2018 Bourton Bike Rack

Jaytee wrote:Interested where you have obtained a list of my engineering qualifications Dave? Just asking 

I did say "most"!
From your response I presume you in turn have total faith in Kaspian's qualifications!!    

We know he was joking, but others may take the comments literally! You have only to consider how many gullible souls have been completely taken in by the annual gassing scares, despite mountains of expert evidence to assure them it does not happen. They would rather believe an internet quote from "my mate's next door neighbour's cousin's dog walker's senile old grandmother" than from an acknowledged expert! 

(No one has yet posted about a catastrophic failure of a bike rack. Until and unless someone does - with verifiable evidence of course - this is all just scaremongering speculation!)

I am just careful not to make assumptions. Plus there was a humorous emoji after my comment  Got to keep it humorous. .

How dare you belittle my c grade pass in home economics at 'O' level.     . Perfectly capable of cooking up an unintentional  storm in a teacup it seems!   
      What I can say is having had the ability and  sheer guts to cut into 2 of our previous coachbuilt motorhomes from brand new to install externally accessible wet lockers , there is not much meat in a coachbuilt  side wall. An internal sheet of 4 mm plywood bonded to an inch of polystyrene bonded to aluminium the thickness of cigarette paper outside. Whatever way we dress it up there is not much to the structure of most motorhomes/ caravans having seen the results of a few accidents.

Jaytee wrote:I am just careful not to make assumptions. Plus there was a humorous emoji after my comment  Got to keep it humorous. .

As you know by now, you'll get no argument from me on that score! 

I have gone a bit more "serious" than usual in this thread though, largely as a consequence of nearly 20 years experience of participating on motorhome forums. It's surprising, and sometimes quite humbling to observe how easy it is for some folk to become genuinely very worried about what we experienced old lags know to be nothing of any consequence. An ill thought comment made in jest, or a fundamentally flawed statement of fact can create near panic in the uninitiated - and I freely admit I've been guilty of the former, though hopefully not of the latter (very often!! )

It's very easy to forget that many newcomers to this game know absolutely nothing. Some of us had the advantage of previous caravan experience, but to others it's a completely blank, baffling and sometimes terrifying canvas!!

kaspian wrote: there is not much meat in a coachbuilt  side wall. An internal sheet of 4 mm plywood bonded to an inch of polystyrene bonded to aluminium the thickness of cigarette paper outside. Whatever way we dress it up there is not much to the structure of most motorhomes/ caravans having seen the results of a few accidents.

Its not a question of dressing it up - its called designed for purpose otherwise we would all be driving around in solid steel tanks and really messing up the planet!
There is not much meat inside the wing of a light aircraft but it is still capable of carrying several tons loading!! 
Any structure, car, aircraft or building, that is mistreated - such as in an accident - will disintegrate and give the appearance of catastrophic structural failure. 
Have faith in the designer!

Don't 'ever' have trust in the designers Liam, just think sprinter rear springs 

Hi  Dave , far be it from me to cause panic amongst newcomers but I understand your thoughts hence the    's in the original post. 
           I would have thought that very few who pay upwards of £60, 000 for a van will take a drill to it to install a bike rack. One therefore has to assume that the 'professionals ' will have known the manufacturers designated strengthened points to attach the  rack .  As someone who is stupid/stupidly brave / confident/ technically able enough to install their own this has always  been the problem. Manufacturers are not always forthcoming with the information as to where the extra straps of wood have been installed. 
           More importantly perhaps is having seen how 'light ' motorhome construction can be is we should be emphasising how important it is not to overload the bike racks from their quoted design limits having followed a van down the M6 last August  with a large Fiamma box, 2 adult bikes on outer tracks  and 2 kids bikes tied on top of the box - all merrily dangling from the rear !  ( and I did keep back just in case )
   And yes Liam , like loads had faith in the designers of the Titanic as being unsinkable etc etc 

Fair points Kaspian - and I wasn't accusing you alone of suggesting the end of the world is nigh!!  

However, it is amazing how major panics often grow from almost nothing - and there are those among us who are never happier than when they have something to worry about!       

More amazing is the immense strength of motorhome construction, when stressed under certain conditions. I recall seeing a Land Rover parked on top of a motorhome with (it was claimed) no modification other than a stress plate on the roof to spread the load of the LR wheels.

