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View Full Version : VIC 2/3rd's of the original suspension travel explained!



Oxer
06-11-2010, 12:34 AM
Most of us have heard the famous words " Your car doesnt have 2/3rds's of the original suspension travel " at some stage, through a friends defect or through your own.

Here is a little information I posted on another forum that acually explains what the rule actually means and how cops get it so wrong on seemingly a constant basis.





the 2/3rd rule has nothing to do with the stiffness of the ride. The next time a cop pushes down on your car put in a complaint.

2/3rds means you take a factory strut, measure the length of the shock from one end to the other with NO weight on it at all. Divide that length by three, then whatever 2 thirds of the original length is is what your new suspension is allowed to be at a minimum...

Example: stock strut is 90mm > new coilovers etc are allowed to be a minimum 60mm in length with no weight on them. (no shit the example is stuped being in mm... )


There are a couple of rules as to the coilover construction (all locking rings have to be the same material as the shock body(eg. metal on metal, alloy on alloy etc.), Rose joints must have large washers so they dont simply pop through etc) but the 2/3rds has nothing to do with the stiffness of your ride quality. Dampners can be set to their hardest setting with 14kg springs and it can still be legal.

This was explained to me by a VASS engineer that specialises in suspension. Damn ****ing straight. He urged me to put forward complaints to any police that push down on the car to supposedly "test".



I elaborated a little more in that quote and thought it would be usefull to most people on here. There arent any restrictions on the stiffness of a cars suspension, For a cop to fine you for a car being too stiff is rediculous, and they dont know what the actuall rules/law are.

In saying that, there are exceptions to the coilovers as I said, aswell as ride height etc, but Im just making you aware that they have no right to push down on your car to "test" the 2/3rds rule as it has nothing to do with stiffness.

I recieved this information whilst talking to Bill Malkoutzis(VASS No.1011/ Talk Torque Automotive 48 Hillcrest Road Ph: (03) 9575 2347.) about engineering suspension work in the civic. We only had a brief chat, and as I said to him Im only looking into it for the time being as the car isnt running yet.

This is the real deal guys.



Pretty self explanitary, Though I wouldnt go telling cops you heard or read this info on an internet forum, as they will laugh in your face.

Red_EG4
06-11-2010, 06:42 AM
Do you know what the reasoning behind the locking rings needing to be of the same construction as the body?
Cheers for the information, handy to know. I might print it out and stick it in my glove box :)

Oxer
06-11-2010, 08:16 AM
Because of the different grades of material. A alloy lock ring can thread on a metal threaded strut, and a metal lockring will sheer on a alloy housing... It probably wouldnt, but technically from an engineering point of view, with enough force they will. The theory is that if its made from the same compound it will take a much much greater force to thred/sheer it.


Like I said, no point in printing this off to show police, because they will laugh in your face. Just question them, and put in the complaint. But you have to know your facts.

This information isnt about coilovers anyway, Its just to explain the 2/3rds rule. Technically, you need to engineer all the components to be 100% stress free.

IEVAQ8
06-11-2010, 10:19 AM
great work man....

Red_EG4
07-11-2010, 03:30 PM
Because of the different grades of material. A alloy lock ring can thread on a metal threaded strut, and a metal lockring will sheer on a alloy housing... It probably wouldnt, but technically from an engineering point of view, with enough force they will. The theory is that if its made from the same compound it will take a much much greater force to thred/sheer it.


Like I said, no point in printing this off to show police, because they will laugh in your face. Just question them, and put in the complaint. But you have to know your facts.

This information isnt about coilovers anyway, Its just to explain the 2/3rds rule. Technically, you need to engineer all the components to be 100% stress free.

KW suspension uses plastic spring lock, interesting.

How can a part in a suspension system be 100% stress free? not sure what you mean there.

Oxer
07-11-2010, 10:17 PM
KW suspension uses plastic spring lock, interesting.

How can a part in a suspension system be 100% stress free? not sure what you mean there.

Are you serious?

I suggest you re-read the last line, several times. If it doesn't make sence after that, book yourself into your nearest tafe's english course.

anzai
08-11-2010, 03:28 AM
just got done for this today. i didnt risk arguing because I knew if i did i wouldve gotten a fine or possibly points. ended up getting a major and roady without fine nor points

Oxer
08-11-2010, 04:51 AM
Pretty sure they cant give you points for driving an unroadworthy vehicle....

Unless the reason they pulled you over was for speeding/reckless driving.


They can fine you for anything....

