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The Z31 Project - Race Car


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#21 260DET

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Posted 20 August 2016 - 05:06 PM

Jason, the best STA suspension mods I've seen are made here in AU for 1600's, there is not a lot available in the US for the Z31 that changes the operation of the suspension like is available for P cars and BMW's. There is no rush for this build so I want to get everything sorted as much as possible, I hate doing fabrication mods after a car is built too, build it properly in the first place so that the basics are right and only bolt on stuff is maybe required later, like say a brake upgrade.


Edited by 260DET, 20 August 2016 - 06:41 PM.


#22 260DET

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Posted 02 September 2016 - 08:29 AM

Have ordered a set of race spec coilovers made specifically for the Z31 so I'm pretty excited about that, other than bolting them in the fronts have to be welded onto the lower part of the stock struts. The term 'race' is over used these days but these seem to be real, comparison dynograph charts with Ohlins below, what do the experts think?

 


Edited by 260DET, 03 September 2016 - 08:21 AM.


#23 260DET

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Posted 02 September 2016 - 08:31 AM

doppelganger


Edited by 260DET, 02 September 2016 - 07:43 PM.


#24 d3c0y

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Posted 02 September 2016 - 08:45 AM

Proof is in the pudding I guess. Really at the end of the day it comes down to the fact what of what does it need to be better than? Even if they are 1/10th slower than the Ohlins but half the price who cares? I'm sure they will be great.

One thing I realised when doing sprints with my 350Z was that I could have spent a million dollars modifying it or just try and get the best possible time I could from the stock setup.

All that changed would change was the lap time on the print out.



#25 PZG302

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Posted 02 September 2016 - 11:02 AM

The Ohlins has 15 more clicks..... That's gotta be better right?????

 

The shock dyno shows that the dampers work, but what about your spring rates, heights, geometry, wheels and tyres used and so on.

 

Suspension set up is part science, part common sense and bark black magic voodoo stuff that only level 15 and above wizards like Gandalf understand. 

 

You really need to look at the set up as a whole rather than take one piece in isolation. What may work well for one person may not work for someone else.

 

Unfortunately Richard you are on a journey of discovery and wonder on your own as not many people have tracked the Z31, and as you have found out there are bugger all off the shelf parts.

 

A bit like my old 180B 3J car, plenty used for rally, but no one really circuit raced them and with the rules I had to run to was rather limited in what i could do, so ended up with very different suspenion to any other 180B in terms of dampers and springs, something like 900lb springs in the front and 1200lb springs in the back to control the trailing arms on the bum of the car while running the standard 5" wide wheels at the standard ride height.

 

When we moved to IPRA spec, the ride height dropped, the wheels went up to 7" wide and the spring rates only got higher as we cut the coils to help control the trailing arms again.

 

My only advice, do the sensible changes and make lots of notes, get the best out of the car and you before making another wholesale change, so when the car goes better or worse you will know whether the time was due to the set up or you.



#26 260DET

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Posted 02 September 2016 - 07:46 PM

There will be some secret squirrel custom work done on the rear suspension, using the OE stuff as a base. Details of that will emerge in due course. At the moment I'm just happy to get some good bolt on stuff as a start.



#27 dat2kman

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Posted 02 September 2016 - 10:02 PM

What sring rates front vs rear are they supplying you?
What is the current corner weights of the car now, in a track ready condition?
The poundage rates front to rear from factory, will give you an idea on fore/aft pitch.
Z31 motor is set back behind front wheel axle centreline, ( mostly) so no need for heavier front spring rate from factory.

Most f the "race spec coil over" type kits, tend to come with ridiculously high rate springs, due to the drift brigade being sold what the manfacturers want them to buy.

#28 260DET

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Posted 03 September 2016 - 08:31 AM

Will be using King springs Jason, supplier suggests 8/6 in kg to 10/8 F/R with their valving, I'll start with 8/6 which is similar to what the 280ZX has. The rear suspension itself will have it's measurements run through Susprog or else I'll get some graph paper and do it the old fashioned way. I like working out all this shit, it's part of the reason for doing this project.


Edited by 260DET, 03 September 2016 - 08:34 AM.


#29 dat2kman

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Posted 03 September 2016 - 11:39 AM

Kilgrams s so wde ranging.
Dont the suppliers talk in pounds ratings anymore?
Something thats 6-8 kg is akin to 225-300 pounds, huge range.
Especally when changes f less than 25 pounds can make big differences.range
Paper calculations are one thing, actual track testing is what shows what has worked.

#30 260DET

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Posted 03 September 2016 - 12:36 PM

US supplier talks in metric, Kings talk in Imperial, work that out lol. As you know Jason it's important that any dynamic suspension changes are favourable eg more camber on bump, more toe on rebound. That's what I will be working on using Susprog or whatever, the suspension design that will be used facilitates such adjustments. With the S30's strut suspension dynamic camber is no problem but dynamic toe is, it is not available. Which is maybe why some of the S30 racers use a lot of static toe.



#31 dat2kman

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Posted 04 September 2016 - 09:39 AM

Programs, and paper are no substitute!
Your true test will be the high speed slight right on the full 3.0 km crcuit at MP, (after the RH turn to older/shorter layout)
Its that fast sweeper, with the multiple pre, mid, and exit undulations, with road camber change, that you need to run over multiple times, to then get a feel, via your bum and hands, as to fine tuning spring rates, and shock bump/rebound settings.

