Mounting ballast

[TXBDan]

I need to add at least 60lbs to my E36 and as much as 140lbs if i want to run even stickier tires. This is on top of a full gas tank and a 40lb spare tire. My front/rear weight distro is pretty damn close to 50/50 as it is. I do have a passenger seat installed.

A) Where would you add ballast?

B) How would you mount the ballast?

C) Where would you get the ballast?

The car would be run with COMSCC and NASA and neither seem very particular about location, mounting, etc, but i want to do what's best/safest. I think i'd like to split it up between the passenger seat area and the spare tire well. One problem with the spare tire well though is that i have a stupid charcoal canister thing there so i can just put a brake rotor or weight plate under the spare.

Should i bolt a 40lb lead brick behind the passenger seat? Bolt a weight lifting plate in front of the passenger seat? The floor under the passenger seat is too lumpy if i remember correctly.

I see raw lead scuba weights near me on craigslist, but i can't imagine melting lead is a very safe/smart thing to do.

Thanks!

[Zxc4]

I use a plate above the weights and under the car and three large diameter grade 5 bolts (nasa requires grade 5) to hold normal weight lifting weights. I mount the weights behind the passenger seat, but other strategies I use to dial in (depending on where I need weight/how much weight needed/what tires I am running) are moving my battery from the trunk to behind the drives seat, using a wheel and tire, or just a tire in the trunk (secured), using cool suit cooler in trunk (secured), etc. I typically run full on fuel every session because I like where that weight is.

You can melt lead in old V8 valve covers, etc, but it's another pain and easier just to buy weights if you have the room to bolt them down.

I think this is the only old pic I got, this was just test fitting it, I went back and smoothed all corners.

EyhABnF.jpg

[CoMZ302]

I added 45lbs under my (non stock) passenger seat, as far rearward as I could. It's all 10- and 5-lb barbell weights. To secure it, I used one 5/16 fine thread grade 8 bolt and appropriate nylock on the top side- I used a 2" by 6" by 1/4" plate under the car and ran the Grade 8 bolt through that plate and then of course through a hole in the floor.

If you need weight in a smaller space than the barbells will fit: Get some square steel tubing to fit your space. Buy (lead) buckshot from Cabela's (et al) - just fill the tubing with shot and weld a plate on the end. Be sure you drill the holes and run the bolts before you pour in the shot.

Or if you have megabucks buy Tungsten blocks - same mounting procedure.

Be aware that some organizations (SCCA) require that the weights be "within the bodywork" which means you can't hang it from beneath the car.

Finally, from a physics standpoint, try to add the weight between the front and rear axles, instead of the tire well. Google "moment of inertia" for a good explanation.

HTH

[TXBDan]

Cool, thanks. Last night i ordered two 26lb lead bricks off ebay. The seller agreed to drill holes in them for mounting bolts as well which is sweet. I'll secure each with two 1/2" Grade 5 bolts. I was thinking of using 2" OD x 1/8th washers under each bolt head and nut. That outta to be secure enough for 26lbs i would think?

I need to actually find/buy some 45lb plates to see what they look like and how i will mount them. But I'll probably use 4 1/2" bolts for the stack of plates and a hefty backing plate under the sheet metal.


Depending on what tires i run i'll either need to run one brick behind the passenger seat plus one 45lb weightlifting plate in the spare tire well (bolted down) or two bricks behind the passenger seat and two 45lb plates in the spare well. Either config puts me at about 49/51% front/rear weight distribution which is about right i think with good crossweights and L/R balance.

[19Spec3]

As always, step 1 is the rulebook:

NASA CCR:
15.20 BallastAll ballast shall be solid metal such as steel, lead, or depleted uranium, and consist of a minimum of five (5)pounds per piece. Each piece shall be bolted in place with through-bolts, fender washers, and a locking-nut /system (e.g. jam-nuts, Nylock, etc.). All ballast shall be secured sufficiently and all bolts shall be of Grade five(5). Nylock nuts or metal crimping lock nuts should not be reused.

If you're willing to remove the passenger seat, I have seen folks mount steel plates to the stock passenger seat mounting points.

[TXBDan]

I did check the rulebook(s). BMWCCA is actually the most rigid and is where i got the two 1/2" Grade 5 bolt requirement from.

BALLAST – Any ballast to meet weight must be placed entirely in thefront and/or rear passenger side floor area and/or the spare tire wellin the trunk, and must be securely bolted to the chassis. Eachsegment of ballast must weigh not more than 50 pounds, and must befastened with a minimum of two 12 mm bolts and positive lock nuts ofmetric grade 8.8 or better, and must utilize large diameter, load distributingwashers. Ballast may not be added or removed during anyofficially timed session.

