[ANSWERED] fishtail to the RIGHT
 

The original question is here.

What about drive shaft rotation and the ring gear location that causes the one side to become heavy and the other side to lift?

So is it generally accepted that cars tend to fishtail to the right? This is not something I've noticed (not saying it doesn't happen, just that I haven't noticed it).

I think I've experienced the same thing. When accelerating heavily on a wet road, driving straight, getting some rear wheel spin, I would experience a yaw to the left or, the rear end shifting to the right (fish-tailing, assuming this is the same thing?). I found that I could repeat this again under same conditions, getting the same movement. I had to steer right to compensate. Other than the road crown, I reasoned that perhaps the torque of the engine, where the crank is rotating counter-clockwise (from the driver's perspective), and creating a torque toward rotating the vehicle clockwise, therefore would transfer a small amount of the vehicle's mass to the right side. With a little more mass on the right side, I would expect the right rear wheel to have a little more traction than the left. If both rear wheels are spinning at the moment (traction control hasn't quite taken over yet), then more traction on the right would yaw the car to the left (rear end then moving to the right).

Road Crown is a coverall excuse......the car can and does break loose causing the rear end to swing to the right.....yes it can and does this on wet pavement, dry pavement and it even happens if acceleration occurs as the tires make contact with road pavement striping. Outside ambient temps above 60 with full sun on the streets/road and the car will break free......something that might be worth looking into is the rubber compound used by Michelin as my tires are the original ones that came on the car with just over 17500 and it is a 2017 Z06 3LZ M7.

I'm not a rocket scientist, brain surgeon, or race car driver I'm just an average guy who does not track the car but the breaking loose of the rear does happen pure and simple maybe not on all Z06's but it does happen.

The original question was about a difference in traction in a right turn vs a left turn. NOT that the car can break traction. If you're looking for a car that cannot break traction, you bought the wrong car.

Well said. I have experienced this with the C4, the C5s, and other sports cars I have owned.

Agreed. I know from personal experience that it also happens with the C4 and C5 Corvettes.

I was thinking this could be related to a recent Ask Tadge response:

https://www.corvetteforum.com/forums...post1598712923

It's the rotation and curvature of the Earth. In Australia, cars fishtail to the left...

No. If there were a solid axle car, the tq imparted on the diff housing by the input would do what you're saying. But the entire drive train is bolted together; one unit from crank damper to the diff cover. In other words, the tq fed into the diff is resolved in the trans housing, tq tube, and bell housing. The net axial tq on the drive train (any one part of all of the drive train wanting to "rotate lengthwise" under the car), should effectively be zero. It should behave like a FWD engine/transaxle w/regard to reaction tq since both are all one unit, all bolted together.

has anyone asked Tadge about why the rear caster setting is backward from what most race car alignment shops (and myself) suggest are the proper settings? (i wont say all shops, because i have not talked to all shops, but all shops i have talked to say to put it the opposite way as what GM suggests for the c7 rear caster)

I believe this applies to this question by the OP, since I have driven multiple C7 that pull to one side or the other severely, which have factory alignments, and then once we reverse the rear caster angle, the car suddenly handles fantastic under hard acceleration, and does not pull or favor to pull to either side in particular (and then road crown does become the determining factor... if the road is sloped left, rear will fade out left, and visa versa for right slope/crown.

Where did GM come up with its rear caster setting, and why?

I don't "get it", what caster has to do with straight line stability (as it relates to the REAR suspension). Can you elaborate on that?

its essentially a known fact at this point that the caster settings on the rear wheels is backwards of what 6 of 6 race alignment shops i have asked, recommend it be.

DSC Sport Mike L. was the first to bring this to my attention on this forum that the rear caster setting IS adjustable on the c7. you see, in the past, a person had to get a coil over suspension on a c5 and c6 to be able to properly adjust rear caster. I could never figure out why the coil overs caused a vette to handle better than the leaf springs, as i see the physics advantages of leaf springs. Hind sight, it was the rear caster alignment that my race shop would do to the rear caster angles with the coil overs and custom mount points for the control arms.

In the "DSC SPORT ALIGNMENT or DSC CONTROLLER OBSERVATIONS" Thread in the c7 and c7z sections of this forum, and several other parallel threads about DSC, you will see a unanimous agreement that the rear caster, when set to the inverse angle as GM recommends, allows the car to handle much better and less over-steer snappy in the rear.

It has also been observed on many peoples cars, including my own, that from the factory, not only were the rear caster angles inverse of what they should be, those AND the Camber were different on one side of the car vs the other.

So what this does is, in WOT acceleration, the car has the majority of its weight on the rear 2 wheels/tires... and this means IF those 2 wheels and tires are not aligned properly, and more importantly perhaps, not aligned SYMMETRICALLY, then the car pulls hard on the rear in 1 single lateral direction every time the rear tires break loose from WOT.

once this is remedied with the DSC Sport recommended rear alignment specs, the cars handle very well and are comfortable and predictable to drive, and forgiving when the rear steps out. To get to the proper rear alignment, washer/spacer/shims have to be removed from the GM alignment settings... it is that LARGE of a change required to make these cars straight.

Most top racers on this forum can be seen on these DSC threads chiming in about how their lap times improved, and from what I can gather, they ALL had to remove spacer/washer/shims to get their rear casters right. In fact, an aftermarket bar sold from Granetelli has to be installed on the car to reach the rear caster settings recommended by DSC and by most race alignment shops, for a safe and balanced automobile, as the GM stock rear links do not even allow for the proper adjustments due to their original lengths and geometries.

