Battery in Nose Box

[Rick Iverson]

Gents;

My midyear VD has accommodations for the battery in the crush structure. As a matter of fact, the battery was in the box when I bought the car, but I elected to move it under my legs in the cockpit, closer to the CG.

Then I thought about it for a while, and considered maybe it was meant to be there for a reason as a factory design: car balance, CG shift, planting the front tires as a function on added weight........

Thoughts?

V/r

Iverson

[Lotus7]

Very simple math to work out the new F/R static weight split and new polar-moment of inertia....

trick is knowing which is better under which circumstances :-)

(and no, I'm not sure I know either)

[Dave Harmison]

I need the nose weight in my car. I hate the fact that the battery is put in harms way and that acid can be spilled. It also doesn’t crush worth a damn.

[BorkRacing]

If I recall when putting my car together we tested positions of a 12lb battery.
Under leg vs on the nose only added 2-3 pounds to the front wheels.

FWIW Robby

[S Lathrop]

I had the battery in the nose box of a few of my cars. But I do not place it there now.

I see the nose box as a major safety structure and I have spend decades reworking the designs to get he box to perform that function well. I have kept many of the nose boxes that came off my cars after crashes. My goal has been to have the nose box fail progressively from the front to the mounting point on the front bulkhead.

Having an opening in the top of the nose box for the battery or for the master cylinders assures that the box will fail at those points and not provide the protection to the frame that is possible and more importantly, not absorb as much energy as possible from an impact during a crash.

The nose box should be a safety structure and nothing should compromise that function.

[t walgamuth]

If you switch to lithium the weight is so insignificant it won't matter where you put it.

my new to me VD has it under my knees but it is hard to reach and I am considering moving it elsewhere.

[MotorCade]

My 94VD had it located in the nose crush structure when I purchased it. I'm assuming this was an attempt to get weight on the nose, as the car has a serious understeer problem. I relocated it back under my legs because I also feel that the crush structure is there to protect my legs, and I like my legs... they're hairy, but they work reasonably well to get me from place to place.

Be safe...

[DaveW]

My 94VD had it located in the nose crush structure when I purchased it. I'm assuming this was an attempt to get weight on the nose, as the car has a serious understeer problem. I relocated it back under my legs because I also feel that the crush structure is there to protect my legs, and I like my legs... they're hairy, but they work reasonably well to get me from place to place.

Be safe...

Usually, more weight in the nose will worsen understeer, not reduce it...

Did you find that U-S worsened when you relocated it? I would think there should have been a slight reduction in U-S.

[alangbaker]

My 94VD had it located in the nose crush structure when I purchased it. I'm assuming this was an attempt to get weight on the nose, as the car has a serious understeer problem. I relocated it back under my legs because I also feel that the crush structure is there to protect my legs, and I like my legs... they're hairy, but they work reasonably well to get me from place to place.

Be safe...

Usually, more weight in the nose will worsen understeer, not reduce it...

Did you find that U-S worsened when you relocated it? I would think there should have been a slight reduction in U-S.

I'm with Dave on this...

I realize it's wandering from the topic, but more weight on the nose would only reduce understeer if there were a way to get it there WITHOUT having to also put more MASS in the nose.

[MotorCade]

Relocating the battery had no noticeable difference in handling that I could ascertain. I just couldn't think of why they would put it up there except to try to get weight on the nose.

[Speed Sport Engineering]

Usually, more weight in the nose will worsen understeer, not reduce it...

Did you find that U-S worsened when you relocated it? I would think there should have been a slight reduction in U-S.

Dave,

Can you expand on why you believe this to be to true?

Thanks,

Michael

[DaveW]

Dave,

Can you expand on why you believe this to be to true?

Thanks,

Michael

Here's a link to my handling presentation on ApexSpeed: https://www.apexspeed.com/forums/att...3&d=1539115694

The page on tire and rubber properties is the key. As you add load, the coefficient of friction in rubber goes down, and so as you add mass at one end of the car, the ratio of available cornering load to mass/weight decreases, lowering the possible lateral G's at that end.

If that doesn't explain it fully, PM me and we can discuss it further.

[DaveW]

I'm with Dave on this...

I realize it's wandering from the topic, but more weight on the nose would only reduce understeer if there were a way to get it there WITHOUT having to also put more MASS in the nose.

That's why aero downforce increases grip. It adds load w/o increasing mass.

