EG Civic - Tail happy?

[m.o.d.aus]

Hi guys,
Just went on and did a defensive driver training course out at Mt Cotton. And the story goes like this;

The course layout was like is - direction, down the page.
KEY: * = cones, silver parts are just the spaces between the cones (wouldnt let me do it any other way)

* ^^^ *


* ^^^ ***^^^ *


* ^^^ *

Okay so, it went like this, the 3 middle cones where meant to simulate some 'kids' stepping out onto the road etc.
The instructor was stand to the side and as we approached to the wet braking part right infront of the 'kids' tell us a direction to turn, either side was possible, to test reaction times/panic mode etc...
Anyways what I'm asking is, keep in mind that is was wet, after coming into the coned section @ 40, 50 and 60 kph, the car was fine, I could easily swerve out of the way, and back again. But once i tried 70, the car got tail happy. Turn time i missed the kids, but spun out, and second time it didnt spin but i cliped the cones. So why is my civic so tail happy?
This is not the first time i've had the tail out in my car, which mind you is 100% stock!
Around wet round-a-bouts, long sweeping bends (mildly wet) and just heavy braking over rocks/wet conditions. Everytime there is the least bit of traction lost, the tail gets happy, why?

PS. Sorry for the long winded explanation, and dodgy sentince style :o

[androo]

Are your tires OK at the back? Not el-cheapos? If not I have no idea mine wasn't tail happy at all!!

[liberx]

Some things to check that may cause the tail to be loose. Keep in mind that any standard car, esp FWD is setup for understeer characteristics, so there may well be something amiss:
1. Tires - same type, size and quality front to rear? Don't go by a quick look - read the brand and model
2. Tyre pressures - either too low or high can cause loss of traction
3. Sway bar(s) - is the front sway/stabilizer connected and OK? Is there a rear bar and is it too thick?
4. rear camber - is it positive? (Bottom are further in under the car). Should be nuetral or slightly negative (-1 deg)
5. Are your suspension bushes worn, allowing rear steer when lateral forces are placed on the rear?
6. Do you have lots of toe out on the rear?
7. rear brake bias - the rears are locking up under brakes - or doing more work than they should (or the fronts aren't working like they should)
8. Shock absorbers/dampers - are rears stiff? or fronts soft and bouncy?

Sorry, that's all I can think of for now ;-)

[m.o.d.aus]

Thanks for the replys guys. As suggested, the cause for my tail happy civic is because i've chucked the cheap tires on the rear when i got new fronts. Plus i know that i hate a little bit more toe in the rear then i should. But other then that its all okay :) thanks again.

[crx51]

Gday mate,

I had the same thing with both my ed9 crx's. The reason the car is tail happy is basically down to driver input and the fact that the car has such a short wheelbase.

In the scenario you were playing out with the instructor you were having to make last-second inputs on the steering as well as upsetting the front to rear weight balance by braking at the same time - moving the weight forward and off the rear wheels affording you less traction to those wheels. Unfortunately when you do this and you have such a short wheelbase it makes it very easy for the rear end to try to overtake the front. Having below par tires exacerbates your problem. The higher your speed gets the more weight transfer that will occur, you passed your limit at 70kmh.

Each car has its traits, and yes most fwd cars (your car included) are designed to understeer mildly as a safety envelope. Your car under power or with a steady throttle and no braking input would push understeer, the time that you would get oversteer is when you have overcooked it into a corner and then apply brakes or back off the throttle too quickly. This will quickly bite you with oversteer because most of the weight in your car is at the front and it's short wheelbase.

For spirited but planned driving you can get around this by knowing your road and not overdoing it upon entry therefore not requiring quick adjustments upsetting the balance of the car (of course this assumes a perfect world where you don't have to avoid animals, potholes, children, cars or motorbikes). In emergency situations of course you can't plan for them. Doing your defensive driving course was a good idea and has at least highlighted that there is an issue there.

The way around your current issue is to fork out for grippier tyres (possibly on 15s or 16s) on the car which means that the little weight left over the rear wheels in these situations will at least have the best chance of still gripping. Stiffer suspension will also help by limiting how much weight transfer is occuring under braking, leaving more downward force on the rear tyres and more evenly weighted between the sides too.

