2019: Why are TT's faster than Class 1 buggies?

michael.gonzalez

Well-Known Member
It is not so much about acceleration as stopping and starting.
Stopping and starting is acceleration. I don't get your statement.

Heavier vehicles STOP better in the dirt, which allows deeper corner speed and less time lost when slowing for obstacles that require slower speeds.
Sorry, but I find it hard to believe that being heavier improves braking performance. Quite the opposite actually.
Again,
Lets get a scenario going. Two TT's coming down a dirt road at 100mph.
TT1 weighs 4000lbs.
TT2 weighs 6000lbs.
Both slam on their brakes at the same time and come to a rest. They do this ten times and each time they both take 500ft.
TT1 wants to stop sooner than 500ft. Should he add 2000lbs to his truck?

Makes sense when you think about it. Dragsters with good brakes will be fastest.
I agree that better braking performance will equate to better overall performance.

But I disagree that adding weight will increase braking performance. Nor is it the best way to increase braking performance.
 

Bro_Gill

Well-Known Member
Ok, let me make this simple for you, on dirt, a heavier car digs a deeper trench when the brakes are applied allowing more stopping power to slow the vehicle. That is why there are HUGE braking bumps ahead of obstacles and sharp corners on the courses. This was not as much an issue when vehicles were on 33" tires and weighed 1500-1800 pounds like they used to because a skinny 700x15 locked up just skipped over the surface. Perhaps you should go drive in some dirt and take notes and see what happens with bigger and littler tires on your truck, especially with regard to width and diameter.
 

Bricoop

Well-Known Member
Stopping and starting is acceleration. I don't get your statement.


Sorry, but I find it hard to believe that being heavier improves braking performance. Quite the opposite actually.
Again,
Lets get a scenario going. Two TT's coming down a dirt road at 100mph.
TT1 weighs 4000lbs.
TT2 weighs 6000lbs.
Both slam on their brakes at the same time and come to a rest. They do this ten times and each time they both take 500ft.
TT1 wants to stop sooner than 500ft. Should he add 2000lbs to his truck?


I agree that better braking performance will equate to better overall performance.

But I disagree that adding weight will increase braking performance. Nor is it the best way to increase braking performance.
If the friction coefficient changes less than the inertia of the vehicles, adding weight will increase the stopping distance. Like you have said.
 

Bricoop

Well-Known Member
Ok, let me make this simple for you, on dirt, a heavier car digs a deeper trench when the brakes are applied allowing more stopping power to slow the vehicle. That is why there are HUGE braking bumps ahead of obstacles and sharp corners on the courses. This was not as much an issue when vehicles were on 33" tires and weighed 1500-1800 pounds like they used to because a skinny 700x15 locked up just skipped over the surface. Perhaps you should go drive in some dirt and take notes and see what happens with bigger and littler tires on your truck, especially with regard to width and diameter.
Changing tire size completely changes the contact patch of the ground.
 

michael.gonzalez

Well-Known Member
If the friction coefficient changes less than the inertia of the vehicles, adding weight will increase the stopping distance. Like you have said.
You cannot change the friction coefficient by changing mass or anything else about the vehicle other than tires. You have to change either the dirt or the rubber to change the friction coefficient.

Ok, let me make this simple for you, on dirt, a heavier car digs a deeper trench when the brakes are applied allowing more stopping power to slow the vehicle.
You are correct. A heavier car will have more stopping force.
As explained previously (Post #66), you NEED that extra stopping force because you have more MASS to stop. No advantage overall.

Excerpt from Post #66
...
A truck that weighs twice as much will have twice the traction.
Twice the traction means you can push on the ground twice as hard.
Good.
You're going to NEED to push twice as hard on the truck that weighs twice as much to get the SAME acceleration as the original truck.

So no advantage, and you still have the disadvantage when you want to go and make a turn.

One of the few ways to INCREASE traction without increasing mass, is to increase DOWNFORCE through aero.
 
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Bricoop

Well-Known Member
You cannot change the friction coefficient by changing mass or anything else about the vehicle other than tires. You have to change either the dirt or the rubber to change the friction coefficient.


You are correct. A heavier car will have more stopping force.
As explained previously (Post #66), you NEED that extra stopping force because you have more MASS to stop. No advantage overall.

Excerpt from Post #66
I learned something, thanks. So the weight affects the force of friction, not the coefficient. The coefficient is based upon how the surfaces act upon one another?
 

