Richard's 620ZX Coupe

[260DET]

Funny how I get asked that occasionally but no way, it's going to be a ripper.

[260DET]

Auto valve body has been removed and tweaked to improve internal oil flow volume and speed to keep up with the extra demands like full throttle shifting. Hopefully this will be it for the auto, better be because the Z is entered for the next A series sprint at Morgan Park over 25/26 June. Now in the process of bolting everything up again, fortunately the hoist helps to get the car high enough to work on properly. Have played with the rear suspension to increase the roll centre too, hopefully this will make the rear end a bit more stable under high load.

 

Pics are of the kit used for the auto with now surplus parts, plus a view from underneath looking forward. 

[Sirpent]

Happy Days at last?

 

Hope it all comes together for you Richard ;-)

[dat2kman]

What do you mean by playing with rear susp to increase roll centre?

Edited June 16, 2016 by dat2kman

[Sirpent]

What do you mean by playing with rear susp to increase roll centre?

 

Relocation of adjustable rear LCA's height position? 

[260DET]

Relocation of adjustable rear LCA's height position? 

 

Yep, something that will get more attention with the Z31 project too. 

[Sirpent]

Yep, something that will get more attention with the Z31 project too. 

 

Same as what I have done with my new mount design with central upper and lower bolt points 

[Gordo]

Love it.

[dat2kman]

Photos showing the ability to "increse" roll centre??

[Sirpent]

Would you call it roll center ? I'd suggest rather center of gravity by raising the LCA pivots higher within the car.

[dat2kman]

I'm very interested to see how roll centre is "increased"

Gotta be a fast racer thing, for a 280ZX and a yet to be Z31

 

The Taxi's have been doing it for years, on the back ends.

[260DET]

On a S30 the front roll centre can be raised by increasing the height of the LCA inner pivot and/or decreasing the outer, using for the outer what are commonly referred to as 'bump steer spacers'. But you already know that Jason as you would know that changing the rear LCA similarly is not so easy. So the problem with the S30 is that it's back to front because it's the rear roll centre that should be raised so it's higher than the front, not vicey versie..

 

S130 and Z31 are of course different with their rear semi trailing arm suspension. To raise the roll centre with them the forward arm pivots need to go up. EG if they are level in height with the middle of the wheel then the roll centre will be the same as half the diameter of the wheel. So way more easy to adjust the rear roll centre height than with a S30.

 

I'm sort of surprised that as far as I know noone has looked at decreasing the height of the rear outer LCA pivot point on a S30 but perhaps there is a practical reason for that. Aaaagh, what the hell has this got to do with eternal project car

[Sirpent]

Dont mean to hijack this thread but as you mentioned the S30 rear...........

 

Well, guess we will find out one day in the future, Peter Mac suggested I build this into my set up as per the photo attached.

 

This photo was taken with the car sitting on the rotiserie on its side before I rotated the photo, therefore the loose brackets on the left are actually hanging downward while the ones on the right are actually positioned in their true position.

 

The lower control arms I am having made will pivot off of these brackets and can be set higher or lower.

 

On a normal S30 set up, because after market adjustable lower control arms replicate the forward mount poistion of the originals, and utilise the body hanger points, it would be almost impossible to create a hanger bracket set up for adjustability.

 

The LCA's Im having made step inwards at each end by 30mm meaning that the hanger brackets will allow for a HT nut and bolt set up to allow for the LCA repositioning. 

 

Cheers

 

John

Edited June 16, 2016 by Sirpent

[dat2kman]

John, that setup is close to/same as the AZC rear lower inner, and yes, it will give ability to change roll center, but, you cant use the stock as supplied AZC rear LCA's.

They need to be lengthened, to suit.

For finer on alignment machine adjstability, the bolts need to be slotted, enabling the inner and of LCA to be moved vertically up/down, thats roll centre adjustment,

 

For the S130 and later Z31 running K frame semi trail arms, the amount f. Roll centre adjstability in the up/down is very minimal, to slight, with the ears on the rear crossmember fully slotted, correctly, the geometry is such that roll centre is in a very clse range with very little ability to raise or lower.

The slotting of the rear ears on the crossmember does give much better control r rear end toe and camber adjustment, which is what will "settle" a IRS K frame rear end down, and give much better handling.

[Sirpent]

John, that setup is close to/same as the AZC rear lower inner, and yes, it will give ability to change roll center, but, you cant use the stock as supplied AZC rear LCA's.

