Major Track Faults of the 370

travisjb

Agree, at the limit T1 at Philips should produce fuel starvation... do you have a way to measure lateral G-loading? also, are you simply coasting from t1 to t2?

other than that, the only two right handers are essentially hairpins, neither of which should cause fuel starvation... do they have any clockwise sessions there? then you'd really get to experience all the fun you've been missing... haha

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2009 370Z #104
*For Sale*

BGTV8

T1 in a Z34 is just a lift, turn in and back to WOT. I have data logging from my race car which shows 1.3G lateral (this car runs 290/625R16 Dunlop SS12 slicks) and a guess for the Zed with Dunlop Direzza's whould be around 65% of what the race car sees - so it will be close to 1G, but wouldn;t be over it.

The fuel pickup is in the same spot, so maybe I'm just lucky with the circuits I run on here.

memorylasts

Not applicable for the topic

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somewhat-journal-thingy

cossie1600

The turn is too short, you need a continue radius

Guard Dad

Some thoughts on the clutch pedal issue. I don't know if this has been resolved or not but the clutch pedal sticking to the floor was a common problem on certain types of muscle car clutches in the 60's. These clutches would essentially go "over center" when fully released and the G forces generated within the clutch at high revs pinned the clutch in the released position. One solution was to install a travel limiter to prevent the over center condition. Unfortunately such a simple solution doesn't seem to apply in this case.

Since my Z is an A7 I can't confirm my theory but I'll put it out for discussion anyway. Many clutch systems have an assist spring on the clutch pedal assembly, if the Z has such a spring we may have a possible answer to the mystery. The assist spring assembly is typically laid out to push the pedal to the floor in the second half of its travel and lift the pedal off the floor in the first half of travel. In this environment if the clutch fluid were to boil the pedal would stick to the floor when depressed. So addressing the overheating clutch fluid might solve the problem.

Pharmacist

i had one experience with fuel starvation this summer. it was at shannonville motor sports park. It was near my 3rd 20 min session. It was between turns 2 and 3. The 2 turns are usually taken together as a single turn at a speed of about 70 or 80 km/h in second gear at about 60 or 70% throttle. Fuel was about quarter of a tank, so 4 dots. As I was between the 2 turns, I lost all drive to the wheels and the engine went down to idle. The car coasted to a stop on the short straight right after turn 3 and the engine just wouldn't rev past idle. I thought it was limp mode but my oil temp was ok. Also limp mode cuts rpm at 5000. Tried shuffling through the gears but the car still wouldn't rev past idle. A couple of cars went right past me at high speed and I was in full panic mode. Eventually after a few seconds I managed to creep onto the grass at the side of the track. After a few seconds of pumping the throttle the engine finally came back to life. Fuel gauge was showing only 2 dots.

Then on that same lap at the hairpin (turn 10) I also experienced the same thing. This is a slow high-g hairpin taken in 2nd gear at 40-50 km/k and exits into a very long straight, so you floor the throttle as soon as you exit. At the exit of the hairpin I floored the throttle and experienced no acceleration for about 3-4 seconds before the car finally responded again. I pulled into the pits after this lap, and slowly after a few minutes the fuel gauge went back up from 2 to 4 dots again. I let the car cool down and then went home.

Here is the track map:

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2009 370z Sport Touring/Nismo shift Knob/Z1 motorsports 34 row oil cooler

travisjb

looks like a fun track! even CCW, you'd get fuel starvation through 6-5 etc... i think you're going to have to carry 3/4 or more of a tank from now on at that track

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2009 370Z #104
*For Sale*

Mike

I have found out today that fuel starvation isn't a problem at Road Atlanta while it's raining heavily.

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NISSAN: 75 280Z / 86 300ZX GLL /87 Sentra SE / 03 350Z / 23 Z
Porsche: 93 968 / 23 Macan GTS / 93 968

travisjb

hahaha!!!

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2009 370Z #104
*For Sale*

Mike

but the slick surfaces exaggerate handling weakness and I think I am in serious need of some more front downforce. The front was really light, causing me to slip and slide quite a bit. It didn't feel so bad to me or the instructor in the car, even though he could tell I was driving on the edge, but two other instructors told him we were sliding all over the place. I couldn't keep up with the modern Bimmers and Audis, but I was slightly faster than the two C6s.

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NISSAN: 75 280Z / 86 300ZX GLL /87 Sentra SE / 03 350Z / 23 Z
Porsche: 93 968 / 23 Macan GTS / 93 968

daisuke149

functional splitter/canards? or a big fat lump of metal bolted to the front

travisjb

some clarification... front was losing traction at low speeds, high speeds, or both? during hard transitions or high-g but lower-rate transitions? during braking or stable front-rear load?

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2009 370Z #104
*For Sale*

spearfish25

Time to buy a second wing and mount it on the hood. Who cares if our cars aren't FWD? It just looks cool.

On a more serious note, could the front tires have been hydroplaning? How much tread do you have left up there?

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2013 Cadillac V-Wagon, RIP Z

Mike

plenty of tread,Yoko AD-08s. Mostly coming out of turns going uphill, low speeds on wet track while accelerating. Fronts would lose grip first, then the whole car would slip a bit. Just seems odd that I couldn't corner as fast as a 330i.

I've never experienced this problem in the dry, I think that if I pushed it harder on the dry than I do, it would happen there too, its just the wet track amplified everything.

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NISSAN: 75 280Z / 86 300ZX GLL /87 Sentra SE / 03 350Z / 23 Z
Porsche: 93 968 / 23 Macan GTS / 93 968

travisjb

process of elimination...

sounds like not a tire issue... can't remember what width you run front and rear... I'm running a square setup, so obviously I get more relative front traction than most setups... assuming yours are not overly staggered and that your front tires were in as good condition as the rears... if so, we can rule out the tires themselves... that is, unless you have something weird going on with tire pressures

didn't occur during braking, so those are out

we can rule out the rear diff

so that leaves setup or driver

on driver... this is a low speed (mechanical grip) corner... you're an experienced driver, so I'm sure you're all over this, but have you tried different ways of entering and exiting that corner? wet tracks = slower in, later apex, more gradual acceleration... and of course when you accelerate you will be transferring weight off the fronts and onto the rears, which brings me to setup

on setup... thing #1 is to disconnect the sway bars in *hard* rain... an old racer trick someone shared with me that tends to alleviate a lot of the twitchiness in the chassis on a wet track...

also, can't remember which coilovers you have... how much adjustability do you have? what are the spring rates you are running front and rear? if you are having this issue of understeer in dry weather as well (you said it was amplified in rain), especially on an uphill exit (where the front *should* have LOADS of traction), then you might think about going up 2K in rear spring rate and before then even try adding some compression (bound) stiffness the rear dampers... and/or maybe take out a few clicks of compression stiffness in front... I always have to remind myself, one change at a time

finally, post up your caster/camber/toe settings on front and rear, if you like and we can comment on those and how they might be playing in... only if that's helpful

others more knowledgeable than me can expand on what might be going on with your setup... also, read these

Effect of Suspension Changes - trackHQ.com - Track Day HPDE W2W Club Racing Time Attack Motorsport Forum
Front anti-roll bar stiffness and understeer? - Corner-Carvers Forums

And final question... please tell us what your tire temps are if you are collecting those (inner, middle, outer) and if there are any obvious wear patterns on the front tires

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2009 370Z #104
*For Sale*