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Old 04-22-2006, 02:53 AM   #6106
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Originally Posted by OldNSlow2
What? That makes it longer!


Ok, just so you all know I am not looking for a fight here, it's Friday night, I'm home watching hockey and reading the "net". Plus I am Old and Slow so I tend to study these things, plus it is what I do for a living.

I will say this one last time. If you lower the upper arm on the inside you will raise the roll center, and increase camber gain. A shorter upper link will cause a more rapid change in camber gain. Please go back and look at the Cauley picture and imagine the upper link on a steep angle down then connect all the lines to this new instant center. The roll center will be higher. I just did it again myself to make sure.

Ain't this fun?
Hi

Your correct. Increasing the angle of the upper camber link at the back RAISES the roll centre. As the roll centre is closer now to the CofG the roll MOMENT (More rotation for the same laterall movement) will be greater and give you more roll and more grip. This is why people see the opposite in practice. They are expecting less grip with increased camber angle

So....

Raising the angle or the camber link raises the roll centre closer to the C of G and gives you more roll MOMENT and therefore more roll and more rear grip.

Also if rolling = more grip why run an ANTI roll bar? I never run a rear roll bar

Cheers
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Old 04-22-2006, 07:02 AM   #6107
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Originally Posted by ziggy12345
Hi

Your correct. Increasing the angle of the upper camber link at the back RAISES the roll centre. As the roll centre is closer now to the CofG the roll MOMENT (More rotation for the same laterall movement) will be greater and give you more roll and more grip. This is why people see the opposite in practice. They are expecting less grip with increased camber angle

So....

Raising the angle or the camber link raises the roll centre closer to the C of G and gives you more roll MOMENT and therefore more roll and more rear grip.

Not quite, the bigger the distance from the C of G to the roll center is (as in lower) the more the roll moment is. If the roll center was exactly on top of the C of G the car would not roll at all, in theory.

Also if rolling = more grip why run an ANTI roll bar? I never run a rear roll bar

You can change roll couple by changing springs or roll bars, they both affect roll. Since we run these cars outside you usually want to have softer springs to absorb the bumps and still need to have control of roll. That is why you use both...sometimes. If you are very loose, changing to a softer spring or smaller bar would both help with rear bite. Also, a softer rear spring will help with forward bite.

It is all a series of compromises, don't forget that the rear and front are still hooked together and the roll axis between the front and rear is very important. If you get one end way out of whack it can hurt perfromance as well.
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Old 04-22-2006, 07:36 AM   #6108
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Todays response in RED
This is all very informative but I have a question. Does it matter that the rear lower arms on the RRR angle down towards the chassis in lieu of being flat or angled up as the diagrams have shown? It seems like most of this discussion is based upon a flat lower arm. Based upon my car, the more angle you give the upper arm, the higher the roll center will be.

I'm very confused.
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Old 04-22-2006, 07:56 AM   #6109
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Originally Posted by jag
This is all very informative but I have a question. Does it matter that the rear lower arms on the RRR angle down towards the chassis in lieu of being flat or angled up as the diagrams have shown? It seems like most of this discussion is based upon a flat lower arm. Based upon my car, the more angle you give the upper arm, the higher the roll center will be.

I'm very confused.
We have to assume that the car is designed correctly in the first place and we are only making minor adjustments. I believe that is true for the RRR because it works so good out of the box with the kit set-up.

As far as my discussion is concerned I am talking theory and what to expect with adjustments they provide us in the design of the car. Such as the angle of the lower arm, that is a much bigger adjustment then moving the upper link one hole up or down.....it must be close or we would not like the car so much. If someone wants to chage roll center more then the upper link provides they can change the inserts in the lower arm hinge pins.

You are correct though, sometimes this stuff is very confusing because so many things are tied together; roll center, roll axis, roll moment, roll couple, instant center, anti-squat, pro-squat, tires, track width, ackerman, etc. That is why Kyosho has a bunch of engineers working on these things and we get to play with them.
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Old 04-22-2006, 08:22 AM   #6110
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To see how things develop, I resisted to the temptation to jump into the discussion on the statements made by myself and Campbell (Palmaris Europe) on the roll center issue, looks great that we're having a healthy discussion on this.

I learnt my stuffs through extensive research readings on the net, one article that helped me in understanding the roll center the most is THIS article by Glenn Cauley in the mytsn portal. HEY this the same one as Campbell quoted?! I might doubt other write-ups from other websites, but definitely not to articles from mytsn and Josh Cyrul's. Was I shocked when Campbell quoted the same article as reference, whilst his findings are different...

