Chassis weight theory

[opek]

Originally Posted by 92LILREDYJ

No a light truck makes less traction. A heavy makes a little more. What I was saying is if it gets too heavy it will not pull itself up because of lack of traction.

Yes you can dial some of the bounce out, with link set up and foams.

What kind of link setup? What kind of foam changes?

[bob1961]

my tigress tubed frame shafty had a weight of 7.6 lbs, each tire/wheel was 1 lb each....first year i ran in 4 comp's and placed with two 1st's and 2nd's and placed 2nd overall....lot of GTG's i beat MOA rigs with her as well, never placed out of top 10 the next comp year the ones i made it to....so high weight rigs with weight down low seem to work good, i seen lots of light weight MOA rigs have troubles where i walked up stuff they spun tires on....plus dig on a shafty i think works better then MOA rigs that couldn't have free wheel in the rear......bob

....

[krawlfreak]

Originally Posted by Chris_The_Battery_Man

Im still not sold on heavier trucks working better than light trucks. Simply because gravity is always the same. So on a really steep climb, with low traction, your truck is being pushed down. A heavier truck will fall faster. Now this is just 1 place I know lighter trucks work better. But I have had much better luck with trucks in the 4.75lb range that I have been competing with for the last 3 years

there is a very good reason people have been putting weight in the wheels of crawlers (1:1 and r/c) for years......that is where it will make the difference.

i think a better test for you to conduct would be a corner weight test....trying to balance the vehicle that way

[adamargue]

Originally Posted by krawlfreak

there is a very good reason people have been putting weight in the wheels of crawlers (1:1 and r/c) for years......that is where it will make the difference.

i think a better test for you to conduct would be a corner weight test....trying to balance the vehicle that way

How do u do a corner weight test?

[Ola]

Originally Posted by adamargue

How do u do a corner weight test?

You use one scale at each corner/wheel.. At least 2 at a time on the same axle.

[Duuuuuuuude]

Originally Posted by 92LILREDYJ

No a light truck makes less traction. A heavy makes a little more.

x2

Lay your hand on the table and pull it towards you. Not too hard.

Lay your hand on the table again but put as much pressure on it as possible, then pull it towards you. Much more difficult.

Your hand didn't change, but the pressure put upon it did.

[demonoid369]

Maybe a thick steel or something heavier for a skid could work or maybe make a side chassis mount that allows to stick weight on it? Kinda like a gas barrel tanks that you see on semi's? Cap on one side to allow a round lead stock or steel stock to be placed in to adjust the weight?

[EeePee]

Originally Posted by Duuuuuuuude

Your hand didn't change, but the pressure put upon it did.

Which is why we tried running really skinny tires in the early years. You make the contact patch smaller and it bears a greater load.

[Duuuuuuuude]

Originally Posted by EeePee

Which is why we tried running really skinny tires in the early years. You make the contact patch smaller and it bears a greater load.

But by doing that you lessen your opportunities for finding grip. If heavy weight + small contact patch = more traction then F1 cars would be running around on pizza cutters.

[EeePee]

Maybe we shouldn't derail the thread anymore...

You go start a thread in some forum so I can move it.

[Duuuuuuuude]

Originally Posted by EeePee

Maybe we shouldn't derail the thread anymore...

I don't quite think we're derailing the thread. Weight vs traction is still pretty relevant and has to be considered.

Originally Posted by EeePee

You go start a thread in some forum so I can move it.

'k. Just remember you told me to. Been quite a while since I've had a thread moved...

[Chris_The_Battery_Man]

Originally Posted by Duuuuuuuude

x2

Lay your hand on the table and pull it towards you. Not too hard.

Lay your hand on the table again but put as much pressure on it as possible, then pull it towards you. Much more difficult.

Your hand didn't change, but the pressure put upon it did.

This is true on a flat surface, as is your F1 tire argument.


