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標題: 假若直路尾髮夾彎反車你會選用…(可選多項) [打印本頁]

作者: billy86che 時間: 2009-5-13 13:48
標題: 假若直路尾髮夾彎反車你會選用…(可選多項)
由於希望只集中討論彈簧, 所以請恕沒其他選項.

作者: ganboy 時間: 2009-5-13 15:08
我1-8 揀哂喎..

作者: billy86che 時間: 2009-5-13 15:33
2# ganboy

No problem. You have your rights.

作者: scalpel 時間: 2009-5-13 17:20

我1-8 揀哂喎..
ganboy 發表於 2009-5-13 15:08

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Any reasons?

作者: ganboy 時間: 2009-5-13 17:38
本帖最後由 ganboy 於 2009-5-13 17:41 編輯

因為反車原因有好多, 彈簧長短軟硬只係其中幾個, 再者, 彈簧過硬或過軟亦有機會做成反車。點揀?　
呢個問題根本就冇標準答案，投票結果亦不能歸立出任何結論，前提係要搵出反車0既原因。

作者: billy86che 時間: 2009-5-13 20:49
本帖最後由 billy86che 於 2009-5-13 21:17 編輯

"彈簧過硬或過軟亦有機會做成反車"
I doubt this.

我當然同意反車原因可以有許多, 但如果單純因為原因可以有許多而不去研討, 只會在車場試這個試那個而沒有任何學術作依歸, 就會花掉太多不應花的時間了.

作者: 邪靈 時間: 2009-5-13 21:17
反車根本唔關彈弓事！係 down & up stop 既事！

作者: billy86che 時間: 2009-5-13 21:19

反車根本唔關彈弓事！係 down & up stop 既事！
邪靈發表於 2009-5-13 21:17

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Wow, what a 'clear cut' answer! Very confident.

作者: billy86che 時間: 2009-5-13 21:53
本帖最後由 billy86che 於 2009-5-13 21:54 編輯

I found this from the net which may change some of your viewpoints:
[attach]256947[/attach]

"The W168 became infamous in 1997 after failing the traditional “moose test” performed by the Swedish automobile publication Teknikens Värld. According to the report, the W168 overturned when maneuvering to avoid the “moose”. Mercedes initially denied the problem, but then took the surprising step of recalling all units sold to date (2,600) and suspending distribution until the problem was solved by adding electronic stability control and modifying the suspension. This marked the world premiere of stability control in a small car. Nevertheless, the W168 A-Class was voted the worst-handling car is Britain in the Top Gear Survey 2007 (completed by owners of the vehicles).
As a result of the suspension stiffening described above, the ride on the W168 is very firm; this combined with the short wheelbase makes this car very jittery over rough surfaces. This is not a problem with the long wheelbase version of the car."

作者: ganboy 時間: 2009-5-13 22:09

"彈簧過硬或過軟亦有機會做成反車"
I doubt this.

billy86che 發表於 2009-5-13 20:49

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than try it
given high grip front tyre, 0 droop, and same amount of spring preload, soft or hard spring which one is more likely to roll over?

作者: billy86che 時間: 2009-5-13 23:17
Of course we have to keep all other things constant when we do any testing, but there are 2 things vitally important :
1. ride height remains the same; &
2. the body shell is not touching the ground at all times.
Or else, the problem will become so complicated that testing becomes fruitless.

作者: ganboy 時間: 2009-5-13 23:41
glad to hear the word CONSTANT, so what is the CONSTANT?
1. ride height remains the same; 0mm?5mm?
2. the body shell is not touching the ground at all times. that mean the roll-over will never take place or you could assame when the car roll-over, it will never land.

what about toe/camber/droop/spring-rate/weight/speed/......etc.?

作者: billy86che 時間: 2009-5-13 23:47
12# ganboy

1. I meant the ride height should be the same even after you change the springs.

2. I meant the body shell should not be an agent that stops the car from flipping over.

作者: billy86che 時間: 2009-5-13 23:51
as for "what about toe/camber/droop/spring-rate/weight/speed/......etc.?", I guess when you change the springs, you certainly have changed the spring rate. But the rest should be kept constant to make the test fruitful.

作者: billy86che 時間: 2009-5-13 23:58
Remain constant= same as before

作者: ganboy 時間: 2009-5-14 00:09
so, what is that specific CONSTANT to start with?
If you taking this as an controlled experiment, you need a specific BASE to start with, and all these (toe/camber/droop/spring-rate/weight/speed/......etc.) contribute to that BASE which need to be specific. And you need to test all combination of these BASE against your assumption. And it turns out exactly what you thought. In this circumstance you can say you have a theory, say, hard spring can avoid traction roll. Or else, you are just talking about a specific case.

作者: billy86che 時間: 2009-5-14 00:15
I don't think I am talking about a specific case. Yes, indeed I wish to find out something like "harder front springs help to stop flipping over" in general.

