NHRA Technical Reminder: Battery Location

SSDiv6 · 05-09-2008, 11:27 AM

Quote:

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 · 05-09-2008, 12:38 PM

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.

charlie westcott · 05-09-2008, 12:46 PM

as far as I know I am the only SS car with this issue. It has been there since 03', now it is a problem. They sent letters to me and my dad saying we were found with a technical infraction at the sportsnats in belle rose, and were required to fix it before the next race. They seemed to get a little defensive when I asked who found the infraction, since nothing was said to me at the race, and the better part was that my dads batterys are already in the trunk! which proves that they were just trying to single me out. The other funny part was that I already moved mine to the trunk before the indy points meet to help combat these junky tracks we are required to race on. The issue is not the batterys, it is that they can rework the rule book in the middle of the season.

cw

http://hemimilitia.com/Index.html

Kenny Wigington · 05-09-2008, 04:58 PM

Last night after I read Travis' response to mine, I realized , that the way I wrote my first comment, was a little on the smartassed side. I didnt mean it as that. If anyone took it as that, thats my fault. I had the brain out of gear then, and had left the mouth, or this case the keyboard, in gear.

Kenny

.

seb · 05-09-2008, 07:49 PM

Well Charlie:

If you weren't so darn fast nobody would care,
I guess you'll just have to slow down a little and
people will quit picking on you.lol

S.E.

05-09-2008, 12:38 PM	#2
Bill Edgeworth Member Join Date: Oct 2006 Location: Tacoma, WA Posts: 258 Likes: 0 Liked 0 Times in 0 Posts	Re: NHRA Technical Reminder: Battery Location 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. __________________ Bill Edgeworth 6471 STK

05-09-2008, 12:46 PM	#3
charlie westcott Member Join Date: Dec 2001 Posts: 131 Likes: 0 Liked 216 Times in 7 Posts	Re: NHRA Technical Reminder: Battery Location as far as I know I am the only SS car with this issue. It has been there since 03', now it is a problem. They sent letters to me and my dad saying we were found with a technical infraction at the sportsnats in belle rose, and were required to fix it before the next race. They seemed to get a little defensive when I asked who found the infraction, since nothing was said to me at the race, and the better part was that my dads batterys are already in the trunk! which proves that they were just trying to single me out. The other funny part was that I already moved mine to the trunk before the indy points meet to help combat these junky tracks we are required to race on. The issue is not the batterys, it is that they can rework the rule book in the middle of the season. cw http://hemimilitia.com/Index.html

05-09-2008, 04:58 PM	#4
Kenny Wigington Senior Member Join Date: Sep 2004 Location: Cumming,Ga. USA Posts: 967 Likes: 36 Liked 60 Times in 12 Posts	Re: NHRA Technical Reminder: Battery Location Last night after I read Travis' response to mine, I realized , that the way I wrote my first comment, was a little on the smartassed side. I didnt mean it as that. If anyone took it as that, thats my fault. I had the brain out of gear then, and had left the mouth, or this case the keyboard, in gear. Kenny . __________________ 2894 STK

05-09-2008, 07:49 PM	#5
seb Junior Member Join Date: Sep 2004 Location: Arkadelphia,Ar Posts: 32 Likes: 0 Liked 0 Times in 0 Posts	Re: NHRA Technical Reminder: Battery Location Well Charlie: If you weren't so darn fast nobody would care, I guess you'll just have to slow down a little and people will quit picking on you.lol S.E.