Well done for getting out and doing a Defensive Driving course mate, get some good tyres and you should be good to go! : )

Hope this helps to some extent.

[string]

Stiffer suspension will also help by limiting how much weight transfer is occuring under braking, leaving more downward force on the rear tyres and more evenly weighted between the sides too.


Myth. You can only change the magnitide of load transfer by reducing the total mass, increasing the track width or wheelbase, or lowering the centre of gravity.

[crx51]

Myth. You can only change the magnitide of load transfer by reducing the total mass, increasing the track width or wheelbase, or lowering the centre of gravity.

I beg to differ mate. Softly suspended cars will easily spin inside wheels on cornering.. Why? Because the suspension on the inside becomes unloaded and weight is taken off the inside wheel because the outer suspension has compressed so heavily.

Softly suspended cars with decent brakes will often lock the rear tyres under heavy braking, again because of the transfer of weight.

If you're standing and you lean as far forward as you can you will feel weight transfer toward the balls of your foot, conversely try leaning back and the weight will be put through your heel. The weight distribution is proportional to your lean. If a car limits how much of this pitching and yawing it does by having tighter controlled suspension it will limit the weight transfer.

I'm not saying that the forces involved in braking or taking a corner magically disappear but they're distributed differently.

[string]

I beg to differ mate. Softly suspended cars will easily spin inside wheels on cornering.. Why? Because the suspension on the inside becomes unloaded and weight is taken off the inside wheel because the outer suspension has compressed so heavily.

You're not describing an issue regarding stiffness, rather one of too much weight transfer occuring at the powered axle, poor differential, too much power, wet surface, etc...



Softly suspended cars with decent brakes will often lock the rear tyres under heavy braking, again because of the transfer of weight.

If you are braking at 1g, changing the spring rates will not change the vertical load on your tyres. Even with no (solid) suspension you would get the same load transfer to the front.




If you're standing and you lean as far forward as you can you will feel weight transfer toward the balls of your foot, conversely try leaning back and the weight will be put through your heel. The weight distribution is proportional to your lean.

This is a poor analogy. In your example, the primary factor for load transfer is the movement of your centre of mass. When a car is pitching and rolling, the movement of the centre of mass is very small. The effects on vertical load distribution on the tyres from this movement is negligible. A car's load transfer is caused by the tyre forces, which results in body roll, not the otherway around.



If a car limits how much of this pitching and yawing it does by having tighter controlled suspension it will limit the weight transfer.
I'm not saying that the forces involved in braking or taking a corner magically disappear but they're distributed differently

"Tighter controlled", sure; "limit" weight transfer, absolutely not. Two cars, one soft one stiff but otherwise identical, during the same 1g of lateral cornering, will experience the exact same total lateral load transfer. You can choose to distribute this load between the front and rear outer tyres as you please, by tuning the ratio of front and rear cornering stiffness (springs, swaybars) but when you sum up the load on the outer 2 tyres it'll be the same. When talking about braking forces, there's nothing you can do but change the wheelbase, lowering the centre of mass or reducing the total mass.

[crx51]

Mate I couldn't be bothered with arguing the point. I was trying to offer some help to someone who asked. You're simply trying to argue with me and are offering nothing to the person that started the post.

"exact same total lateral load transfer"

I know there will be the same TOTAL, not once did I say the weight of the vehicle changes. My "poor analogy" is simply an exaggerated situation in order to make it easier to demonstrate my point. I couldn't be bothered responding to the rest. Congratulations on your incredible disection of my advice, feel happy that you are of such ample knowledge..

""You're not describing an issue regarding stiffness, rather one of too much weight transfer occuring at the powered axle, poor differential, too much power, wet surface, etc...""
??? What causes the weight transfer mate? The cornering load! Yes poor diff, too much power and wet surface add to the problem but that's pure common sense and not worth even mentioning. You say wheelspin occurs due to too much weight transfer yet in another argument you say weight transfer is negligible. The wheel is able to spin as the downward force is reduced as the weight has caused the car to pitch on its side and put all its weight on the outside wheel..


I'd love to see your explanation as to why a racecar uses stiff suspension though if it has nothing to do with weight transfer...

