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  #121  
Old 25th May 2018, 09:35 PM
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REDXS. with your 300mm rears are you getting the full stroke? you dropped your diff which helps get stroke. full stroke or not yet? whats binding, trailing arm? do you have any spacer on the trailing arm?
1" rear subframe spacers and 3" trailing arm spacers give me full droop. With my old 40mm trailing arm spacers the trailing arms were binding and limiting droop. As stated above the modified SG top mounts remove 25mm of travel. Without modification you lose 50mm of travel.


275lb/in 14" springs are advertised with 232mm travel. You would want your springs to have more travel then that. Hard to say with out knowing all the specs of your car and what you are using it for, but you will probably max the spring extension before you max the shock extension which makes full droop pointless.
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  #122  
Old Yesterday, 02:23 PM
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car is to be used for rally raid. rear overhang chopped and further chopped into pickup.


locally 60kg front and 55kg is the popular choice for rally.


i am thinking 60kg fr and 45kg rr in straight spring.


good for 242mm fr and 258mm rr travel per eibach



add/deduct bumpstops at 30mm i think i should be good?
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  #123  
Old Yesterday, 03:43 PM
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above are 16 inch straight spring
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  #124  
Old Yesterday, 11:50 PM
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Th stiffest 14" Eibach barrel springs I can find advertised is 4.5Kg/mm, this has a stroke of 244mm. The 12" come in 5.8Kg/mm and 6.3Kg/mm, this has a stroke of 205mm. Do you have a link to the springs you are looking at?



On my SG, while stationary on level ground, the springs support 365Kg on each front corner and 325Kg on each rear corner. An Sf will probably be a bit lighter, especially on front, but depends on mods ect.


While the car is sitting stationary, 6Kg/mm springs on front will compress 365/6=60mm. This is about 30% of your shock travel, I think rally you want about 1/3 for rally, so you're about right. If your car is much lighter then my SG maybe consider 1 step lighter rate. Low speed 4wding you want the car to sit closer to 50% of shock travel, hence softer springs. Keep in mind if your car is sitting at 30% shock stroke it will be higher then 2" lift. If you wind down the preload adjustment to lower car, the springs won't extend to full shock adjustment and you will need helper springs to maintain preload. The part of the stroke where the helper springs extend is wasted stroke IMO as they take negligible load.



4.5Kg/mm springs on rear will compress 325/4.5=72mm. Which is also about 30% of shock stroke. So about right again.



So springs are about right for what most people like for rally. Providing there are ones long enough in those rate.



I briefly drove my car with 55Kg and 45Kg springs and personally I thought they were good on tarmac, but destroyed grip as soon as the gravel road got rough. But I'm not a rally driver and wasn't on rally roads, just corrugations.
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  #125  
Old Yesterday, 11:54 PM
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Oh straight springs...


The issue with straight springs is they bend under compression and rub on the shock housing.
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  #126  
Old Today, 08:20 AM
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thanks redxs for the explanation. very valuable.


the 'safari spec' usually runs a stiffer spring than regular gravel spec due to rougher conditions.


targeted suspension lift was 2.5fr and 3.0rr. tires should give another 1 in maybe 1.5



barrel springs not an option would have to go for straight, as below


1600.300.0250S and 1600.300.0350S
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