GodISmE

Local company: http://fotele-speed.pl/index.php?str...kubełkowe
Solid and very comfortable but really cheap! I can't believe how different it now feels to drive this car? I can finally feel what's happenng to it all the time. Amazing.
They make FIA, check their website. I think they ship overseas.

GodISmE

First time on the Nordschleife in the Zed! Perfect car and set up - I just need to learn how to better drive it now and go back there next year to do some crazy hot laps!

armt350z

iTrader: (6)

Any laps in the dry or was it damp the entire time?

GodISmE

It rained for half a day but then it cleared up. Next year I'll be going there for two days around July/August or maybe even earlier.
This was just a test to check if I'm going in the right direction with the mods and the set-up.
Everything was ok but the back end gets still a bit loose at fast left handers, for example the one right after the Carousell. I had the same symptom at Hungaroring (Nigel Mansel corner). Any tips?

Current set up:
- stock weight
- Hotchkis sway bars: front 2nd, rear 3rd (softest)
- front -3.0 camber, 0.05 degrees toe in; rear -2.5 (decimal) camber, 0.10 toe in
- dampers 6th click from the softest (6/16) all wheels
- springs 14/9 kg
- 28 psi cold all wheels (semislick hard compound)
- height dropped by 2 cm with 10 mm rake

armt350z

iTrader: (6)

Your talking about the fast left right before hohe acht right? Wierd, That curve is only a slight lift before the corner on my car and then constant throttle with it not even trying to step out.

Where in the turn does it step out? (turn in, Apex, exit etc.)

is your car corner balanced?

GodISmE

Yes, the fast slight left just before Hoche Acht. It steps out at Apex or right before it... here at 7:13 (only slightly but I clearly felt it go and it would've been a lot worse if I was going at full speed):

... or here a lot more at 13:12:

That car is not corner balanced - to be honest with you, I don't even know how to do it
Do you think it's because of the driver's weight on the left?

armt350z

iTrader: (6)

Here is a great resource that explains it:

https://robrobinette.com/corner_weight.htm

Basically you will get the front left and rear right tires to carry the exact loads of the front right and rear left. It could cause a problem your mentioning.

If that is not your problem then you're looking at a setup issue.

Is the car bottoming out on the rear right? If yes then increase your rear spring.

If not then your looking at a low/mid speed compression issue so is your car rolling excessively, I can't tell from the camera with the head movement.
If yes :increase spring, roll bar or rear compression dampening
If no: soften your rear spring, roll bar , increase compression or decrease your rebound dampening

From what you said about your setup, if its not the corner balance, you are likely running too much rear spring.

GodISmE

I don't think the car is bottoming out.
The first one at Hungaroring was actually on stock suspension with only Hotchkis bars added - the rear one was set to the stiffest; rear camber was -2.5. I think it got better after putting the full coilovers in with 14/9kg springs and setting the rear bar to softest but I am still not fully trusting the car during those fast left handers.

After doing a bit of reasearch, I think it's a typical throttle lift off oversteer (snap oversteer). It happens during or shortly after trailbraking or when I just lift off the throttle. The weight of the car is probably transferred to the front and the rear wheels lose grip. I have a feeling it's becasue of too big rear camber but I don't know. It's my first RWD car so maybe a driving technique thing - for example instead of fully lifting off I should hold a balanced throttle during such corners so the rear wheels keep pushing?
I'll try the following next time:
1) less rear camber - maybe down to 2 degrees
2) less pressure in rear tires
3) less rake so lower the rear
That should help, right? I'm only basing this on my simracing experience!

I'll look into corner balancing as well.

armt350z

iTrader: (6)

good info!

The first trackday was likely caused by your rear bar setup.

In the second event I would really throw out previous problems since you changed so much. Are you applying throttle while trailbraking? Lift off oversteer would occur the moment you come off throttle and doesn't normally occur during trail braking. You could be unloading the rear end during braking and it trying to step out but that normally occurs during the initial turn in.

Since you say it occurs near or at the apex where you should have already progressively released the brakes and been on partial throttle, I would think we could rule out braking oversteer as well.

camber - probably not, but check tire wear and pyrometer readings to see if you need more or less. FWIW I run -2.2 in the rear.

2. possibly, what are your hot pressures? This is a personal setup. I like to run slightly lower pressures, 2.25 bar, people with the same tire like up to 2.4 bar. But its tire and feel oriented, dont be afraid to play around.

3. Your rake is only at 13mm right? Thats within the norm for a lot here, I've seen everything from 0mm to +26mm. I personally have around 18mm.

06platinumG

iTrader: (1)

If you have gone to a true coilover in the rear and are running a 14/9 set up I think your problem with oversteer is to much spring in the rear. I would change your rear to a 7

GodISmE

Yes, maybe. Folks have been warning me about 9kg at the back. I'll see if I can dial this oversteer out with the set up first and if not, I'll change the springs.

I forgot about this spin (2:46) which was actually the worst even though speed was low. This was already on full coilovers but with a huge rear camber (-3) becasue I had not gotten a chance to get a wheel allignemnt done before hitting this track.
It definitely happens at turn in when I stop braking (trailbraking) and let the engine brake before I get back on throttle - just like at Hungaroring!
So maybe I got it wrong - it's not the typical snap oversteer ... I don't know ... need to read more


PS. This one has great info.
http://www.drivingfast.net/car-control/oversteer.htm
http://www.drivingfast.net/car-contr...-transfers.htm


Now that I think about it - this is exactly what's happening to my BMW GT3 in iRacing in places like the 12th turn on Mount Panorama - if I completely lift off it spins out but if I keep a bit of a throttle it keeps going straight! Ha, simracing is useful after all

GodISmE

Here's a clip from my second last track day of this season (5th overall). I disconnected the rear swaybar and put 0,2 bar less pressure at the rear to get rid of that oversteer. It helped but still the rear steps out when on a limit (as you can see at the end of the video).

