Okay, terminology, the tire with traction sees an equal amount of torque at zero RPM. You're saying Quaife should call their product not an automatic torque biasing diff, but an automatic RPM biasing diff?

 

Oh, in your lifted tire scenario, although it is not really the case I could argue the stationary wheel really is seeing zero torque at zero RPM, and the torque does not begin to exist until the exact moment drag is applied to the spinning wheel.

This is the age old thing like trying to push a house, you sweat and expend a lot of your own physical energy, but you're really doing zero work (and zero power....)

 

torque is a rotational force

& no offense, but you whole post sounds wrong...

EDIT:it took me a while to spell offense right...heh


[Modified by b18cya, 3:50 PM 8/14/2002]

 

Yeah wait a minute wait a minute. Torque is a force applied over a distance, right? Be it degrees of rotation or length of string winding around a crank.
Say I have an open diff and my motor has 150 wheel lb ft. My car is in the air, my friend puts it in gear and step on the gas. You're saying 150 lb ft of torque is being evenly distributed across the front wheels? I guarantee you I can hold one wheel still as my friend steps on the gas. I am not certainly capable of holding 150 lb ft with my bare hands am I? Plus as it's not turning, no distance traveled, zero torque. What gives?
Then again electric motors make torque at zero RPM.

 

I think you can hold 150lbft of torque. But with the tranny, the torque is multiplied.

Still clueless, but trying.

CB

 

That's exactly it. The stationary wheel really is seeing nearly zero torque (I did say nearly zero because of friction in the opposite side driveline) because it takes nearly zero torque to spin the wheel that's in the air.

 

Power is force over a distance as in HP = (torque(ftlbs)*RPM)/5252 (interesting trivia - at 5252 RPM an engine is ALWAYS making as many ftlbs of torque as horsepower)

Like the pushing the house example, you are exerting a force ("linear torque", if you want to think of it that way)but there is no distance involved. If there were distance involved, you'd have done *work*, as you say.

When you friend steps on the gas, 150ftlbs of torque will be applied to both wheels equally, accelerating the unloaded wheel. AND because of the rotational inertia of the unloaded wheel, there is a torque developed and that will be applied to the stationary wheel until the spinning wheel stops accelerating (when the engine reaches redline because there's nothing keeping that wheel from accelerating infinitely because nothing is pushing back @ 150ftlbs (ok, just some friction but it's a huge RPM where that cancels the torque)).

Does that make sense?

As far a a welded diff goes, it does NOT guarantee equal torque, it guarantees equal *speed*. If you have one wheel on concrete and the other on ice, full torque will be applied to the wheel on the concrete because there's nothing puching back on the ice wheel and that creates a condition of no torque on the ice wheel.

So do this, put the drive wheels of your car in the air, start it up and let it idle in 1st gear. Put on some heavy gloves, go to one wheel, and have another person do the same with the opposite wheel. You'll find that when he does not apply any torque to his wheel, you can freely stop yours and vice versa. But as soon as he starts to apply torque through friction, you will get just as much resistance to stopping the wheel as he applies to his - and also vice versa.


[Modified by 'scortRacer, 2:15 AM 8/15/2002]

 

Nope, because of the bias ratio of a helical limited slip device, the loaded tire will get <bias ratio> times the torque as the unloaded one. If you jack up one wheel of a helical limited slip, it will rotate freely just like an open diff because if there is zero torque on the unloaded wheel, 0 times anything = zero.

 

Didn't mean to spark a differential discussion but informative nonetheless

BTW it wasn't the power steering cutting out. I'm 100% sure of that. Must've been understeer. And that was because of the turning/accelerating thing...which in turn is from slowing down too much going into the corner...I think.

