Design Weights

[Tazzzzman1]

Hi,

 

Had an issue at SVA yesterday with design weights....I know I know this has been covered many times before...

 

I had researched and took advice from this site and Richard at GBS. Stated 500 for rear and 450 for front and combined of 950. This was deemed as inaccurate by the tester. After weighing mine came in at a miniscual 270kg front and 310kg rear (thats even with a fat bugger like me 100kg+ sat inside). Guess I must have put it on the Atkins during the build (un-intentionally).

Fortunately he is altering the paperwork for me on my re-test.

[Guest gdc]

you may find that the total was wrong .

in that there was no real diff between the combined axles and the total .

imho there should be a difference ie approx 100kg or whatever .

ie 450 front 500 rear and total should be arround 1150 .

ready to buy a parachucte !

 

graham

i think total should exceed the axle weights .

 

graham

i did say i think imho

[Guest robinj66]

I don't understand what causes the tester to reach his conclusion.

 

The design weights are just that - design weights. Surely the design weight should exceed the actual weight (otherwise the limits of the design are being reached/overtaken)

 

the only real issue is that these stated figures come into play when determining whether your brakes are up to the job.

 

 

 

I'm sure I'm missing something fundamental here - so can someone put me put of my misery?

[Guest gdc]

prob is that we havnt designed it ?

the weights are assed re the type of car .

the total weights imho sould exceed the 1 and 2 axcle weights cos otherwise the car isnt capable

of being on the road and whithstanding its own loading .

the weights are fed to us via the manufacture to the web site .

where else would we get them ?

then the brakes are tested to suit .if axcle 1 was 400 kg and axlel 2 was 400 kg you couldnt put 800 as the total

as there would be no leway and the car might break. not a 2 b though

graham

[Longboarder]

Design weights are the maximum weights that the car or rather the two axles are designed to safely carry and have very little to do with what the car itself weighs. They must exceed the possible/reasonable/probable weight that the car may reach when all seats are occupied, the boot contains luggage for said occupants, spare wheel fitted, reasonable tools carried, full tank of petrol and all fluids topped up and checked (+map, smarties, coke, sarnies, sunglasses etc). By definition if the laden weight of the car can exceed its design weight it would be overloaded and thus unsafe to drive. Therefore the car must be designed to safely carry itself plus more weight than you could reasonably be expected to get in it.

The likely reason to change your submitted design weight figures is they are too low. 450 - 500 - 950 is a bit low and you risk exceeding this fully laden. You are better with 500 - 550 - 1050 or even more! The running gear, suspension, brakes etc are from a sierra and clearly can carry twice that weight and the chassis of a 2B is overengineered so you could put 750 - 750 - 1500 and be happy it was true.

You say the car weighed in at 270 + 310 = 580kg with your 100kg butt on board. So your 2B weighs 480kg. I suspect there is an error in these weights. They usualy weigh around 700kg built.

I hope he's revised them to 550 - 600 - 1150 and gets his scales checked.

 

Nigel

[Bob Tucker]

My sliding pillar 2B at SVA weighed 710 KG empty.

No screen, boot interior, heater, spare wheel, interior skinning etc etc.

 

RHE stated design weights for the SP 2B were 500kg front 650 kg rear.

 

My SVA tester allowed another 200 kg for 2 passengers and a boot load of tools/spares etc.

so the overall road weight could have been 910 kg, I suspect thats why your failed, being too close to the 950 on your form.

 

Give em a call before the re-test to say that you have got the correct figures from the factory.

 

HTH Bob

[Guest robinj66]

If it helps, I put 525kg + 650 kg with a gross of 1175kg for my stainless monocoque S7.

[Tazzzzman1]

Confusing aint it!

 

He stated that the 2 figures should when added be the combined weight figure (not slightly more), Also stated that the car had failed as I had overstated the design weights. I tried to argue the point, however thought better of it when he said he would just alter the paper work when I go back for re-test.

 

Guess just another case of right hand not knowing what the left hand is doing!!

[Guest robinj66]

I think your tester has got this completely wrong and I would be talking to the technical guy at VOSA Central.

 

The danger of using the true weights is, as has been stated above, that if you drive the car with added weight, you would be driving an overloaded vehicle.

[Longboarder]

the 2 figures should when added be the combined weight figure

That's true but it is not supposed to be the weight of the car as it stands all fluids topped up and a full tank and usual tools. That measurement is called the kerbside weight and is the actual sum of the measured/weighed axle weights on the scales. There is an addition of 68kg per person/seat and 7kgper seat luggage to be added to that kerbside weight to make the calculated gross weight. There is also a sum to do which apportions the added 150kg (split 68kg in each seat and 14kg in the centre of the boot area and uses measured distances from the front of the car to each axle,seat centres and centre of the boot)and allows calculated maximum axle weight in this loaded condition. The declared maximum gross weight and maximum permitted axle weights (Called the Design Weights) must not be less than the calculated max gross weight and calculated max axle weights.

Put kindly the tester is confused. In the real world just let him do his thing as he seems intent on making it pass his odd interpretation of the rules (and it does pass the proper interpretation of the rules). So no harm done. (Unless these weights get recorded on the V5C in which case you will never be able to drive the car as it will be instantly overloaded as soon as you plant your bum on the seat.)

 

Nigel

[thespannerman]

Just passed SVA on Monday at 1st attempt (Beverley). Series 3a- 519 front and rear- 1038 combined. These are the weights in the original Richard Stewart SVA booklet which I included a copy of in my SVA application. Tester ran rear brake test 4 times to let the drums warm up till it just past, said I should have left a spare wheel in the boot (left it at home thinking it would pass easier with less weight -WRONG).

Ran a single brake pipe to rear with mini brake limiter in line (blank of spare connector with bleed nipple). No servo fitted. Tester said front to rear bias was spot on.