On the other side of it, put a semi on a steep hill, and a honda civic. Release the e-break in both, and see which one moves faster. My whole argument on the light truck thing isn't that the heavier=more traction is false, but that the more mass you have going up a steep hill, or even on a steep side hill, the easier it will be for gravity to push it down. Really all we need weight for, is balance, off the front for ledges, and out on the ends for side hills.


Now I do believe in a really COG. However, for all around driving purposes, a little chassis weight probably wont hurt the trucks performance enough to really matter. I mean c-mon, a good driver will still beat you, provided his truck is not a total POS. Tanis has proven this many times.


My motivation for this is not to make it a main stream practice, but to open the door to more tuning opportunities. Who knows where the hobby will go. Maybe it will be as big as racing, where you need to tune for each location. And on a course with not many hill climbs, but an obstacle where chassis weight is good, this could be beneficial to someone.

[ozyint]

Originally Posted by Chris_The_Battery_Man

This is true on a flat surface, as is your F1 tire argument.


On the other side of it, put a semi on a steep hill, and a honda civic. Release the e-break in both, and see which one moves faster. My whole argument on the light truck thing isn't that the heavier=more traction is false, but that the more mass you have going up a steep hill, or even on a steep side hill, the easier it will be for gravity to push it down. Really all we need weight for, is balance, off the front for ledges, and out on the ends for side hills.


Now I do believe in a really COG. However, for all around driving purposes, a little chassis weight probably wont hurt the trucks performance enough to really matter. I mean c-mon, a good driver will still beat you, provided his truck is not a total POS. Tanis has proven this many times.


My motivation for this is not to make it a main stream practice, but to open the door to more tuning opportunities. Who knows where the hobby will go. Maybe it will be as big as racing, where you need to tune for each location. And on a course with not many hill climbs, but an obstacle where chassis weight is good, this could be beneficial to someone.

The civic vs semi argument would be valid only if we did not run a drag brake. It's like locking the brakes every time we stop hence like leaving the ebrake on. Leave the civics ebrake on and the semi's parking brake on and use an outside force to push them backwards down the hill, the civic will move with far less force upon it. The semi is also capable of pulling far more weight up the hill than the civic, largely because of the HP difference but also because of the weight difference.

Semi is more weight and more contact points to the ground, hence a heavier crawler with more contact would work better in theory. And rovers are wider and usually a softer compound than stock axial rock lizzards so they grip the rocks better.

There are so many things that come into play when talking about traction. Weight is only one of them. Really we have two civics, one with f1 tires weighing 5k lbs and one with stock 14" tires weighing 2k lbs. the lighter is still easier to push down the hill with the brakes engaged.

I have actually been messing with the weighted links thing for a little bit now, and it actually seems to make quite a bit of difference. Running an aluminum steering link vs a solid carbon steel one, I now run the carbon steel one. The only issue is you create a disadvantage for the rod ends because they are automatically under more stress from the added weight, so break more often than when using a lighter link. That's my two cents anyway...

[EeePee]

Originally Posted by Duuuuuuuude

I don't quite think we're derailing the thread. Weight vs traction is still pretty relevant and has to be considered.

Well, I'll bring up the F1 tire width thing again, cause it'll keep the thread moving.

F1 tires are wide these days to manage heat and since aerodynamic enhancements are involved making cornering speeds much higher than they were without aero, they need the wider contact patch to manage the higher cornering speeds. A shorter, but wider contact patch which is better for corners. Wings and aerodynamics for cornering speeds brought the fat tires to F1. Has nada to do with weight.

Conversely, a drag tire is skinny and they have a longer contact patch footprint for acceleration reasons.

On my Honda autocross car I ran a front tire 1.5 inches wider than in back. I could work them hard enough to get them up to operating temperature. But the rears I couldn't, so I went narrower to get any amount of heat in them I could. Not only me doing that, all the FWD cars in my class would do that.

