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Old 09-12-2013, 02:42 AM   #1
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Default How much does an EMPTY car weigh ?

Hi !

I find myself asking the same question on various threads so I figured it would make sense to create a thread for it. Recently I have noticed important weight differences on very similar looking empty TC's. Sometimes up to 50 grams ! I think everyone will agree that giving a RTR weight indication is close to useless.

When someone tells me his car weighs XXX grams with XXX and XXX electronics, I think it's a loss of time and it does not bring any usable info. I don't know how much your servo weighs, I don't care, I don't want to look it up, and there are differences between the manufacturer data an real-life weight anyway. Same goes for a body: OK you use a LW LTCR but what paint brand ? How many coats ? How many stickers ? We can all agree this makes no sense. The same exact body can be 15 or even 20 grams heavier depending on how you decorate it.

So I suggest people start using the " empty " method to try and get more meaningful numbers.

By empty I mean car RTR except:

. No electronics of any sort
. No bodyshell
. No wheels

That means you keep bodyposts, bumper, wheelnuts, wheel hexes, servo mount etc, in the car. You get the idea.

This does not forbid to give additional info on your build, such as: steel/aluminum screws, turnbuckles or bones. Still much more useful info than the current "method ". Why not post a pic on your car on the scales ?! it doesn't prove anything but can give info you overlooked, and start possibly interesting discussions.

You can use this thread to post your opinion and your findings. Please refrain from debating whether or not a 10 gram advantage is perceptible or not, whether a driver is or isn't able to make a bobble-free 5 minute run, blah-blah-blah. This is NOT the place to discuss this. Let's stay factual. Give precise, gram measurements.

What I think would make sense to discuss though, is whether such and such weight savings are preferable or not because of strength, rotating mass or unsprung weight issues.
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Old 09-12-2013, 02:54 AM   #2
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A picture of WTCC's empty TC5 with Ti turbuckles :

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Old 09-12-2013, 05:16 AM   #3
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Almost a pound, huh. I've weighed individual parts but never just the chassis.
Example:
Lipo 266 or 310-313
Motors 167-177
Motor fans 18-28
Jaco Blues 115 (worn 111)
Motor wire 1.5-2 per inch
Bodies 106 or 112 (add one gram for paint, once dry and one gram for stickers)

...and so on. This what I can remember off the top of my head. These calculations I checked a few times in the past. The painted body thing surprised me but it is true. Dry paint only added one gram of weight. Airbrushed using five colors plus one coat from a rattle can.
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Old 09-12-2013, 08:25 AM   #4
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70g for a motor ? You're off by at least 100g.

Anyway I posted WTCC's picture just to show how big the weight difference can be from one chassis to another. According to the Xray guys, the latest T4 is around 510grams out of the box for instance.
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Old 09-12-2013, 08:52 AM   #5
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On one hand, I can totally see where you are coming from with the "I don't care what your motor/servo/ESC/battery weigh" but on the other hand, I'm not quite sure what the point is. This might be me showing my inexperience, so please take these questions as an honest inquiry, and not an attack on the idea, because I don't mean it as an attack....

When you race the car, you have all the electronics in it, so isn't that the most important part (regardless of what brand/model of electronics)? I mean, someone who runs a really heavy motor may add some weight to the other side of the chassis to balance it, but then remove weight from the center line to bring the overall weight back down, yes? Don't you still have to meet minimum weight requirements, regardless of how little the chassis weighs or how much the battery weighs? Or is this more for a racing class with no minimum weight restrictions?
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Old 09-12-2013, 09:36 AM   #6
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well for me...when I got my 1st TC5 and was looking to go to my 1st big race...I checked everything...chassis,esc,motor,body, tires, rims, ect...everything...to make sure it was completely balanced and at the proper weight.

TC5R 525
LRP SPX 24.5
Spectrum RX 6.5
Futaba 9551 45
Novak 21.5 SS 191
heat sink 22
5 spoke rims 120
HPI Mustang 126
SMC lipo 4000 245

ect

this was for the USVTA Nats 2009

it helped alot
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Old 09-12-2013, 09:38 AM   #7
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Quote:
Originally Posted by BlueGlowBoy View Post
On one hand, I can totally see where you are coming from with the "I don't care what your motor/servo/ESC/battery weigh" but on the other hand, I'm not quite sure what the point is. This might be me showing my inexperience, so please take these questions as an honest inquiry, and not an attack on the idea, because I don't mean it as an attack....

When you race the car, you have all the electronics in it, so isn't that the most important part (regardless of what brand/model of electronics)? I mean, someone who runs a really heavy motor may add some weight to the other side of the chassis to balance it, but then remove weight from the center line to bring the overall weight back down, yes? Don't you still have to meet minimum weight requirements, regardless of how little the chassis weighs or how much the battery weighs? Or is this more for a racing class with no minimum weight restrictions?
Well said. I was curious about this as well. If a sedan is 1450g total, does it really matter what the bare chassis weighs?
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Old 09-12-2013, 10:08 AM   #8
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The weight that counts is the final balanced and ready to race weight..... Although weighing the Car without the battery will give you an idea how light your battery needs to be for you to make weight while balanced...
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Old 09-12-2013, 10:46 AM   #9
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This is a good idea. Having the bare chassis weight gives you an idea of how much each car compares against one another. I'll see if i can't contribute.
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Old 09-12-2013, 12:24 PM   #10
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Quote:
Originally Posted by bertrandsv87 View Post
The weight that counts is the final balanced and ready to race weight..... Although weighing the Car without the battery will give you an idea how light your battery needs to be for you to make weight while balanced...

I agree. The only weight that counts is the weight of the car as you intend to race it. You're not going to race without wheels or electronics, so I don't think the officials care what your car weighs without them.

On the other hand, if you're asking because you want to find the lightest possible "empty" chassis to start a build from, I can see a point in this method of weighing. If you're trying to build the lightest car possible, it makes sense. If its for racing purposes, it doesn't make any sense.
More often than not people come in under weight and need to add weights to the chassis to meet weight.

If you're coming in over weight, it's probably be easier/cheaper to source out one or two lighter weight parts, rather than look for a lighter chassis.
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Old 09-12-2013, 12:58 PM   #11
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My bad, I should have made clearer that I wanted to be able to compare one chassis to another, all other things being equal. And the easiest way to make all other things equal is to get rid of them all ;- )
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Old 09-12-2013, 12:59 PM   #12
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Quote:
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Or is this more for a racing class with no minimum weight restrictions?
Exactly.
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Old 09-12-2013, 01:08 PM   #13
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OOOOH, so you want to be able to build the lightest chassis, with the lightest option parts, and then throw in your own choice of electronics, assuming the lightest ones that still perform sufficiently.

That makes sense to me.

My car is no where near light enought to justify attempting to help you out here....around here, all the classes that I have seen run at our tracks have a minimum weight, and though they aren't strictly checked at club races, we would razz the hell out of anyone who was obviously underweight, whether they were a top contender or not.
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Old 09-12-2013, 04:23 PM   #14
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welp, I'm no help then. I doubt you'll use a Sprint 2 for competitive racing. lol
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Old 09-12-2013, 04:52 PM   #15
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Weighing all the Parts going in your Car can be overwhelming, but at least weighing your Tires can boost Performance, even if they are spec Tires.... Two to three gram difference on each of your four Tires can make a huge difference.... Some of my qts 32 Tires weigh as much as 8grams less than others: that's 32grams less in rotational mass.... I'd rather loose these 32grams on the Tires than worry about 50grams less in chassis weight....
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