Resolved Best battery location for handling (roadracing)

[TAMA_player]

My car will be prepared in two weeks with a rollcage and i was wondering for the best location for the battery (to fabricate a box or firewall at the same time).
Right now the batt is located in the rear corner opposed to driver.

Most of the time i feel the car have to much weight transfer in the rear. (entering the corner)
Considering that my car is a lill tail happy, what would be the best location for the batt?

This is the local track where i race sometimes. (we use the inner course, and 80% of the oval)

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Thanks in advance!
(please fell free to move this to newbie area if required )

 

[gofer]

The lower and more center you put the weight from the battery the better. In your case, I'd say to move it to the spare tire well. It would center between the rear tires and lower because you'd be dropping it in the well.

 

[TAMA_player]

Gofer. Im missing something? 1g dsm dont have a spare tire well. It have the oposite

The lower and more center you put the weight from the battery the better.

So it will be better to put the batt where the rear seats was?

 

[gofer]

You're right, I was thinking 2g for some reason. Sorry about that. Centered in the trunk but the lower the center of gravity the better...

 

[bjones18]

When is your car tail happy? Many drivers have no idea... and could not identify oversteer... even after they go off the road to the inside of the curve.

1. Steady-state oversteer: Driving a constant radius... constant speed... counter steer is required. (wet /and/or/ dry mu)
2. Transient oversteer: Many options here.
a. corner entry
b. corner exit
c. on brakes hard / corner
d. on throttle hard / corner
e. progressive with roll.
f. etc.

It is very important to single out what conditions are causing the oversteer.

With wet pavement (low traction)... means body-roll is low... your sta-bars are NOT wound up... very little wheel-travel (read this as very little-roll-steer F/R) hence... look at weight distribution... or F/R tire sizing/grip balance.

Corner entry oversteer... brakes on? (load transfer)... dry pavement - peak roll event - look at F/R stabar balance, shock-valving F/R, wheel-rates F/R, roll-steer F/R, and just about everything else.

Ferretting out the elements of oversteer can be challenging.

Believe it or not... the best way to see where your battery should be is to put your car on four scales (with driver mass in place). I would find it EXTREMELY hard to believe ANY DSM has a 50/50 weight distribution UNLESS they worked REALLY hard... or put a dead cow in the hatch. Why do I say this? The engine & transmission are ahead of the front wheels.

The fastest car through the corner will be the one which loads all four contact-patches evenly while maintaining speed... 50/50 and CG on the ground. Soooo.... battery low and placed to achieve closest to 50/50... THEN resolve steady-state & transient oversteer with your other tune-ables.

 

[TAMA_player]

Wow what a technical response! bjones18!!

The car have oversteer on corner entry, with or without brakes. In the low speed corners, that feels awesome. But is a little scary on the hi speed corner entry. (the third arrow from the chequered flag in the pic i posted).

I have two options for batt placement right now. And no way to get scales for the car sadly T_T.
1.

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Any input for a happy batt?

 

[RipperXX]

Wow what a technical response! bjones18!!

The car have oversteer on corner entry, with or without brakes. In the low speed corners, that feels awesome. But is a little scary on the hi speed corner entry. (the third arrow from the chequered flag in the pic i posted).

I have two options for batt placement right now. And no way to get scales for the car sadly T_T.
1.

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Any input for a happy batt?

Are you allowed to mount the battery outside of the cabin?

I ask because when I bought my 1g someone had installed a battery behinds the passenger side rear wheel up under the rear bumper cover/bumper. Seems this farthest point might offset the weight up front more. And possibly be lower At the same time.

 

[bjones18]

Bathroom scales... YOU NEED DATA:

http://grassrootsmotorsports.com/forum/grm/grassroots-4-corner-scales/26863/page1/

Sorry to be a dick here... but if your car scares you going into your most important corner... you need to fix it. If you choose to fix it by moving the battery forward... you might as well install a roof-rack with luggage.

Your battery is about the ONLY thing you can move to get closer to 50/50. I would stick it as far-rearward, and low as possible.

Driving a car by the "seat of your pants" is possible... adding sensitive palms/fingers on the wheel helps... a good VESTIBULAR gene-pool is also key.

NOW....setting up your car "by the seat of your pants" is futile, and a losing proposition. No excuses. Throwing a car together doesn't even win demolition derbies. There is SCIENCE behind a WIN... and un-answered questions surrounding defeat.

You need to collect data and read previous forums. Collecting corner weights and wheel rates by using scales & weight bags is step 1. Without this information... you have chosen a long and confusing path to success/failure. You might need to team up with someone local to set up your car. Choose your path... waiting to see where the path takes you.... takes you no-where in racing.

I have been on a "closed course" many times with many different cars.... One memorable AND fun car was a Ford Festiva. Why? it was predictable. Come into the corner hot... throw it to the side.... know where you're gonna be at the corner exit.

Ahhh....Soooo.... yung-glass-hoppa you need to be ONE with CAAH... or else CAAH will bite you... (Chinglish)

 

[gofer]

BJones is right, the only way of knowing exactly where you should put the battery is using scales and moving it around the cabin. Ideally, you'd set the suspension up to get a crossweight as close to 50/50 as possible with you (or your weight) in the driverseat. Then move the battery to a location in the car that improves that percentage, getting you closer to 50/50.

Moving the battery to the right side of the trunk will offset your weight when you're driving the car and also put more weight over the rear suspension, helping your 50/50 weight distribution. But, putting it in the back of the car and outside of the wheel base will make the car oversteer (tail happy) more than it already does which is something you're already complaining about.

Since you don't have corner scales I'd say (theoretically) the best place to mount the battery is on the passenger side of the vehicle (to offset your weight when you're in the car), inside the wheel base which will help transitional handling response, and as low as possible.

So, ideally, on the floor right behind the passenger seat.

 

[TAMA_player]

Thanks bjones18 and gofer for the input. You are right, trying to throw a car together by the "seat of your pants" method is stupid. I don't have a team behind me, so i read a lot and ask every time i can.
I will get 4 wallmart scales and make that home made "device" . It will be useful for many things. Here im just the "Guy with an eclipse". Racing with the stock V8's. The last time i went to the track i was able to grab a 4th place. I want to say so many things about that but my english is not good at all. The car is good just scare me, maybe because im not the right driver for her. And thanks for that 4th place im not allowed to race again without a full cage. And i was trying to improve the car at the same time.

bjones18 i tried every translator i can to translate your last sentence , seems is something funny but i cant get a translation for that

I will close this until i can get a way to take data
Thanks everyone for the input!