Extended Shackles
- Thread starter Navara09
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They're illegal for starters, in every state of Australia, so if you've got 'em, you could be given a defect notice for them, or worse you could be considered liable in an accident.
There has to be some advantage in them, because quite a number of people seem to use them. I haven't explored any engineering reason why they'd be bad for the vehicle, I might do that soon.
There has to be some advantage in them, because quite a number of people seem to use them. I haven't explored any engineering reason why they'd be bad for the vehicle, I might do that soon.
Okay, here goes, the advantage is that they're very cheap and very very easy to install.
The disadvantages are you need a four inch increase in shackle length to get a two inch ride height lift, in a leaf suspension system the leaves act as both the spring, to a certain degree as an inherent dampener, and do the work of axle location, when you fit extended shackles you are increasing the axle's moment arm about the chassis and therefore increasing the loads subjected to the chassis mounts and shackle over what was designed in from factory to the detriment of axle location. Usually extended shackles are home made and designing for infinite fatigue life (as well as the quality assurance of the manufactured product) is beyond the spectrum of most DIYers. These are the main reasons why engineers won't approve them and they are unroadworthy.
You could argue that a spring shaped for a ride height increase would also increase the moment arm about the chassis mount to the detriment of axle location so really there's no way to ever win. A shaped spring is preferable though.
A
ants_oz
Guest
As Tony said, they are illegal. That is the reason they are bad.
Engineering reasons? Kind of irrelevant seeing as though they can't be engineer approved.... The original shackle length for that vehicle is all that can be engineer approved. It's not up to the discretion of ANY engineer in ANY state or territory - it is a federal legislation issue.
Have an accident and if the prang gang inspect your vehicle and find them, it will be deemed to be unroadworthy. Therefore it will be deemed to be without registration and without insurance (without third party insurance, which covers personal injuries to others).
Pay your money and take your chances.
Engineering reasons? Kind of irrelevant seeing as though they can't be engineer approved.... The original shackle length for that vehicle is all that can be engineer approved. It's not up to the discretion of ANY engineer in ANY state or territory - it is a federal legislation issue.
Have an accident and if the prang gang inspect your vehicle and find them, it will be deemed to be unroadworthy. Therefore it will be deemed to be without registration and without insurance (without third party insurance, which covers personal injuries to others).
Pay your money and take your chances.
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If the axle can move around more, that increases the chance of the drive shaft working its way out as well?
If that's the case, then one could argue that fitting extended shackles isn't only against the law, it's inherently dumb.
If that's the case, then one could argue that fitting extended shackles isn't only against the law, it's inherently dumb.
Well the driveshaft is notionally permitted a certain freedom of movement by the rubber boot over the centre driveshaft bearing, and the sliding splined shaft into the back of the transfer case, and extended shackles probably shouldn't cause the axle to exceed this freedom of movement, the issue is more about vehicle stability when cornering - you can get some weird effects from the chassis crabbing excessively in relation to the axle.
Spacer blocks aren't much better, and introduce axle wrap problems, so they're off the menu too.
A
ants_oz
Guest
The interesting thing is, if you look at just the rear suspension - you need a pair of new shocks to allow the rear end to travel, so that cost is fixed.
A pair of extended shackles (legalities aside) seem to cost around two hundred and some dollars. A GOOD quality pair of rear springs are only around five hundred and some dollars. The cost isn't that much more in the great scheme of things, when you put it into perspective....
