USAC Racing Forum

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.

put it under the drivers legs, right in front of where the crotch belt fastens.

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.

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.

Stretching the weight out over the length of the car will hurt performance. As close to center and low as possible is always best.

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. :) 

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.

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

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.

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.

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.

Why are you adding weight to the nose on longer tracks?

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.

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.

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?

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

That's true only if you are travling in a straight line. And on a tractor trying to overcome the torque trying to lift the front. Give the driver a steering wheel and put some banking in front of him and all hell breaks loose. In a left turn on about every track the weight transfers from left rear to right front and then loads the right rear. I say take away the steering wheel.

Weight does transfer to corners but not directly from LF to RR or LR to RF. Your right, in a turn weight transfers to the RF first (LF to RF transfer), but not from the LR, thats done with cross or dynamic cross, then loads the RR (front to rear transfer), 2 seperate actions. If there was braking before the corner you would have transfer from rear to front first. Ya, I know, took me awhile to think differently.

Pulling tractor example was just a funny, but actually all realitive.       

Well crap. Now you want to give them brakes. Be easier to stick with the tractor.

New Q as it relates to wieght........we just started running light WF and some of the guys are adding wieght above the minimun buy as much as 30#'s. What is your opinion on running over wieght or should you be able to get the grip with out the extra wieght.

Lighter is faster but it don't matter if it won't turn or stay on the ground. Do what ya gotta.

Should you periodically check spring force/rates to make sure they have not changed over time?   I have never had to in the past, but driver is just now getting competitive so things that I never messed with before, I now have to be concerned with.

While the spring "rate" will not change the installed height will due to repeated compression cycles. If you are checking the ride heights and adjusting when needed there will be no problem.

Swartz...NO! LOL  I would never purposely add more weight than is needed.  Certainly not anymore above the required weight if I can help it.  In my son's Hvy Hnda and Hvy 160 we normally cross the scales between 326 and 328.  I keep it tight!  we will have a problem in the Sr Animal this year because with NO weight in the car he will be about 318-320.  Nothing I can do about it.  Wanted him to run Hvy WF, but he said he would rather run the Animal class.  Just wish we had a Hvy Animal class as well! 

Always...if at all possible, stay as close as you can to legal weight.  Pick up a 10# chunk of lead and spin around with it a few times...it will tire you out!  I once won a 50 lap dirt race and went right to the scales after the race.  The tech guy looked puzzled so I asked what was wrong.  He said I made weight by 1 (ONE!) pound!  I always cut it close, but this race had a few more cautions then normal and I was really close!  But still got the trophy!  LOL 

I always ran our cars 3 to 5 lbs heavy. Not taking any chances. One of the funniest things I ever saw was the hissy fit Blomquist threw at Eldora when he scaled, if I remember right, 3 lbs light.

That is why Bloomer alway runs his car through any muck he can find around the track before he goes to the scales!  I remember that night at Eldora.

Yeah, back in the day you could pick up 20 lbs running up over the cushion or driving through a puddle along the infield wall. Now dirt tracks are run in like soft asphalt.

LOL  YOu have not been to Oakshade Raceway have you?  They have a GREAT track and it is a blast to race on!  But if you run down near the infield you can still typically find some mud to pick up.  Just gets dry slick in the racing groove.