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Author Topic: Weights and Placement  (Read 5848 times)
ezoner
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« on: February 22, 2010, 04:54:28 PM »

Just curious what others are doing about adding weight.  My daughter will be running heavy class and I will need to add about 40-50 lbs of weight.  The rule states weight must be basically under the driver, or can be part of the floor.  But question is I dont want her setting on a mushroom of 50 lbs  -- how are people getting that much weight into the car and how are they placing it.

I did see a site where someone sold lead in 12" 12" sqaures, like an 1/8" or less thick.  Cant seem to find that site now.  But wondered what others did.
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ssssmoke
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« Reply #1 on: February 22, 2010, 06:08:27 PM »

put it under the drivers legs, right in front of where the crotch belt fastens.
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dmmc
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« Reply #2 on: February 22, 2010, 06:08:54 PM »

A thick steel belly pan (3/16") can be a quick way to add some weight without putting a pile under the seat.  It's as low as you can get it, plus a little sturdier if you're going to be bolting down more lead to it.  Directly in front of the seat, under their legs, seems like a good spot for my drivers.  I sometimes conterbore the boltholes in my lead blocks so the nut and bolt doesn't stick up out of it also.
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Swartz
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« Reply #3 on: February 22, 2010, 06:14:25 PM »

When we had to add that much weight, been a couple of lunches ago, I had steel plates cut that would fit between the frame rails and mounted them on 3/16 thick, 1 1/2 x 1 1/2 steel tabs welded to the chassis on 2 sides on all 4 corners. We used 3 different plate gauges so that later we could remove, or add, weight in 1.5, 2 and 5 lbs. increments. A stack making 40 lbs. was about 3/4 in. thick. That kept the weight low and in the center with a lot of quick adjustment as the driver and scales at some tracks, changed. MAKE SURE, lead or steel, THAT IT IS SECURE IN THE CAR. Getting hit by 40 lbs. flying round at 40 mph is not good for anyone. Yes, the welding messes up the powder coat. God, I hate powder coat.
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Swartz
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« Reply #4 on: February 22, 2010, 06:19:32 PM »

A thick steel belly pan (3/16") can be a quick way to add some weight without putting a pile under the seat.  It's as low as you can get it, plus a little sturdier if you're going to be bolting down more lead to it.  Directly in front of the seat, under their legs, seems like a good spot for my drivers.  I sometimes conterbore the boltholes in my lead blocks so the nut and bolt doesn't stick up out of it also.

Stretching the weight out over the length of the car will hurt performance. As close to center and low as possible is always best.
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sfreitas20
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« Reply #5 on: February 22, 2010, 06:27:21 PM »

It really depends on where you need the weight...with my little driver we needed front weight badly so I have a block on the belly pan in front of the axle.  The rest is pretty much under his seat. 

A nice seat like LaJoie makes will add about 12 - 16 pounds too and the best part of that weight is it is actually helping keep the kid safer instead of just sitting there doing nothing but being heavy. Smiley 

I have all my weights wrapped in bright orange duct tape and labeled with the weight (all are in about 5 or 10 pound blocks) and they all have the hole drilled in the same location so I can swap weight around all the time without re-drilling any holes.  Makes messing around with location and how much is where pretty easy.
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Scott Freitas
Patriot Motorsports Inc.
Kendall42
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« Reply #6 on: February 22, 2010, 10:44:56 PM »

Where are you located?  I have 3 of the heavy belly pans.  I used them in our cars.  But my son is heavy enough now he does not need them and my daughter quit racing.  They say it hurts performance, but I do not completely agree with that theory.  Yes, I understand chassis flex..I raced dirt late model for 15 years, you want to talk chassis flex!  But in these cars with the down bars and other triangulation, I do not think the affect is that big. The bigger affect on performance is the right springs and shocks, the flex is a crutch.  The bigger advantage is the weight is LOW! 

I do add weight to my son's cars still because he is about 10# light for the heavy classes still, so I just bolt a couple 5# chucks of lead to the belly pan.  I used to put 1/2 inch thick weights under his seat, but he is 5'10" tall now and I do not need him any higher in the car!  So I just put the weight in the RR corner of the belly pan and in front of the seat by the crotch strap mounting point. 

Adding 40-50# is a whole different story.  I would probably consider leaving your child in the lighter classes for a while longer.

Brad
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Swartz
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« Reply #7 on: February 23, 2010, 10:19:05 AM »

It really depends on where you need the weight...

There is no such thing. If you are adding weight it is to meet an arbitrary weight established by the rules. Closer to center and low as possible is always best. If you need to move weight forward, back, up down, to get weight transfer something is wrong.
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racemom2000
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« Reply #8 on: February 23, 2010, 12:19:30 PM »

Swartz, I think what Freitas was referring to was nose weight, which is an important variable whether you're running a short or long track. Our home track is long, where its best to use a different nose weight value.
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Katherine Weaver
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Swartz
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« Reply #9 on: February 23, 2010, 12:57:14 PM »

Weight is weight. If you need to put weight on the nose then the spring, and probably shock rates are wrong preventing weight transfer under load and making the car harder to turn.
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clouse55
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« Reply #10 on: February 23, 2010, 01:25:23 PM »

Why are you adding weight to the nose on longer tracks?
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Swartz
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« Reply #11 on: February 23, 2010, 01:29:01 PM »

I'm going to bet the front track is too wide and the panhard bar is too low. Probably the spring is too weak delaying the set point or maybe the shock is too stiff slowing the roll motion.
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Kendall42
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« Reply #12 on: February 23, 2010, 02:18:23 PM »

Swartz...I agree with you for the most part.  I would never add weight to the nose of a car.  On pavement weight low is always better.  On dirt, weight high is better...on our dirt LM's we have even mounted weight right below the rear decking or even sometimes on the rear downbars to induce chassis roll.  But on pavement, it should not be like that.  The weight closer to the center is always better for polar moment.  Added weight to make a car heavy enough should always be at polar center of the car if possible.  However, if you need left or rear weight to get your static percentages right for handling, then you have to move the weight around.  In the case of my son, because he is 5'10" and 140#, I have my weight more rear and right in his car...he has too much left side weight, but needs a bit more rear weight.  I have spent a lot of time moving weight around in big cars...we used to add 400+ pounds of lead to our LM and I would have some bolted to the very center polar post, some in front of the RR tire, some back next to the fuel cell, some over the LR shock, etc.  But never had any bolted further forward then the center of the car.  Of course in big cars, the motor is in the front, so rear weight has to be added.
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Swartz
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« Reply #13 on: February 23, 2010, 03:55:32 PM »

Yeah, been there but in that case you are trying to offset the boat anchor between the front wheels. Are you saying that you are adding weight on the qm above the minumum required combined weight to get the static percentages right?
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clouse55
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« Reply #14 on: February 23, 2010, 04:20:46 PM »

A few thoughts to ponder:

Weight transfers from left to right
Weight transfers from front to back
Weight does not transfer directly diagonal through chassis
Pulling tractors place weight in front of front axles
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