Gym weights - ballast

[Pranav]

Anyone know where I can find this stuff? Borrowing some from Mike for now, need to return to him at the end of NOLA, and I'll need more when I take my passenger seat back out...

[BryanL]

Academy-generally any sporting goods store. Maybe a second hand sports store has some as well.

[Dulaney]

Yep, got mine at Academy, a little less than a buck per pound. I bought the smooth ones, and found they're nearly impossible to drill through, so I used a large bolt through the center hole (had planned on 4 smaller bolts).

Lowes carries grade 8, 3/4" diameter bolts. Highly recommended, along with giant fender washers. I later mail-ordered a nylock nut for them, but can't seem to find where I put them, so I'm using lockwashers and loc-tite.

[Suck fumes]

Lead bricks are easier to work with. You'll spend a couple hrs and break several drill bits in a drill press trying to go through dumb bell weights. Don't ask me how I know haha.

[kbrewmr2]

Go secondhand on these - should be on the order of $0.50 to $0.60 per pound. No need for new, costs twice as much and it's not like they can wear out or anything. Drilling wasn't bad on the ones I picked up.... Play It Again Sports iirc.

If you make lead bricks be careful and stay away from the fumes - bad juju

[AllZWay]

Probably not healthy......but we made our own from lead weights from a tire store melted down into a valve cover.

[Suck fumes]

Clever!

[Pranav]

Good idea James, I by chance happen to have a spare valve cover sitting around. I'm gonna stick with gym weights for now as one 50lb stack with a 3/4" bolt thru the middle should accomplish what I need. Four coats of plasti dip, the fire system, and the coolsuit box along with other stuff I need to finish throwing on the car (wipers, defoggers, oil cooler, etc) should take care of the rest, hopefully by Hallett...

[HoustonNW]

Here is what the CCR says about ballast:

Unless superseded by class rules, all ballast shall be solid metal such as steel, lead, or uranium, and consist of
a minimum of five (5) pounds per piece. Each piece should be bolted in place with through-bolts, fender
washers, and a locking-nut / system (e.g. jam-nuts, Nylock, etc.). All bolts should be grade five (5). There
should be at least one 3/8” diameter, or larger bolt for every ten (10) pounds of weight (e.g. 20 pound block
uses two bolts). Nylock nuts or metal crimping lock nuts should not be reused.

I'm not sure if one 3/4" bolt equals five 3/8" bolts. Just an FYI in case they are strict for your annual.

[kbrewmr2]

Do the CMC rules address ballast? If not, then yeah you're stuck with the CCRs super strict waayyy over the top rule. Break out your drill bits!

[cobra132]

It would be easier to weld mounting tabs on the weight. FMR

[Suck fumes]

You better take the extra time to drill holes in the weight otherwise if you hit something hard enough the weight will become a flying saucer and someone or something is getting hurt.

[GlennCMC70]

Here is what the CCR says about ballast:

Unless superseded by class rules, all ballast shall be solid metal such as steel, lead, or uranium, and consist of
a minimum of five (5) pounds per piece. Each piece should be bolted in place with through-bolts, fender
washers, and a locking-nut / system (e.g. jam-nuts, Nylock, etc.). All bolts should be grade five (5). There
should be at least one 3/8” diameter, or larger bolt for every ten (10) pounds of weight (e.g. 20 pound block
uses two bolts). Nylock nuts or metal crimping lock nuts should not be reused.

I'm not sure if one 3/4" bolt equals five 3/8" bolts. Just an FYI in case they are strict for your annual.

Marshall Mosty addressed this issue w/ NASA HQ #2 in charge. This rule will not be enforced as written. 1 3/4" bolt will be OK. I have never seen a failure given for ballast mounting.
The CCR really needs to be corrected.

[marshall_mosty]

Here was what I proposed to NASA. I have a copy in my logbook...



