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Just Discovered, Bolt Sheared Off From Hitch Damper, Check Your!


boatrusper
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Hi,

Whilst carrying out some routine maintenance this afternoon, I noticed that the hitch seemed to have a degree of play vertically, which I hadn't particulary noticed previously.

On further examination from below looking up under the plastic cover it became evident that the rear bolt which secures the damper unit to the carraige system bolted to the front of the A frame has sheared off .( 1 at the front was ok) Basically I had one bolt securing the hitch to the tow bar. I haven't had the caravan serviced yet this year and would imagine posssibly that this would have been flagged up? I did have a new Alko stabiliser hitch fitted last summer and all was well! However,just like your car on the day its MOT'd it would only be applicable on the day of the inspection. I. e this could of happened on any one the remaining 364 days of use. I have sent Alko a email but don't expect a reply, bolts fail. However, please check your tow hitch for excessive vertical movement and if in doubt take a look from below with a torch I'm glad I did. The bolt in question was in line with the jockey wheel post for location.

The caravan is a 2006 Hymer Nova 545, on a alko chassis, which I believe is a very popular mainstream chassis irespective of make of body shell above.

 

Regards Paul.

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For a bolt to shear in that position, there would have been something wrong. Most likely the bolt has either been over-tightened, or less likely under-tightened and then loose. . I would change both bolts and correctly torque them if I were you. Follow this up with a torque check after a couple of trips. Use bolts supplied by ALKO (I assure you there is a difference), Do not lubricate them when assembling.

Ern

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Well spotted. ..I had a smashed hitch which could have happened at any time post previous service and it put my 'van out of action for nearly two months whilst the replacement etc. .was sorted. Al-Ko are not best repliers to e-mails I'm afraid but of you feel you have an issue with them only let me have a PM and I will pass contact details there. .

 

geoff

Kia Sorento KX-1 CRDI 4WD towing an Elddis Affinity 530

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Hi,

 

I didn't get in early enough tonight to take any photographs or do the job. The sheared bolt is a M10 socket bolt graded to 9. 8, I can't make out any other references due to the condition. I intend replacing the bolt with a YFS socket bolt graded to 12. 9, and as per the OP I will change both. I also intend to use Locktite. Does anyone have a torque figure for this location?

The shear line is roughy the same depth as the nut. I don't see the necessity to source the bolt from Alko, The replacement bolt was purchased from a fixings retailer, (construction industry) and not at B and Q for instance. unless Im missing something? My brother has a twin axle Swift Charisma,(Alko chassis) I've suggested he checks his before he ventures out again.

 

Regards Paul.

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When fitting new hitch the torque setting is not very high .

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Hi, Just found this on the internet.


M10 torque to 90 % of maximum tension = Nm 95. 7 Nm.
With reference to your question, using your picture from the link, the damper housing forward of the rubber dust sleeve. The complete assembly when unbolted from the A frame, if this is turned 180 degress/ upside down, differcult with the brake cable connected the damper housing is held in place by 2 M10 socket bolts which clamp through the carriage unit. The give away for me was the entire hitch with excessive up and down movement, the sheared bolt was still in situ, and for the record unable to retract any further due to insufficient room to withdraw, so it still held the clamp in a partial connection to one side if this makes sense.
I will post pictures tomorrow evening.
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Hi,

Please see attached, the new shiny BZP bolts are the replacements, please use the photograhs as a process of identification.

 

The hitch is now secure and there isn't any vertical movement what so ever, I would suggest that this had been loose for some time, and I had got use to the play.

 

Regards Paul. post-35451-0-15355500-1395170993_thumb.jpgpost-35451-0-86283700-1395171025_thumb.jpgpost-35451-0-07767600-1395171063_thumb.jpg

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Have you checked the damper if it is working correct as a impact shock of a sudden braking could cause something to shear if it has not been overtightened ?

 

 

Dave

Jeep Commander 3. 0 V6 CRD

Isuzu D- Max Utah Auto

Elddis Crusader Storm 2000 Kgs, Unipart Royal Atlas Mover .

 

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Hi,

Damper seems fine.

I do carry 3 mountain bikes on the front, and the jockey wheel guage can sometimes register around 130 kg's although the loadings for the bolts are massive in comparrison. I put it down to just one of those things, occasionally bolts fail.

Regards Paul.

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No, the average is around 110kg, cars good for 130kg I believe if not more, can't remember.

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Not sure about the Hymer but I believe that most UK built caravans on an Al-Ko chassis have a max tow hitch load of 100kg.

The max load should be stamped on the hitch & possibly in the handbook.

Edited by Caravanmedicswindon

For any additional information or advice please have a look on my website. .....

www. thecaravanmedic-swindon. co. uk

 

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Not sure about the Hymer but I believe that most UK built caravans on an Al-Ko chassis have a max tow hitch load of 100kg.

The max load should be stamped on the hitch & possibly in the handbook.

Caution with that.