I could keep typing, but there is a magnitude of information right here on this forum alone, about this exact topic, and how berserk so many people's rear alignments are, on their new c7 vettes, off the truck, straight from the BG factory.

Once I used the DSC street/track alignment the Z stopped breaking to the right. It just squatted and went.

The reason the car has a tendency to fishtail to the right is primarily due to engine torque. In a car as stiff as the vette, you can't really see the weight transfer onto the right rear wheel. But if you look at a car with poor suspension setup like this old boy here, you can better visualize the weight transfer that's happening:

https://cimg8.ibsrv.net/gimg/www.cor...2096e55e88.jpg

So what happens is the left rear tire, having less weight on it, loses traction first resulting in a net force pushing the car counter clockwise around the cg of the car.

No. Already addressed....
The car you posted a pic of is a solid axle car. In a solid axle car, the engine/trans package reaction tq, acts on the frame/body of the car and causes it to tip to one side as a result. As already stated above, In a Corvette (or any IRS vehicle), engine tq is resolved in the structure that ties the rear diff and the engine, together. In a C2-C4, that would be the car's frame rails. In a C5-C7, it is the tq tube. IRS 'Vettes launch level, with IRS.

https://cimg6.ibsrv.net/gimg/www.cor...1e12e237da.jpg



https://cimg7.ibsrv.net/gimg/www.cor...7acbb1fc13.jpg

Not true on our cars, they have torque tubes, if the car was twisted, the torque tube would have been cracked like a roll of muffins. Thats the reason our cars dont do this... torque tube connects trans, rear diff to the engine. Its all 1 piece, or its broken if its 2 pieces.

has little to nothing to do with the type of rear axle... it is the torque tube that unites the engine to the trans and the rear diff as one piece.

It's not about launching level. It's a question of basic physics. Newton's 3rd law, to be precise (for every action, there is an equal and opposite reaction). The motor twists one way, it's going to twist the car the opposite direction. No matter how well the car is set up, that right rear tire is going to initially have more traction due to weight transfer from engine torque. Solid rear, IRS, torque tube... doesn't matter. You still have two big old engine mounts up front that are going to throw a certain amount of the engine's torque directly into the body of the car without going through the suspension. And that is going to initially transfer more weight to the right rear tire than the left, causing the car to fishtail to the right.

The top fuel guys tried to solve this back in the day by running a "sidewinder" engine. It was a good idea in theory but there were some practical obstacles that never got solved adequately.
https://cimg5.ibsrv.net/gimg/www.cor...7231801d6d.jpg

You're not "getting it". It does matter. Here is an opportunity for you to learn a thing, so pay attention....
Look, take your example in the pic above. Lets say that engine makes 500 lb-ft. The trans is bolted to the engine; they're one unit. The trans multiplies engine tq by about 3:1 in first gear, so we're sending ~1500 lbs off tq down the drive shaft, right? Right. You are right in this example, the 1500 lbs of REACTION tq (the opposite and equal reaction) is going to be send into the frame/body of the car, causing it to tilt. But the car stops tilting at some point, right? It doesn't barrel roll down the track from reaction tq of the engine/trans, does it? Where does that tq resolve...and stop the car body from listing to one side? Through the rear springs (and fronts, if it's still on the ground).

Now look at an IRS car. ANY IRS car. Let's use the C2/3/4. Same 500 lb-ft engine, same gearing, so engine/trans "unit" sends 1500 lbs down the driver shaft. At launch, you're putting 1500 lbs of twist into the rear diff housing...right? Right. If that Diff housing weren't bolted to the frame of the car, what would happen to it? It would twist clockwise like a mofo! It would spin uncontrollably, in the same direction as the drive shaft it turning. Since it IS bolted to the frame of the car, that force is sent into the frame of the car. SO, you have the engine/trans unit at then front of the car applying 1500 lbs of reactive tq to the frame, in a CCW direction (opposite crank rotation as view from front of car). You have the diff housing, applying 1500 lbs of reactive tq to the frame, in the CW direction. That tq is resolved through the frame of the car...or the frame twists up like a candy cain if it's a real shit box. :lol:

Now, in the C5,6,7, the whole thing is simplified b/c those opposing, reaction tqs between the front and rear are resolve w/in the assembly itself; the engine/bellhousing/Tq tube/trans/diff....b/c they're all bolted together in one piece. The only meaningful tq exerted on the body is the tendency to lift the front end; the reaction tq of the drivetrain trying to rotate the rear tires. That's precisely why my pics show IRS 'Vettes launching level...and you're SRA car launching all "crossed up".




What kind of "obstacles"? I think that nearly every FWD car, motorcycle, and snowmobile would beg to differ with you on that. :yesnod:

No, YOU'RE not "getting it". So pay attention, you may learn something. No matter how you bolt the powertrain into the car, the crank still rotates. And Newton's 3rd law states that in order to accelerate the crank, you have to exert an equal and opposite force. So you have a twisting torque trying to rotate the car against the crank, lifting the left side wheels and pressing the right side wheels into the ground. Thus you have a higher coefficient of friction on the right side than you do on the left, and if you apply enough force to break traction on both tires, the car will lose traction on the left side first, causing the fishtail. The reason I posted that pic was because it illustrates this very well. Just because the corvette suspension is more sorted out doesn't mean the forces don't still exist.

