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Shackle length

Posted: Sun Jul 25, 2004 5:39 pm
by sierrajim
Ok Ok I know this has been raised 12 billion and one times but i have a question re shackles.

How long are the factory ones?

I'm now at the stage where i need to fit the diffs on the zook. Want to fit extended shackles but not sure how long. I've done a search and everyone mentions 25-35mm over stock but the car i'm doing does not have factory shackles in it.

Can anyone help?

Posted: Sun Jul 25, 2004 6:00 pm
by moose
is this for the new "trailer queen" ?

if so , on road drivability , wont be an issue !!

so , basically , throw all others opinions out the window !!

go with wat you want , for off-road comfort & flexibility !!!

Posted: Sun Jul 25, 2004 8:15 pm
by Gwagensteve
Hmmm very helpful Moose.

Jim asked how long stock shakles are.

Stock sierra shackles are 70mm long. (pin centre to pin centre)

I just measured the rear ones on my Zuk ( I made these about 7-8 years ago) they are 120 centre to centre.

With proprerly located bump stops so you are not over compressing the springs, you shouldn't need to go over 120. This is longer than most cars in the club, including Critta with MQ springs. It is also longer than pretty much any factory shackle including applications with far more travel than a stock Zuk.

I think that there is no advantage in going over the shortest shackle that permits full spring travel, without overcompressing the spring. (that is heavily inverting it) so shackle length will be related to bumpstop placement and shock travel.

Remember that shackle length stuffs caster angles and is a really bad way to add lift - you only get 1/2 the lift of the shackle @ the chassis, also, if the shackle is loose enough to allow articulation, it will make the car pretty "loose" at speed once it gets too long, hence my idea to run the shortest shackle you can get away with.

You can always prevent inversion of a slightly too short shackle with chain, plates or by adding an extra bolt across the shackle like the ARB/OME 70 series greaseable shackles.

Cheers, steve

Posted: Sun Jul 25, 2004 9:48 pm
by sierrajim
thanks guys. Shackles made. Will update build up thread tomoz.