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xssteeb's Fairlady 200ZR


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@Bling

It took me way too long today to make two of these for mounting my new radiator

r2ofRmq.jpg

I had to make new mounts cos i gambled on a 300zr radiator being same size as 200zr. Turns out its 50mm taller. So Ive cut and rewelded the lower mounts and made these as top tank cradles to hang the top of the radiator. Had to do all that cos at 50mm taller I couldnt get the nose cone back on

Ill stick some rubber inside these

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  • 1 year later...

mmkay, so I want to slam the fairlady, been getting some work done by Tim at TTT on minor bits and pieces. He can get ok prices on a coilover brand called gecko, which while distributed from states appears to be generic taiwan spec like BC/D2 stz.

First question is how horrible are these likely to be, Tim reckons go for softer spring rate to achieve 40mm droop and probs get less of a  bang bang ride. I'm only looking to get slammed and enjoy driving, track days probably unlikely in Z as its targa top and I dont want to die

Z31 has a spindle spec mac strut on front so need to weld on, no major dramas there 

The rear features separate spring and shock, it seems many (japan, usa) just mount the coilover in the shock hole. Allegedly can thicken or seam weld some stiffness, or do gussets, strut tower brace if really needed. @cletus what would cert god say?

Gecko Site

https://geckoracingusa.com/

Rear Damper/Spring

IMG_0454.JPG

 

 

Rear Subframe stz

Hicas_hr31rear_end.jpg

 

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With the coilover rear you may need to modify the bottom mounting point too for weight loading. The Gecko stuff does look the same as the rest in that price range. Ideally you'll want to pick spring rates and have the shocks valved to suit. Gives you better ride quality and easier to get the droop/bump requirements covered. Not sure what options there are for your platform though. I run divorced setup in the rear which I did so that I didn't need to modify the car. If you're happy to get those mods done to strengthen it up, then it could well be a good option. Can at least run keeper springs in a coilover setup, if needed. Depends how low you want to go too really. Rear is easy as you can potentially go for custom springs and shorter shocks. Just have to do lots of maths to work out spring specs to suit height / spring rate you want. Can get shocks valved to suit. 

Swift springs seem to be well reviewed. Can get them for coilovers too. Can pick spring rates, spring length etc. Such a big topic, will leave it at that for now. I spent hours on the calculator working out spring rates vs height vs droop etc.

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I run a s-chassis hsd coilover setup in my z31. Used to be in my r31 which was pretty much bolt on. 
In the z31 it’s welded to the front spindle. 
3 or 4 kg front springs can’t remember what I used. 
In the back I still have divorced spring shock with the shock from the coilovers in normal spot. Spring is a “custom” 9kg in the rear in normal spot. 
Car is pretty decent and not crazy stiff. 
Did 9000kms trip a few years ago and was fine partner also never complained.

I used what I had lying around so there will be better ways to do it but I’m pretty happy.

You quickly run into toe and camber issues with these rear suspensions. So look into that also. 

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Its probably easier for cert to keep the spring and shock separate, have been asked by LVVTA for finite element analysis on a hub to see if its strong enough to have the spring on the shock mount on a car with IRS before

And you would likely have to strengthen the shock tower

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@srf @cletus @Bling

Cheers guys, 

srf, good to know there's another z31 out there on OS, would be keen to chat

Clint, yeah I had previously spoken to sheepy who suggested retaining the divorced spring and damper, tbh thats my preference rather than fuck around too much. It's only been in looking at what people are doing in US and JP that it seems really common to use the damper mounts - and thats what is supported off the shelf - but all reasons listed above are what's in my mind and TBH I'd rather not be pulling the interior apart and welding things in just to make some coilovers work

do you reckon there is any value in creating some sort of adjustable spring platform for the rear springs, or just try get it right? I saw the setup @sheepers constructed one @Snoozins KP on the live axle which made me think of this - am I right Richy that that's what you were intending to wind some height or low in should  you need it?

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  • 1 year later...

mmmkay so I've been dilly dallying on this, between having the busiest couple of years in my life with work and kid and waiting for bits and pieces to come from japan I am at a point where i need to make a call on how to proceed with suspension.

@srf keen to know what sort of height you achieved with divorced damper and spring in the rear, i keep reading online about issues keeping the spring captive when going low which led me down the path of looking again at coilovers for both front and rear.

Fortunately (I'll find the silver lining) with my delays/procrastination over the last couple of years there has been a whole lot more interest around the world in the Z31 chassis, (Helped along a bit by Brandon Miller of speedhunters fame doing a pretty epic build: http://www.speedhunters.com/2021/05/project-z31-432-getting-technical/)

Eyeing these up currently, just trying to work out if the fronts are going to be able to meet NZ regs or if i can get a naked set and weld the spindles on here

https://technotoytuning.com/nissan/z31/full-front-coilover-conversion-z31-300zx

https://technotoytuning.com/nissan/z31/rear-coilover-conversion-z31-300zx

I've slid into Clints DMs enough today, and was gunna post into the cert thread, but ended up a bit of a brain dump as much for me to remember to come back to ... so here goes

so like i say, going slightly down a rabbit hole but as i have been doing more research into Z31 suspension there are some limitations with the stock arrangement, particularly in the rear. As above going low in the rear creates some tow and camber issues I havent thought too much about or how to overcome if they come up with the stock rear.