You can see in these two shots, that even though the vette is launching better than that old impala, the left wheel is higher.

https://cimg6.ibsrv.net/gimg/www.cor...d858f985c9.jpg

https://cimg7.ibsrv.net/gimg/www.cor...baff63e357.jpg

As far as the sidewinder dragsters, you can look those up yourself. Don Garlits was the one I remember as a kid running a top fuel sidewinder. Look him up.

You just posted pictures of 2 c4 vettes, and guess what neither of those 2 cars have? A torque tube :willy::thumbs:

As to your "weight of the crank being enough to exert force to one side of the car or the other to cause frame twist" theory....

then revving the car in my driveway in neutral will show the total force you speak of. :rolleyes:

Further, most people launch at 2-3000 rpm anyway, so the crank has already undergone its acceleration and has already exerted its force on the car, and then everything equalizes again once a steady RPM is reached (but still, this is a tiny force to begin with)

The twist that you are siting in the photographs is on cars that have a conventional drive shaft, and the frame of the car has to prohibit the engine and trans spinning one way, and the rear diff and rear axle spinning the opposite.

It would help your argument if you posted photos of cars with torque tubes , and then showed me THOSE CARS twisting. I'll go grab a snickers while you look for one :lurk:

Please, think about this a little longer this time because i know im correct. You are not.

https://cimg3.ibsrv.net/gimg/www.cor...a6b9cc5554.jpg

well, you are about to have a whole forum of people politely come down on you, because a car with a torque tube cant twist its frame unless the torque tube is also twisting, which they don't do, they are solid or they just snap.

They are made out of barrel woven/rolled carbon fiber these days in the c7z's.. where the whole thing is made from a single strand of carbon fiber that is ran up and back the tube during construction like kite string or fishing line on a spool.

Pretty brittle stuff.. aka no give.

And the reason why torque tubes DO CRACK is because they are FIGHTING TO PREVENT THE CAR FROM TWISTING 1 IOTA DURING THE CAR'S LAUNCH, and cars with enough Torque and Traction sometimes win the war and get the car to twist, and that equals a cracked torque tube.

Post up another smart guy meme, and pretend im the dumb one.
https://cimg5.ibsrv.net/gimg/www.cor...f995fd6a06.jpg
https://cimg6.ibsrv.net/gimg/www.cor...382574c6a6.jpg


https://www.corvetteforum.com/forums...e-cracked.html

I don't think your mind is where it needs to be for learning to occur.

I posted a pic of a car w/a tq tube; a C5. I also posted a pic of a IRS car w/o a tq tube; a C3. Doesn't matter; the tq is resolved w/in the frame of the car, either way.

Who said anything about "the weight of the crank shaft"!? Not me.

Finally, I don't need to look up Don Garlits; know who he is...but far more importantly, I know how well transverse mounted engine work in cars, bikes, snowmobiles and other machinery. Since we as humans, already know that transverse mounted engines work...the burden of proof is on YOU to show how the millions out there running around, "have obstacles" the prevent them from working. :lol: :thumbs:

You are not correct and repeating the same comments over and over about solid rear axle cars, ain't gonna change the facts that pertain to an IRS car. You need to open your head and use your brain. I'm thinking about the "leading a horse to water...." right now. :ack:


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Read the 4th paragraph/sentence down....

RESOLVING ENGINE TQ THROUGH THE FRAME

From the Engineer:
"A channel section is a very poor conductor of torque. Round sections are used to do that i.e. the round shape of a hollow drive shaft.

One other thing, the rocker beams are vey effective in resolving the torque exerted by the engine and differential through the engine mounts and bat wing as the rails are far apart from the center of the car. The torque gets resolved into a force couple that is extered up and down on each side of the frame rails."

Note from the first sentence, about a round tube for managing tq. Like the tq tube in the C5* cars. :yesnod:

BTW; the two cars that you posted pics of a solid rear axle cars. That's why the left wheel is up higher. Gotta have all your facts right to have credibility and make a point. :thumbs:



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Here's why sidewinder dragsters don't work, for those of you too lazy to look it up: https://www.nhra.com/news/2018/don-g...der-top-fueler which probably explains why they're not used by a single top fuel or funny car today.

And I'm thinking of "You can lead a fool to knowledge but you can't make him think". You guys are claiming that the torque tube and IRS in the vette is a perfect system and zero torque escapes. Wouldn't that require aluminum and steel to be perfectly rigid materials, not to mention the frame to also be perfectly rigid? Which I guess you can pretend it is as long as you're not actually out on the drag strip.

For someone who doesn't 'get" forces and basic physics, you come off pretty damn cocky.

Can you explain to us how "tq escapes"? WTF does that even mean!? Wow...yikes.

If you put a tq wrench on a long extension and apply 100 lb of tq to the extension, you'll twist the extension -like a torsion bar. You're applying 100 lbs of tq to a slightly twisted bar which is connected to a nut that's not turning. Is torque....."escaping"? :lol:

Nice rip-off and reword of my horse/water phrase. :roll eyes:

And FYI, I'd bet that I drag track my cars more than you do...but that ain't necessary to know how a car, structures and basic physics work. You read the link I provided? :toetap:

??? you were not the one i was tango'ing with, it was the other guy. I have no objection to your original posts. Your c5 photo proves my points. I thought you and I were in agreement?

but now I am seeing that we arent, so this is funny...

alright, lets explain this in a way you can imagine...

have you ever seen a c5 rolling torque tube? (its like a rolling chasis, except the frame is absent.

