What causes the rear end to swing to the right under acceleration?
The rear end is posi-track which to me means that both rear wheels should
be pulling equally. But, the rear end swings to the right from low speeds or from a standing start... Does anybody know what actually causes this? |
Re: What causes the rear end to swing to the right under acceleration? (Marlin in Minn)
T :conehead O :conehead R :conehead Q :conehead U :conehead E :p:
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Re: What causes the rear end to swing to the right under acceleration? (Marlin in Minn)
Actually it's your posi that does it. If you didn't have a posi you would just light up one tire. Usually mine kicks right only when I actually break the tires loose. Or for instance if you're in the rain and you punch it, tends to go to the right. Something about the direction of the rotation, blah, blah. I wish I knew the physics behind it but I don't.
All I know is that without a posi you will just spin one wheel all day long and on a GM with a Posi you will move, just sideways :) Ever notice how ever car that pulls the wheels off the ground has one wheel higher than the other? Ever notice how it's always the same wheel. Except, and I've never really paid much attention to this one, a friend of mine tells me that mustangs will pull the opposite tire off the ground first. Like I said, I've never noticed, could be true who knows. This same friend tells me that Mustang's actually spin the opposite direction of GM's, i.e. if our motor turns clockwise theirs goes counter, and hence the reason they pull the other wheel off the ground. He could have also just inhaled too many fumes from the track. Can anybody prove or disprove this? |
Re: What causes the rear end to swing to the right under acceleration? (Marlin in Minn)
One of Newton's laws. For every action, there is an equal and opposite reaction (or something like that). The action is torque rotation in one direction and the car rolls in the other direction
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Re: What causes the rear end to swing to the right under acceleration? (Marlin in Minn)
Muskrats and other cars with solid rear axles spin one wheel even with positraction because driveshaft torque which is also applied to the rear axle tries to lift one rear wheel and push down on the other. The wheel being lifted spins and loses traction and the assymmetrical accelerating force on the rear wheels causes the car to turn away from the wheel with traction.
Since 1963, all vettes have independant suspension and the differential is bolted to the frame, so driveshaft torque does not get applied to the rear axles. Since your rear tires do have the EXACT coefficient of friction nor the EXACT same weight on them, the wheel with the combination of less weight and coefficient of friction will spin first, lose traction , you will have assymmetrical thrust on the rear wheels which causes the car to turn away from the wheel with the most traction. The biggest reason the rear swings out is due to the weak wheel losing traction first and the other wheel begins to spin which reduces its tractive force with the pavement and it then cannot resist sideways movement very much and away she goes. |
Re: What causes the rear end to swing to the right under acceleration? (jfb)
Gyroscopic Procession. :cheers:
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Re: What causes the rear end to swing to the right under acceleration? (jfb)
Muskrats and other cars with solid rear axles spin one wheel even with positraction because driveshaft torque which is also applied to the rear axle tries to lift one rear wheel and push down on the other. The wheel being lifted spins and loses traction and the assymmetrical accelerating force on the rear wheels causes the car to turn away from the wheel with traction. Since 1963, all vettes have independant suspension and the differential is bolted to the frame, so driveshaft torque does not get applied to the rear axles. Since your rear tires do have the EXACT coefficient of friction nor the EXACT same weight on them, the wheel with the combination of less weight and coefficient of friction will spin first, lose traction , you will have assymmetrical thrust on the rear wheels which causes the car to turn away from the wheel with the most traction. The biggest reason the rear swings out is due to the weak wheel losing traction first and the other wheel begins to spin which reduces its tractive force with the pavement and it then cannot resist sideways movement very much and away she goes. |
Re: What causes the rear end to swing to the right under acceleration? (kabnvtt)
Correct Spelling is "Precession".