""When talking about braking forces, there's nothing you can do but change the wheelbase, lowering the centre of mass or reducing the total mass""
Can you even see the contradiction in this? Why lower the centre of mass if the weight on each of the wheels during cornering or braking is always the same""? And the pitching of the car makes no significant change to weight distribution? Your argument is ill informed and you contradict yourself..

Speak with a race team or somebody you respect as knowing a lot on this subject and try to force your argument on them.. Really though why don't you try to offer advice rather than flame other peoples advice to increase your feeling of self worth..? I'm out as i'm not interested in having an online debate, nothing I say will change your opinion so talk to some others on the topic. Nothing you say will convince me you're correct so this is a waste of time..

[chargeR]

String didn't flame you in any way he stated his points in a fairly clear and polite manner I thought. He is also correct, and trying to correct some of the misinformation in your post, which is a fair thing to do. The internet lends the incompetent the same credibility as the knowledgeable so it is important that the knowledgeable make the effort to spread correct information.

To make Strings point regarding lateral load transfer maybe slightly more clear let me give an example. I use the word "load" in place of "weight" because I often think that "weight" is too closely associated with mass in many peoples minds but what we are really talking about is forces rather than masses. Imagine 2 cars, one heavily sprung and one extremely softly sprung, no sway bars to confuse the issue. The cars are otherwise similar in suspension geometry, have the exact same mass, track width and centre of gravity location. Put both cars in a steady state corner and neglect migration of the centre of gravity due to roll etc. Both cars will be experiencing the exact same lateral force.

This lateral force will create a moment between the centre of gravity and the tyre contact patch and this moment must be resisted by vertical forces at the tyres. Since the centre of gravity height of both cars is the same then the moment induced must be identical. Since the moment induced is exactly the same in both cars and the track width is the same then the load transfer, increase in vertical load on the tyre at the outside tyres and decrease at the inner tyres, must be exactly the same. The more softly sprung car will have more visible roll but the vertical load on the tyres will be exactly the same as the more stiffly sprung car (if you make the simplifications I mentioned earlier :p).

Race teams don't run stiff springs and sway bars to reduce load transfer across the chassis, there is a myriad of reasons why but that isn't one of them.

[liberx]

It seems to me CRX51 is talking about the transitional loads, while string is referring to steady state situations.

From this perspective you both makes valid points.:cool:

[e240]

wow...All I know is, the when the tail comes out, get on the gas and hope for the best...:-p LSDs will help..

[crx51]

ChargeR- Fair enough, the other thing with communicating via text is that intent can be misconstrued. Maybe he wasn't trying to flame me. On topic though-

"Put both cars in a steady state corner and neglect migration of the centre of gravity due to roll etc. Both cars will be experiencing the exact same lateral force. "
I know mate, but you're both neglecting the one thing I was talking about- the fact that the geometry and centre of weight change as a car rolls and therefore different tyres are experiencing different loads from each other.. Outer tyres will experience a higher load than the inside tyres. This can be seen by the wear difference of race car tyres on a course of predominantly right or left hand corners. To neglect the factor of "roll" is ignoring the fact that makes my point correct. Of course if roll is ignored then a statement that is in relation to roll is going to be incorrect. Roll is unavoidable. Wheels on race cars are cambered, why?, to take give a better contact patch when the suspension compresses during cornering flattening the tyre to the road.

"Race teams don't run stiff springs and sway bars to reduce load transfer across the chassis, there is a myriad of reasons why but that isn't one of them. "
Would you mind telling me what the reason is then if it nothing to do with quelling roll and distributing load better across its four contact patches?

[mmmmChicken]

Hi guys,
This is not the first time i've had the tail out in my car, which mind you is 100% stock!
Around wet round-a-bouts, long sweeping bends (mildly wet) and just heavy braking over rocks/wet conditions. Everytime there is the least bit of traction lost, the tail gets happy, why?


How To... Getting Fwds sideways without the handbrake
1. approach a corner just a little too fast
2. Enter corner still going a little too fast.
3. Back off the throttle suddenly and/or dab the brakes a little
4. countersteer and get back on the throttle and hope you haven't gone in just that little bit too much!!
Rain/slippery conditions "enhance" the experience :D