Help with standard 260 suspension set up

[designark]

Afternoon all
Can anyone advise on what I need to achieve as near to stock late 260 suspension set up as possible please with new strut inserts and springs in mind. I don’t know how old my old springs are so going to update as a precaution. Any advice very welcome!!
Thanks
Jon

 

[AliK]

Hey Jon,

Firstly I have to ask:

1. What year / model type is your 260z? E.g. is it a UK or US car? Is it a 2 seater or 2by2?

2. Why stock? What are you trying to achieve? Nostalgia of stock handling or correct ride height etc.

Reason being that spring rates vary between model types and US v UK.

Also struts are different dimensions depending on what year / market.

Having said all that, while there are many options for strut inserts out there, my money would go (and has gone) on the Koni Adjustable shocks sold by the ZStore.

Motorsport Auto - The Z Store - KONI Sport Adjustable Gas Strut, Front, 74 260Z 2+2, 9/74-78 260Z-280Z

KONI Sport Adjustable Gas Strut, Front, 74 260Z 2+2, 9/74-78 260Z-280Z

www.thezstore.com

The beauty of them is that they fit as the stock items do but allow for tuning to your preference by just taking off the cover at the top of the strut towers, inserting a knob and turning a screw. I can adjust all 4 for full soft / medium hard or track day action in under 90 seconds.

From everything I’m reading, the eibach progressive springs are to be avoided. But happy for someone with actual experience of them to correct me or give a different perspective!

 

[designark]

Thanks for the advice Ali? Forgive me if that is not your name!
It is a late uk 260 model (first registered 1978) and a 2 seater.
The adjustable set up sounds ideal. I generally want to create as close to the original ride height / quality as possible but probably would not mind lowering an inch if that is the result of using new Eibach springs or other? If any one has any further advice on springs to complement the Koni inserts that would be great
Thanks again
Jon

 

[Albrecht]

Thanks for the advice Ali? Forgive me if that is not your name!
It is a late uk 260 model (first registered 1978) and a 2 seater.
The adjustable set up sounds ideal. I generally want to create as close to the original ride height / quality as possible but probably would not mind lowering an inch if that is the result of using new Eibach springs or other? If any one has any further advice on springs to complement the Koni inserts that would be great
Thanks again
Jon

According to the late (1977) factory workshop manual which covers the UK market 2-seater RS30QU '260Z' model:

FRONT SPRINGS:
Active turns of coil: 8.5 (standard) 7.5 (hard suspension)
Free length: 381mm (standard) 341.5 (hard suspension)
Spring constant: 2.06kg/mm, 115.4lb/inch (standard) 2.59kg/mm, 145lb/inch (hard suspension)

REAR SPRINGS:
Active turns of coil: 9.5 (standard) 7.5 (hard suspension)
Free length: 406mm (standard) 350.5 (hard suspension)
Spring constant: 1.84kg/mm, 103lb/inch (standard) 2.59kg/mm, 145lb/inch (hard suspension).

 

[AliK]

That is indeed my name! But it’s Prince Ali if we want to be formal

Here is a photo of my ‘77 260Z’s ride height at the front + the car viewed from the side if helpful. BTW it’s on stock sized wheels / tyres but with quite an offset to get the deep dish look.

I REALLY like the way the car sits and it clears every road hump etc with ease. As a rule of thumb, if you can get a trainer shoe between the wheel and the wheel arch it needs lowering - Jeremy Clarkson! It really does work though!! Try it on any car




I suspect my car has been taken down an inch - we need the same measurement from a stock late 260z setup to be sure.


This may help but it’s for a 240z and doesn’t have the same datum point I’ve measured. The key measurement to look at is the floor supports to ground at 161mm or 6.3”.




On the rear view photo below you will note the MSA exhaust that came on the car used to hang unnaturally low and that one did catch every now and then. But I suspect the PO didn’t take their time fitting it properly and the interference joints were heat welded solid so the sections couldn’t be adjusted.