作者: billy86che 時間: 2009-5-14 00:20
Do tell me if one day you make your car flip over more easily just by changing to harder front springs. I am really interested in understanding why and how that something like this would happen.

作者: ganboy 時間: 2009-5-14 00:20
本帖最後由 ganboy 於 2009-5-14 00:21 編輯

I don't think I am talking about a specific case. Yes, indeed I wish to find out something like "harder front springs help to stop flipping over" in general.
billy86che 發表於 2009-5-14 00:15

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I can tell you, negative. This only works to a certain point.
Please try out all the combinations if you insist... XD

作者: billy86che 時間: 2009-5-14 00:26
Sometimes we don't always have to try out something by ourselves. Doing a survey like this sometimes helps. We can gain knowledge from others' experience. Afterall, knowledge is collaborative.

作者: billy86che 時間: 2009-5-14 00:32
I can understand what you are driving at. I do agree that RC is a kind of "Chaotic Science" that involves a lot of uncertainties and element of luck, but I believe there are still a lot of 'truths' and formula that we can rely on and save our time.

作者: ganboy 時間: 2009-5-14 00:33

Sometimes we don't always have to try out something by ourselves. Doing a survey like this sometimes helps. We can gain knowledge from others' experience. Afterall, knowledge is collaborative.
billy86che 發表於 2009-5-14 00:26

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survey comes up with a common view not a theory.
a large amount of people elected a president does it means he/she is perfect?
I have no air to play with an ox skin lantern with text, discuss with you on track~

作者: billy86che 時間: 2009-5-14 00:36
The charts show the view but the talking can show some theories, don't you agree?

By the way, I look forward to seeing you every Friday.

作者: ganboy 時間: 2009-5-16 05:12
本帖最後由 ganboy 於 2009-5-16 05:13 編輯

I put it this way, given the highest grip tyre all round of the same width,
other factor being CONSTANT (need to be rational of course), 2 major
factors contribute to the relation of spring-tension and
chance-of-traction-roll are:

1. Track width to CG ratio
2. Droop

The lower the above 2 value, the greater the chance of traction roll. It is
because they have different number of spring to choose from. Considering
there is a window of spring choice, different combination of the 2 value
adjust the window (size and location) of spring choice.

In graphical terms:
Hard(Solid)　　　　　　　　　　　　　Soft
|-----------[　window　]---------------|

For instance, a double decker bus (with default high droop value already), its window lies on some where here. Will a bus with solid suspension flip? no doubt.

Hard(Solid)　　　　　　　　　　　　　Soft
|--------[window]----------------------|

For a F-1 (ultra high Track width to CG ratio), its window like this.　Will a F-1 with solid suspension flip? I guess so.

Hard(Solid)　　　　　　　　　　　　　Soft
|-[　　　　w　i　n　d　o　w　　　　]-|

Do you agree my points?
The above is just my 2 cents, not a theory.

作者: billy86che 時間: 2009-5-16 12:43
本帖最後由 billy86che 於 2009-5-16 12:45 編輯

But it seems that you have not considered one very important factor on the difference between the bus and the F1, which is the distance between the roll centre and the CG. For a bus, the CG is certainly higher than the roll centre, but for an F1 they are very close to each other (CG can even be lower than the roll centre if your suspension system allows).

I suggest other than CG & width, you also have to understand the 'roll centre'.

Next, my hypothersis is that, provided a harder front spring, rolling is reduced and so is the traction, and that causes less steering and thus lower the possibility of a flip over.

作者: billy86che 時間: 2009-5-16 13:04
One possibility of why you found softer front springs cause less flipover in your driving experience may be you change to a pair of softer springs without maintaining the same ride height. If you just change to softer springs, the ride height is certainly lowered (I hope you had not over preloaded your springs too much to the extent that your car did not droop) and thus lowering the CG and then the possibility of a flipover.

Tell me, when you changed the springs, did you readjust the shimming (shims) to KEEP the ride height you were running with?

作者: relo 時間: 2009-5-16 14:49

I can understand what you are driving at. I do agree that RC is a kind of "Chaotic Science" that involves a lot of uncertainties and element of luck, but I believe there are still a lot of 'truths' an ...
billy86che 發表於 2009-5-14 00:32

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非常同意, 遙控車甚至四驅車都和真車一樣, 是複雜的物理結果, 問題只在於我們沒有明白其中的知識和觀察力

作者: samy 時間: 2009-5-16 16:05
use 40 front and 10 rear and try la.

作者: samy 時間: 2009-5-16 16:14
by the way, if you only think about a part of the track, it is useless. see whole picture better than a small part of it.

