NHRA Technical Reminder: Battery Location

[SSDiv6]

In today's NHRA website:

http://www.nhra.com/content/news/28815.htm

NHRA Technical Reminder: Battery Location
5/8/2008
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Technical reminder to all Stock and Super Stock classes: All batteries must be in their original location or may be relocated to the trunk per NHRA Rulebook:

NHRA Rulebook pg. 88 Section 4 - General Regulations; Electrical/Control: 8:1 Batteries “Batteries may not be relocated into the driver or passenger compartments.”

NHRA Rulebook pg. 144 Section 9A – Stock Cars; Electrical: 8 Batteries “Must remain in the stock location and be of sufficient capacity to start car at anytime. Second battery permitted if securely mounted in trunk.”

NHRA Rulebook pg. 154 Section 10A – Super Stock; Electrical: 8 Batteries “Trunk installation permitted; two batteries permitted.”

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National Hot Rod Association
http://www.nhra.com/

[Kenny Wigington]

I take it, they are looking at batteries for the next few races ?

[Travis Miller]

Originally Posted by Kenny Wigington

I take it, they are looking at batteries for the next few races ?

A S/S car was found with the batteries mounted in the wheel tubs ahead of the rear tires...NASCAR style. That modification was ruled to be out of compliance with the rulebook.


Travis

(Disclaimer: Opinions expressed by me on this forum are exactly that, my opinions.)

[Kenny Wigington]

Ahead of the tires? Good reason to look then.

[SSDiv6]

Originally Posted by Travis Miller

A S/S car was found with the batteries mounted in the wheel tubs ahead of the rear tires...NASCAR style. That modification was ruled to be out of compliance with the rulebook.


Travis

(Disclaimer: Opinions expressed by me on this forum are exactly that, my opinions.)

Not only NASCAR...that is an ideal place to put ballast in many cars.

[Travis Miller]

Originally Posted by SSDiv6

Not only NASCAR...that is an ideal place to put ballast in many cars.

Although it has been a while since I read his suspension book, as best I remember Dave Morgan wrote that an ideal place to put ballast was from the centerline of the rear axle to just ahead of it. The heavier the car is at that point, the harder it will plant the tires when the rear suspension tries to spread on a launch. If the car goes into a wheelstand the weight is still right where it is needed. His theory is putting ballast closer to the rear bumper on a car with a long overhang is a waste and causes the car to pivot on the rear tires.

Travis

(Disclaimer: Opinions expressed by me on this forum are exactly that, my opinions.)

[Daran Summerton]

Does this mean you have to have plates and acid in the front battery???? See, this rule book is so vague...

[Michael Beard]

Originally Posted by Daran Summerton

Does this mean you have to have plates and acid in the front battery???? See, this rule book is so vague...

If there are no plates and acid, then it's not a battery, is it? (unless it's an Optima-type deal)

[SSDiv6]

Originally Posted by Travis Miller

Although it has been a while since I read his suspension book, as best I remember Dave Morgan wrote that an ideal place to put ballast was from the centerline of the rear axle to just ahead of it. The heavier the car is at that point, the harder it will plant the tires when the rear suspension tries to spread on a launch. If the car goes into a wheelstand the weight is still right where it is needed. His theory is putting ballast closer to the rear bumper on a car with a long overhang is a waste and causes the car to pivot on the rear tires.

Travis

(Disclaimer: Opinions expressed by me on this forum are exactly that, my opinions.)

You are correct...that is the reason why many cars do a porpoise movement while going down the track: they have put ballast close or behind the rear bumper.

[Bill Edgeworth]

It’s a very common mistake that many people only look at ballast and weight distribution based upon static conditions. You really need to look at what happens during the dynamic state of the car (acceleration) takes a little bit of math but if you do a few vector calculations you will find that weight added behind the rear axle, depending on position in relation to horizontal and vertical centerline of the axle can actually take weight off the rear tires during launch!
The simple analogy is to take a look at all the ballast behind your axle centerline during launch and realize the fact that the rear tires are pulling it along not pushing it. Then ask yourself if the ballast is helping pull the tires down or up. There is a book called “Door Slammers” written by Dave Morgan who Travis mentioned which goes into some fairly good detail on the subject.