cct7kitcars
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| posted on 4/7/06 at 07:55 PM |
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car weights
need a bit of help about car axle weights
back at sva soon with a car and had probs over the weight and the brake forces
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stevec
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| posted on 4/7/06 at 08:23 PM |
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What car is it?
Steve.
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cct7kitcars
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| posted on 4/7/06 at 09:02 PM |
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my own build that i make dry weight is 480 kgs
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nitram38
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| posted on 4/7/06 at 09:12 PM |
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Just been through this and failed on brake effciency.
They put a pressure pad on their foot and aply a set amount of pressure and take readings.
Mine failed because the total efficiency was 50% (mot standard) but needs to be 60%. The tester emailed me the calculations, so I suggest you get
your axles weighed and take a trip to your local mot station and get them to give you your brakes figures off the rollers.
What the sva man said to me:
"We add all the footbrake figures together from each wheel, then divide that by the calculated weight of the vehicle and then multiply by 100.
This gave you an overall result of 50% efficiency. Now this is fine for an MOT but we look for 60%, however if more that 2 of the 4 wheels lock out
then you automatically achieve a pass result regardless of the figure gained. Your problem was because of the service brake pedal adjustment the rear
brakes wouldn't lock out."
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wilkingj
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| posted on 4/7/06 at 09:27 PM |
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Front brakes MUST LOCK BEFORE the rears.
Also the weights I userd for my viento were off the Luego Website. No way is my Viento 1200kgs (Fully laden), but the figures you give are part of the
brake calculations.
Do you have a manufacturer you can ask?, or is it a book locost / home brew?
Have a look at the Luego Website, it will give you an idea, as they have Viento, Velocity and Locost figures
Luego page
Then look in the Build Doc, section 12 SVA & Registration. Then about 2/3 down that page.
It will give you some idea, as long as your vehicle is simmilar.
I am not saying to use those weights as they refer to Luego products. however, they will be simmilar, and give you a relative starting point for three
different size 7 based cars.
1. The point of a journey is not to arrive.
2. Never take life seriously. Nobody gets out alive anyway.
Best Regards
Geoff
http://www.v8viento.co.uk
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cct7kitcars
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| posted on 4/7/06 at 09:32 PM |
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the car i produce is lighter than the luego was talking to dean the owner today good friend of mine the info i need to know is my car weighs 480 kgs
dry what do i put down for gross weight
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nitram38
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| posted on 4/7/06 at 09:36 PM |
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Brakes do not have to lock at all to pass. They only have to have an efficiency above 60 % overall.
The fronts must start to work before the fronts though.
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cct7kitcars
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| posted on 4/7/06 at 09:40 PM |
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no offence i know about braking forces and what they should do what i need to know what do i put as my gross weight
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nitram38
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| posted on 4/7/06 at 09:45 PM |
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Sorry, you mentioned brake forces in your original question.
As to weights it is difficult if you have changed the original spec so it would be best to get the car weighed.
All you need to do is find a weigh bridge and weigh each axle seperately.
You do not need to supply gross weight for the sva, only axle weights and design weights.
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cct7kitcars
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| posted on 4/7/06 at 09:52 PM |
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erm ok what you mean by design weight
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nitram38
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| posted on 4/7/06 at 10:01 PM |
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Design weight is the weight the car was designed to carry plus the gross weight. In otherwords it is the maximum loaded weight of the car, including
passengers, luggage fuel etc.
It is always best to give a reasonably high design weight because they use this to see if the brakes are suffcient.
If your car is lighter than the original, still give the manufactures design weight, then you can't be wrong.
If you give weights under those found by sva on the day, you will fail. Going over will allow you to pass as long as you do not over do it.
They use design weights for braking calculations, so too heavy a given design weight and you will fail on the brakes not being efficient.
[Edited on 4/7/2006 by nitram38]
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Chippy
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| posted on 4/7/06 at 10:55 PM |
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I think you will find that the design weight is used just to check the tyre ratings are correct. You can just make up a figure,ie,Axle 1 =
450 kg Axle 2 = 500 kg Gross weight 950 kg.. It bears no relation to the vehicle actual weight. They will weigh it at SVA and tell you the
correct weight. Be sure that your design weight is far higher than the actual weight, because if its lower they will fail you on incorrect design
weight. Oh and when you arrive at SVA, make sure that the fuel tank is full. Hope that helps. Ray.
It does NOT relate to the brakes, they have to work to 60% eficiency, or better, regardless of the cars weight
[Edited on 4-7-06 by Chippy]
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nitram38
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| posted on 4/7/06 at 11:09 PM |
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"We add all the footbrake figures together from each wheel, then divide that by the calculated weight of the vehicle and then multiply by 100.
This gave you an overall result of 50% efficiency. Now this is fine for an MOT but we look for 60%, however if more that 2 of the 4 wheels lock out
then you automatically achieve a pass result regardless of the figure gained"
Weight is used in the calculation to determine brake efficiency.
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scoop
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| posted on 5/7/06 at 07:39 AM |
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Dont you have to get it weighed prior to SVA with you, passenger and full tank of fuel or is this another one of those SVA chinesse wispers?
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nitram38
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| posted on 5/7/06 at 07:58 AM |
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No you do not have to get it weighed before sva if you already know what the design weights are.
I put down 450kg per axle on mine and I was ok, but if my supplied axle design weights had been under the actual weight per axle that the sva
checked, then I would have a fail against me.
The sva would then require a letter from the manfacturer of the kit, giving a new design weight.
In my case it would be a letter from me as I designed the car and I have myself down as the manufacturer on the sva form.
You do not have to supply the gross weight as the sva will weigh the car and come up with a calculated weight.
They will then measure the seating postion/wheel base and then calculate your design weights come within your supplied weights and check that at
least 30% of the weight is over axle 1.
They will also work out your centre of gravity.
All of this is done on a computer/brake/weighing machine and it will issue a printout with all the figures and pass or fail against each item.
[Edited on 5/7/2006 by nitram38]
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Marcus
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| posted on 5/7/06 at 08:05 AM |
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quote:
The sva would then require a letter from the manfacturer of the kit, giving a new design weight.
Yup, that's what I had to do. No hassle really, had already 'failed' on gear knob radius! (yes, really!)
Marcus
Because kits are for girls!!
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