The can fine you for your hairstyle if they really wanted to

anzai
08-11-2010, 04:56 AM
oh really? i think ive heard of people getting points while getting defected. not sure tho

anyway, whats annoying is the fact that it had to happen during exams period. fml

i might just sell up and buy a stock car haha. im so devoed i cant believe im still awake lolll

Red_EG4
09-11-2010, 09:51 PM
Are you serious?

I suggest you re-read the last line, several times. If it doesn't make sence after that, book yourself into your nearest tafe's english course.

Alright, I see what you're saying. In a topic where we were talking about engineering and material components my mind was relating stress to materials. Chill out brother.

mnc
12-01-2011, 03:15 AM
They probably got fined for being defected because they were perhaps driving a high powered vehicle under the p plate restriction laws?

Zilli
14-01-2011, 02:59 PM
will this stand in court? this sort of precedent will actually render the law useless

EK1.6LCIV
14-01-2011, 06:35 PM
got done the other day with my koni yellows and koni springs for this 2/3 bs, had to get a safety certificate on the whole car and send it in with a $100 defect... bs really and the report said the suspension was fine

Oxer
16-01-2011, 02:11 AM
will this stand in court? this sort of precedent will actually render the law useless

Yes, it will. Like I said, If you are done for 2/3, then report the officer. When I was pulled over (see UMAD defect pics) They tried to get me for 2/3rd's... I explained it exactly as I have here and schooled them, but they wrote down 'suspension to be engineered' in regards to the coilovers.


got done the other day with my koni yellows and koni springs for this 2/3 bs, had to get a safety certificate on the whole car and send it in with a $100 defect... bs really and the report said the suspension was fine

That is rediculous, Koni shocks meet the 2/3rd rule no problems. As you found out, when roadworthy certificate was written out, there was no problem. If you had have agued the point they wouldnt have got you for that, but iff they felt like arseholes, they would have made up some bs list regardless.

trism
16-01-2011, 08:33 AM
good shit Ox, you the man.

also, just know that an an Engineers cert wont make you invulnerable to defects, they just make it easier to clear them. means you dont have to put the car back to stock.

EK1.6LCIV
18-01-2011, 02:04 PM
exactly and the safety cert is only good for a few months or 2000kms to keep them off my back

Stig
03-05-2011, 01:50 PM
bumping this up, section 5 first paragraph

http://www.vicroads.vic.gov.au/NR/rdonlyres/CC48FC10-4D57-4F04-82E1-3BD72EF88340/0/VSI8.pdf

string
13-06-2011, 11:16 AM
bumping this up, section 5 first paragraph

http://www.vicroads.vic.gov.au/NR/rdonlyres/CC48FC10-4D57-4F04-82E1-3BD72EF88340/0/VSI8.pdf

"...clearance between a suspension component and its associated bump stop is not alterered by more than 1/3..."

Measuring the total length of the shock makes no sense. The above document talks about bump travel. The 90-01 Civic/Integra doesn't have much shock travel once you lower it. Won't take more than a couple of inches to cut in in half. Annoyingly ambiguous wording indeed.

Oxer
02-08-2011, 01:38 AM
"...clearance between a suspension component and its associated bump stop is not alterered by more than 1/3..."

Measuring the total length of the shock makes no sense. The above document talks about bump travel. The 90-01 Civic/Integra doesn't have much shock travel once you lower it. Won't take more than a couple of inches to cut in in half. Annoyingly ambiguous wording indeed.

from an overview point it does make sense, its basically a guide. If your shock is xxxmm long with no load on it whatsoever, then you cant install anything less then 2/3rds of that length. I know technically the length of the shock has nothing to do with the throw of the shock, but with knowing this info I have gotten out of the 2/3rds rule whilst being defected many times.

Technically a honda bump stop is a small piece of rubber that is located just inder the top spring perch, around the shaft of the shock. If you pulled your springs out, your bump stop does absolutely nothing anyway.

liberx
08-08-2011, 09:34 PM
String is spot on - overal length means nothing, as does change of length without knowing what the travel was to start with.

It is the available suspension travel (bump and rebound) that must be at least 2/3rds of OEM. Problem is - it is very hard to measure because the bump stop is a real complication - they are designed to be progressive so it comes into play earlier than most think, and also means the point of max bump is hard to pinpoint.

Having said all that, if you convince a cop that you know what you are talking about with a lesser fine - then it's all good :-)

A cop testing suspension movement - while being far from scientific, may be trying to see if the car is sitting on the bump stops - an instant fail. Problem is - firmer springs will feel much the same...