[Speed Sport Engineering]

Here's a link to my handling presentation on ApexSpeed: https://www.apexspeed.com/forums/att...3&d=1539115694

The page on tire and rubber properties is the key. As you add load, the coefficient of friction in rubber goes down, and so as you add mass at one end of the car, the ratio of available cornering load to mass/weight decreases, lowering the possible lateral G's at that end.

If that doesn't explain it fully, PM me and we can discuss it further.

Got it - thank you. I was missing the decrease in the coefficient of friction of the tire with load in my thoughts.

[problemchild]

I won't argue any theory, but in moving batteries from the nosebox to under the driver's legs (for obvious reasons), I have absolutely found a loss of front grip. Now using lithium batteries, it becomes less relevant, but I have no doubt as to my conclusion.

[MotorCade]

That's why aero downforce increases grip. It adds load w/o increasing mass.

This depends heavily on where on the curve you are when you add the mass. The capability increases at a rate of decreasing return. There's also the part where you're not increasing mass across the entire vehicle, you're shifting load from one end to the other. That affects your static weight distribution and therefore will affect your initial turn-in more than your steady state, though it will also change the amount of weight you're able to shift rearward. Still, we're only talking about 10lbs total, and it's too small to feel with butt-dyno.

[DaveW]

I won't argue any theory, but in moving batteries from the nosebox to under the driver's legs (for obvious reasons), I have absolutely found a loss of front grip. Now using lithium batteries, it becomes less relevant, but I have no doubt as to my conclusion.

IMO, if that is the case, it is likely that the tires are either too stiff, compound too hard, too big, too highly inflated for the load or a combination of those. Usually what it means is that the tire is too lightly loaded to get the compound to a good operating temperature or get enough footprint area. Also, too much suspension friction can cause skating and loss of grip, especially under lighter loads. In those cases, what you say can occur.

[problemchild]

IMO, if that is the case, it is likely that the tires are either too stiff, compound too hard, too big, too highly inflated for the load or a combination of those. Usually what it means is that the tire is too lightly loaded to get the compound to a good operating temperature or get enough footprint area. Also, too much suspension friction can cause skating and loss of grip, especially under lighter loads. In those cases, what you say can occur.

That describes half the race cars that I have ever worked on (lots of FVs), and a majority of the cars in club racing.

[DaveW]

That describes half the race cars that I have ever worked on (lots of FVs), and a majority of the cars in club racing.

Obviously you've made them work in spite of those issues!

[BeerBudgetRacing]

The nose box should be a safety structure and nothing should compromise that function.

So, like many my 94 VD has 3 sections in the crush box. Front has the wing pole. Middle is empty (where the battery was) and the rear section is open to the back and is access to the masters.

What is the simplest, first step improvement for safety?
Fill the middle section with foam?

[DaveW]

As Steve has said, the most important things are (1) to make sure the box won't tear off at its roots if loaded sideways, and (2) it crushes progressively from the front. So a bit of analysis and/or intelligent inspection is in order.

[Lyngengr]

I won't argue any theory, but in moving batteries from the nosebox to under the driver's legs (for obvious reasons), I have absolutely found a loss of front grip. Now using lithium batteries, it becomes less relevant, but I have no doubt as to my conclusion.

I switched from an AGM battery that weighed 21 lbs to a Li-Ion battery that weighs 4 lbs this year. Had to fabricate a new bracket because the Li-Ion battery is physically smaller. Didn't notice any change in front grip. I did make some changes to my driving, using more trail braking in low speed corners, and that substantially reduced exit push.

[jrh3]

I had the battery in the nose box of a few of my cars. But I do not place it there now.

I see the nose box as a major safety structure and I have spend decades reworking the designs to get he box to perform that function well. I have kept many of the nose boxes that came off my cars after crashes. My goal has been to have the nose box fail progressively from the front to the mounting point on the front bulkhead.

Having an opening in the top of the nose box for the battery or for the master cylinders assures that the box will fail at those points and not provide the protection to the frame that is possible and more importantly, not absorb as much energy as possible from an impact during a crash.

The nose box should be a safety structure and nothing should compromise that function.

it would be very educational to see pictures of the used boxes.

[t walgamuth]

I am thinking I will move my lithium battery to the nose so I can see the connections when I want to. Also less likely to kick a connection loose. With the lightness of the lithium I don't expect it to affect handling.