As best I remember my physics, here goes: Any rapidly rotating object, such as a gyroscope, tire, or flywheel, possesses angular momentum. The ability to twist, or cause angular momentum is called torque. Greater torque= greater twisting effect. Precession acts at a 90 degree angle to the rotation, so when both rear tires lose traction during a burnout, the car precesses (yaws) to the right. On a car without positraction, one tire still has traction and so the car cannot yaw. This is related, but not the same as the "equal and opposite reaction", which is why the engine or body rolls to the right when you blip the throttle. Again, caused by torque, but a different effect. Hope this helps! |
Re: What causes the rear end to swing to the right under acceleration? (tkrussell)
I'm a physics major, and the reason you slide sideways is called
TORQUE, its your friend :D |
Re: What causes the rear end to swing to the right under acceleration? (vader86)
Thanks for the replies..
So if I'm understanding this correctly, if the engine and drive train rotated the opposite direction, then the rear of the car would swing to the left when you spin the tires?? Is there any way to compensate for this to help the car pull straighter under hard acceleration? |
Re: What causes the rear end to swing to the right under acceleration? (Marlin in Minn)
Well the wheels are gonna rotate in the same direction if youre moving forward, so youll always swing right.
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Re: What causes the rear end to swing to the right under acceleration? (Marlin in Minn)
Ugh, physics :smash: :smash:
J :seeya |
Re: What causes the rear end to swing to the right under acceleration? (Nathan Plemons)
Hopefully, no one will bring up the ugly discussion of 'beam plates' for the 'c' beam....ooops! :blueangel:
[Modified by GRX, 5:48 PM 9/23/2002] |
Re: What causes the rear end to swing to the right under acceleration? (GRX)
If you are pulling to the right without spinning your tires then I would check your rear bushings. Mine did the same thing and when I jacked up the back I could move the wheels around. Changed the bushings and she pulls straight as an arrow. Hope this helps. Robert :flag
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Re: What causes the rear end to swing to the right under acceleration? (rspvette)
If you are pulling to the right without spinning your tires then I would check your rear bushings. Mine did the same thing and when I jacked up the back I could move the wheels around. Changed the bushings and she pulls straight as an arrow. Hope this helps. |
Re: What causes the rear end to swing to the right under acceleration? (BBA)
Actaully, streets are crowned to allow for drainage this can direct the direction of the rear once traction is gone. I have launched in a parking lot that was flat and got an occasional leftways launch. I hope thats not defying physics, just a observation. :)
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Re: What causes the rear end to swing to the right under acceleration? (blk90rdstr)
Why is everyone assuming that he is referring to the wheels breaking free? Mine did the same thing under hard accel. The way I read the first post he is talking about that and not burning out. Most of you guys only think about spinning tires and 1/4 miles. Some people want good performance and mods without tearing things up and saying OOOPS. IMHO.
:boxing |
Re: What causes the rear end to swing to the right under acceleration? (rspvette)
Why is everyone assuming that he is referring to the wheels breaking free? The 1/4 mile is obviously not the only performance measure out there, but it's a good common reference. If I say that my car runs 12.8 in the 1/4 and then I go on to say that your car goes from 0-60 in 4.3 seconds, who has the faster car? How can you know? What if my car runs that same 0-60 in the same time, but your car only runs 14.0 in the quarter. What then? Well maybe we can see that my car makes more power in a different powerband. 1/4 mile times and drag racing references are not the end all be all, but they provide a means of presenting information that most people can easily understand and recognize. But if you don't like that sort of measure than let's do it a different way. The car kicks to the right because the coeffiecient of spam between the tires and the ground is traveling at the speed of blue. |
Re: What causes the rear end to swing to the right under acceleration? (Nathan Plemons)
My God you guys just don't read what other people write do you? You're still talking about spinning wheels and 1/4 miles and 0 to 60 . All he wanted to know is why the rear end moves to the right under ACCELERATION!!!! This would have NOTHING to do with WHO IS FASTER. Sometimes you can't see the obvious. We know that a lot of you have built up and then destroyed your motors in the quest for MORE POWER but not everyone is interested in "shaving a tenth" and just needs a question answered without alot of BS. Read then type, OK. Thanks. :sleep:
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Re: What causes the rear end to swing to the right under acceleration? (rspvette)
Read then type, OK. |
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