BenH
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2WD TractionAfter another evening of plodding through forums with my little pinch of salt, I thought I would return the haven and ask those I entrust most with the answer to the following query.
Given a mid mounted motor in the X6, and S2 (But focusing on the X6) people say - there isn't enough traction without the motor hanging out the back of the car.
If there's not enough traction how is it possible to flip the car. 
By the resulting flip under power it surely says there is enough traction. 
However - Based on your ideal B4 (motor hanging out like a giant boil) settings, do you change the set up to increase traction, but lose something in the corner because of this? Or is the above - (no traction statements) - more giant helpings of Bull Pong?
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Zipper
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From what I understand, the X6 struggles in wet conditions for traction.
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andy east
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Re: 2WD TractionBenny,
You have asked a very difficult question there. Opinion and theory is all well and good, but it can only really be answered with pitching the two concepts against each other.
Given the same settings for both cars I would expect to find that the mid-motor car would have more rear grip (up to a point) and a much sharper response, however, I would expect the rear end to snap away rather than drift away like a conventional 2wd car with the weight outside of the wheelbase. This snap would probably happen slightly later than the point where the conventional car would begin to drift, but it would be very aggressive when it does let go, very difficult to catch and ultimately slower.
To counter this I would begin with a lower roll centre at the rear, and run slightly softer rear suspension to help slow the rear end snap and make it more progressive. I would also run the shocks an extra hole inwards on the rear shock tower, a shorter rear camber link and slightly less negative camber when the car is at ride-height. I would run the diff tighter and I would run a less aggressive front steering system that offers less ackerman effect to help the rear stay stable in the mid-corner and exit of turns. Other set-up adjustments would certainly be needed, but only understood when you run the car. There are so many possibilities that you could easily go down the wrong route and not even know it, one step at a time and the answers will come to you.
The major issues come when the grip level is low, the point where the rear end snaps away will come much sooner and you would be fighting a very awkward and unpredicable rear end. Development would cure this, but to find the direction you need you would have to get out there and run it in these conditions, find your problems and then solve them.
Contrary to belief, the issue is not so much about traction on it's own. It's the relationship of all the aspects that are required to make a car work.
Believe it or not, the major gain to be had through the mid-motor car is to be found at the front end...
If I had more cash to hand i'd make one just to prove the concept, and it wouldn't be anything like the X-Fagtory (that's not a typo either).
I hope that helps answer your question, it is a very difficult question to answer though! 
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BenH
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I am shocked that you have taken the design white paper from the B2000; used all of it's terms and failed to cite it in your response. 
Back on track.
Bear with me: -
The snap on the rear you mention will be a result of the centrifugal force applied versus weight/ traction on the rear. The centrifugal would increase it's effect on the rear of the car if there is more traction and control applied to the front as a result of mid mounted motor.
If there is only so much weight available, then in theory, there is only so much traction that can be applied to any one point based on the weight and maximum tyre width.
Based on the above, the car has plenty of traction in a straight line and will kick it's rear out mid corner. Setting the camber to lose more traction in a straight line should be achievable without actually losing drive and now by offering it to the rear in terms of camber to prevent the snap?
Maybe?
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andy east
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Of course, the B2000 will rectify all problems, even world hunger.
You are right on all counts apart from the camber. I would run a shorter link and less camber so that when the car is facing straight ahead the tyres are flatter to the ground (increase tyre footprint), but in a corner the outside rear wheel runs slightly more on the inside edge to make the slide more progressive when it does eventually happen.
Once you have the basics out the way you are always looking to improve driver confidence in the handling characteristics, a progressive slide that you can catch is always better than a snap oversteer, especially true when you are not sitting in the car and have no link to it other than hand-eye co-ordination, you need to know what is going to happen if you push the car past it's optimum limit.
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BenH
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I'm loving the optimism. Ever thought of being sales rep for the B2000
Ah - I get you!  Big angle on the camber link, as the lean starts it pulls in quicker offering increase in neg camber as it rolls resulting in the above.
....or maybe another option to include - Variable mounting position for the inside mounting of the camber link.
Exaggerated to emphasise a point (Also bit difficult to draw to any level of accuracy )
I think - this will not adjust camber for fairly big bumps holding the traction for forward drive, but once the roll kicks in the neg camber will increase greater for the solving of the above theoretical problem?
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andy east
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I don't follow your variable mounting idea... do you mean it will be a floating inner joint? or will it be fixed, but adjustable?
The upshot is that the mid-motor has the potential to totally blitz the conventional layout, but it will take development and time, X-Factory have started the ball rolling, it's only a matter of time before the convention swings the other way.
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BenH
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| andy east wrote: | I don't follow your variable mounting idea... do you mean it will be a floating inner joint? or will it be fixed, but adjustable?
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Fixed but adjustable. Adjustable on a horizontal plane, but mounted slightly higher than the top of the rear carrier at the stationary level setting. Therefore allowing lot's of personal adjustment with reducing or increasing spacers.
(I did think floating but the anti-gravity was a stumbling block )
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andy east
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Gotcha fella
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John Myall
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Re: 2WD Traction | andy east wrote: | | I would expect to find that the mid-motor car would have more rear grip (up to a point) and a much sharper response, however, I would expect the rear end to snap away rather than drift away like a conventional 2wd car with the weight outside of the wheelbase. |
Far be it for me to disagree, but my own experiance, with a B4, and now the X-6, has shown me that the X-6 has way more on power steering, but you can slide it out of corners, as it will drift much nicer then the B4, which just wants to throw its self off the track if you go near a corner carrying any speed.
Still not sure why it suffers with wet weather traction, as its dry traction is way above a "normal" 2wd that has its motor in the wrong place 
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LBC
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It's all to do with mathematics: one quantity y is said to be a function of another quantity x, written y = f(x), if a change in x results in some corresponding change in y.
Thus sinx or logx are functions of x. If y depends not only on x but on several other quantities as well, y is called a function of many variables. There, what could be simpler!
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andy east
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Interesting to read that John, I'm surprised to read it has more traction than a conventional 2WD though.
The additional front end on power is exactly the reason why mid-motored 2WD's will become the norm, not at all surprised to read that.
The ability to drift your X-6 may be the result of the development they have done to the car... I can't imagine it was like that from the beginning!
Jim, your post was more difficult to understand than Bens, and I had to read his through 6-7 times to make sense of it!
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