Camper bed one of the reasons for Manx MOT Failure

[mshaw1980]

Hi all

So I had my Manx MOT today and failed on a few things which I expected but was very surprised by the advisory on the camperbed I bought from M1 camperbeds.

It is a full width rock n roll bed with three full seatbelts with the inertia reels attached to the rear of the seat. The tester failed it because he said the m8 bolts that are used in the pivot points of the seat back wouldn't be strong enough in the event of a crash. I explained that a manufacturer had made this and it passes the UK mot and he looked surprised. He told me I need to use at least m10 bolts for the pivot.

I phoned m1 camperbeds and the guy was very helpful and explained that they use these bolts in pull tested beds???

So I am in the position of having to grind off captive nuts then enlarge the hole in the framework for the larger bolts however before I begin what are your thoughts on this? I can understand what the tester is saying but to shear 8.8 tensile m8 bolts would involve a huge amount of force would it not?

Comments appreciated

[937carrera]

He may have a point, without going into the grade of bolt and strength, most seat belts are anchored by M14 bolts, so he would probably just see them as being a bit skinny. Only an advisory though, not a reason for failure.

I suggest you give the supplier a call, see what they say ?

E D I T - see you've already done that, test the feedback with your MOT guy. Not sure what "pull tested" really means, do you ?

[mshaw1980]

Thanks for the response carrera.

No it's a fail over on the IOM as we don't have annual Mots. When you import a vehicle here you have one test then you can register the car on the island. It is then your responsibility to maintain your vehicle.

Pull tested is not something I completely understand but think it simulates a crash test.

[937carrera]

Done a bit of reading

https://www.eng-tips.com/viewthread.cfm?qid=87318

I suppose it all depends what rate of deceleration you want the bed to protect against.

I did a bit of maths, I could be wrong on the approach, as follows:

Grade 8.8 bolt has tensile strength of 80kg / mm2

An 8mm nominal thread has about 50mm2

Shear stress is about 25% of tensile strength

80 x 50 x .25 = 1000 kg

Assume a 100kg passenger, then a single bolt would shear at a 10g deceleration

Wait for a proper engineer to come along

What about simply changing to a 10.9 bolt ?

[mshaw1980]

I didn't realise shear strength was so much less than tensile strength. I like engineering

So based on that calculation the vehicle examiner is spot on. Hmm. Seems a bit of a grey area then in terms of vehicle examinations.

[937carrera]

I like engineering

Good, you can have a read of this https://www.amesweb.info/Screws/Metric_ ... ength.aspx and maybe let me know where I went wrong then, it's only my interpretation of the data in the first thread

You can see comparative strength on 10.9 and 12.9 bolts too

I don't know to what extent UK regs apply in IOM, but depending when your van was first used in '87 you don't actually need to have any seat belts

https://www.gov.uk/government/publicati ... e-vehicles

Work with your MOT guy, if he's a decent engineer he'll probably be OK with the better grade bolts as I doubt there is just one bolt under load.

What are the other issues?

[mshaw1980]

What are the other issues?[/quote]

Need to radius the spreader plates for the camperbed underneath the van. ( didn't know about that so easy fix with die grinder / angle grinder.

Split pins missing from track rod ends (school boy error)

Oil leak onto exhaust. ( oil temp sender gauge is leaking oil, pooling on top of engine. Unfortunately on the Subaru engine it's buried under hoses and inlet manifold)

Drivers door lock decided not to unlock at the test centre

Headlamp alignment more or less in the sky ( fitted the 7 inch aftermarket land rover lights covkid recommended but I didn't even try to adjust them as knew it would fail.

And as previously mentioned the camperbed pivot bolts.

The tester was a good guy. Said the van looks good underneath, bit of surface corrosion on some brake pipes so sand and paint and sort the other issues.

[adie89]

The main issue seems to be whether these M1 beds are crash tested by a regulator? In Europe if it hasn’t been tested you can’t have it.
As for pre 87 belts, like everything else in the construction and use act, if it’s there it must comply.
Tensile strength, your body can become 30-50 times heavier in a crash or rollover, will those bolts hold now? Would it be simpler to remove the belts for test and follow the pre 87 regs, then fit body mounted belts on the correct mounts that have been tested and are rated?

[mshaw1980]

Shouldn't be too hard to grind the welds off the captive nuts, elongate the hole and put bigger bolts in. I didn't think a lot of beds had been crash tested. Don't some on here have wooden rock n roll beds and pass the mot?

[adie89]

Shouldn't be too hard to grind the welds off the captive nuts, elongate the hole and put bigger bolts in. I didn't think a lot of beds had been crash tested. Don't some on here have wooden rock n roll beds and pass the mot?

Yes my original bed is mounted on a wooden box, but the seatbelts are mounted to the bodywork with the correct fasteners and factory spreader plates like those available from BW. Which makes me think the issue is less the tensile strength of the bolt and more the pull through of what it is secured through.

[shepster]

Take the seatbelts out for the test ,then put them back in?

My van hasn't got any in the back and never been failed, not I.O.M though so may be different.