Weight Management

[Fast Co.]

Let's talk about weight management.

No, this has nothing to do with getting more exercise or cutting back on greasy, cheesy slot burgers.

I'm talking about managing the ballast in your 1/32 scale slot car.

I usually approach weight management as a last-ditch effort to improve a car's performance after I have done all of the usual tuning tricks, preferring to keep my car as light as possible so as not to degrade it's acceleration and braking characteristics.

However, there are times when a car absolutely benefits by the addition of some judiciously placed ballast.

One of the most obvious is when a car is top-heavy and has a tendency to roll over in corners. Weight placed low in the chassis will lower the cars center of gravity.

But where exactly do you place the weight? Along the centerline? At the flanks? On the chassis or the motor pod? How far forward or back? Is there an ideal front to rear weight balance?

"I'm all verklempt. Talk amongst yourselves"... ~ Mike Meyers

[modernslots]

Had to look verklempt up

[Fast Co.]

From an old Mike Meyers sketch on SNL.

[War Eagle River]

There isn’t any right place or how much when it comes to weight/ballast placement. It is a personal option that only that driver and specific car can figure out. Way too many variables…track, car, driver, etc. Can be frustrating at times to get that ‘magic’. But when it all comes together it’s euphoria.

[Fathead59]

I guess you can say that it is , test and tune , what is good for one guy might be bad for another guy

[Bal r 14]

A Di Falco controller made a lot more difference than weight management for me.

[strangebrew]

I agree 100% with "FastCo". I build exactly the same way. Just like the 1:1 days, build light & add ballast where needed.

I also agree, it's kind of hit or miss where to put it. Things like tire traction, lifting guides out of the slot,
tipping in the corners...etc. I admit to not being an expert on setups, Seems like what works today.....don't tomorrow!


There's a group of guys on Facebook, that use a separate scale for each wheel & add ballast accordingly.
If your chassis is rigid & has no suspension, & no tire pressure adjustments, I don't see this as being useful.
On the other hand, if your chassis flexes, all these "static" weights are "out the window"....Again. just like 1:1 setups.

Enough weight to keep the guide in the track....(sometimes why I still build the old fashioned drop arm chassis)
& maybe a little down low on the chassis works for me...........MOST OF THE TIME
I don't like to add it to the body if I can avoid it since Most of the time the body has some float & the ballast will "float" with it
& tend to upset the balance of the car in the corners.
I've had some tipsy cars that I had to really work over the tire edges to keep them from "catching" edges corners & upsetting the car.

This sounds like I really know what I'm talking about............but I'm a trial & error guy. (see line #2 above)
Once in a while I just put a car on the shelf, because it'll never work........... Brew

[BIG E]

Nice article by master slot builder Chris Walker in issue #44 of SLOT magazine about this very subject.
Well worth reading. -- Ernie

[Dodgefarmer]

Link?

[BIG E]

Sorry, there is no link, it's a print magazine by Scalextric from the UK. I buy it off the magazine rack in the local Barnes and Noble bookstore. Being an import it's a bit pricey, but worth the price. They may be able to source a back issue for you.

[Fast Co.]

Strangebrew...

[Aptosc6]

Quick and dirty guide to what works for me in order of importance:
Get chassis to float slightly on all directions.
Eliminate unnecessary weight high up in the body. Lower if allowed.
Allow motor pod to float.
Set the guide so you can plant an elephant on the axial pivot without causing the rear wheels to lift.
Add weight under rear axle and just in front of motor.
Weight the chassis to compensate for off axial inbalance caused by non in line motor configurations.

This all assumes trued tires, smooth gears, etc.

[Mickey thumbs]

For dealing with tendency to roll, think of the centerline as the axis of rotation or pivot point. A given amount of weight placed on the outside edge of the chassis will exert more anti-roll force than an equal amount placed near the midline due to the longer lever arm. Therefore you can add less weight to get the same ant-roll effect, minimizing the toll on acceleration.
And they said high school physics was worthless!😄

[Broman62]

Great topic FC...can't wait to hear all the input from others...good advice already!!!

[slothead]

Back to Strangebrew's post (#6) I'm nerd enough to think knowing the weight at each tire would be fun for oval track cars. I'd create spreadsheets to assess different setups for different cars understanding many factors such as tires, turn radius, surface friction, etc. also played important roles. This also has me wondering about weight at the guide. What is it and what role does that play? I like cars with all 4 tires on the track even though I know the fronts create friction in the turns. Whenever possible I have freewheeling fronts on my oval cars to help compensate for this.

If some weight setups were bad, then by default some would be better. Not looking for a singular overall advantage, just curious what different settings would do. A great excuse to run a bizillion time trial laps.

[Kevan]

When I first started racing slot cars in 2015 I read posts about this subject from many years ago and the guys who have raced forever say keep adding weight until you start going slower. I tended not to believe them but did come round to that way of thinking.

Yes too much weight retards acceleration/braking on the straights but the #1 point of adding ballast is to be able to corner quicker and stay in the slot...that's where the majority of lap time is won or lost.

We have classes that only allow minimal changes to a standard car, where scratch built brass or aftermarket chassis aren't allowed, removing body parts and grinding also not allowed so it doesn't matter how much time and effort you put into polishing that turd because underneath the shine...it's still a turd. Whilst club members sneer at those who race heavy cars, guess what, they're always on the podium at the end of the night.

Also don't forget ballast isn't just to keep the guide in the slot if you're adding ballast make that extra downforce work for rear traction, preventing the ass end swinging out is going to take tenths off your lap times and make your car more predictable.

One thing that stuck with me through decades of onroad r/c car racing was never add ballast behind the rear axle as it can really mess up the cars handling - this seems true of slot cars also.

[Cgyracer]

This write up is perfect. Well done Kevin.

[strangebrew]

...........Another thing.............If it sticks in the corner without tipping..............You won't get "nerffed-off" at HRW

[Rodalan]

One of the most important parts of tuning a slot car is balance. As in full size cars a slotcar must be balanced left to right and front to rear.
If a car is heavier on one side it will corner better one way than the other. What you need is consistency.
With regard to balance front to rear you need to have the right Balance Ratio.
It is generally agreed the balance ratio should be about 40/60. this means that 60% of the weight of the car should be to the rear and therefore 40% of the weight should be to the front of the car.
This only relates to slot cars, not full size cars.
The problem is, how can you measure this weight balance easily.
Some people say put a small scale under each wheel and check the weight of each wheel. You have to work out what 40% and 60% of the total car weight is. Of course the two front wheels should be the same and also the two rear wheels should be the same.
This method is complicated and costly as you have to buy 4 scales that are identical.
There is a much easier way of checking the left to right and front to rear balance ratio.
Go to Slotcar Corner, they sell a product called a Slotcar Balance Device. there is a link to a video that shows how the device works.

[Kevan]

Let's look how costly...four 500g digital scales... £8.96 all in... including shipping