A c5 c6 c7 rolling torque tube... can be driven, you could sit on the torque tube and run throttle controls manually, as long as you mount a gas tank to the thing. You could have subframe at the front and a separate sub frame at the rear, but NO FRAME RAILS CONNECTING THE FRONT AND BACK OF THE CAR.... ONLY THE TORQUE TUBE.

Lets say you take off WOT... and lets say you COULD get grip...

the front axle and the rear half shafts will NOT twist/clock/torque from each other. The torque tube prevents it. If enough torque overcomes the torque tube, it cracks, and now the frame of the car feels the force for the first time.

But assuming it does not crack, the only force you have left is the force of the crank weight and a thin driveshaft which weighs very little.

Again, that "force" of the crank and the drive shaft, can be felt just by putting the trans in neutral and revving the car from 1000rpm to 6500rpm in the blink of an eye.

now, a real car going down a track does not go from 1000 to 6500 in the blink of an eye, so the energy/force is broken up over more time, so its even less force than the force you feel revving your car in neutral.

The frame of the car DOES NOT FEEL TORQUE when a car has a torque tube, not from acceleration at least. Curves and driving, different story.

The back half shafts and the rest of the car only feel a torque which tries to make the car wheelie... there is no barrel roll torque force on the car (except the amount of force you feel when you rev your car in neutral in your driveway... which is next to nothing.)

Any questions class?

You could remove the front axle and ride a wheelie.. and with the engine up in the air in front of you, and no frame in the front of the car at all... the engine will stay level with the rear axle... there is not exerted force, the torque tube STOPS IT FROM OCCURRING...

its like me saying im going to push you really hard, but there is a brick wall in my way... between you and I. I can push on the brick wall as hard as I want, and you on the other side of the brick wall, and you will feel nothing, you never feel my force... unless i break the brick wall, and then you feel my force... just like the cars frame feels no force until the torque tube is broken, then it feels barrel roll direction of torque.

The torque tube stops all barrel roll torque from occurring on the rear of the car, let alone the front. The only force is the crank and drive shaft inertia/momentums as the engine accelerates or decelerates rpm..... the slight force you feel when you rev your car in neutral... that's it.. thats the total force all packed into 1 second when you rev your engine in neutral. And its a tiny/negligible force

So what are you guys talking about right now?!?

The small force does on average cause the one tire to get slightly more grip and the other to break loose first... but once the car has launched, assuming both tires are now "hooked up", then these forces you are speaking about become a moot point.

So, if a person's rear end breaks loose and the car always pulls to one side, that can be changed by the toe and the camber and the caster of the rear wheels.

For instance, if I align the wheel that grips to point to the left, then the car will go left when the other breaks loose. If i align the wheel to the right, the car will go right when the other breaks loose.

Alignment is everything on cars with rigid carbon fiber torque tubes, and the DSC rear alignment settles the car down in a hurry. Which is why im saying, what you guys are talking about has nothing to do with solving the problem, and it CAN and has been solved many times.... with corrected alignment

Sorry, I responded to and quoted some of the wrong posts. My bad.

No, you and I are in complete agreement. W/the tq tube, you're not going to be lifting the left front wheel, and there is no reason why the car should slide one way or the other in a burn out, other than something is broken or out of alignment, or road crown. Just as Tadge suggested.


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Tom400CFI is correct.

Per Thomas Gillespie's "Fundamentals of Vehicle Dynamics" :
"Transverse weight shift occurs on all Solid Drive axles, whether on the front or rear of the vehicle. The basic reactions on a rear axle.....The driveshaft into the differential imposes a torque T_d on the axle. ...The chassis may roll compressing and extending springs on opposite sides of the vehicle such that a torque due to suspension roll stiffness, T_s, is produced. Any difference between these two must be absorbed as a difference in weight on the two wheels. ...."

This applies to solid rear axle vehicle not our Corvettes. As Tom400CFI stated, with our cars the Torque imposed into the rear axle is absorbed by a torque tube or by the frame rails on a C2-C4. Say traction is completely lost and the rear tires no longer have a coefficient of friction with the road surface (It's only diminished in the real world not eliminated) the torque produced through the drivetrain is absorbed by the torque/frame rails meaning that there is no effective weight difference applied to the wheels save for the static loading which is generally driver heavy. NOTE: I'm talking about a standstill burnout. The cause of the Yaw is most likely the road surface. When a 0.035G turn effect acts over a period of time the car is going to move unless something acts against it. Generally the forces presented through the tire friction and into the sidewall stop this from happening but once the coefficient of friction is greatly diminished it makes it more "difficult" (Physics people don't hate me for saying that) for the tire to stop the yaw from happening. Say we have an AWD vehicle with LSD front and rear. If they were doing an AWD burnout and "eliminated" (not really the case) the coefficient of friction then they would slide off of the road. In reality, if you can calculate the coefficient of friction of the heated rubber in a kinetic state and you knew your weight at each rear tire you could estimate if the C of F can retain the vehicle through sidewall force. This is actually a much more Dynamic problem that gets deeper than this but that is the basics of it.

Colton @ CSM Performance LLC

Here is some reading for you....

