ARB dual wheel tyre carrier Cracking

Submitted: Sunday, May 09, 2010 at 23:39
ThreadID: 78347 Views:9086 Replies:4 FollowUps:6
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Well fellow ExploreOz members, Bushtracker Owners Group, I thought that it was time to give you an update to the Cracking ARB rear tyre carrier come tow bar.

This is written for the information of visitors and members. If you have an ARB rear tyre carrier fitted you need to be aware that there could be an issue if you use a non standard ball mount ie; Treg or AT35 in conjunction with Hayman Reese Weight Distributing Hitch.

Now, I am not writing this to bag ARB because I am of the opinion that they make an excellent product! But to make people aware that they could have an issue with their warranty.

I was advised that ARB had not conducted any stress tests but had made calculations by information I had supplied, measurements and weights of the caravan.

This is a reproduction of the correspondence that I received from ARB
Engineering have made some calculations based on simple linear measurements. Whilst these figures do not provide stress details on the various parts of the RSTB, they do give a clear understanding of why the failure has occurred.

• For every 10mm increase in the distance of the fulcrum point from the bar, represents a reduction to the standard 350kg ball loading of 3.3%
• In this case the pin (fulcrum point) is approximately 200mm to the rear of the centre point of the tow ball in the standard ball mount.
• 20cm x 3.3% = approx. 66% reduction in the ball weight capacity.
• In other words the maximum ball weight for this set up would be approx 120kg.
• His Bushtracker van has a tare of 2610kg and an ATM of 3500kg.
• Normally the ball weight should be approximately 10% of the mass ie: between 260kg and 350kg
• The designed maximum ball weight for this bar is 350kg. the setup as being used equates to a ball weight between 430kg and 580kg

The reason for the failure is clearly due to the extra leverage cause by the non standard ball mount setup. This product has been fit for the purpose for which it was designed and has not failed as a result of design or manufacturing defect, but as a result of misuse. It is therefore not covered under the terms of the products warranty.
Signed;
Roger Chestney
National Customer Service Coordinator.

Therefore their product was not at fault, no warranty claim.

ARB removed, striped the old carrier and painted and refitted a new one at a cost of $1076.

I just wonder how many tyre carriers ARB have sold and clients using the same setup as I use and are unaware that they are voiding their warranty through no fault of their own, I say this because ARB did not supply any documentation as to what is recommended for their tow hitch. I make this comment because I am not an engineer and believed I was using the equipment purchased in good faith and this is the same with the Hayman Reese 750 Weight Distributing Hitch. The hitch comes supplied with a pre drilled hole in the shaft and no distance information regarding attaching to the hitch receiver.

Contact with ARB:

I was content with the outcome as it stood but what I was disappointed in was that no one contacted me to explain anything, or give an undertaking that ARB would supply instructions with the ARB rear tyre carrier so to avoid simular issues arising in the future.
Roger Chestney contacted me and the following e-mail was received.

Hi Erik,
We hope you are well and that your refund cheque has arrived.
We said we would update you on what we were going to do to prevent the same issue happening to other customers.
We have taken on board your concern, and agree that most customers would not realise the consequences of using non-standard ball mounts.
To this end, an Engineering Change Notice has now been raised that will lead to a warning being added to all relevant Installation instructions on the use of non-standard ball mounts. A warning sticker is also to be produced that is to be attached to each rear bar during installation.
Thanking you for your input into this issue and for your patience during the process.
Regards
Roger Chestney

THANKS ARB THAT’S ALL I WANTED,

THANKS


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Reply By: Ozhumvee - Monday, May 10, 2010 at 08:15

Monday, May 10, 2010 at 08:15
This problem has been around for a long time and not just with ARB towbars/steps.
I brought this up in a post a few weeks back about extending/dropping the towball height by extending the length of the tongue and was howled down.
As ARB has pointed out whenever you change the distance/position of the actual coupling from that supplied with the standard towbar you are changing the load on the hitch, may increase the actual ball weight and exceed the rated capacity of the towbar.
Even fitting a different type of hitch eg: a Treg type in place of a 50mm ball may change the ball weight/leverage applied to the towbar if the fulcrum point is moved from that as it is with a 50mm ball.
Peter
1996 Oka Motorhome

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Follow Up By: Alloy c/t - Monday, May 10, 2010 at 08:26

Monday, May 10, 2010 at 08:26
Makes the HylandHitch a better proposition for larger vans.
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Reply By: Member - Doug T (NT) - Monday, May 10, 2010 at 09:34

Monday, May 10, 2010 at 09:34
One of the reasons I like the K&N WA built tyre caddy is that it is a separate item from the Towbar, so when fitting a K&N the you leave your towbar in place,
(not writing this to bag ARB because I am of the opinion that they make an excellent product!)
I believe they do NOT make the tyre carrier, it's Kaymar.

.
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Follow Up By: Member - Phil G (SA) - Monday, May 10, 2010 at 17:58

Monday, May 10, 2010 at 17:58
Doug,
ARB make their own carriers these days - no longer Kaymar.
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Follow Up By: Member - Doug T (NT) - Monday, May 10, 2010 at 19:09

Monday, May 10, 2010 at 19:09
Phil
Say's so on the website....KAYMAR

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Follow Up By: Member - Phil G (SA) - Monday, May 10, 2010 at 20:09

Monday, May 10, 2010 at 20:09
Gday Doug,
Coops owns an ARB rear wheel carrier for his 100series which is not a Kaymar:


The Kaymar equivalent for the 100series looks like this:


The bumper bar is a totally different design, with the Kaymar looking solid and the ARB looking swish.
I have a friend who has had both and much prefers the Kaymar product.
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Follow Up By: Member - Phil G (SA) - Monday, May 10, 2010 at 20:11

Monday, May 10, 2010 at 20:11
ARB photo didn't work - here it is again:
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Reply By: Member - Rodney B- Monday, May 10, 2010 at 10:02

Monday, May 10, 2010 at 10:02
Guys, a photo of the failed hitch would help us visulise the problem and is probably worth a thousand words. (was this an earlier post that I missed)

I use a Highland hitch and I guess this does not extend the hitch distance.

Glad that you have resolved the issue and it would seem ARB did the right thing eventually.
AnswerID: 416087

Follow Up By: Member - Coops (WA) - Monday, May 10, 2010 at 10:26

Reply By: Member. Rob M (QLD) - Monday, May 10, 2010 at 20:23

Monday, May 10, 2010 at 20:23
Hi Erik,

I am a little confused as to the meaning of
" The reason for the failure is clearly due to the extra leverage cause by the non standard ball mount setup."
I have the same replacement bar and there was no "standard ball mount setup"
supplied with the bar, so obviously assumed that any hitch would be suitable to be used with the rear bar.
I don't tow anything as heavy as your van but use standard ball for boat, orac offroad coupling for trailer and a hayman reece weight disribution hitch fo a 2400kg van.
I think I will be looking a little closer at the back of the car when washing it from now on.
Thanks for the heads up.
Rob M

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