How much rake? Weight distribution question

[dP3NGU1N]

Hello everyone,

From what I know, the weight distribution of the 370z with full everything is roughly 54/46 with driver (info from: Corner weight stock vehicle/weight distribution sports package). After gutting the interior of the car in the rear hatch; all tools out, no spare, etc. I expect that the number is probably closer to 56/44. Now I'm about 50lbs lighter than the author of that original post, however, it seems that the driver has very little effect on weight distribution. Nissan seems to have placed the driver as close to center as possible; his 200lb frame only shifted the weight dist a little over half a percent.

I don't have easy access to corner scales so I'm wondering about how much rake other people who regularly track their cars are running. I'm currently running about a half inch lower in front than I am in the rear when measuring the wheel arches (26.5F / 27R) compared to the stock height with full fluids the car sits fairly even (27.87F / 27.99R). Theoretically would that half inch of additional height in the rear put me back to similar weight distribution as stock since I have removed weight from the hatch area? From what I know, the higher a portion of the car is, the more static weight you are placing on that portion.

Yes, I'm aware there's a lot of guestimating here, but short of actually putting the car on scales it's the best I've got right now.

If more info is necessary I will do my best to provide it. I hope this turns into good reference for others since I'm not seeing a whole lot of discussion regarding corner balance.

Thanks for any help, cheers.

[patabq]

Subscribing for same concerns.

On my 350 I guestimated and tuned w track feeling. I start by lowering the driver front corner 1/4" and driver back 1/8" to shift drivers weight to the right and back. The front will be about 1/2" lower than back to shift weight back (need oversteer). I am planning KW V3s so min drop is 0.8" in front.

Therefore, drop from stock: LF 1.05, RF 0.8, LR 0.425, RR 0.3
Of course, if you want more drop just add constant to all four.

I will align to this set-up and iterate a few times. Then leave it, drive it and tune w shocks and sways for tire wear and track conditions.

I am still researching to get these numbers closer to start with for this car.

[Dwnshift]

So much depends on everything else. We would run the rear down further if we could but restricted per ride heights. 2.5" clearance on underside of car.
Dont put anymore weight on the nose than you need to.
But again.... Everything depends on everything else.


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[j-rho]

Changing rake doesn't really change static front:rear weight distribution. All you can do with corner weighting is get cross weights balanced.

[dP3NGU1N]

Originally Posted by Dwnshift

So much depends on everything else. We would run the rear down further if we could but restricted per ride heights. 2.5" clearance on underside of car.
Dont put anymore weight on the nose than you need to.
But again.... Everything depends on everything else.


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I'm not running any further aero parts other than stock sport package things for now because I'm not sure how to balance the car without an expensive wind tunnel; and I'm not competing so I'm certainly not going to lay that sort of money down. I had looked into diffusers and wings but never pulled the trigger because I don't want to add something that I *think* is functional that upsets the balance of the car. Too much downforce in the rear making the front light and understeering or too much downforce in the front and the tail coming around are things I'd rather let other people experiment with and I will emulate their results if they are good.

As far as weight on the nose is concerned. I've been playing with the idea of moving the battery to the rear, just haven't gotten around to it yet. Seems like a simple enough thing to do and I've read several threads on it. I think one of them was written by you? I can't imagine what else you can add to the front though other than front aero to balance out a big wing.

Originally Posted by j-rho

Changing rake doesn't really change static front:rear weight distribution. All you can do with corner weighting is get cross weights balanced.

Ah, I wasn't aware of that. I remember reading some other articles regarding corner balance and I recall it mentioning that if you raise ride height it would redistribute the weight. In hind sight it may have been describing cross weights only and not so much front to rear or side to side. I have no way to confirm this on my own, of course, so I hope others will chime in to either corroborate or refute. Thanks for your info!

[synolimit]

Last I weighed my car I split the wheel hubs in half and pulled onto the scale front then rear. I was 57/43. So clearly, gutting will increase the front unless you pull A/C, ABS etc. I've done all the aero now but of course $2000hr isn't in the budget although very close to me for a wind tunnel. I have no clue about moving weight around but in my head it seems like a double edge sword from the vid below. Rake my help me with aero but I'm so crazy on oversteer it'll probably only make it worse. So what's better? Aero with no front lift? Or make oversteer worse? Idk. Food for thought.

https://m.youtube.com/watch?sns=em&v=Pgpawejpi6o

[synolimit]

Originally Posted by dP3NGU1N

compared to the stock height with full fluids the car sits fairly even (27.87F / 27.99R).

Thanks for this. Looks like I'm 1.87" and 1.99" lower.

[Dwnshift]

Aero... Is a tricky subject as well. The OEM Nismo nose and Wing are very efficent if u track your car and are running DoT tires. (Hoosiers, Contis, etc)
Get the suspension right first.
Dont be tricked out by aero kits.... There are far more important things than big wings and fancy looking splitters.
Again... We run OEM nismo nose and rear wing.... And we seem to do okay





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[synolimit]

Originally Posted by Dwnshift

Aero... Is a tricky subject as well. The OEM Nismo nose and Wing are very efficent if u track your car and are running DoT tires. (Hoosiers, Contis, etc)
Get the suspension right first.
Dont be tricked out by aero kits.... There are far more important things than big wings and fancy looking splitters.
Again... We run OEM nismo nose and rear wing.... And we seem to do okay





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But you're forced to. I wouldn't be surprised at dropping a lot of time with better aero. Like that vid I posted, over 600lbs of down force is gonna do something and it's adjustable. Nismo can't do either.

[RN SHARK]

To help the front weight I pulled the windshield washer reservoir. Don't drive it daily, so not necessary.

[Dwnshift]

We just ran at Watkins glen... From turn 1 to bus stop... 3rd gear to 5th ... Braking at 400 marker... Flat 157 mph on DoT's...and factory Nismo body work.
Just sayin



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[dP3NGU1N]

Originally Posted by RN SHRRK

To help the front weight I pulled the windshield washer reservoir. Don't drive it daily, so not necessary.

How big is the windshield washer reservoir?

[patabq]

Leaving the rear higher shifts weight to the back. If you have oversteer, you want to stiffen the front sway/soften rear sway and/or lower the rear/raise the front.

The reservoir is large. We need a small one like with the AEM cold air system.

[GSS138]

Originally Posted by Dwnshift

So much depends on everything else. We would run the rear down further if we could but restricted per ride heights. 2.5" clearance on underside of car.
Dont put anymore weight on the nose than you need to.
But again.... Everything depends on everything else.


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Is that 2.5" between tire and wheel well/fender liner(whatever it is called)?

[Dwnshift]

No we have a clearance rule where IMSA slides a 3.5" (not 2.5" my bad) alum bar under the car... If it hits ANYTHING You are not legal.
This is why at the end of the race you will find mutiple cars driving offline to pick up as much junk on their tires as possible.



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