Current plan for the short/near term is get the suspension sussed with stock control arms etc, in the rear due to the setup, going lower is going to add more and more camber which i'll have to try and find a happy medium for cert so i can use the car a bit more than nil (its almost a barn find as it sits) - this ticks the get it lower and on sweet rims and drive it box.

Longer term though I am kind of interested in optimising the setup, ive started down a little rabbit hole as mentioned and the overseas approach is a little bit weighted to rough and ready/hektik spec or there doesnt appear to be the same adherence to rules etc like we have so not sure would meet NZ reqs...So starting from a place of ignorance has anyone done anything to modify suspension geometry significantly/is there some stuff I should read? 

Stock - subframe with lower control arm, divorced spring and damper: (my short term thinking is replace with coilover in line with damper as online feedback suggests issues with keeping the spring captive when trying to go as low as you would with coilovers)

image.png.dd2313482b6881de4d13870e449d57ff.png

 

S14 subframe retrofit this is from the Z31 build mentioned above - appears to be have been done with little expense spared so I am assuming its a quality arrangement, however its USA based so not sure how a similar approach stacks up in NZ - apparently this guy used some sort of 'kit' to adapt the S14 subframe, presumably to fit the Z31 mount locations. not sure if these control arms are off the shelf or bespoke but appear to be adjustable length (ignorant question...are these even road legal in nz?):

image.png.e3391e6854af6d6e71e1d9c1fb046643.png

 

This also got me thinking a bit more about the front setup - there's basically a lower control arm and a castor rod

Stock:

image.png.3a262dbca601b1d663fe5b04af70432f.png

Below is the T3 replacement product which provides a whole lot more adjustability but wondering if these sorts of setups have any hope of being legal in NZ? Rose joints ok? Welds/materials need to meet a certain spec?

https://technotoytuning.com/nissan/z31/gtx2-front-lower-control-arms-and-tc-rods-z31-300zx

image.png.83ac9fe555d454e26f523f6cda12f079.png

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330mm hub to arch is what I have. 
Not for any reason other than that’s what I got with the springs. 
 

I have a fully adjustable coilover shock. Just without the spring on it so would be able to adjust to keep any spring hight captive. So long as it’s on the nub on the arm and in the cup on the body.
 

toe and camber are ok. Camber has to be close to stock for cert.  I made the non adjustable mount adjustable like the factory one. It got it close enough for cert. any lower and would not be possible to get close enough. 
 

I would say that the rear is compromised in most ways at anything but stockish height without a ton of work. 
 

Compared to my other Nissan rear suspension setups the semi trailing is definitely the worst.
 

The datsun rear mac strut type 240z gets way more power to the ground. And the s14 type is well sorted at most ride heights.  
 

diff swaps are a breeze tho. 
 

 

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mmmkay had a yarn with Clint on what's the latest in cert world with suspension. Based on the info the T3 guys emailed me it doesnt look like their design for front coilovers will pass in NZ (appears to be butt welded to spindle stub not pressfit sleeved and plug welded)

The rear coilovers looks like is becoming a ball ache as there is starting to be requirements around engineering analysis for changing the load points - paraphrasing, likely as a result of 350z guys doing the same thing replacing divorced spring/damper setups with coil overs in place of damper albeit with the mounting of the damper being on an aluminium control arm (arguably steel would be better suited) but it looks like this route is going to get harder/shut down

The T3 control arms and the like also seem to be getting out of favour as a result of being highly adjustable and having aluminium tension rods (hard on for steel)

So likely taking another route here

Dealing with rear camber, Clint let me know this is an issue the E30, cressida etc guys have too and could be solved with some eccentric bushes/bolts on the semi trailing control arms - or modify the mounting points. Looking a bit deeper online it appears there are some camber correction kits available with variations on the approaches above

dumping these here for future reading:

So Clint based on below I can go to max -2.42 degrees in the rear

image.png.3f57b2d224e00a29abd665ce8cdd97e6.png

 

Eccentric bush:

https://k-mac-camber-kits.com/product/datsun-541326-h-rear-300zx-z31-4-trail-arm-to-crossmember-bushes/

Redrill mount location 'kit'

https://www.thezstore.com/page/TZS/PROD/23-4177

https://z31performance.com/forum/z31-performance-upgrade-forums/suspension-chassis-and-brakes/16563-fixed-rear-camber-template-modifcation

^also mentions using RX7 (presume FC due to the semi trailing arm) subframe mounts in place of Z31 as they have inner and outer adjustment - will look into this too

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  • 1 month later...

@85_z31 made an adjustable rear set up for his z31. 

There's probably a thread for it at nzdatsun.com. (I doubt hes been here in a long time?)  James is a super smart cookie too.  (I dont recall exactly what he did tbh, but he did help Greg ( @datto_610) design and build his set up. 

 

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