作者: ganboy 時間: 2009-5-16 16:35
本帖最後由 ganboy 於 2009-5-16 16:38 編輯

I dont have professional knowledge in this area of engineering, all the points above just a summerization of my sense and experience. I merely know what is roll-center, also understand that spring rate affects the movement of roll center, but I cant tell where is the roll center in my AWD...XD

I agree, harder front spring, rolling is reduced and so is the traction. But, IMHO, harder front spring also has a more direct response when you entering a corner and so is the front traction. And it cause CG fliping in a larger dynamic rage. If the suspension and the chassis could not response to the rapid shift of CG, roll over is the result.

um...do you think a F-1 chassis mounted a double decker bus body and with the same CG of a real double decker has could turn fast without traction rolling when using solid block as spring in its suspension?

For the question "when you changed the springs, did you readjust the shimming (shims) to KEEP the ride height you were running with?" The answer is no unless the spring rate different is large, I see the difference neglectable.

作者: ganboy 時間: 2009-5-16 16:42
I love this kind of fruitful discussion, but only me and you contributing is insuffisient and boring....perheps this is not the right place to discuss this kind of topic....

作者: ganboy 時間: 2009-5-16 16:49
本帖最後由 ganboy 於 2009-5-16 16:55 編輯

by the way, if you only think about a part of the track, it is useless. see whole picture better than a small part of it.
samy 發表於 2009-5-16 16:14

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I wanted to point out this in the very beginning, but he wants to focus on a specific kind of turns and a specific kind of problems I try not to OT in this respect. XD

作者: billy86che 時間: 2009-5-16 21:39
本帖最後由 billy86che 於 2009-5-16 21:51 編輯

30# ganboy

You said,' harder front spring also has a more direct response when you entering a corner and so is the front traction. And it cause CG fliping in a larger dynamic rage. If the suspension and the chassis could not response to the rapid shift of CG, roll over is the result.'
You are absolutely right to have pointed this out. I had been thinking about that. A bumpy track gives an opposite answer, particularly when people put a 'disc' at the corner which 'stands' up. I have to admit that I had been assuming a flat surface. I wish to keep things 'clean' so we can focus.

作者: billy86che 時間: 2009-5-16 21:44
本帖最後由 billy86che 於 2009-5-16 21:47 編輯

30# ganboy

But when you said ,"The answer is no unless the spring rate different is large, I see the difference neglectable." I can't agree with that. I don't think the difference is negligible. A pair of softer front springs that give a lower ride height make a big difference. Though I do not always measure the ride height, I can still tell the difference. I do not usually use shims at the bottom to shim down the chassis. I usually let it droop so I can tell that more easily.

作者: billy86che 時間: 2009-5-16 21:49

I love this kind of fruitful discussion, but only me and you contributing is insuffisient and boring....perheps this is not the right place to discuss this kind of topic....
ganboy 發表於 2009-5-16 16:42

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Samy & Relo are joining. and I guess there are a lot others who read and later they will contribute too.

作者: piano 時間: 2009-5-17 16:37
35# billy86che
經過多日研究兩位偉人嘅理論，以及嘥左成千銀去三聯書局買左三本字典去查你地啲咁深嘅英文，得出嘅結論係.........我揀等無人喺度嘅時候，鬼鬼鼠鼠咁改左條track，改到佢唔cup 車為止，想即刻唔cup又得.....慢慢唔cup又得.....得左

作者: billy86che 時間: 2009-5-17 17:21

35# billy86che
經過多日研究兩位偉人嘅理論，以及嘥左成千銀去三聯書局買左三本字典去查你地啲咁深嘅英文，得出嘅結論係.........我揀等無人喺度嘅時候，鬼鬼鼠鼠咁改 ...
piano 發表於 2009-5-17 16:37

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正衰鬼黎嫁!

作者: teamlosi 時間: 2009-5-29 01:31
改track是最根左性的,換乜鬼彈彈wo,不如討論乜星座配乜彈彈重好！

作者: billy86che 時間: 2009-5-29 10:50
本帖最後由 billy86che 於 2009-5-29 14:59 編輯

"改track是最根左性的"? I don't understand.

作者: DriftNoobie 時間: 2009-5-29 17:00

"改track是最根左性的"? I don't understand.
billy86che 發表於 2009-5-29 10:50

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要洗多成千銀去買埋中文字典... 但結果都係唔明.

作者: Love_stephy=) 時間: 2009-5-29 18:41
軟D 好 =) 無錦易反

作者: wongching 時間: 2009-7-25 23:13
慢車...慢慢行...

作者: kim 時間: 2009-8-25 21:33
直路收油啦師父......

作者: hunghung 時間: 2009-8-25 22:00

直路收油啦師父......
kim 發表於 2009-8-25 21:33

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agree

作者: Carsong 時間: 2009-8-29 09:50
I have read the "放車基本法" & just read again this post, understand more now. Thanks for above CHing's sharing & discussion.

I just elected "Harder Front & Softer Rear" Spring, according to the "Apex Line" drivng theory.
But I don't understand the effect / result of the "different Length of Spring".
Can some CHing explain about this please?
Thx.

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