Technical Leaf springs MOT failure

[Peter James]

Apparently some inexperienced MOT testers have wrongly failed the new Ducato on the grounds that the rear springs are sagging and touching the 'bump stops'
Unaware that these are not 'bump stops' but spring assisters, designed to work with the spring. They only become 'bump stops' when fully compressed. At anywhere near full axle load the spring will be touching the spring assisters even when the springs and van are brand new.
The cases I have heard of have all been motorhomes because, unlike commercial vans, they are always presented for test close to fully loaded condition.

 

[T14086]

Had this discussion many times and the outcome has always been 'testers discretion'.

 

[Peter James]

Had this discussion many times and the outcome has always been 'testers discretion'.

Sorry, not seen it on here before.
But 'testers discretion' is barmy because I looked under 4 brand new X2/50 motorhomes in Brownhills yesterday and every one had the leaf springs touching the spring assisters.

 

[cris1117]

I am pretty sure you can appeal and take your van to the ministry of transport test centre for a test.
If what you are saying is correct then you will be refunded the original test fee.
It may be worth a chat with your local fiat garage to verify that you are correct first.

 

[T14086]

Sorry, not seen it on here before.

Not here just in general everyday chat.

But 'testers discretion' is barmy because I looked under 4 brand new X2/50 motorhomes in Brownhills yesterday and every one had the leaf springs touching the spring assisters.

Motorhomes are converted (non-standard) though and I think this is where things get complicated and confusing. A motorhome must after all weigh a lot more than a standard vehicle so should the motorhome builders fit uprated springs if this is the case?

Any MOT testers on the site who have came across this?

 

[cris1117]

http://www.motorhomefacts.com/ftopic-93316-days0-orderasc-10.html

 

[Peter James]

A motorhome must after all weigh a lot more than a standard vehicle so should the motorhome builders fit uprated springs if this is the case?

I guess a motorhome tends to weigh more than a standard van when its presented for test because of all the fittings permanently inside it, wheras the van would usually be presented for test empty? But some of the brand new motorhomes I was looking under were only the same weight the panel vans would be when they are loaded, and well within the manufacturers plated weight, but the leaf springs were touching on the spring assisters.

 

[keithmw]

go to website mot testers dot co dot uk and select the vosa links, then top link which will take you to the MOT Testing rule book for all vehicles tested. unable to post link at the moment (forum rules)http:// motinfo. gov. uk/htdocs /m4s02000401.htm (take out spaces)
this is the vosa MOT testing guide link to what we testers use during the test, ie the law. just to note we test all sorts of vehicles, what the differance betweeen bump stops and spring assisters? we see a rubber block above the spring at the point of the axle and this is seen as a bump stop. until vosa decide to update the manual on this point all testers have to follow this manual by law or we could face losing our job - no joke.
best bet is to complain - enough complaints force vosa to issue a special notice about this which is a way of updating testers rules on this subject.
Testers wont be held accountable for following the book but will be accountable for not following the book. by the way - garages also receive warnings on incorrect tests by the tester.

personnaly I hope you complain and I hope VOSA send out a special notice so this is clearer. I have tested all sorts of vehicles from scooters to double decker buses, if there is clearance at time of test, pass, if its close to touching (within 5mm) then pass and advise, if no clearance - as per MOT Guide then fail, by the way - remove the blocks then retest - pass

 

[T14086]

the differance betweeen bump stops and spring assisters?

I think this is where the confusion lies, there was a recent article written about this exact subject in the MOT mag not so long ago.

 

[Adrian Bravo]

Keiths Link http://www.motinfo.gov.uk/htdocs/m4s02000401.htm

 

[fubar70]

hope this helps.

Spring assisters and bump stops
[FONT=Helvetica 45 Light,Helvetica 45 Light][FONT=Helvetica 45 Light,Helvetica 45 Light]Quite a few van manufacturers use ‘spring assisters’ to support the base spring, especially on models which have low load heights or are usually run full or part loaded. Typical examples include motor homes, which use the basic chassis/cab with quite a heavy body, and vehicles such as the ‘tool van’, which always have a fair amount of heavy stock on board.
Spring assisters are usually either extra leaves (more common to heavy goods vehicles) or rubber/ polyurethane cones – also known as Aeon springs (more common on the types of vans we see for MOT testing). Both types act by stiffening the suspension once deflection of the base spring reaches a certain point, affording maximum comfort whether the vehicle is empty or loaded.
On vans, the preferred method is to use a rubber cone, which keeps unladen weight down and allows a low load height. These cones look like oversized rubber bump stops but work in a different way. The centre of the cone is hollow (see Fig. 1) and when the suspension oscillates, the rubber compresses – effectively dampening the spring oscillation. The compression rate is progressive until eventually – at full load – the cone is fully compressed and then acts as a bump stop. When the suspension rebounds, the cone decompresses and re-forms to its natural shape.
Because of their size and design characteristics, these cones may sit very close to or even on the base spring (see Fig. 2), yet the suspension appears to be in its normal running position. This is, in fact, a design feature – but some testers interpret it as a failure under IM 2.4A1: [/FONT][/FONT][FONT=Helvetica 45 Light,Helvetica 45 Light][FONT=Helvetica 45 Light,Helvetica 45 Light]‘inadequate clearance between bump stop and chassis or a suspension unit so weak that the body or other part of the vehicle fouls a road wheel or would do so if the vehicle was laden’[/FONT][/FONT][FONT=Helvetica 45 Light,Helvetica 45 Light][FONT=Helvetica 45 Light,Helvetica 45 Light]. Before failing a vehicle under this RfR, testers should first determine if a spring assister is fitted, and whether the suspension really is so weak that the body would foul a road wheel. Fig. 1 Fig. 2
[/FONT][/FONT]Using Vehicle Specific Information (VSI)
[FONT=Helvetica 45 Light,Helvetica 45 Light][FONT=Helvetica 45 Light,Helvetica 45 Light]When registering a vehicle for test, some makes and models appear not to be on VSI. This is because VSI checks against how the vehicle is registered on the DVLA database, not the manufacturer databases. The most common examples are vehicles registered as MPV instead of estate (or vice versa) and manufacturers registered as Jeep instead of Chrysler-Jeep. If you have problems finding the correct category for the vehicle you are testing, exit and then reselect VSI. Although this means starting from scratch, you should get all the makes and models you need. If you still can’t find what you are looking for, try the VOSA service desk on [/FONT][/FONT][FONT=Helvetica 55 Roman,Helvetica 55 Roman][FONT=Helvetica 55 Roman,Helvetica 55 Roman]0845 071 1973[/FONT][/FONT][FONT=Helvetica 45 Light,Helvetica 45 Light][FONT=Helvetica 45 Light,Helvetica 45 Light].
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