240Z Eibach Springs in 260Z

[LeonV]

I'm rebuilding the suspension (bushings, springs, shocks, etc.) on my 9/73 260Z and I just ran into something unsettling. I installed Tokico HPs and Eibachs which are both listed as compatible with the 240Z and early 260Z. When I put in the HP inserts, the gland nuts almost bottomed out. They are tightened but very close to the strut top even with the gland nut spacer. But this is not the main problem.

While I was putting the springs on I noticed that my 260Z spring perch sits noticeably lower than the 240Z struts I have to compare with. I decided to go on anyway, because the springs are listed as the same for the 240/260Z (early). I installed the struts on the car (ARB or steering rack uninstalled, but that doesn't make a difference) and I have virtually no bump travel with the ES bump stop in there. Cutting or removing the bump stop will help but not by much, as I think it would still bottom out all the time.

The springs are installed correctly, with part number 6305.001 in front.

Now I'm thinking someone installed later struts but I measured the strut ID and it was equal to my 240Z strut tube! My strut inserts fit snugly into both my 260Z and 240Z strut tubes. The difference being that the 260Z lower spring perch sits lower than the 240Z spring perch. I don't remember there being much of a difference in overall height.

At this point, I'm not quite sure what's going on here. Are there three types of stock S30 struts? It does not look like someone cut the perch and welded it lower. I suppose I can get longer springs (maybe some 280Z performance springs), but what is the issue here? I've been searching and haven't seen this problem.

Here are some photos for reference:

[Zs-ondabrain]

Something sounds wrong. You should have Some play in there.

I have a 4/74 260Z and a 70' 240Z. You'll see the comparison below.

The fronts were a sloppy fit until weight is put on them. Probably about 1 inch of slack between the upper perch and the top of the spring.

The rears almost fit perfectly, though I did have to put about 125 of weight on them to get the nut started on the strut, thru the upper cup

Now I can't honestly tell you how the car will sit until EVERY thing is back on and in the car. Though I was told by Garrett at MSA that I might wanna cut the rear bump stop in half to avoid premature bumping.

If my project car was back together, I could help more.

Dave

[LeonV]

Dave,

Your post is very much appreciated, especially the strut differences. That's why the gland nut almost bottomed...

The difference I see is in the springs you're using. My springs are the 240Z PN and your's are the 280Z ones I believe, maybe I'm wrong. As you can see, my front springs needed a spring compressor to install. Your springs also look different, as they seem to be linear (not progressive) in front, unlike mine.

Haven't done the backs yet so I guess we'll see how that turns out.

Here is my logic in this situation. As your picture shows, the 260Z spring perch is one inch lower than the 240Z perch. The Eibach kit is the same for the 240Z and early 260Z. That means that using the same spring lowers the 260Z an extra inch.

Therefore, if these Eibachs are designed to lower the 240Z 1-1.5" as advertised, that means that the 260Z is lowered 2-2.5 inches! Nevermind the essentially complete loss of bump travel.

I suppose the first course of action is to cut the ES bump stops, like I should have done in the first place. If that doesn't help then I might just have to buy some 280Z springs and save the Eibachs for the '71 240Z.

Oh those quirky 260Zs...

[John Coffey]

Blame Eibach. They try to get by with as few part numbers as possible (especially for such a low volume seller as the S30 chassis).

[LeonV]

Yeah, that's what I figured. Nobody wants to make springs/shocks specifically for the early 260Z, which have different strut tubes than the 240Z and late 260Z/280Z as we've shown. Early 260Z owners just have to adapt to what is out there.

[John Coffey]

Tokico does.

[LeonV]

Do they? Where can I get these early-260Z specific shocks/springs?

[Zs-ondabrain]

I just noticed something. My springs are 6303 001's

and yours are 6305's

I have an early, or mid 260Z 4/74' and they should be the same??

Though as pictured above, my front springs are also short. I wonder if there is a company that stretches springs. Same spring rate but taller??? maybe?

Dave

[LeonV]

Yeah, I noticed that too. Our springs are definitely different, visually and part-number wise. Mine are from a 240Z, are your springs the 280Z ones? I'm thinking that if I don't have enough bump travel that I'll just get the 280Z Tokico springs and cut them.

The rear suspension is off the car, so tomorrow I will hopefully get the spindle pins out and work on the rear struts. I'll be sure to measure and note any differences between my early 260Z and '71 240Z struts.

[John Coffey]

http://forums.hybridz.org/index.php/topic/88025-installing-tokico-280z-hp-springs-in-a-240z/

[LeonV]

Thanks John, I've read that thread already in preparation for what may be inevitable. I'll have to bust out my spring formulas and do some calcs to really nail down the height and spring rate I want.

I'll see what the rears look like today, and shave my front bumpstops before I take it on a test drive. What I'm putting in will definitely be better than the cut stock springs that were in there.

[LeonV]

Took the rears apart today and measured. Thankfully, my rear 9/73 260Z struts essentially match up to 1/71 240Z struts.

Here are the numbers (240Z/260Z):

Inner Overall Height: 16.6875"/16.75"

Spring Perch to strut top: 13cm/13cm

ID: 46mm/46mm

When I install those back onto the car I'll update this thread.