Having replaced it with the Z story exhaust after these photos I’ve not had that issue.

Now then, as to what springs I have, I have no idea! All I can say is at full extension they are loose and can be moved by hand.


A great discussion / read here: https://zclub.net/community/index.php?threads/spring-rates-little-bit-of-advice-needed.16963/

 

[AliK]

My reply must have crossed with Alan’s, apologies!

 

[AliK]

According to the late (1977) factory workshop manual which covers the UK market 2-seater RS30QU '260Z' model:

FRONT SPRINGS:
Active turns of coil: 8.5 (standard) 7.5 (hard suspension)
Free length: 381mm (standard) 341.5 (hard suspension)
Spring constant: 2.06kg/mm, 115.4lb/inch (standard) 2.59kg/mm, 145lb/inch (hard suspension)

REAR SPRINGS:
Active turns of coil: 9.5 (standard) 7.5 (hard suspension)
Free length: 406mm (standard) 350.5 (hard suspension)
Spring constant: 1.84kg/mm, 103lb/inch (standard) 2.59kg/mm, 145lb/inch (hard suspension).

This should be a stickie!!

Edit: I just tried to count mine and thought this maybe useful to anyone else who like me doesn’t know how to count coil turns:

 

[designark]

Thanks for the additional feedback guys.
Ali - Your car looks great and the ride height looks ideal. I wonder if your springs are refurbed originals?

 

[AliK]

Thanks for the additional feedback guys.
Ali - Your car looks great and the ride height looks ideal. I wonder if your springs are refurbed originals?

Thanks fella.

After Alan’s far more informative post, I went back to my other photos and counted coils which don’t correspond at all with what Alan posted - unless I’m counting them incorrectly. For example, I can only count 6 active coils on the front.

I suspect they are aftermarket springs, but I have no idea about spring rates etc. Sorry I can’t help with any other details

 

[Albrecht]

After Alan’s far more informative post, I went back to my other photos and counted coils which don’t correspond at all with what Alan posted - unless I’m counting them incorrectly. For example, I can only count 6 active coils on the front.

I think its especially important to correctly identify - where possible - the factory part number on the strut tubes, as spring seat position moved around according to original fitment. Also important to ascertain whether the lower spring seat has been moved up or down at some point in the strut's life.

There were many small rolling changes to struts as production went on. For example, looking at the factory parts manual which covers UK market models you can observe no less than NINE iterations for RH Front strut assemblies up to October 1973 (E4215, E4126, E4127, N3425, N3725, E8125, E8126, N3525 & N4025). From '74 up there were many more...

With cars that are at least 45 years old at their youngest, pretty much anything could have happened to them over that time. In my experience, people often used to source used struts and then modify them to swap out with the originals. Some specialists in the UK used to offer suspension struts on an exchange basis, so if a car has been modified at all it is very likely that the struts on each corner are not the originals. That can make it difficult to put it back to 'stock'.

 

[AliK]

I think its especially important to correctly identify - where possible - the factory part number on the strut tubes, as spring seat position moved around according to original fitment. Also important to ascertain whether the lower spring seat has been moved up or down at some point in the strut's life.

There were many small rolling changes to struts as production went on. For example, looking at the factory parts manual which covers UK market models you can observe no less than NINE iterations for RH Front strut assemblies up to October 1973 (E4215, E4126, E4127, N3425, N3725, E8125, E8126, N3525 & N4025). From '74 up there were many more...

With cars that are at least 45 years old at their youngest, pretty much anything could have happened to them over that time. In my experience, people often used to source used struts and then modify them to swap out with the originals. Some specialists in the UK used to offer suspension struts on an exchange basis, so if a car has been modified at all it is very likely that the struts on each corner are not the originals. That can make it difficult to put it back to 'stock'.

Super interesting Alan, thanks for the info. Sounds like a minefield to know exactly what one has. I'll have to go back through the billions of receipts / papers that came with my car to see if I can find something relating to springs / struts etc.