Vehicle Engineers reports, 4WD Modification rules, whats allowed, what not...

[mudski]

Be interested to know why as I run 305"s off-road - I wouldn't think the additional width / rolling weight would have thrown things out that much?


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Yeah not sure mate. He was talking so much i wish i had recorded what he was saying. Haha.
Im sure that probably 90 percent of Patrol drivers running 305's wouldn't see any issues. Maybe its just a comparative between the two sizes and that 285s would be a better choice for the expert? Or someone who knows their shizz.
TD runs 305's and i know he doesn't see any issues etc etc.
Pretty impressive place too he's got. He must get real busy as i reckon there was 20 4wds in the car park there.

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[nissannewby]

It effects the geometry slightly. Different contact patches, even offsets will change what the vehicle does. But as you say for the most part most people wont really notice.

[jay see]

Pretty impressive place too he's got. He must get real busy as i reckon there was 20 4wds in the car park there.

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Ever since he did Simon's 80 series v8 conversion (featured on 4wd TV) it went full on. That was done out his old shop on high street, even then he always had a few parked up, but now it's like a full car park always.

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[mudski]

Ever since he did Simon's 80 series v8 conversion (featured on 4wd TV) it went full on. That was done out his old shop on high street, even then he always had a few parked up, but now it's like a full car park always.

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Yeah i was a bit taken back by how many there was. Hes in a good spot too and theres another mech workshop and an auto elec shop(pretty sure it was) in the same factory lot. So its pretty much a one stop shop.

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[the evil twin]

It effects the geometry slightly. Different contact patches, even offsets will change what the vehicle does. But as you say for the most part most people wont really notice.

Agree but would add that width can (not always but can) have a strange effect.

Most people increase offset to deal with a wider tyre IE the inside wall stays about the same and all the width goes 'out'.
This means the track increases but the geometry does not.
That in turn means two things, one is a change in the load on the swivel hub bearings and more importantly a change on the scrub radius (well at least that is the term i am familiar with)

A change in scrub radius means rather than the wheel and tyre 'pivoting' when you turn it, now has to travel thru an arc as the track is no longer near the centre line of the king pin or whatever and has been effectively moved out.

This can give you some interesting new handling issues under brakes.
I can't recall at the moment whether was under or oversteer, my boy racer days are too long ago, but IIRC it was unpredictable understeer

[nissannewby]

I believe contact patch and offset can effectively alter your akerman angle. While only small changes they can alter the way the vehicle feels and drives. Akerman being geometry....

[threedogs]

Would anyone know 1,, how the Police measure a 2" lift and 2,,,what parameters are they bound by,
As is there a magic number that cant be beaten.
Just saying cause there can be big differences in height with 2" lifts from brand to brand

Maybe someone with a 3" lift can measure from centre of front hub to under the guard to get a 3" number

[Throbbinhood]

When the police got me, they didn't bother measuring.. They just wrote it on the defect notice - 'lift not to be over 2 inches'.

I guess it would depend on what height specifications the manufacturers put out.. When I measured my lift, the specs I found for stock were from diff to bumpstop. My 3" was exactly 3", I was impressed haha.

This was what I used for heights.

[LostBenji]

Would anyone know

1. How the Police measure a 2" lift?
2. What parameters are they bound by?
3. As is there a magic number that cant be beaten?

Just saying cause there can be big differences in height with 2" lifts from brand to brand
Maybe someone with a 3" lift can measure from centre of front hub to under the guard to get a 3" number

Sorry, my OCD got the better of me there.

Very good questions and I do like Throbin mentioned.

[mudski]

I've just added two Youtube Vids on swerve tests. Just so you can see how its done.