A GOOD READ

another way to think about it is...

if you attached a shopping cart crazy wheel to the bottom of the engine oil pan on a c5-c7.. and only had the torque tube as the only member going forward to the engine, and had the complete rear sub frame and axles and diff...

so you have a trike now basically, with no frame rails of the vehicle to the front of the car....

and you floor the car WOT while the car is in first gear, the engine will stay level side to side in the barrel roll direction.

So if the engine stays level there, how on earth is it exerting force on the frame of the car, as other car makes and models DO since they LACK a torque tube?

Again, its like someone being on the other side of the brick wall, and me pushing on the brick wall, i am exerting a force, but the brick wall is stopping it. Only if I break the brick wall, does the person on the other side feel my force....

Only if the torque tube breaks, does the frame feel any barrel roll torque rotational forces... otherwise there is no extra force on one wheel vs the other, other than the negligible force of the crank and drive shaft inertia/momentum.

What's in a name? The Torque Tube
 

I hate to jump into the middle of this but respectfully, I think there is some misunderstanding of what a torque tube is. It’s not meant to deal with torsion along its axis (although that’s what it sounds like - as in a Chrysler torsion spring). If you look at the three items below:

1. A WIKEPEDIA article:
https://en.wikipedia.org/wiki/Torque_tube
see where it states, “CONSTRUCTION
The "torque" that is referred to in the name is not that of the driveshaft, along the axis of the car, but that applied by the wheels. …”


2. A comparison (crude drawing),
"Hotchkiss drive and Torque tube drive":


3. Best of all, A Youtube with Tadge explaining it on a C7 assembly line. Watch Tadge between 1:32 to 2:25 minutes.
"(MOTO-MAN) Chevy Corvette Stingray C7: Behind the Scenes of it's Design, Engineering & Build - Part One":


The torque tube in cars like C5, 6, &7’s takes on a tremendous amount of torque that is trying to lift the front end of the car by the differential reacting to the rear wheels (as Tadge explains). I don’t believe the torque tube makes any difference as far as “fish-tailing” forces are concerned and also wether there is independent rear suspension or solid. The engine is mounted to the frame, the differential is mounted to the frame or the solid axle which is mounted to the frame thru the suspension(wether there is a torque tube present or not). If the engine is developing torque there is an equal and opposite torque that the engine block is applying to the frame through its mounts. If the wheels are kept from turning (locked for the sake of argument and the engine is still producing torque at zero RPM), then an equal amount of torque is trying to twist the differential, frame, and torque tube (if there is one), leaving a net rolling/rotational force of zero. It doesn’t matter wether there is a torque tube or not. Either there are torsional forces on the torque tube and the frame, or just the frame. If nothing bends or breaks, it’s all the same. When the car is launching and the rear wheels are digging in (or burning), there is less torque trying to twist the rear of the frame (in the same direction as the drive shaft) as large amounts of torque are applied to the rear wheels against the pavement but, the engine block is still applying torque in a counter direction, to the frame, through its mounts, undivided. therefore there is a net rotational force tending to rotate/roll the car clockwise putting more weight on the right side. There are probably hundreds of variables that will vary this effect like transmission and differential gear ratios, suspension, weight distribution, wheel span, center of gravity, etc., but it’s there.

This part? Correct. Dead on, right.


This part? wrong. How much tq the engine block is still applying torque in a counter direction, to the frame, through its mounts....if you remove the drive shaft from the car? Effectively, none. As tire traction diminishes, tq load on the entire drivetrain does as well...all the way to the clutch plate. The only tq the engine block is applying to the frame through it's mounts, is the reaction to accelerating the crankshaft, flywheel and harmonic damper...which I'm going to go out on a limb and say is essentially meaningless -especially since most of us don't launch a car from 0 RPM.

The tq tube does do double duty as acting like a tq arm under acceleration...but that's not all it does.

I have to correct you so the other guys dont group you with me.

THe torque tube does change fish tailing characteristics for all the reasons all of us explained above.

A car where the frame twists with NO torque tube, it puts more weight on one rear wheel, so the other has less weight and breaks loose first.

if i sat in the passenger seat of your car and you went WOT at 30mph, and I could control with a switch which of your 2 back tires would break loose first, then i could systematically control which way your car would initiate its fish tail, assuming there was no crown in the road and your steering angle was straight, and your alignment symmetrical.

So, yes, torque tubes affect which way a car fish tails more often than not, for that reason.... or more specifically, preventing it from favoring one side.

Disection:
Wiki and vid #1: Here you are comparing a live axle, using a Tq tube...ready for this? That is not connected to the transmission in a way that provides radial stability. IOW, the tq tube you used in your example has some type of "ball and socket" attachment to the trans or frame of the car. The Corvette, the diff is bolted to the trans, rigidly. The trans is bolted to the tq tube, rigidly. The tq tube is bolted to the bell housing, rigidly. The bell housing is bolted to the engine block, rigidly. They're effectively ALL ONE UNIT...just like that in a FWD or for that matter a mid engined car....just spread out more. Any tq that the engine imparts on the diff housing during a launch is immediately resolved, back through the diff case, trans case, tq tube, bell housing and back into the engine block.

Vid #2: Tadge is totally right. The reaction tq to wheel tq is sent down the tq tube, trying to lift the front of the car. He neglected to mention that the reaction tq to engine tq is also resolved through the tq tube. In realty, the first force, wheel reaction tq is sending a BENDING force down the tq tube, trying to bend it as it lifts the front of car. The engine tq is trying to twist it against the diff. That twist is equal and opposite the resistive forces of traction and trying to accelerate the car...so, they effectively cancel each other out.