What about a rear wing? Would it help?

armt350z

iTrader: (6)

The rear wing will act as a bandaid. It will cover up some existing problems as well as increase front understeer. Although on the flipside, it would work well with stiffer spring rates if you do a balanced aero package (front and rear). Your problem will be if your current setup is not dialed in and you add a balanced aero package then you will be back to square one, with a car that is biased to oversteer.

The driver mods are of course, always a great improvement!

GodISmE

Last one of the season!

I've learnt a great deal about the car and even more about what I still need to learn as a driver!

During winter I will be putting in OS Giken 1.5. What can I expect after this mod? How will it change the characteristics of the car?

I am also thinking about 3.9 FD. Which one should I get?

I will also build a full custom exhaust similar to Milltek's one. Resonated test pipes and the exhaust will hopefully add around 10hp and 15 Nm.

I am a bit afraid to throw out the audio and reduce weight this way because I'm struggling with corner entry oversteer right now. I need to address it before I do anything else. I've narrowed it down to one root cause: it happens when I stop tailbraking and move my right foot to a balanced throttle - this is exactly when the back end loses traction (2:05 in the clip above).

Fixing it is probably going to be a combination of better driving technique (left foot braking and more balanced throttle) and the car set-up (softer rear springs, less rear toe, lower rear, maybe stiffer front, etc.)

Are you guys all running such soft rear springs (5-7 kg) with full coilovers? Is this not affecting the overall speed in corners?

GodISmE

Best photos from my 1st season in 350z ... and actually the 1st season in my own track car!

Plan for winter mods:
1) Full custom exhaust with test pipes
2) Installing the OS Giken 1.5 diff; is it worth doing the 3.9FD mod at the same time? is it ok to buy it used?
3) Removing rear spring buckets and replacing them with aftermarket toe arms (which ones should I get?)
4) Softer springs for the rear - should I go with 5, 6 or 7 kg to match 14kg front? I need to dial out that corner entry oversteer!
5) Rear wing - which one would be best for a track?; do I need to add a front splitter to make this work best?

armt350z

iTrader: (6)

I cant comment on the FD since it would be useless at my power levels, but a used diff is fine if you plan on rebuilding it. I think the OS G rebuild kits are around $250.

The toe arm is a very simple piece and kinda hard to screw up, go with a company you trust.

I would say 5 or 6kg is a good place to be with 14 kg front springs.

If you get a functional rear wing then you will upset the balance of the car very easily. Its a whole new ball of wax and a whole separate element thrown into the chassis tuning arena. I usually save aero until the very last thing on the car. I prefer to get the mechanical grip and setup maximized before I move onto that.

GodISmE

My rear true coilovers are valved to take in 9 kg. If I get 6 kg springs, do I need to adjust something? I read somewhere that up to 2kg change is fine but more might require an adjustment but I am not sure how to do it?

armt350z

iTrader: (6)

Ask the coil manufacturer. Some have wider ranges like Koni 3011/12 shocks for example have valving ranges that suit a spring range much larger than +/- 2kg. If they say you only have 2kg of adjustment range, you will need to send them in to a service/repair shop that supports those coilovers to get them revalved.

GodISmE

First event this year - small and very technical track, great for testing suspension set up though (lots of turns, curbs and one hill). This time I ran -3,2f/-2r, 0f/+0,05 toe and no stab at the back as I could not get any softer rear springs over here to fit the Stance coilovers. I will probably need to buy the Swift springs in the States and ship them here! Dampers were set to 13/16f / 3/16r (more = stiffer). Tires: r888 255/35/18, avon zzr 268/35/18. 14/9kg Swift springs.

It wasn't so bad though, certainly not as bad as on faster tracks where I was getting a lot of snap oversteer at corner entry. I actually start to think that I would be ok with 9kg at the back as soon as I drop the OS Giken 1.5 in, which will add some understeer! Well, we'll soon find out. One thing is for sure, the stock VSLD is crap - no traction out of the corner and the inside wheel spinning a lot. Also, the stock 3,5FD needs to go! I will be replacing it with 3,9FD when installing the LSD.

The only problem I have is a soft brake pedal but I think I know what the problem is: either a bad brake pump or air in the ABS module. I will sort this out soon. Apart from that, the car is a great joy to drive even though everything apart from seats, hood, wheels and suspension is still stock!

One thing that I am still not sure of after this event. The temperature outside was pretty low: 6 C / 43 F. I ran 1,9 / 1,8 bar cold but my friend went as low as 1,6 / 1,5 bar cold with his r888! According to this set-up advice, we shouldn't go lower than 1,8 cold, especially on such a cold day! What do you guys think?

There were five 350z on track that day and only one of them was faster but it's a gutted one with 370 hp!

I kept up with this M3 e46 on full slicks, 200kg less and 20hp more

Dblock55

iTrader: (4)

^^^ Nice to see you representing the Z in Poland!!! 5 Zs at one track day, thats impressive! Its rare to see that even here in the states. Where in Poland are you located? Im from Swientochlowice.