From: marshall mosty [mailto:marshallmosty@hotmail.com]
Sent: Wednesday, December 29, 2010 6:01 AM
To: jerry@drivenasa.com; jlindsey@drivenasa.com
Subject: CCR Rule (15.20) Ballast

Jerry, John,
I'm not sure who to address this to and wanted an official ruling. The CCR's are kinda fuzzy, since they are written around 3/8" bolts for 20lb plates...

If I'm going to mount 135# of ballast (rectangular plates), how many fastener's do I need to run and what size? I'm going to be drilling them and want to make sure they are properly secured. I'm thinking two grade 8, 1/2" dia bolts.

Here are my nerdy engineering thoughts:

A 1/2" grade eight coarse thread bolt has a tensile breaking strength of 21,300 lbs. According to the Maximum Distortion Energy Theorem, to convert to shear breaking strength, multiply by .577 This gives 12,290 lbs per bolt, or 24,580 lbs total bolt strength if two are used.

A conservative approximation for a "worst case" crash with a concrete barrior at 150mph would be approx 80g (3 ft compression impact in 135 milliseconds from 150mph to zero, assuming linear deceleration), so the 135 lb plate stack will weigh 10,800 lbs during the impact.

Therefore, if I run the two bolts as mentioned above, I will have a factor of safety of approx 2.27.

Should be plenty, right? The AI series rules say, "...securely fastened and approved by NASA tech and safety officials..."

Last year I was able to use 2 7/16" dia bolts for two 45lb plates (90lbs total)... but need to stack all three together for my current mounting setup...

I will be finalizing my ballast setup this coming weekend and would like to be able to not have any issues at the first event.

-Marshall Mosty
AI #67
NASA TX


and then Jerry K's response:


From: jerry@drivenasa.com
To: marshallmosty@hotmail.com; jlindsey@drivenasa.com
Subject: RE: CCR Rule (15.20) Ballast
Date: Wed, 29 Dec 2010 12:05:46 -0800

Marshall,

Your thinking is sound and the setup you are asking for is acceptable.
Please print this email, in case a local inspector needs to see it.

Jerry Kunzman
Executive Director

[Fbody383]

Marshall, well done.

So the bolts won't break/shear but will the floor pan?. I know Glenn is cautious about ballast to the floor, but the cages are attached there, with support in multiple dimensions and rockers/plinths etc.

What are you using to spread load across the floor plan at the ballast location?

Glenn/Al - can a CMC car add a reinforcement between the OEM seat rails for the purpose of mounting ballast?

[marshall_mosty]

I have a 2" steel strap (1/8" thick) between the two mounting bolts which also extends several inches on either side to spread the load. There is a subframe connector between my ballast and the tranny tunnel. The geometry change of the floor at the tranny tunnel in conjunction with the subframe connectors (welded thru the floor on my car) make that area stiff as hell.

Regarding caution, you can't think of ballast in the same way that you would consider a bolt-in rollcage unsafe. On a rollcage, the small pad is being hammered thru the floor in a roll over accident (very dangerous), but in a forward impact, the bolts will be in shear and will try to "peel" the floorpan like a tin can. Unless you already have cracks in the floor pan or other holes nearby to serve as a point of crack propagation, I'd say the weight we use is pretty safe. The backing plate under the car is the key to being able to transmit the load in an accident.

[Fbody383]

Regarding caution, you can't think of ballast in the same way that you would consider a bolt-in rollcage unsafe. On a rollcage, the small pad is being hammered thru the floor in a roll over accident (very dangerous), but in a forward impact, the bolts will be in shear and will try to "peel" the floorpan like a tin can. I tend to agree, just looking for "reasonable;" I don't want ballast bouncing around loose either.

[Pranav]

FYI, I never was able to pin down any good used sources, but Walmart had what I needed (1" hole dumbbells) at about $0.75/lb. Academy was right about there in price too.

[kbrewmr2]

garage sales and any of the second hand sporting goods places like Play it Again Sports could help you?

[Pranav]

Meh, didnt have much time to bother trying...