The other sequence, for lateral adjustment tuning, is the uphill right/left flip flop, coming onto main straight, also on 3.0 km circuit, it has a short bit of straight between each turn, that settles the car.

The Proddie cars cant fine tune/adjust, like you will be able to, they get a bit ragged, on these two sections of track.
The full adjust cars, ie Sports Sedans, open wheelers, 2A Sports, can dial in to suit, as will you be able to!

#32 260DET

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Posted 04 September 2016 - 05:06 PM

Seeing that the body is at rest it's a good time to cut things so some of the top radiator support panel has been removed, mainly to lower it for easier engine removal purposes, the replacement is some 25x25x1.6 square tube which will be welded into place. New radiator is a V8 Commodore all aluminium replacement which will be mounted vertically and not at an angle like the original. It's a little bit smaller in size, not much though, but the core is about twice as thick so with proper venting it should do the job.

 

 

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#33 260DET

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Posted 10 September 2016 - 05:25 PM

Radiator and fan mounts all done so that can be put aside until assembly time, next job is mounting the DBW accelerator pedal and modifying the pedal box so the electric steering mechanism clears. Pic shows the fan which came with the radiator properly mounted not using those plastic retainers which thread through the core. Pads on the bottom sit inside cups welded to the body while the arms near the top bolt on. Yay, the first fabrication job is done, progress  :)

 

DSCN0319.JPG


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#34 260DET

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Posted 17 September 2016 - 04:42 PM

Electric steering is now mounted internally using some fabricated parts including a new 30x30 dash bar and retaining the stock pedal box, drive by wire accelerator pedal is also mounted. The supplied steering assistance variation adjuster will be dash located eventually, the supplier wired that. In all one of those awkward, time consuming jobs that at the start is a bit of a 'will it all fit' adventure. Now to remove it all, finish welding and paint the OE unpainted pedal box. Obligatory pic shows the steering motor in the middle right behind the dash bar..

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Edited by 260DET, 17 September 2016 - 04:45 PM.

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#35 d3c0y

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Posted 20 September 2016 - 08:19 AM

You've probably already explained this, but why electric power steering? Packaging and ease right?



#36 260DET

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Posted 20 September 2016 - 08:51 AM

You've probably already explained this, but why electric power steering? Packaging and ease right?

 

Gets the weight back, a PS pump and mount has to be added to a crate engine. less complication and space needed with no reservoir, custom lines or a cooler required, potential oil leaks avoided, dash control of steering effort, less power loss.. Overall weight I'm not sure but probably a bit less but the weight is a bit higher and it needs a fair bit of power to operate. And of course here the steering shafts have to be matched up and a support bearing installed although being custom the steering wheel has been able to be repositioned.

 

Besides I like to try new things although often that gets me into trouble :)


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#37 260DET

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Posted 23 September 2016 - 05:19 PM

More of the trivial that eventually ends up as a race car, I love the practical detail, working out what will do the job reliably, simply and which involves minimum weight by paying attention to design. Underneath all the crap the Z31 is quite decent, the body carries very little extra weight and should be quite stiff when everything is done. Today we are getting really trivial, the steering wheel adapter was a real lump of pot metal so we got stuck into it and carved off about half of the original weight by the simple expedient of chopping a chunk off it, the other pic shows the replacement steering wheel after drilling and tapping what was left of the adapter and screwing the wheel to it. Total weight 140 g compared with 223 for the original wheel.

 

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DSCN0325.png



#38 260DET

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Posted 08 October 2016 - 01:12 PM

Rust 'repair' race car style. If the part is non structural, like a front guard, then just fix it up the easiest but permanent way possible. If it is structural then my procedure is to clean the area removing all loose rust, hit it with rust neutraliser then work out if the part should be made stronger/stiffer during the 'repair' process, always keeping weight to a minimum. On the Z31 the top of the rear panel that meets the bottom of the hatch was significantly rusted in several places, it's certainly a structural piece so the decision was to plate the entire panel using stiff zinc plated 1.2mm sheet. I avoid using plain mild steel for any structural part. Pics show what was done and the procedure, note that the back edges of the plates will be welded when on the rotisserie and the whole job will have a final dose of fish oil.

 

DSCN0327.JPG  DSCN0328.JPG  DSCN0329.JPG  DSCN0330.JPG



#39 260DET

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Posted 11 October 2016 - 10:04 PM

As well as rust repairs these bodies have some large openings for various purposes, my idea is to weld all but the few essentials up. Pictured are before and after shots of a vent opening in the lower B pillar which had weakened it so much that both sides were cracked at the top outside corner of the opening. Also shown is a large hole rusted through both inner and outer panels just forward of the A pillar door hinges on both sides, caused I suspect by the car being parked facing up hill so water could not get out the drain holes. There are a few bits like this that need repair and which could not be seen when inspected, the bodies on these cars have lots of double panels and are way more complex than a S30's.

 

DSCN0331.JPG DSCN0332.JPG DSCN0334.JPG

 

 



#40 260DET

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Posted 14 October 2016 - 05:35 PM

OK, a break from my dodgy looking but effective welding, the coilovers have arrived and are presented to you in all their not Tein green glory. Imported without springs, Kings will be used and when changes are likely it's best to stick with the one brand.

 

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