle weight.

 

[Richard n Ann]

We had a scooter rack fitted onto the chassis with 2 arms so it's very sturdy and made for the job. It's removable if you want to tow anything. Fitted by Watling Engineers at St Albans. Very knowledgeable chaps.
Just an option

 

[Geo]

Your vehicle and your tow bar should have Manf plates with S values stamped onto plate, these are the static loads you need
you use the lower of the figures available as common sense dictates
ergo Vehicle Manf says 85KG max Tow Bar Manf states 150KG = 85KG would be the figure to work to
If you need to go greater than those specified you are firmly in the suck it and see brigade

 

[pelican]

Hi
Cannot help with your question but would be interested purchasing the tow bar you are removing as have the same vehicle.
PS really enjoying the Apache its been trouble free.

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[Stealaway]

Any advice on how I can derive some figures to determine the maximum load would be hugely appreciated!

Somewhere on here is a MH weight calculator done by Jim.
I know a tow ball has a maximum load of around 120 Kg but my rack is supported by two high tensile 16mm bolts but I have no idea how much they will support.
I do carry 180 Kg - but I always worry and only single journeys to the IOM and back.

Testing with double the weight?

 

[EX51SSS]

 

[Bernie Jones]

Many thanks for your replies. Unfortunately there is no such info on the vehicle plate which gives the maximum and individual axle weights but no 'S' value. The current towbar is plated at 65kg but that will be going to be replaced by a bike carrier.

I've now emailed a few fitters - including Watling Engineering (thanks) - so hopefully one of them will have an idea.

Thanks,
Bernie

 

[Badknee]

I searched for this answer and failed dismally. The manufacturers of tow bars design them for towing not carrying weight, caravan manufacturers want you to put a nose weight to make the caravan more stable. So you can reasonably expect the bar to cope with that.
I ended up having the tow bar that was fitted beefed up, I removed it and added extra steel angle the length of it, gussets on the carrying joints and extra mounting bolts through existing holes in the chassis.
This was done many thousands of miles ago and a recent check showed no movement or cracks, but, as has been said you need to suck it and see because there doesn't seem to be any infornation on the tow bar side of things in a downward direction.