January '19 acquired a 72 240z.  Previous owner installed a Wilwood brake kit, 17" wheels, upgraded suspension.  QA1's with chrome coil over springs, 200# in front, 350# in rear, adjustable camber plates in front.  As I've been driving it, have been thinking that front suspension is too soft and rear is too stiff.

Over the two years I've owned it, have been noticing that it's harder and harder to get my floor jack under the front cross member, for jacking.  Initially could have a 2x6 on top of the rotating cup, then it wouldn't fit anymore, had to ditch it.  Next had to ditch the rotating cup.  Now I have to remove the floor jack front wheels, to slide it underneath.

I've measured other 240z at 6" of ground clearance.  My '72 is down to 3 1/2" today.  Parking lot speed bumps are a problem.

Searched the forums for "sagging springs" and other variants, came up empty.  Don't know anything about suspension adjustments.

Would appreciate a clue or two.

https://www.zcarblog.com/2020/12/04/performance/ready-to-rally-kens-1971-datsun-240z.html

Is that the red one you are talking about? 👀

Can you get some pictures of the suspension setup on the car and of how the car sits right now? Where was the ground clearance measured from?

So as far as the spring rates go based on TechnoToyTunings spring rates they sell for their kits are 3KG(Front)/4KG(Rear) for street use.

https://technotoytuning.com/nissan/240z/four-corner-weld-coilover-kit-datsun-240z

Based on https://www.redline360.com/garage/spring-rate-conversion-chart-easily-convert-kgmm-to-lbsin

(edit)Take this with a pinch of salt, i might be wrong -> It seems like the spring setup you have is 200/56 ~= 3.571 (front) and 350/56 ~= 6.35KG (rear)

Edited January 13, 20214 yr by heyitsrama

Yes, the red one.  Selling it as soon as ground clearance issue is fixed.  The green one has gotten some sweet upgrades from Rob and is a keeper.

Here's some images of the QA1's with their springs and collars.  Don't know how the collars could have changed over two years.  

Just adjust them until the clearance between the ground and the cross member is back to 6", which is what I want?

 

Edited January 14, 20214 yr by kenward1000
forgot to attach images

Yeah certainly looks lower one side, maybe it loosened itself up. Try adjusting the lower side up to match the high side. 
 

ive seen people use tape under the collar to keep it clean, not sure if it helps keeping it from undoing itself.

Didn't notice that they were adjusted differently until these images.  Looks like I'd have to jack it up, remove the front wheels for access, needs a special tool to loosen the collar jam nuts then turn the collars.  Which way would I turn the collars in order to increase ground clearance?  Towards the top of the shock or towards the ground?

You would want to raise the P/S coil up towards the top of the shock so it looks like the D/S, the proper collar tool is nice to have but in a pinch you could use a piece of aluminum rod and a hammer.  The bottom collar is the locking nut so once the top collar is adjusted properly you'll need to hold it where it is when you tighten the bottom one.  Clean any grease off of the mating surfaces of the two collars, that will help with the grip.

I remember something..

The weight on the front springs is different (on a 240z) and therefore these springs are on a different setting? Do some investigation.. the orig. springs of a 240z front have different strength's.. (not interchangeable)

Progress has been made.  Got the correct collar adjustment tools, raised the passenger side collars up to where the driver side collars are.  Front cross member ground clearance has been increased from 3.5" to 4.5".  I'd like it to be another inch or so higher.

First tried to adjust the collars with some makeshift tools, only succeeded in marking up the aluminum collars.  Getting the right tool for the right job made the task much easier.

Thanks for the suggestions!