Bro_Gill

Well-Known Member
If there is no advantage to bigger tires, larger brakes, more horsepower, etc... Then why are TTs faster???
 

pdailey

Racer
It is not so much about acceleration as stopping and starting. Heavier vehicles STOP better in the dirt, which allows deeper corner speed and less time lost when slowing for obstacles that require slower speeds. Larger tires hook up better for acceleration, and few of the current class 1 cars are running 40s, but they are moving that way. Last- drive train in TTs has better development for 800+hp than IRS derived transmissions, so there is that as well. Many years ago, one of the great riders and drivers with many overall wins on bikes and buggies got a truck ride and suddenly, he said he could stop in the dirt. Changed his mind about buggies. I don't think he ever went back. Makes sense when you think about it. Dragsters with good brakes will be fastest.
sorry I disagree. My class 10 car stops light years better than the Honda truck I’m currently driving and that truck stops pretty damn good. Maybe the buggy the person you’re referring to drove had crappy brakes to begin with.
 

isdtbower

Well-Known Member
If you want to increase front brake friction force. Wouldn't you choose to raise and move forward the CG?
TT's might run larger brakes with larger wheels for more consistent braking.
4WD rear brake trucks can actually help the front brakes stop thru the mechanicals. No need to bias.

If your low travel buggy is in the air more, with no force on the ground. it's not stopping or going.

I think you guys are discussing TT vs TT, CL1 vs CL1, or Mc vs MC........ and not TT vs Buggy.

I think a buggy CG would be lower and further back than a TT. So there is more thrust forward in buggies than downward for braking friction. Is all the rear weight for steering accuracy or to bring the rear tires into the accelerating AND braking world?

Bonneville cars are also heavy so they don't fly. Wings might be great going forward but when they spin, all bets are off on staying on the salt.
 

wayne matlock

Well-Known Member
When has a bike's top speed been limited by tire-spin?
Have you ever noticed that they are faster on the pavement than they are on the dirt? You think that might be tire-spin?
We have actually tested the difference in weight on moto and ATV riders, and done the same for UTV's. Our UTV loses 3 to 4 mph at top speed when the codriver gets out.
 

Bricoop

Well-Known Member
Have you ever noticed that they are faster on the pavement than they are on the dirt? You think that might be tire-spin?
We have actually tested the difference in weight on moto and ATV riders, and done the same for UTV's. Our UTV loses 3 to 4 mph at top speed when the codriver gets out.
Have you tested how it affects acceleration or braking?
 

Robin Hood

Well-Known Member
There is book smart, street smart, hands on experience and just plain don't get it.

"YOU DON'T KNOW WHAT YOU DON'T KNOW"
 

Bro_Gill

Well-Known Member
The problem is Michael seems to think every change creates a lineal change in the performance of the vehicle. It does not.
 

Honda48X

Well-Known Member
Thank god my Toyota Tacoma can stop faster then that heavy Dodge 3500. Wait how can that be. Most of you are saying a heavier truck stops faster. And Bro_Gil you drove fire trucks....
 

jon coleman

Well-Known Member
Stopping and starting is acceleration. I don't get your statement.


Sorry, but I find it hard to believe that being heavier improves braking performance. Quite the opposite actually.
Again,
Lets get a scenario going. Two TT's coming down a dirt road at 100mph.
TT1 weighs 4000lbs.
TT2 weighs 6000lbs.
Both slam on their brakes at the same time and come to a rest. They do this ten times and each time they both take 500ft.
TT1 wants to stop sooner than 500ft. Should he add 2000lbs to his truck?


I agree that better braking performance will equate to better overall performance.

But I disagree that adding weight will increase braking performance. Nor is it the best way to increase braking performance.
in f1, all the nasty braking is actually done right away, Thats when the car is a few thousand pounds heavier from df, as car quickly slows, brake psi is modulated to match loss of df,( i watched a show on speed vision years back on f1 braking subject) Down force can help braking, but, u gotta slow extra lbs if That is your down force, trade off, tt seem to have a good package of df& braking power& tire grip
 

Bro_Gill

Well-Known Member
Thank god my Toyota Tacoma can stop faster then that heavy Dodge 3500. Wait how can that be. Most of you are saying a heavier truck stops faster. And Bro_Gil you drove fire trucks....
You're confusing pavement with dirt. Huge difference.
 

Big Hock

Bababooey!!!
Without the science though, simple answer is that extra foot (yes foot not inches) of rear wheel travel has a lot to do with it.
 
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