Can We Legally Go Lower Then 100mm?

[Ruffels]

Ok, so before people rip me apart.. this is just a theory that some mates and i have come up with..

we have been reading through the Australian Design rules, which are basic safety and design laws that are applied australia wide and as far as i know over rule state laws as far as basic automotive safety guidelines are concerned

we believe that infact on some cars, you are elligble to have the lowest point in the CENTRE of the car to sit lower then 100mm

i will show the ADR rules exactly as they appear in the adr listings and then discuss how my friends and i have interpretted these rules!

i would then like everyones feed back to know if we have gotten it right or not!

________________________________________________________________________________

43.4.4. 'Ground Clearance’

The 'Ground Clearance' of a vehicle, other than an L-Group vehicle,

measured from a horizontal road surface to any point on the underside of

the vehicle except the tyres, wheels and wheel hubs shall, under the

conditions of ‘Maximum Loaded Test Mass' loading as specified in the

relevant braking Rule, be not less than:

43.4.4.1. for any point in the. width of the vehicle which is within one metre fore

and aft of any 'Axle', 100 mm;

43.4.4.2. for the mid-point between any 2 consecutive 'Axles', the dimension in

millimetres obtained by multiplying the distance between the 2 'Axles' in

metres by 33.33; and

43.4.4.3. for any other point, ‘Ground Clearance' such that if the wheels of one

'Axle' are on one plane and the wheels on the next consecutive 'Axle' are

on another plane which intersect the first so that the angle between them

is 7 degrees 38 minutes the point will pass over the apex transverse to the

vehicle formed by that intersection, as shown in Figure 3.

________________________________________________________________________________

ok basically

what they are saying is .. 1 metre either side of each axle (front and rear) you have no choice but to abide to 100mm minimum clearance,

However if the distance between front and rear axle is greater then 2m then it can sit lower ...

So if the wheel base is more then 2 metres you are allowed for that centre section to sit lower then 100mm based on the calculation of wheel base in metres mulitplied by 33.33

... then result is then to be expressed in millimetres and thats the new minimum allowable clearnace for that centre section !

FOR EXAMPLE

i went outside to measure the rough wheel base measurement of my r33 gts-t and measured about 2700mm

this measurement is larger then the 2m i spoke of earlier, so therefor there is a centre section of about 700mm that does not fall under the 100mm clearnace law and can sit lower!

2.7 x 33.33 = 89.991mm ... so in theroy basing upon the ADR's that 700mm centre section of my car can sit as low as 89.991 mm which would work well for people who have low exhausts, which generally reach thier lowest point around that part of the chassis!

anyways... this might be old news... it might be all crap... just thought i'd post it up and see if anyone can correct me or pick holes in my theory

[R31Nismoid]

Yes, you can go lower than 100mm in certain circumstances, no question there.

1 metre either side must be 100mm, otherwise it can be as low as the calculation allows.

However most exhausts fall low around the rear muffler where they go under the diff, and that's where skyline owners have the issues.

I think you might have a small allowance around the centre of the car, but that's generally not the lowest point of exhausts, in some cases its the highest!

Issue is though, being its the 'middle most point', lower than 100mm it'll scrape on speed humps (again, in some cases)

There is another way around it as well, put a Ferrari badge on your car and you can have it as low as you want because its factory!

[some_cs_student]

This looks identical to:

http://www.vicroads.vic.gov.au/Home/RulesS...rdsInformation/

I've read it and agree with your ideas, but it will be interesting trying to convince law enforcement

[Phatboy]

OK, maybe you are onto something here in the ADR, but

1. As Ash said, why/how on Earth would the lowest point of your car be in the middle? Unless you've got a 200L aftermarket supplementary fuel tank for those 24 hour races or something???

2. Regardless of ADR, cops will still fine you. An example which comes to mind is the 10% inaccuracy leeway of manufacturerd speedos allowed in the ADR yet you get speeding fines for speeding over 5%, when your speedo could very well have read the proper speed limit. Go figure.

[_Ryan_]

yup, means my cat and mid muffler could be low as f**k, unlike now.... would that get me street cred?

on a more serious note, i don't see the point in sooooper low, its annoying, gets you in trouble, handles crap unless you re-enginneer for it... where is the plus?

[Ruffels]

hmm interesting.. because ive never heard any mention before about going lower then 100mm... ive always been told 100mm allround, fullstop no arguments!

i'm not saying that i want to have my car rediculously low.. i just put whiteline control springs in last week, and the car sits at a tasteful level, its not draggin on the ground, but its not kangaroo spec either..

yeah good point ash, the jap exhaust systems do tend to drop around the rear axle then come back up, what i meant to say was in my case the lowest point is the cat, which is in the middle of the car (700mm section) sits at 101mm pushing the boundaries..

a couple of months of sag into the springs and it'll probably be under the 100 no worries... however i should be alright, according to the adr's and that vic roads link which states the same!

[R31Nismoid]

On other models of cars i can see that law being applicable, but ye... skylines with 'under diff' exhausts are always gonna struggle with the 100mm on the diff when you factor in a 3" pipe, and then flange edges

It certainly can be used though, friend of mine did on a big old fairlane (cats were hanging under 100mm middle of the car, injected V8), the real long wheelbase ones where there is almost a footy field between the front and rear axles

[Ruffels]

it works the opposite for stretched limos.. i was thinking about this driving next to the pink hummer the other day.. i was like... hmmm 6 or 7 metre wheel base x 33.33 ... that needs a min ground clearance of alot more then 100mm