I run with COMSCC, not NASA or BMWCCA, but i figured i'd do something that is sensible for them as well.

I gotta keep the passenger seat for my class, but that would be a great spot. I thought about trying to mount the weight under my floor/side mount adapter plates somehow or directly to the adapter plates, but i'm not sure its worth the effort.

[emoore924]

Keep in mind, it isn't the 26lb static weight that you need to secure the ballast for, its the 30G impact you have with the wall that turns the 26lbs into 780lbs that wants to kill you.

[Fair]

Ballast Weight Box

We have come up with an easy way to add ballast of varying amounts very quickly. Once you build the structure you can change the weights in "ones of minutes", without having to unbolt 25 nuts and bolts.



We have run this TTD classed BMW E46 330 at 2 different declared weights in the same weekend, and we can swap in 160 pounds of ballast or remove it all, plate by plate.



We built a ballast bracket for use with round plate gym weights earlier this year for this ST3 classed Mustang; he has to add ballast to stay within that class' power-to-weight limit. On that car we added two "stacks" of weights with the ability to fit 250 pounds of ballast in the back quickly. The spare tire well places the weights very low in the car and at the rear.



Like the race prepped Mustang, our TTD prepped E46 is getting lighter in the rear faster than the front as weight is reduced. So when we add 80 pounds of ballast with a points change this season we built a similar rear trunk mounted ballast rack - bolted inside the spare tire well. This structure was fabricated using thick walled 1"x2" rectangular tubing, generous mounting flanges, and large bolts to the chassis with reinforced heads on the back side.



On the BMW bracket we used only a single square threaded bench press bar post (passing thru and welded to the tubing on both sides) and a single stack of weights, but on the Mustang we used two posts. Purchased a "Beginners" weight lift bar & weight set at Academy Sports - one stop shopping! More plates can be purchased and added to reach the final race weight and then removed for test days and HPDE events, to reduce consumable wear. With square thread shafts and two locking collars on each (secured to each other), the weights stay tight all weekend. This system passed NASA tech on two cars on multiple occasions, so we're going to keep using it.



Once we had the weight bracket built, the weights added to hit our 3205 goal (3220 with a 15 pound buffer) we got the car to a 52.4% front weight bias (see above), which was an improvement of 2 points from before (before ballast). Adding the weight at the rear is usually the best place to put it, as long as you can keep the weight LOW (for CG height). Cars tend to get lighter at the back when stuff is pulled out, so rear mounted ballast can correct for that somewhat.

Just my two cents.

[TXBDan]

That's pretty slick, but an awful lot of potential weight out far in the back end. Have you tested with weight in the passenger seat area? I'm curious about the trade between a lower moment of inertia and even f/r weight distribution.

I'm currently planning on 75lbs behind the passenger seat and 75lbs as far forward as possible in the spare tire well. Each set having two 1/2" Grade 8 bolts and 3" OD washers. I might use a 2" steel flatstock strap across the two bolts on the backside as i'm growing suspicious that the 3" OD washers are too small.

[Fair]

That's pretty slick, but an awful lot of potential weight out far in the back end. Have you tested with weight in the passenger seat area?

Well on my other race car we built a weight box it in the passenger seat area.



We ran this 1992 Corvette in TTC in the 2015-16 seasons like this.

I'm curious about the trade between a lower moment of inertia and even f/r weight distribution.

Yep, we did it because it should have less of a polar moment as the weight is right in the middle of the car.

I'm curious about the trade between a lower moment of inertia and even f/r weight distribution.

Its VERY hard to quantify this... but we did run two back-to-back events at the same track in the TTD BMW above with and without the ballast installed. For HPDE events I take all of the ballast out, to conserve tires/pads/etc. And you know what?



With and without ballast (waaaay back in the trunk) it handles EXACTLY THE SAME. Granted it was only an 80 pound difference, and with 160 pounds of ballast we might feel a change in turn-in or mid-corner handling. But I doubt it.



Running the ballast in the trunk allows you to run a passenger seat. After a year of racing the Corvette without one, it became a real hindrance - there's always a student, customer, or friend that wants some right seat time.

[TXBDan]

Interesting, thanks for the info. Right now my plan is 75lb in the spare tire well and 75lb behind the passenger seat. I found that if i use 25lb plates, i can stack three and they'll fit behind the seat ok. So it seems at least, I don't have it mounted yet. I do have the spare tire weight installed using two 1/2" Grade 8 bolts. I have doubled up 3" OD washers on the back side.

ballast1.jpg