Actually there was nothing mentioned in the original question about turning left or right. In fact I took it as meaning accelerating in a straight line which way the rear end stepped out. Because honestly I'm not sure how you could compare fishtailing when turning left or right. You're obviously not going to have that back end swing to the right as you're turning right LOL
And the rear does always seem to prefer to kick to the right when accelerating in a straight line from my experience in C5s, 6s, and 7s.

I’m not sure I explained my original question as well as I should have. Maybe, I should have said…

On a totally flat road, turn off TC and StabiliTrak, point the steering wheel straight ahead, put the car in first gear, and, floor the accelerator. Does the car fishtail to the LEFT, -OR-, to the RIGHT, -OR-, does the car go precisely straight ahead, AND, why?

I suppose this is reasonably, easily test-able, but I was looking for an engineer’s perspective to validate my perception that the car will fishtail to the RIGHT (meaning the rear of the car kicks out to the RIGHT). If the road is crowned, you could do the test on "both sides of the crown”.

I had already seen where Tadge said that manual trans C7Z06 and C7ZR1s have different shafts to prevent “power hop”… https://www.corvetteforum.com/forums...and-axles.html #hammerdown

Once you break the rear tires loose, you have no meaningful lateral connection to the road (CSM performance already covered this in post #31). The rear of the car will drift left, right, or not at all depending on the forced acting on the car. The forces would be:
*Gravity -if the road is tiled, crowned...whatever
*Forces exerted on the chassis by the rear tires -if your rear toe alignment were off, or your thrust angle were off, it would be inclined to push the rear of the car in one direction.

If I truly wanted to diagnose this, I'd start by getting a spot-on alignment (factory alignment is almost for sure, not right), then go do some burn outs and ascertain the levelness of the road. In reality though....who GAF? Do a burn out, if the car steps slightly to one side or the other, steer with it, and enjoy the ride....right?


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And yet, despite all of that pontificating, the vette still fishtails on a flat surface. Not a crowned road. A parking lot. I guess his torque tube is busted. :shrug:

ZMMMMM asked a great question...one for the ages and Tadge’s response was both enlightening and educational. One of the best “Ask Tadge” to date :thumbs: :thumbs:

top fuel dragsters have the back wheels close together so they don't fishtail on burnouts or at top speed. . try doing a burn out on the other side of the road where the low side of the road would be on the left of the car and see what happens

Now wait a second. On the first burn out, rear of car went right...."like all Corevettes do" (apparently). Right? Then when that tool turned around and came back...rear of the car went LEFT. Wait...WUT?

In both instances, car's rear went very slightly to the camera person's right. I'd say the parking lot sloped slightly to the right. Broken tq tube or not. :rolleyes:

I said road slope matters.

I said vehicle barrel roll torque does not.

You finally agree with me Tom and Stone.. im just going to see how long it takes you to realize it. Few more hours perhaps. Slowly but surely.

The fact that the car fish tailed one way going one direction, and the other way the other direction, shows that Stone's theory that the cars torque weights and favors 1 wheel, is not true.... not when a torque tube is solid and doing its job properly.

Torque tube is not busted Stone, it did its job very well.

...Few more hours perhaps? Maybe days? Sooner or later though, Slowly but surely.

That's pretty sad, that this is the "tech" people want to glean from Tadge. Then they argue about what the guy told us. :rolleyes:

Say what? I never disagreed with you. And I've realized that all along. :confused:

the "broken torque tube or not... and eye roll"... made me think we are on different pages.

I will state that IF the torque tube was broken, then there would be frame twist in the barrel roll direction, and that WOULD affect one tire breaking loose first each time, and that WOULD cause the car to fishtail to one side most of the time (unless the slope it was on was pretty severe to one side or the other.)

I got you. No, I was poking fun at stone for the "broken tq tube" comment b/c of course we all know it wasn't broken.



Nope. The frame is way, WAY more than capable of resolving the tq between the engine assy and the diff. The frame would not flex in a meaningful way. Not sure if the diff ears/frame mounts on the C5^ could handle that load since it wasn't designed to though.

it actually would flex, and that slight bit of momentum/inertia will always put weight on one side of the rear axle and on one rear tire beyond the other... if there is no torque tube to keep it all very rigid.

I guess. I mean, even granite flexes, so yeah, it'll flex. A meaningful amount? No. Just like even though an aluminum (of steel) tq tube can flex ('cause everything flexes some)...it ain't a meaningful amount as it relates to this conversation.

The C4's frame is designed such that it's stiffness is ~2770 ft-lb/degree in torsion. Well...the baddest assed engine ever put in a C4 made 375 lb-ft*2.66 first gear ratio...so that car is sending 997.5 lb-ft down the drive shaft, into the diff and into the motor and diff mounts in reaction tq. So maybe it's twist the frame 1/3 of one degree? Not sure how much "momentum" you're going to build in the twisting direction with that degree of amplitude. Not much. I'd bet money that you get more twist, slop and variances in all your rubber bushings -drivetrain mount and suspension mounts.

The frame doesn't flex in torsion, a meaningful amount.

its not the flexing 2 inches that matters, its when the frame catches and rebounds a bit.