It's funny, it's a good thing tire temps aren't that large of a deal with our little RC crawlers, though I've been know to do burnouts before my runs, thinking tire temperature helps with grip.

[TEDROCKZ]

Originally Posted by EeePee

On my Honda autocross car

Was it yellow?

[Robbob]

Originally Posted by EeePee

It's funny, it's a good thing tire temps aren't that large of a deal with our little RC crawlers, though I've been know to do burnouts before my runs, thinking tire temperature helps with grip.

Ive seen it experimented with lol. I also know a Boss Claw holds heat better then a Rover after each run in a 50/60* building

I would think the lighter a rig the softer the suspension and the wider the tire/contact patch.

Im with krawlfreak about balancing the four corners. Not just by adding weight where needed but also by tweaking the rig.

[EeePee]

Originally Posted by TEDROCKZ

Was it yellow?

Chrome.

Originally Posted by Robbob

Ive seen it experimented with lol. I also know a Boss Claw holds heat better then a Rover after each run in a 50/60* building

I would think the lighter a rig the softer the suspension and the wider the tire/contact patch.

We bring space heaters and warm up the whole truck, burnouts waste tire.

Tire carcass shape has a lot to do with everything. If they're kind of flat like a Boss Claw, narrower wold probably be better if looking for more grip while moving forwards. If it's rounder, like a stuffed Sedona I guess, realize how much of that tread is touching the ground. Not a lot if it's kind of stuffed full with a foam.

The Rover had a stock foam that was too short to fill the tire, making the contact patch pretty large.

Mashers were wide, Moabs were narrow. I think the Moabs won that battle if traction was present.

Lots of tuning options that I would gather not a lot of people consider.

[Duuuuuuuude]

Originally Posted by EeePee

F1 tires are wide these days to manage heat and since aerodynamic enhancements are involved making cornering speeds much higher than they were without aero, they need the wider contact patch to manage the higher cornering speeds. A shorter, but wider contact patch which is better for corners. Wings and aerodynamics for cornering speeds brought the fat tires to F1. Has nada to do with weight.

That makes sense I guess. But aero is essentially weight. It's downward force applied to the car, same as gravity. The difference being that it is adjustable and variable with speed.

I'd also like to point out that the Honda vs Semi is a bogus argument. Apples and oranges. Though you could do a Honda at stock weight vs a Honda with 6000 lbs of ballast added to it and make it arguable. But still, with all other things being equal, they'd roll downhill at the same rate. Gravity does not change according to mass.

[opek]

Originally Posted by Duuuuuuuude

That makes sense I guess. But aero is essentially weight. It's downward force applied to the car, same as gravity. The difference being that it is adjustable and variable with speed.

I'd also like to point out that the Honda vs Semi is a bogus argument. Apples and oranges. Though you could do a Honda at stock weight vs a Honda with 6000 lbs of ballast added to it and make it arguable. But still, with all other things being equal, they'd roll downhill at the same rate. Gravity does not change according to mass.

But traction increases logrithmically as weight increases, and only when the weight is pushing perpendicular to the surface. So is the trick finding the balance between traction vs. inertia then?

Without a doubt a heavier truck will make less traction than a lighter truck on a vertical, wooden surface. I know this because of my wooden fence! I wonder at what angle the weight begins to make more traction? I wonder how the surface smoothness affects the angle at which you make more traction?

[Duuuuuuuude]

Originally Posted by opek

Without a doubt a heavier truck will make less traction than a lighter truck on a vertical, wooden surface.

I look at traction as a potential with upper and lower limits. Somewhere in the middle is the place where the most potential lies. Not all tires are the same, not all offer the same amount of potential traction, and they certainly don't all work equally well on vehicles of different weight. Too little or too much weight can yield poor results from even the best of tires.

A heavy truck doesn't "make" less traction, its weight has simply exceeded the amount of traction available from the tires it has and the surface they are on. The same truck on the same surface but with different tires may do just fine.