My Hymer 546 is physically fitted with a 150 kg "S" hitch, but the handbook quotes a 100 kg limit, a figure confirmed by the importer to be dictated by the limits of the chassis itself.

My earlier 545 was fitted with a 100kg "S" hitch.

 

Bolts don't just fail, there is always a reason.

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Hi,

Unladen weight of van is around 1340 kg without adding in the mover. I have never felt the need to use a weigh bridge due to the ratio between the car and caravan. The chassis is rated to 1700kg, applying the recognised ideal 7% tow hitch/nose load requirement gives you a ideal 119 kg hitch load.(tow car allowing) The Alko AKS 3004 stabiliser has a maximum nose load of 150kg.

Basically all is well. On changing the front bolt still insitu it was found to be handtight, I would then suggest that this would possibly ended up shearing eventually to.

 

The alko A frame on the hymer (German /European biase) is also long enough to accomadate a Fianna bike rack supporting 3 bikes. With this facilitity it could be that not all Alko chassis are equal? I also wonder what the safety factor multiple is with your hitch, seem to remember top gear picking up a caravan, with a crane by its hitch. I would therfore imagine that your rear suspension would be on the floor long before the hitch failed?

 

Regards Paul.

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The chassis is rated to 1700kg, applying the recognised ideal 7% tow hitch/nose load requirement gives you a ideal 119 kg hitch load. (tow car allowing) The Alko AKS 3004 stabiliser has a maximum nose load of 150kg.

 

 

It sounds that Hymer built your van the same as mine, with the 150kg hitch; however as I said my handbook still said the noseweight is limited to 100kgs.

 

I asked the importer to check this difference between the hitch's capability and handbook statement. The answer they got for me is I must keep within the 100kgs, because that is the limit of the chassis.

 

The 7% is a red Herring, it is just an old UK idea, Hymer you will find recommend the German standard of between 4% and the caravan's limit, in our case 100kgs.

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Interesting, where abouts in the handbook did you find the reference to 100kgs?

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Hi,

Please see attached, the new shiny BZP bolts are the replacements, please use the photograhs as a process of identification.

 

The hitch is now secure and there isn't any vertical movement what so ever, I would suggest that this had been loose for some time, and I had got use to the play.

 

Regards Paul. attachicon.gifIMG_1124. JPGattachicon.gifIMG_1125. JPGattachicon.gifIMG_1123. JPG

 

 

Were the originals 8. 8 grade?

 

If it sheared because of a to and fro action it would elongate the mounting holes before "chopping" the bolt. If it sheared in line with the end of the nut it suggests it was overtightened and should show signs of a 'twist' on the break surface. .

Edited by beejay
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Interesting, where abouts in the handbook did you find the reference to 100kgs?

 

In the supplied big white Hymer handbook titled “ Instruction Manual” **

 

Page 32 Section “3 before the journey” clause 3. 5. 4, I quote it in full together with its associated note:

 

3. 5. 4 Caravan load, nose weight and axle load

The nose weight of the caravan may not exceed 100kg.

(note> The non-observance of this [info above] can lead to damage being caused to, or inside the vehicle)”

----------------------------------------------------------------------------------------------------

** The document's footer designation is:

caravan ENEL/ENG-04/07 – englisch (EN)- 1571397- HYW -0145-06EN”

-----------------------------------------------------------------------------------------------------

This same 100kgs nose weight value is printed in the actual caravan’s “Technical Build Specification” that came with the van.

 

It is also again on the pre order data sheet I had prior to contracting its construction. (The van is a “S” series 546, specifically built with our selections from Hymer’s option list.)

 

At this moment I have not got these other documents to hand.

 

As I said it is built with a 150kG “S” rated Al-Ko stabilising hitch. However they confirmed that the documentation take precedence, the limitations being determined by the chassis not the hitch used.

Edited by JTQ
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Wow,

 

Thats some reply thank you.

I have all of the original documentation, and cannot find any reference to maximum nose weight. My instruction manual makes reference to the Caravan load, nose weight and axle load on page 33, clause 3. 5. 3 and only suggests the towing vehicle documentation is followed in line with the maximum nose weight . Ie this figure is specfic to the car and not to be exceeded. To be honest I am surprised that this isn't stated as per the information you hold. I guess the responsibility is now on the tow car selected and not what the caravan could impose. From memory the landrover products offer a maximmum of 150 kgs nose weight, my Touareg at 130kg which matches the plate on the tow bar . Most vehicles which are not of full 4x4 capability I would imagine offer only around 50 -70 kgs. So my theory is still open to intrepretation.

The bolt has been not been streched or deformed, and looks as it has been cut with just a slight raising around the thread. I could post a photograph if you like? its also black across the shaft, as in its got dirty and has been that way for a while.

Regards Paul.

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The bolt has been not been streched or deformed, and looks as it has been cut with just a slight raising around the thread. I could post a photograph if you like? its also black across the shaft, as in its got dirty and has been that way for a while.

Regards Paul.

 

 

It suggests it was seriously overtightened or it is faulty. .

Edited by beejay
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