How many threads on coilover to be safe?

[AlbatrossCafe]

I have FINALLY finished just about everything for my coilover conversion in my 1978 280z with Stance coilovers. I also have TTT control arms. I am at the point of dialing-in the ride height. Stance gave me four 6" threaded sleeves. I had them welded right to the hubs in the front and 3" above the hubs in the back. I was hoping to maintain stock height or maybe 1" lower than stock.

 

Well after getting everything on and lowering the car, it looks like the front was lowered around 1" and the back was lowered around 2". I would like to crank the rear up another inch. The problem is, the threaded sleeve is currently only on by about 5 threads in both front/rear. I am afraid to crank it up in the back because I feel like the coilover will sheer off if I go any higher with so few threads holding. So my questions are...

1. How many threads are "safe" when screwing the sleeve into the coilover?
2. I have not done anything with alignment, track width, etc. Will any of these affect my ride height?
3. What are my options for raising the car if I can't unthread the sleeves anymore? Can I use a top-plate spacer or something?

 

[Zed Head]

Looks like an interesting problem.  Not sure of your terminology though, can't really figure out what you mean.  "Coilover" is a word with broad meaning, often incorrectly used.  It's just short for coil-over-strut.  I think the more correct term is MacPherson strut in the front, adn Chapman strut in the back.  What people commonly call coil overs, are actually adjustable spring perch struts.  Or mixing wrongness, adjustable coilovers.

It's not clear how yours work though, because the tube that seems to thread in to the remnant of the original strut tube should only be adjusted to fit the shock insert inside, to create the tight rigid structure necessary to allow the spring and shock to work correctly.  The spring perch should be used to adjust ride height.  Seems like you're asking about the tube that sets the length of the shock insert portion of the strut.  If that's what you're asking about.

Maybe take a picture with a finger pointing at the threaded area you're worried about.

https://en.wikipedia.org/wiki/MacPherson_strut

https://en.wikipedia.org/wiki/Chapman_strut

 

[Zed Head]

I see the difference now, with Stance's inverted shock technology.  Still, the "sleeve" would be used to adjust shock travel range, and the spring perch to adjust ride height.  If you're adjusting the sleeve to get the shock stroke where you want it and running out of threads at the desired ride height, I think that would mean that you need a longer shock.  Stance's design is an adjustable spring perch AND an adjustable shock perch.  Basically, it's an external shock.  You adjust the sleeve to determine where you want the shock piston to start its travel from.  You have to consider wheel travel.

https://stance-usa.com/about/faq/#toggle-id-1

[zKars]

I would think the mininum threaded engagement would be 1 to 1.5 times the collar diameter. 5 threads ain't gonna do it. 

[Zed Head]

Just realized my understanding of the Stance setup was wrong.  I think that there shouldn't even be a question of "5 threads".  The sleeve is supposed to be screwed all the way in.  The threads for ride height adjustment are under the collar, which has plenty of thread left, in the picture.  No offense Alby Cage but I think that you might be adjusting the wrong part.  Screw the sleeve in and the spring perch up.  I might still be wrong.  I'd like to see it in action, with no spring, to be sure of full stroke, no binding, etc.

The moving part in that strut is the piston inside the shock tube, and the outer portion of the shock tube inside the sleeve.

Edit- actually, the best way to adjust it might be so that the shock body bottoms out in the bottom of the strut tube before the internal piston (moving upward in their drawing).  Seems like a damper/bumper in the bottom of the tube would be a good idea also.  Otherwise it's metal on metal if you hit a big bump.

Edited March 5, 2018 by Zed Head

[AlbatrossCafe]

@Zed Head you are confusing me lol. I feel like all 3 of your posts have different understandings. Let me try to clarify... I didn't realize that Stance may be weird. I had measured length of stock coilovers beforehand and thought that I had cut at the right location.

The welded part is fine. I left length of the original strut tube inside the bottom of the adapter sleeve. The problem is at the TOP of the sleeve where I need to screw in the top part (the part with the spring/shock) of the "coilover".

