Weights... where to put them?

[Bal r 14]

I have some cars (anglewinder and sidewinders) that due to chassis design, make it incredibly difficult to add lead weight. It seems the only place I can add weight is the motor pod. But, I don't think that works very well. So, time to quiz the experts. I run silicone tires on a 60' MDF track. Track and current nemesis car (MRslotcar Porsche GT) images are shown. I have tried adding weight everywhere possible with no improvement in traction. A comparable NSR car, or inline Slot.it car, has no problems.

[ALS]

Brand of tires does madder

[Bal r 14]

Quick Slicks, firm compound. I have tried Xtra firm, but that didn't seem to make a difference.

[Pappy]

On a sidewinder I like to fill the small areas in the motor pod with about a 1 /16" thick lead weight. That's the only weight I use and they seem to handle the best that way.

[Kevan]

The pod is one of the best places to add ballast, don't forget whatever you add to it will impart onto the fixing positions of the chassis.

[War Eagle River]

Try this.
1. Triangle of .016 sheet lead in front of pod to see how it reacts.
2. OR Fill entire pod in front of motor with .016, see how that does.
Add small rectangular piece under rear axle.
2 very small pieces of tungsten putty pressed in behind the guide.

Of course this all personal preference, and driving style, track, etc. Too many variables.

Pic for reference.

[Kevan]

Bear in mind if you put ballast behind the rear axle you're reducing front end downforce.

[War Eagle River]

With QS, a small amount weight under the rear axle does a lot for hooking up the ass end. Doesn't take a lot. In my experience anyways on a lot of different model cars.

[Bal r 14]

I know it's a bad idea to put weight behind the rear axle. I was just curious to see if it had any affect, good or bad. It didn't seem to matter. As you can see, by the blue putty residue, I have tried weights all over the place.

[HO RacePro]

The weight distribution is more important than how you arrange the weights. From what I have heard the favored weight distribution seems to be 40/60 -- 40% on the front wheels, 60% on the rear.

It is relatively easy to measure the weight distribution. A small electronic scale is all you need. Weigh the whole car, then weigh again with just the rear wheels on the scale. Divide the rear-wheel weight by the weight of the whole car, multiply by 100, and that gives you the rear weight percentage. The remainder is the front weight percentage.

There is nothing magic about 40/60, but that should work pretty well as a starting point. You want enough weight on the front to keep the guide in the slot, but no more. At least that is what I try to do. Experiment.

[Kevan]

Or balance it across your index finger to see where the balance point is, nearer the rear than the front is best.

[HO RacePro]

Just for fun I measured the weight distribution of my fastest car. Turned out it was 39% front 61% rear. I actually think it might benefit from a bit more weight in the front. TBD.

[Bal r 14]

I followed some of the recommendations given as far as weight placement and distribution. I think that is the best I can do for this car. It didn't help as much as I would like, but I have a feeling the track is to blame. After experimenting, I believe the track is not flat enough to provide consistent contact. It looks flat, but it has some camber in just about every direction. I got a little too cute with the design. No matter, it's coming down soon. Time for track number 4.

[HO RacePro]

If your track has camber/twist that is upsetting your car, your car should benefit from some flex between the front and rear. Many custom chassis have a pivot in the center so the front and rear can twist independently, keeping all four wheels in contact with the track. And if the front axle and guide are a rigid unit the guide will stay square in the slot.

If your chassis has a motor pod just loosening its mounting screws can provide a substantial amount of twist freedom.

All of the above are proven chassis tech. Enjoy.

[Bal r 14]

The pod is pretty loose. I have had some issues with unexpected de-slotting with stock guides, but the Slotting+ deep wood guide takes care of that very nicely. Custom chassis with some center articulation would seem to be a good idea. I guess I learned something about track design. Next track will be better. I think one more after this next one and I'll have it about right.