So lets say the drives side goes down and passenger front frame goes upward (im too tired to think which way it should or shouldnt go right now, so just roll with me here for a sec)

Lets say car could pop a wheelie... and does...

passenger side starts going up and drivers side down... it only goes so far before frame stops it... so as the frame stops it, the front has momentum in the counter clockwise direction. For the rear of the car to stop this, it has to have force in the clockwise direction...

and this puts a lot of extra weight for a moment on the drivers rear wheel, and lightens the load on the passenger rear wheel, and thats that... passenger side unhooks, and its over.

Happens like clockwork every time (but i cant remember what side right now because im tired and getting old)

2 inches?? Who said anything about 2 inches? Not me. I said, 1/3 of 1 degree. That is such a small amount, you couldn't see it happen. I highly doubt that there is much "rebound" from that....just as the "rebound" in flex of the tq tube is meaninglessly small.



Yeah? Here is a guy on the C4 forums that has an '84, IRS intact. I don't see the frame bouncing/rebounding/momentum....It just launches straight and level. Like ANY IRS car should.

C4 Launch/fast pass on IRS

Also note that his rear didn't (ahem) slide to the right. :lol:


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i believe torque tube prevents it, and ill leave it at that. 2 c4 photos above launching wheelies easily demonstrate AT LEAST 2 inches of rotation to the front of the car. And yes, that is well over 1 degree.

Right. Those two pics were of C4's with a solid rear axle conversion and are not relevant to this conversation. Any IRS prevents it b/c the tq is resolved through the frame, which is way stiffer than stiff enough....and I'll leave it at that. :thumbs:

It happened to me when I kicked down at 70mph ZR1 ( a little scary )

And yet the car fishtails. You guys are grasping at straws. :lol:

https://cimg7.ibsrv.net/gimg/www.cor...34e91f22c0.jpg

Found a Meme you like? :rolleyes: You going to use it in ALL your threads now? :beatdeadhorse:

Are we? Here is what Tadge (the chief engineer for the car) said.

Quote:

---

Originally Posted by Tadge

I think you guessed the major factor in your question: Road crown. Although barely noticeable on many roads, virtually all have some degree of crown.

---

Likewise although barely noticeable in many parking lots, virtually all have some degree of slope...for drainage. :yesnod: The car in the vid went to the opposite directions in both burnouts. What's more likely: the parking lot was sloped to the camera man's right? Or the engine was running in reverse rotation for the second burn out?

Talk about grasping at straws. :crazy:



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Of course it is going to fishtail, but how much relative to another format or moment in time? One tire is always going to break loose before the other. Top fuel dragsters may slightly fish tail during their burn outs, and they are designed not to at all.

We dont know what the driver was doing or how flat the surface the driver was on.... does not mean torque tubes still dont make your original posts null and void about frame twist. Torque tubes do, your first post was irrelevant to our cars c5-c7

Forward to 1:30.

:lol:

Must have had a broken Tq tube.

https://cimg9.ibsrv.net/gimg/www.cor...8945a854b6.gif

where did the car twist? something else was the problem, not the car twisting. You guys dont even make any sense anymore.

Every time the car spins, it's fishtailing to the right. You can see that Cleetus has to correct the same way each time the car spins, turning to the right to keep the car straight. This is on a perfectly flat drag strip, so no sloping parking lots or whatever excuse Tom was trying to use with the last video.

First it was IRS cars don't transfer weight unevenly, then when I showed a pic of a C4 obviously doing exactly that, suddenly it shifted to torque tube cars don't transfer weight unevenly. So I showed a vid of a car doing exactly that, and the excuse was a sloping surface. Well, that's a drag strip and it's as level as it gets in the real world. That car, Leroy, is a torque tube car and it consistently fishtails to the right when it spins. Tadge is going to have to come up with another explanation.

show me a car with a torque tube, twisting as it wheelies?

you wont find one unless it is made out of not so rigid metal that has fatigued over time

And ill bet a lot of money that a different alignment fixed their problem, and if not that, then changing out the rear diff/axles

Those 2 are the problem on these cars, not the frame twisting.

I dont see why this is such a hard topic for you to agree with and grasp.

I was joking. It was a joke.

My BET is that the track DOES have a slight grade. It's needs to shed water to some degree. Otherwise, I'd put money on alignment. There is nothing magical about corvettes that make them "go right". They're not George Costanza.

https://getyarn.io/yarn-clip/embed/0...autoplay=false

https://getyarn.io/yarn-clip/35afc2f...9-3bc3da25b893



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Never said frame twisting was the issue. I said the physical forces are distributed unevenly to the rear wheels, whether solid axle, IRS or torque tube. The torque tube design is certainly superior to the solid axles, but it's not perfect. Tadge thought it was the road crown causing the fishtail bias to the right, but a video of a stock car in a parking lot and the vettecart consistently fishtailing TO THE RIGHT going down a perfectly flat dragstrip, prove conclusively that the system isn't perfect.

I dont see why this is such a hard topic for you to agree with and grasp.

and i said the only force that puts more weight on one side of the car vs the other, is the momentum/inertia of the crank...

which can be simulated by revving your engine in neutral in your driveway.

All the other forces you speak of are blocked by the torque tube, and you still dont get it. Its like me pushing on you with a brick wall between us... you feel nothing.

how many times do i have to explain this. The crank's inertia/momentum forces are it. And its not much.