They need to be lengthened, to suit.

For finer on alignment machine adjstability, the bolts need to be slotted, enabling the inner and of LCA to be moved vertically up/down, thats roll centre adjustment,

 

 

Richard, I’m sorry this thread is being hijacked, so this will be the last post I make here on the S30 set up I’m building.

 

 

My set up is a bit different from AZC set up

 

 

The tubes in my photo are fixed in place and also form part of the diff cradle, whereas the AZC and other set ups rely on the LCA tubes bolting into the chassis and the rear moustache bar drop plates.

 

 

These permanent tubes replace the traditional set up and incorporate the hanger brackets that will carry the LCA's with fully adjustable rod ends at all 4 bolt points (2 at the LCA Chassis mount and 2 at the spindle assy)

 

 

My LCA's are being fabricated by John Lange specifically to make up the width and length difference creating this cradle assy dictates, however as I will have 4 point adjustment, I will have  a fair degree of length adjustment between chassis and spindle points. I have attached a pic of the ends I will have on the LCA's.

 

Cheers

 

John

[RLY240]

 

 

I'm sort of surprised that as far as I know noone has looked at decreasing the height of the rear outer LCA pivot point on a S30 but perhaps there is a practical reason for that. Aaaagh, what the hell has this got to do with eternal project car

 

You mean like this? No, not mine.

[260DET]

Those rod ends ^^ look the goods John, who sells them? 

[260DET]

 

You mean like this? No, not mine.

 

 

You mean like this? No, not mine.

 

Yes, but a bit more attractive than that HybridZ effort.

[Sirpent]

Those rod ends ^^ look the goods John, who sells them? 

 

Synergy in the USA

 

Used on aftermarket Jeep suspension set ups

 

I have to put in my order in the next few days so John can build the LCA's now that I know the positioning and dimensions

 

http://www.synergymfg.com/Synergy-Double-Adjuster-Tube-Adapter-p-19276.html

[Cozza]

Those rod ends ^^ look the goods John, who sells them?

Yeah they look pretty and simple but at almost a kg??? There must be a typo.

[260DET]

The first sprint using the V8 and auto today with only one problem, in 3rd gear which is good for ~200 clicks it seems like there is some internal slippage at lower revs when winding it right out. It's almost like two stages so I'm thinking that line pressure will have to be increased at lower revs. Other than that it's a rocket which on a cold track with old tyres means slippy slidey fun, on the Morgan Park D circuit I found that leaving it in third all the way was best, particularly for corner exits.

 

So I'll have a chat to the guru but other than that it's all go finally, I really was getting to the end of the effort to keep trying. Compared with the VG30DET 425 horses at the wheels setup it's heaps different now, much more usable power and more of a challenge to drive requiring a different technique. Relieved to find out that I'm still able to do it all too, very relieved.

[Sirpent]

Congrats Richard ;-)

[Riceburner]

Is the auto slipping at low rpm with WOT? I guess once you get that it sorted you'll be able to bang it back through the gears and get some engine braking too. How did you compare to previous lap times with the VG30?

 

It's all good news Richard, sounds like the real fun is about to start!

[dat2kman]

Circuit D, is Turn Right after bridge, then Turn Right into Esses, to rejoin front straight.

You'll mever see "20 clicks" on that short course!

Better off sing a lower ratio diff to get it out of corners quicker.

You'll find the other Z's are doing this!

 

But, then again, you're a bit different, and proud to be so!

 

Typo,,, 200 clicks,,, not 20!

Edited June 26, 2016 by dat2kman

[260DET]

You gave me an idea Gareth, will have to see if the TCU can be programmed to deliver full line pressure at WOT, at present line pressure is governed only by engine revs. 

 

Driving a big V8 auto Jason just can't be compared with the usual setups eg effective throttle control in 2nd coming onto the straight was beyond me, it was faster to leave it in 3rd to avoid wheelspin. Don't forget there is a torque converter in the drive line and this one seems to be a good choice, effective torque multiplication with not a lot of slip at higher revs. There is also the torque converter clutch which it would be pointless to try to use on short tracks like MP, it is now manually switched and I anticipate using it at Bathurst on the two long straights there.

 

Lap times will be on the timing site MP use, I was in group 1 Sports Sedans.

Edited June 26, 2016 by 260DET