fyrstormer

iTrader: (1)

When I say "base weight", I mean not including batteries or balancing weights. I know ROAR publishes minimum weight requirements, but those are gross weights that include everything. I just want to know what's a good starting point to aim for when building the chassis, to give myself a reasonable amount of room to add balancing weights where appropriate, without making the chassis so light that it breaks all the time.

urnotevenwrg2

iTrader: (1)

I know you like to do stuff differently, but in this case what you want to do makes no sense. Attempting to place ballast before you have everything needed for the car to be track ready is not going to get you anywhere.

Which electronics you choose, how you install those electronics, and how you wire up the electronics all have an influence on the weight distribution. So placing extra weight before all of those things are decided is very likely to not help the balance of your car.

Racing is completely different from bashing. You have the clock as an absolute measurment of improvement. How good of a driver you are has a vastly greater importance. You can spend a bunch of time and money improving the car, but if you can't drive it right to the limit, you will not see any decrease in lap times. Seems a lot of people miss this entirely.

Your best bet for on track success is to build the car as perfectly as you can with the kit setup, get a fresh set of the correct tires for the track where you plan to run, and choose good electronics and set them up correctly. If you do all that, the only thing left is to drive the car, and that is going to be the hardest part.

If you do all that and you are off pace, have one of the fastest drivers at your track drive your car. They will be able to tell you if it is your car or your driving that is holding you back.

billdelong

iTrader: (33)

+1

Also consider a corner balance system with 4 independent scales to get 50/50 weight distribution from left <-> right then depending on the geometry some cars start around 50/50 front <-> rear and depending on track conditions you move the weight slightly forward or backward depending on what you want to do to either get more steering or more stability out of the car.

At our local turf track, we're finding that the heavier Tekno EB410 tends to jump farther with the extra weight and is more planted in the corners... this goes against what was common knowledge to have the lightest car possible for the old clay track that our club used to race on. Not sure if this is a factor of traction condition or jump angles, maybe a little of both, so every track could present different results based on layout, etc...

fyrstormer

iTrader: (1)

I didn't say anything about wanting to place ballast before installing everything else and tuning the suspension. I asked what is a good target weight AFTER everything else is installed and BEFORE adding ballast.

sgtlt

iTrader: (5)

I think most cars will be around 1600g with everything but a battery. Not sure if that is what you were asking ?

fyrstormer

iTrader: (1)

Yeah, that's what I was asking. Apparently I made my question sound more complicated than it actually is.

sgtlt

iTrader: (5)

I have a Xb4, Yz4, and new Yz4sf and they all are very close in weight.

urnotevenwrg2

iTrader: (1)

Well that makes more sense, but still not something worth worrying about. Also it is not something you can really do. You need to pick which electronics you want to use, and see where the car is with everything in place. If it is under weight, add the amount to get the car above the minimum. If you want to add weight to adjust the handling, you need to drive the car first (which obviously requires all of the electronics to be in place) to establish where the weight needs to go, and how much weight you want to add to make the car handle the way you want.

You can try to guess what your car will weigh based on the weight info the manufactures give for components, but I've found those numbers can be off. Different tires and inserts are going to have different weights and handling on track.

Ultimately, because the point of racing is to go as quickly as possible within the rules, you need to spend time with your legal car on the track in order to make improvements.

That said, your driving ability will be the place where you can gain the most time. You could, by blind luck alone nail the setup, but you will still have to drive the car correctly to utilize the perfectly setup car.

fyrstormer

iTrader: (1)

I understand all of that. I just wanted to gauge how much money I'd need to invest in lightweight parts during the initial build, in order to reach a competitive weight.

SocalSnakeEyes

iTrader: (6)

Competitive weight is always going to be as light as the class allows. However, competitive weight may not be what your truck, driving style or, track may want.

If I get the right idea your trying to lighten a pre existing kit or build your own. If this is what your after and still keep it ROAR rules, try taking the wight of all the gear (Batteries, ESC, motor, RX, Servo, tires, transponder and, even body)*as well as all the drivetrain parts if it is a DIY truck* and get a wight on those. Then subtract that from ROAR rules. This will give you good idea how much of a diet you can put the truck on. Watch where you take out wight. If you cut the wrong places, the chassis will flex like crazy. That will make the truck act real funny on the track. And make sure not to cut so deep it brakes in half after the first landing. I've been there. Carbon or graphite chassis is always been a good upgrade in my past experience. If none are available there are places that will cut ones based on the info you send them. That is all in how much you want to spend. Me, I'm allergic to spending money.

Doing small things like cutting out the center of diff outdrives or slipper pads can help bring not only static weight down but also rotating mass. Good for quicker lunches. In lose conditions this can make the truck harder to control. Carbon rods can for idler gear shifts, top shafts and center shafts if your good with making parts and your not running to much power to them.

Maybe if we had an idea what truck you where specking of, we could help better.

Hope this helps some.

urnotevenwrg2

iTrader: (1)

You don't need to spend money on light weight upgrades. Any current car with the proper electronics will be at a competitive weight. You need to get everything together and on track. If you have money to burn and you want to make upgrades that is fine, but you have to be a really good driver to take the small gains light weight parts create and translate them into faster lap times.

I know you like to upgrade your other cars to make them more capable for specific environments and situations. Than isn't going to be much of the same case for building and setting up a car for the track. What you get in the box of a quality race kit has been developed by teams of engineers and drivers to be really good. You have to be a really good driver to be held back by any modern car.

Last, I will leave you with this. My 2wd 17.5 car has had $800+ in upgrades. I run it about 40 grams over the minimum because I like the way it drives at that weight. To get it to that weight I have over 100 grams of weight added to the car. I also run a front wing with a mount that puts the front wing in front of the tower, an aluminum cooling fan that has a high voltage fan control box that allows me to turn my fan on and off from my transmitter, an extra capacitor bank, and a slipper clutch. All those things add weight, but they also add functionality to my car. My 4wd on the other hand is a pig. I weighed it today just to see where it is and it was 1815 grams. I have a D413, which has steel ring and pinion gears, 3 fluid filled diffs with metal gears and pins, and all of the driveshafts are steel. I replaced the stock carbon chassis for an aftermarket aluminum chassis that adds 80+ grams. I knew the car was heavy, and that because of where the battery was positioned a light weight battery just wouldn't cut it. So I run a 6100mah battery for balance, and to have plenty of juice moving that pig around the track. Spec class racing is all about momentum and corner speed. Yeah it is nice to have a car with all light weight stuff, but by no means is it necessary.

fyrstormer

iTrader: (1)

Fair enough. I'm so used to having to tune every vehicle I get to work well in the environment I intend to use it in, I kinda forgot that buggies are designed to work well on tracks to begin with.

Now I just have to swallow the $20/day or $120/month fee to use the track near my apartment.

urnotevenwrg2

iTrader: (1)

Yikes. If you have not already bought the kit you want, see if that track has it or can get it. Then see if they will throw in a month of free practice or some free racing. I have raced at a few different tracks that had that policy.

sgtlt

iTrader: (5)

our local track is only $ 5 a day 20 for race day 10 for extra car

SocalSnakeEyes

iTrader: (6)

You have one of those too. I guess it's a thing now. At least yours is close. I have a 2 1/2 hour drive to San Jose for an indoor track that has club races. And, that darn membership.