I've been pondering the problem all day long and to be quite honest this is the way I see it right now; there seems to be a lot of confusion relating to strut differences between years and variations in Euro vs US springs. As far as I can tell, the early 260z rear strut is identical to that of the 240z. The front strut is identical to a 240z front strut apart from the fact the lower spring seat is 1" lower down. As for the differences in Euro / US springs... well really who cares? It just complicates matters and isn't significant in the least bit as the springs are being replaced. As long as the differences of the struts are understood then it should be as simple as getting springs manufactured to 240z specifications with the only difference being that the front springs are 1" longer when unloaded.....
I find posts like the above depressing. If the differences were
properly understood and recorded accurately then problems like the ones you are experiencing would be a lot more unusual.
Of course the differences between market models matter! Differences in spring seat heights and differences in spring rates, compressed and free lengths for "240Z" and "260Z" models ( those "240Z" and "260Z" names mean
nothing on their own ) are the very reason why you and the people trying to help you are confused, let alone the spring suppliers.
The first thing people seem to do these days is look at the USA-based sites for data on springs and dampers, then confuse themselves by believing that the USA-referenced data applies to UK market cars. They also read about so-called "Euro" springs and think this refers or applies to the UK models ( it doesn't! ).
morbias said:
Basically what I think I need;
rear springs = exactly the same spec as 240z lowering springs.
front springs = same specs as 240z lowering springs, just 1" longer unloaded.
See? What are
"240Z lowering springs"? It's meaningless!
If you have a UK market 'RS30' 2-seater model ( and/or its 'Q' suffixed variant ) then your ORIGINAL spring specs should be as follows:
FRONT:
( 'Standard' ) Active turns of coil: 9.5, Free length: 384mm, Spring constant: 1.84kg/mm ( 103lbs/in )
( 'Hard Suspension' ) Active turns of coil: 8.5, Free length: 362.5mm, Spring constant: 2.06kg/mm ( 115.4lbs/in ).
( 'Europe' ) Active turns of coil: 8.5, Free length: 362.5mm, Spring constant: 2.06kg/mm ( 115.4lbs/in ).
REAR:
( 'Standard' ) Active turns of coil: 9.5, Free length: 406mm, Spring constant: 1.84kg/mm ( 103lbs/in )
( 'Hard Suspension' ) Active turns of coil: 7.5, Free length: 350.5mm, Spring constant: 2.59kg/mm ( 145lbs/in ).
( 'Europe' ) Active turns of coil: 7.5, Free length: 363.5mm, Spring constant: 2.59kg/mm ( 145lbs/in ).
At least with
some kind of datum point you'll be able to figure out what direction you are going in.