 

Try to force yourself to go slower in a corner like that. You will be amazed when you can finally force yourself to do it. When I was new, I used to go through sweepers stuck on the outside, four wheels a-squealin', unable to do anything about it. Then I finaly made myself slow down and it felt like my car had twice the grip! Likely, you're full-throttle with the front tires sideways to the direction of travel and don't realize it. When you get in that situation again, try straightening the wheel out a bit - it's difficult to overcome the sensation that you're steering off course but try hard - and you may find you get MORE turning grip with LESS steering because you'll be sliding the fronts less. Just like braking, once you pass the limit of grip (i.e. like brake lockup), you get a lot less grip. If you want a visual, go watch a 5.0 Mustang and see how he uses all that power to push the front tires sideways

Work on "blending" inputs (i.e. braking and steering, steering and throttle) while not overloading the outside front tire. Get an experienced driver to ride with you and maybe drive your car (with you as passenger) on a couple runs, you'll eliminate months of trial-and-error in a few runs.

 

In my inexperienced mind, I assumed that the thing to do when entering a corner would be to brake hard first...slow myself down...then make the turn, and ease into the throttle as I was coming out. Slightly easier said then done

What I ended up doing every time, was braking too hard (in my mind) and slowing myself down too much. Then, when I would be going through the turn, to me it didn't feel like I was using my tires 100%. I can't honestly remember if there was squeel or not. I think there might have been some protest from the rubber, but in the car at that moment I felt that there was room for more speed.

So I would start to get on the accelerator a little earlier than I should have.

Was I really using all my grip and I just didn't know enough to realize it? That what you mean by "Likely, you're full-throttle with the front tires sideways to the direction of travel and don't realize it."?

After my third run I should have asked for an instructor to ride along, but I didn't feel there was anything I could really improve on besides just pushing the car more

This is what lead to 4 consecutive runs of 52 seconds. I just could not go any faster. I originally thought it was because I couldn't really get the hang of a tight slalom part, but more and more I'm coming to the conclusion that it was this damn corner that threw me off.

 

Getting on the gas early is something you'll find is a Good Thing but you MUST start straightening the wheel (turn-out) sooner than you think. Most people hold on to a big steering angle far too long then snap it to center once the car is pointing down the straight - and they're trying ot accelerate the whole time, too. Sometimes I find myself sawing at the wheel a bit looking to see if I'm over taxing the tires (especially on a low-grip surface). If I can straighten the wheel slightly and the car stays on the same line, then I was overdriving the tires. Then I might straighten out a little more and repeat maybe 4 times in a longish turn. The straighter the wheel - while maintaining the same line - the more grip you'll get which can then be "budgeted" to acceleration - and the less drag slowing the car down. Remember a tire only has so much absolute traction - what you use in acceleration or braking takes up some of the "budget" and leaves less for turning - and vice versa.

I know that's really wordy but try to grasp the concepts, then you can go practice. If you have a practice day where you get a lot of runs or your local region has a novice school - take it. And if you find yourself doing the same thing again, work on that turn without worrying about the rest of the course or your final time. When you get that turn right, you'll KNOW it!

 

Wil,

does you have problems with the power steeirng in slaloms cutting out??

Every Ford I've ever driven at an autoX howls in disgust when you have to turn the wheel too many times..

The RSX is like that also, makes you "feel" like you're behind on the steering inputs, but then you realize, you're on, and the car is slow...

The Civic Si (02) on the other hand, is quite different, always spot on...


Back on topic...
Understeer=bad
Torque steer=good (means you're making power
Open diffs=good for street, bad for everything else
Swallowing pride and getting an instructer=faster lap times and more fun

Jeff

 

I haven't had any problems with power steering. Don't forget it's not a Ford, it's actually a Mazda Protege with the Ford "body and interior kit". It's even got a power steering cooling loop in front of the radiator.

 

Huh, they actually thought of a p/s cooler???

My wife has one of those Mazda/Ford things..

626 ESV6 5 speed...what a really nice car for $21,000...

You are headed to Nats right??

If so, good luck...and have fun...

Jeff

 

Sports Car (the SCCA mag) picked me to win STS at Nationals but my wife is almost ready to give birth to twins so I won't be able to make it. It is just autocross, after all...


[Modified by 'scortRacer, 12:29 AM 8/19/2002]

 

Thanks for the help