Go rev your car over and over in your driveway and make a video of how much the car pushes to one side. Better, yet, go put your car on a 4 point scale system and rev it over and over there, and report back to us, that fluctuation in weight from one side to the other is the total force a c5-c7 feels during launch... and technically, it is much less, because the crank is accelerated much faster in neutral than it is at a track, while in gear, so the forces at the track are probably 1/4 the weight transfer that you will achieve revving your engine on a 4 point scale.

Is it enough to break one side loose before the other? in some cases yes. Is it also possible to put extra weight on the other side of the car to counter it and make the extra weight on one side balanced out? yes....

So your theory is not absolute, nor is it as much force as you are leading on... WHEN A TORQUE TUBE MADE OF SOLID CARBON FIBER IS INVOLVED.

GET IT YET?!

Keep pretending im the one who is confused, ive clearly explained this from my first posts.

You are the one people are laughing at.

Right? I was thinking the exact same thing! Weird how that works. :lol:

Ahhh...dude. The video that YOU posted to drive home your point? The Parking lot vid? The car fishtailed to the right leaving the camera man....but it fishtailed to the left, coming toward the camera man. Go re-watch your own video.

You video supports the point that the car is going to drift in the direction of the slope....just like the chief engineer of the car says it would. I dont (sic) see why this is such a hard topic for you to agree with and grasp.

Nope.

the LG video you posted i agree with, and it has nothing to do with barrel roll frame twist from front to back of the car...

instead, it has to do with rear suspension, and the control arms bending forward equally on both sides, as each tire pushes the car forward under hard acceleration.

So why would you post "nope"?

go look in the mirror and say "nope" because this video proves what i have been saying all along.

Yep. You do realize, that both wheels are deflecting the same amount....right? So how would that undesirable characteristic, always make the "Corvette go right"? It's not George Costanza. :lol:

I noticed that the car went to the right while on the drums under acceleration in the video. Should have been level, so something caused it. Always thought that it was the left wheel being pushed down and the right lifting due to the driveshaft torque direction.

This has been thoroughly covered in this thread already. An IRS car can not "push down" on either wheel, harder than another wheel due to driveshaft tq. That tq is resolved through the frame of the car, or in the case of C5^ Corvettes, it's resolved through the tq tube. There is also the issue of the jointed axle shafts which are very poor at exerting "downward force" through their joints.

The car on the drums could have only "went to the right" as a response to tire direction -alignment. The gooey bushing exacerbate the situation making it harder to align such that the wheels are pointed straight under load, but both wheel arm bushings should flex similarly and have similar, error in their toe, etc.

Amazing you were able to measure the wheel movement on both sides from that video, especially when they only showed the driver's side wheel. :lol: My x-ray vision doesn't work as good as yours. What I did see, though, was thateven with the bushings replaced by monoballs,the rear of the car STILL shifted right under acceleration, even on the dyno. The car fishtails to the right. No slope or road crown necessary.

You need to look in the mirror and ask yourself if it's actually more important to solve the real world problem posted by the OP or convince yourself that you've "won" a forum thread.

Don't pay any attention to him. He initially denied the car had an issue with fishtailing to one side, and now he's like that guy in the left lane that passed you, then slowed down, but doesn't want to give up his position even though he made a mistake, so he keeps speeding up to get ahead of you, but then slows down, until you catch up again and he speeds up again; when he just needs to move to the side and admit he can't keep up.

both rear wheels move forward (toe in) under hard acceleration, its common knowledge. Quit pretending they dont. The entire rear end is not shifting to the right, the torque tube and car's frame make it impossible for the whole rear assembly to shift right. You are so far in left field now, its unreal.

im done here, you aren't all there upstairs.

Likewise. You post a video contradicting your own point...then continue to argue. https://www.corvetteforum.com/forums...lies/crazy.gif

I totally agree. Your brain should be able to recognize that both wheels are going to do about the same thing. Should. :rolleyes:

Sounds like you have some experience with this? I've seen you out on the road. :yesnod: :(

S-breaker...why don't you just go run a test w/your own 'Vette? See what happens? :yesnod:

Good point

I have an 08 Z06 It ALWAYS kicks the rea out to the right when the wheels slip. That includes burnouts at the drag strip (dead flat concrete pad)

Not sure why

Right Hand Rule for Torque
 

This was the way I learned about this years ago. High school physics as I recall.
whttp://hyperphysics.phy-astr.gsu.edu...gmec/vtord.png
When you spin your tires, torque is applied 90 degrees to the plane of rotation. Assuming a flat surface (no crown), the torque applied to the axle(s) is to the driver's left as shown in the diagram. The equal and opposite reaction to this torque is your rear end stepping out to the right. Happens to me all of the time. :D

Saaaaayyyyyy......WHAT!?

I have a fairly extreme case of yaw on acceleration. I have a 07 Z06 with 560 crank horsepower that only weighs 2851 pounds. In second gear with a 345 tire I can slowly open the throttle near idle and at WOT and 3200 RPM my tires will spin violently. I don’t want to jump into the theory battle, I only want to add my experience. With me in the car it showed 210 pounds more weight on the left side of the car. I assumed that I was getting more left side bite causing my car to yaw right under wheel spin conditions. I added a little wedge to the chassis. Left front up half a turn and right front down half a turn. In the rear, half a turn down on the left and half a turn up on the right. Now, instead of a hard yaw to the right I get a tiny wiggle left then it goes dead strait. I did this strictly for the street and I do not track the car. I have never dragged the car but it might help there.
Gary