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Tech Spam thread - because 1/4" BSP gets 5 hand spans to the jiggawatt


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  • 4 weeks later...

Going against oldschool protocol here but at what point would you need a cert for raising a car and chucking a set of mud tires on it?

Assuming there's no tire clearance issues on suspension components and structural bodywork and guards flared to cover tires.

How much higher with say aftermarket springs could you go before all the suspension geometry goes out the window?

This is all hypothetical but keen for a laugh to have a lifted shitbox on mudders. 

I understand a 195/60r15 tire is around 24inches high and going to 32 inch muds would give 4 inches more ground clearance.  

Is it legal to put spacers between the front and rear subframes (if applicable) and the body to achieve a body lift?

Cheers.

Pic for inspiration/ clarification.

images?q=tbn:ANd9GcQ_uMdYu3kkKv2CjxoJ3NY

Edited by a.craw4d
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Have a look at the modification threshold on lvvta.org.nz.  that shows what you can do without cert

It wouldn't be much though. Tyre size would be limited by no more than 5% greater overall diameter, offset rules limits how sticky outy the wheels can be, and lift would be limited by what springs you can fit in a factory shock and still have 40mm droop

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9 hours ago, Nominal said:

Any idea what a good choice would be for steel selection for a torsion bar spring.  Needs to be something I can get in NZ.

OD ~11mm, length ~1140mm. I need it to twist about 90 degrees.

@ajg193 @sheepers

i don't have any experience with spring design, so can't really help you here. Looks like some people see bars made from 4340, I'd assume heat treatment would be required after manufacturing?

Some simple calcs estimate you'd have around 160 Nm of torque on it to get 90 degrees of twist from end to end.

This torque will give a shear stress of like 600 MPa - this is getting quite high. You'd want a material with at least 1200 MPa tensile strength.

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1 hour ago, ajg193 said:

i don't have any experience with spring design, so can't really help you here. Looks like some people see bars made from 4340, I'd assume heat treatment would be required after manufacturing?

Some simple calcs estimate you'd have around 160 Nm of torque on it to get 90 degrees of twist from end to end.

This torque will give a shear stress of like 600 MPa - this is getting quite high. You'd want a material with at least 1200 MPa tensile strength.

Thanks. It's a torsion bar that goes inside the tailgate hinge for my woodie. The ends are ground square to fit into a cast bracket. One end shown below.

P1050493.JPG

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19 hours ago, Nominal said:

Any idea what a good choice would be for steel selection for a torsion bar spring.  Needs to be something I can get in NZ.

OD ~11mm, length ~1140mm. I need it to twist about 90 degrees.

@ajg193 @sheepers

You won't be able to harden a length like that after you've shaped the ends so get a bit of spring steel already heat treated from somewhere like CMI. 

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  • 2 weeks later...

Anyone have a link to the exact COVID WOF extension dates?

All I can find is documents saying there is an extension but nothing that says what the end date is and what qualifies.

The Datsun and Niva both expired during lockdown and wouldn't mind throwing rego on for a month to give them a legal spin around the block.

/useless at the google

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Just now, NickJ said:

Anyone have a link to the exact COVID WOF extension dates?

All I can find is documents saying there is an extension but nothing that says what the end date is and what qualifies.

The Datsun and Niva both expired during lockdown and wouldn't mind throwing rego on for a month to give them a legal spin around the block.

/useless at the google

https://www.nzta.govt.nz/about-us/coronavirus-disease-covid-19-services-update/documents-with-temporary-extensions/

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