Here are some pics of the adapter part only:

 

In this picture, the red arrow show the collars for adjusting the spring height. The blue arrow points to the collar that locks out the adjustment for the total height of the coilover. The top part (spring + shock part) can screw into that bottom collar. I assumed that the blue arrow part was for adjusting ride height, and that adjusting at the red arrow would be for adjusting preload. Wouldn't adjusting at the red arrow raise the resting point of the shock up and reduce your down-travel?

Edited March 5, 2018 by AlbatrossCafe

[AlbatrossCafe]

If you look at their website, it says "The damper threads into a weld-on threaded adapter tube, allowing for adjustable right height with no loss of travel."

http://sakuragarage.com/products/datsun-suspension/

can see in one of their pics that the threads start to be seen in the sleeve itself. Mine are still way above that cutout. However, these pics are a couple years old and appear to be using difference sleeves so...

Edited March 5, 2018 by AlbatrossCafe

[Zed Head]

5 minutes ago, AlbatrossCafe said:

@Zed Head you are confusing me lol. I feel like all 3 of your posts have different understandings. Let me try to clarify... I didn't realize that Stance may be weird.

Wouldn't adjusting at the red arrow raise the resting point of the shock up and reduce your down-travel?

Sorry, I was confused myself.  Yes, the Stance system is weird.

You want to adjust the strut length so that the piston can travel up also.  Basically you trade some down-travel for some up-travel.  Not sure what the general rule of thumb is but I'm sure it's out there somewhere.  2:1 or 3:1 or something like that, compression to extension.  Then adjust the spring perch to the calculated ride height.  You have to do two separate adjustments, not just start with the shock fully extended.

Many struts don't use preload.  The typical Tokico lowering spring has no preload.

So, yes it's an odd system, and I'll bet that may people don't have theirs adjusted for best performance.  I would assemble thew struts without the springs and put them on the car and run them through their travel at the height you want.  Set the sleeve so that the piston travels in the range that you want.  Insert a bottoming cushion/bumper for the shock body so that you don't damage anything if you hit a big bump.  Put the springs on and set the perch to ride height.  Hope that you chose the right spring rate for a good ride.  That's how I'd do it.

[Zed Head]

5 minutes ago, AlbatrossCafe said:

If you look at their website, it says "The damper threads into a weld-on threaded adapter tube, allowing for adjustable right height with no loss of travel."

Yes, "loss of travel" could mean loss up, or loss down.  

cgsheen might have some setup advice.  @cgsheen @cgsheen1

Not sure which is him...

[AlbatrossCafe]

Yeah, I have been trying to call since I ordered parts through him.

Seems like I just needed to cut my struts a couple inches higher than I did since I don't want my Z to be lowered 4-5"... hmm....

[Zed Head]

Edit - if you need to keep preload on the springs, you could add a spacer between the spring and the perch.  That would allow you to lower the sleeve.  If you find that the parts are not right.

Well, turns out I wrote a bunch of stuff while I was learning.  And most of what i wrote is wrong.  Except the first post about nomenclature, words, labels, etc.

It's looking like your struts might just be too short.  Not sure what you do about that.  Maybe you can add an extension.  Good luck.

They say to do what you're doing.  

https://stance-usa.com/about/faq/#toggle-id-9

 

Edited March 5, 2018 by Zed Head

[AlbatrossCafe]

Welp, after some discussion it sounds like I accidentally included the top pillow mount of the stock strut in my measurements. When converting to camber plates, you don't use that pillow mount anymore. That thing is a good 2-3" thick, which explains why my car is so much lower than I expected. DOH!!

I either need stock strut tubes welded back in for extra length or some new hubs. I'll talk to the shop I used and see what they are capable of.

You can see in this pic that I have the length similar with the pillowtop mount still on the OEM strut. I should have put the top of the coilover tophat at the bottom of the pillow top. Lessons learned for next time...

Edited March 5, 2018 by AlbatrossCafe