Physics question for hardcore stangers

[StangBangRicers]

I have noticed this on more than one stang... can you explain the cause?

Whenever I see a fox body get an awesome launch and pull a wheelie the right rear corner dips more than the left...

Is this from torque or weight?


Why do people relocate batteries to the right rear?
Why not the left if this is a common occurence?

 

[TIMMY2734]

torque

 

[88stangmangt]

fox bodys have a uni-body which is weak so tourque would twist it. as for the battery could be tons of reasons looks? extra room for a turbo saves weight up front too you can put the battery where every you want either side i have seen em go everywhere.

 

[Michael Yount]

The engine rotates counterclockwise as you're standing in front of it. The torque it puts into the unibody twists the unibody that way. Cars that have proper unibody reinforcement, and suspensions optimized for drag launches don't do that - they launch straight and even side to side.

 

[StangBangRicers]

I see... the torque comes from the driveshaft between point A & B(a = engine, b= axle). Torque makes the body twist like a pretzel between A & B as more torque is applied to the driveshaft...

 

[perkys stang]

if the car is setup right for drag then typically it shouldn't do that... Look at my avatar// With my Anit-roll setup the car leave nice and level every time.. As for the battery I think some people do it to try and even out the driver some... Mine is located center of the hatch.. Also with the spare tire well back there it's much easier to put it on the side..

 

[88stangmangt]

^^^^^^ that is a sick a@@ launch props on that

 

[perkys stang]

here is a bigger pic

 

[perkys stang]

^^^^^^ that is a sick a@@ launch props on that

thanks

 

[88stangmangt]

what kinda setup you runing? didnt u once say upr?

 

[98yellowstang]

You asked for physics, which should be more like kinematics:

The torque=Force*distance
Newtons law is that for every force there has to be an equal and opposite. So what you see is the resulting force and distance that has to be displaced in order to compensate for the force the motor is putting into the chassis in the opposite direction.

Later
Jason

 

[GT40XStang9]

So what you see is the resulting force and distance that has to be displaced in order to compensate for the force the motor is putting into the chassis in the opposite direction.

Later
Jason

Finally, someone said it! When the body rolls, it's the response of the torque being applied through the drivetrain.

 

[StangBangRicers]

"Cars that have proper unibody reinforcement, and suspensions optimized for drag launches don't do that - they launch straight and even side to side."

What do you mean side to side?

 

[Mavrick]

I think he meant, that the car is even one side to the other... same height on either side.

 

[ERnotch]

The reason behind placing the battery over the passenger rear tire is to add more weight over that tire specifically. When the car launches the passenger rear tire is forced upward into the body while the drivers rear tire is forced out of the body. So, even though it looks like the passenger rear tire has a lot of downward force on it, it actually has less force than the drivers side tire.

 

[Michael Yount]

Stangbang - I meant exactly what Perky said 2 posts later, if fact we both said almost exactly the same thing - look at his launch - straight and level side to side; both front wheels pulled an even amount; rear end is level too. The more the unibody is stiffened, and the rear suspension is optimized to launch straight and level, the more the engine's torque gets applied to moving you forward quickly (assuming traction) instead of some of it being absorbed in twisting the chassis.

The engine rotates in a counterclockwise direction. As someone correctly stated about Mr. Newton's discoveries, there's an equal and opposite reaction to that tortional force. Watch your motor from the front as the throttle is goosed - it will rise on the driver's side and dip on the passenger's side - that's the equal and opposite reaction to the torque production of the motor. It would be exagerated if you could watch it while the car is actually accelerating - more torque is created than when you're just revving the engine with no load. So in response to the torque the engine's creating, it pulls up hard on the driver's side motor mount, and it pushes down hard on passenger side motor mount. Since the stock unibody is fairly flexible, if you pull hard enough, you can actually twist the unibody. That's what's happening when you see cars pull the driver's side front wheel, and dip down hard on the passenger's side rear. Related to this you now can see why people use solid motor mounts or chains/struts to limit engine movement. With elastomeric motor/tranny mounts (rubber, polyurethane) some of the engine's torque is consumed pulling against/compressing the motor mounts. It's a small amount, but in some rules-constrained classes, even 1 or 2 ft-lbs/hp can make the difference.