NevadaRC

All things being equal (driver ability, track surface, setups, etc.) does a lighter weight car make any appreciable difference to lower lap times? I get that this might be difficult to quantify scientifically but I suspect that if people are spending a significant amount of money, someone might have tested this in the past.

Brandon11m

In spec classes saving weight can be really important to get that extra punch and make the most of the limited power that you have but in mod classes where you can just use power to overcome the extra weight it doesn't matter nearly as much. Lower weight may help some in the corners but it seems like RCs don't lose much corner speed with extra weight

RC10Nick

iTrader: (9)

Weight is one of those things that's really tricky to test in isolation, it's a foundational aspect of a car's setup and when you change a car's weight it has so many knock-on effects on the rest of the car that you can't really say what you feel on the track is a result of the change in weight.

RetroThutmose

iTrader: (1)

Yes. Lighter weight can mean faster laps. That's why every class has a minimum weight. Where you save weight can be very important too. If you can remove as much weight (and friction) from the drivetrain you are essentially getting "free" power. If your chassis is below the minimum you can also add weight to where you need it or where it will benefit you versus just wherever it is. Usually try to eliminate weight from the highest points on the chassis and move down, as a general rule of thumb.

staiguy

iTrader: (7)

Trying to keep all things equal is kinda hard only because of where the weight will go. For blinky stock you want to be around the old limit of 1500grams. A little under or over is fine. Right now im kinda fortunate my "un-weighted" LD3 sits in around 1490. I can throw on a battery brass weight and there's a little more side-to-side weight transfer. Take it out and its a little more flat, but can be prone to traction rolling. I could also figure out a way to get it brass more in-line and get the weight more centerized, giving me just more weight down low.

In terms of spending money, especially for stock, I would go ceramic bearings over titanium everything. I realllllllly like how the LD3 came in 3 different flavors, mod, dirt and stock spec. Stock spec came with a lot of the weight upgrades already included, CF motor mount, CF filled transmission case, CF chassis, and slipper eliminator included. without weights this thing would probably weight in around 1400 grams. money was spent ON weights . Brass radio tray, brass under servo weight and aluminum bulk head, and aluminum camber blocks. Weight was more of a tuning thing where it was all loaded up towards front. The battery weight is easily removed if needed as a tuning thing.

My LD1 has the aluminum chassis that had me chasing the weight savings. If you like a lightweight car, dont prefer aluminum over plastic. Plastic will always be lighter

nielsm

I like the Lotus philosophy: Power makes you faster in the straights, lightness makes you faster everywhere.

BuggyFan21

I only race mod, but typically I find a lighter car easier to drive in low grip, but I always need to add a bit of weight in high grip to calm the car down a bit.

​​​​​In mod I don't think total weight matters as much as weight distribution though.

billdelong

iTrader: (33)

I have found that my results change from layout to layout.

In 13.5 spec, I would tend to run LCG shorty packs with high speed flowing layouts, but I'd run a heavier standard shorty with large jumps and hairpin 180°s where the larger capacity pack would offer more punch so this contradicts somewhat with less weight offering faster acceleration.

I don't think the overall weight of the car matters nearly as much as reducing the weight of rotating mass.

By far the most significant advantage I've found is running 2WD wheels on 4WD front with staggering results explained here:

• 2WD Wheels on 4WD Wheeler

BeefHead

My son races expert 17.5 and mod buggy. The mod car is full weight no hopups at all,and the stock car has about every hopup on it. 17.5 car is exactly 1474 grams ready to race. The setup on both cars is identical but for some reason the 17.5 car handles mutch better on every section of the track. Only deference is the mod car we run slightly heavier shock oil. I just can't figure out why it handles better but I keep working on it.

staiguy

iTrader: (7)

the shock oil could be a difference but also the 17.5 power band could be more more aligned with the setup. Maybe it’s power to suspension squats better. Also since it’s “slower” it’s usually easier to drive. Are times about the same or is there a difference? Lots of drivers who run 17.5 and 21.5 have almost the same times. Next time I can ask if there’s any major differences. I know one guy says he runs a lighter diff oil to compensate for the power difference. I usually go a step down in diff and anti-roll bars. Suspension link points,shocks, and oils are the same

Brandon11m

That doesn't really contradict with less weight being better, that's just the advantage of larger batteries outweighing the effect of added weight. Having a larger battery with the same weight as an LCG would have even more punch

billdelong

iTrader: (33)

+1 to "slower is faster"

I once had a sensor wire go bad on me during a race where I got maybe 50%-60% power coming out of the motor, I was essentially driving the car WOT but was barely able to clear the jumps, it was very frustrating because I felt like the car was going excruciatingly slow, but I continued the race just because I wanted to get the practice on a new layout. To my surprise, my hot lap was a pinch faster! That's when I learned how much I've been blowing corners and over driving my cars... I rarely run 100% EPA on my throttle anymore and I play around with different throttle settings until I find the optimal speed for a given layout.... hence... "slower is faster"

RC10Nick

iTrader: (9)

Even with the same "setup", the two cars will have different amounts of weight transfer, different suspension frequencies, different roll moments, different damping rates, etc. I'm sure the lower weight itself probably does help in some way, but the difference in total weight means these cars have two entirely different setups even if you have all the other adjustments identical between them.

And outside of the car's weight, just the difference in power between stock vs mod can drastically change how even the same car feels to drive. For instance a mod car can accelerate out of a corner much harder than a stock car and that will cause the mod car to understeer noticeably more than a stock car.

So really if you want the best out of each car, you can't think of them as being the same, because they're really not. You have to treat them as two separate cars and tune them independently of each other.

Sir 51D3WAYS

Theoretically, a lighter car is always faster. Certainly at least according to His Quagrainess. And I put a lot of stock by him, for obvious reasons.

The problem is, our springs and dampers (and possibly subsequent kinematics) are often poorly matched to the lighter car. The usual problems are not having a spring that's soft enough, or a lack of fineness in the range of springs
Then there's our famously imprecise dampers. So weights are used to "bump it up" to the next possible spring/damper rate.

tortoise 1

• Less responsive car so easier to drive
• Ratio of sprung to unsprung mass is improved so the car performs better over bumps.
• Centre of gravity is typically lowered which reduces weight transfer. (Note that if a thicker battery is used as opposed to chassis weights the opposite is true)
• Weight distribution can be optimised.
• Adding weight can prevent wheelies.

• More power is needed to achieve the same acceleration.
• Adding weight generally reduces the coefficient of friction of the tyre.(less grip).