Extended Shackles-Shock Length Question

[beefa125]

Ok Guys I am about to get a set of extended shackles

They are 75mm longer than standard and give 50mm in lift

My question is how much longer do my shcoks need to be than standard, 50mm or 75mm

Cheers

Beefa

[grimbo]

75 mm extended shackles will give you 37.5mm lift not 50mm. Extending shackles doesn't mean you extend the shock length the same.

You will need to work that out once the shackles are on. Flex the vehicle through its full range of travel and get your measurement from there. Adding longer shackles can increase and affect suspension travel differently on different setups and vehicles.

[Henry M]

Your lift will be directly proportional to your current shackle angle and leaf length. Unless you gather a few measurements it will be very difficult to calculate. If you are determined to install 75mm extended shackles (this does seem a little excessive), then do as Grimbo said and cross up your suspension to full extension and install a shock that exceeds the extended length by approx 10-15mm.

You will have to check your compressed length as well. Measure your shock at static height, measure your bump stop gap, subtract bump gap from static height - this will give you your compressed length - if your shock will not compress at least 10mm past this point then you will need to add spacer blocks under your bump stop rubber. This will eliminate premature failure to your new shocks.

[sudso]

Dont you have to make sure too that when your springs are compressed (or fully stretched out flat) that the extended shackles arent trying to rip the spring eyes or hangers out because of the shackles extra length.
Got to measure the springs elongation eye to eye centres and then from the springs front eye to the centre of the bottom pin of the extended shackle when its angled right back.

If the first measurement is shorter than the second you'll have problems. If I'm wrong someone correct me.
I've heard that too much shackle extension can adversly affect articulation too.
I extended mine only by 30mm and it lifted 25mm. This was done to give the ute a bit of "rake" so it levels out when loaded. The shackles are still angled back a bit at static ride height. I gave it heaps with a bit of speed in a comp. on the weekend and they didn't invert at all.