Yes but anything with a stress plate big enough to spread the load will do- think snow shoes in deep snow as opposed to stillettos!  I once almost bought a Hobby caravan from  a dubious travelling community owned dealership. The salesman climbed on the roof and tap danced the length of it and jumped 2 feet in the air and landed as a showstopping end to his performance! Then again they are not light but I bet if you tried the same in a British made van of the same year you would have landed in the kitchen sink!
         Designers are giving what the punters want and this is deemed as complicated water / space heating systems, fancy interiors big cookers ovens and  fridges etc weight wise something has to give and that seems to be exterior build. Funny thing is I once asked a designer at Elddis on a factory visit why they used real wood framing on doors and he replied durability and WEIGHT! Real wood is lighter than the mdf/ wood effect paper replacements! Such is progress - however now off topic so.....

kaspian wrote:Yes but anything with a stress plate big enough to spread the load will do- think snow shoes in deep snow as opposed to stillettos! 

I'm beginning to worry about you Kaspian!!!     

Try not to wear them outside as they pinch the toes!  Stick to my regulation steel toe caps but brutal in this cold weather as they act as a heatsink!

kaspian wrote:Hi  Dave , far be it from me to cause panic amongst newcomers 
   And yes Liam , like loads had faith in the designers of the Titanic as being unsinkable etc etc 

If I recall rightly the cause was as a result of an error on the Captains part - the effect/result was tragic. 
Nothing in this world is indestructible - its just the human interface effect that is the problem - like overloading a structure beyond the designed limit.

Jaytee wrote:Don't 'ever' have trust in the designers Liam, just think sprinter rear springs 

Agreed John,
But I am sure the design is correct its just that AS "motorhome designers" specified the wrong springs IMHO!
When are you have the new ones fitted?

Liam wrote:
Agreed John,
But I am sure the design is correct its just that AS "motorhome designers" specified the wrong springs IMHO!
When are you have the new ones fitted?

Hopefully next week 

PLOUGHLIN wrote:When I asked AS for the detailed location of the reinforcement for my Gloucester, they refused. "Professional install only Sir". That lets Marquis out then.

Managed to get them for my Winchcombe albeit labelled Worcester which apparently is the same. Can emailto anyone  who wants a copy.

Liam wrote:
If I recall rightly the cause was as a result of an error on the Captains part - the effect/result was tragic. 
Nothing in this world is indestructible - its just the human interface effect that is the problem - like overloading a structure beyond the designed limit.

Correct, and perhaps, also, we should remember that the Titanic was a one-off build, not one of hundreds of thousands. design experience and Quality Assurance systems are a key element of good product design.

I have no fear of taking a drill or even router to my new motorhome, and although I do have the AS drawing of the construction of the rear panel, I opted to have a dealer fit Fiamma bike rack because if I got it wrong, there could be liability issues.

Peter Brown wrote:

To be fair, AS design motorhomes not chassis.  They go to a vehicle manufacture and say we want to put this body on one of your chassis, what do we need to buy from you?  When they have completed the conversion, they get formal sign off from the chassis manufacturer that all aspects of the conversion comply with the chassis manufacturers requirements to ensure that the chassis warranty is fully honoured.

In Jaytee's case, the first spring failure was in the warranty period and it was MB that honoured that warranty obligation without quibble.

If there is a design fault in this case, it lies with Mercedes-Benz.

I don't disagree Peter, and I have no doubt that all of the proper design interface data between MB and AS is/was fully shared at the finalisation of the design point. And indeed is exemplified by the relatively few MB/AS interface issues that appear to have manifested themselves over my period on this forum.
However, as an example, you may recall the electrical issue with my generation of van whereby the MB SAM unit failed (there is a separate thread on this) on a number of vehicles because there was (as I understand it) a misunderstanding between MB and AS on the electrical connectivity in the locking elements between the vehicle cab and habitation door. True, this was corrected by the fitting (FOC by AS) of a Sargent interface unit and now it works fine.
But to have one vehicle incur two failures on the same spring (and not forgetting Beagle and his Beckford where both failed) it begs the question  - is there something inherently wrong with the design, or is it just a QA issue or perish the thought, have both of our esteemed "forum colleagues" been mistreating their vans? To be fair, my van (and most of the others manufactured in that timescale)  are fine (so far as we know) with no broken rear springs.
Sorry, this has gone a tad off the "bike rack" thread.

Peter, you have sussed it !!! I'm not carrying enough wine 

I had forgotten - roll on June!!