Anyway, I spent time experimenting with the roll centers in real life, what I've found is like what the article stated - lower roll centre, roll more; higher roll centre, roll less. In terms of whether which generates MORE or LESS traction, it's pretty subjective an issue to me; of which I would also like to give some input here, that CAMBER also plays an inegligible role in determining the traction!

At low traction track surface, more bodyroll does not necessary means more traction IF the tire choice is wrong. Sometimes, with the RIGHT tire choice, the tire may give the traction one needs EVEN THOUGH the roll centre is set to the highest. So it's a matter of getting the right balance, under the right conditions. The theory findings may not necessay be 100% true in every situation, deviation takes place all the time accordingly to different conditions; Glenn Cauley's article made the theory clear, it's up to individual perceptions on the understanding of it.
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Old 04-22-2006, 10:09 AM   #6111
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Originally Posted by tommi
To see how things develop, I resisted to the temptation to jump into the discussion on the statements made by myself and Campbell (Palmaris Europe) on the roll center issue, looks great that we're having a healthy discussion on this.

I learnt my stuffs through extensive research readings on the net, one article that helped me in understanding the roll center the most is THIS article by Glenn Cauley in the mytsn portal. HEY this the same one as Campbell quoted?! I might doubt other write-ups from other websites, but definitely not to articles from mytsn and Josh Cyrul's. Was I shocked when Campbell quoted the same article as reference, whilst his findings are different...

Anyway, I spent time experimenting with the roll centers in real life, what I've found is like what the article stated - lower roll centre, roll more; higher roll centre, roll less. In terms of whether which generates MORE or LESS traction, it's pretty subjective an issue to me; of which I would also like to give some input here, that CAMBER also plays an inegligible role in determining the traction!

At low traction track surface, more bodyroll does not necessary means more traction IF the tire choice is wrong. Sometimes, with the RIGHT tire choice, the tire may give the traction one needs EVEN THOUGH the roll centre is set to the highest. So it's a matter of getting the right balance, under the right conditions. The theory findings may not necessay be 100% true in every situation, deviation takes place all the time accordingly to different conditions; Glenn Cauley's article made the theory clear, it's up to individual perceptions on the understanding of it.
aiyoh.... beri chim again... catch no ball...your statement indeed have '' ink-water "
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Old 04-22-2006, 11:07 AM   #6112
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aiyoh.... beri chim again... catch no ball...your statement indeed have '' ink-water "
KNN...this one chim or not?
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Old 04-22-2006, 12:09 PM   #6113
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hi all

ive been training today for the meeting of tomorow and i find out that my car has much less bottom speed then the other cars with the same motor. i already changed my clutch, it helped a bid buth not enough, i find out that the other drivers drove with a lighter gear ratio, i still have the standard gears:

pinion 16/21
spur 61/56

wich gear do i need? pinion gears 15/17 - 21/22/23

spur gears: 59/60 - 55

its not a very big track, with a couple of short corners. i don't want to lose to much top speed.

thnx
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Old 04-22-2006, 01:02 PM   #6114
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Originally Posted by nismo46
hi all

ive been training today for the meeting of tomorow and i find out that my car has much less bottom speed then the other cars with the same motor. i already changed my clutch, it helped a bid buth not enough, i find out that the other drivers drove with a lighter gear ratio, i still have the standard gears:

pinion 16/21
spur 61/56

wich gear do i need? pinion gears 15/17 - 21/22/23

spur gears: 59/60 - 55

its not a very big track, with a couple of short corners. i don't want to lose to much top speed.

thnx
If it's not too big a track, it will sound like you're losing out in the short sprints (acceleration), and you were not able to make use of the motor RPM to make up your top speed. Go a tooth down on both the pinions, 15T on 1st and 20 on the 2nd, it should improve; if you're still not happy with it, change the spurs as well to 60 on 1st and 55 on the 2nd. IMO, these combinations are handy to have besides the stock ones - the 60/55 spurs and the 15/20 pinions.
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Old 04-22-2006, 01:21 PM   #6115
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really thanks mate! like you say out coming of the short corners to the next short corners i don't have enough acceleration.

i buy tomorow the pinions and the spurs and a new clutchbell to make a nice set of it
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Old 04-22-2006, 07:11 PM   #6116
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Quote:
Originally Posted by jag
This is all very informative but I have a question. Does it matter that the rear lower arms on the RRR angle down towards the chassis in lieu of being flat or angled up as the diagrams have shown? It seems like most of this discussion is based upon a flat lower arm. Based upon my car, the more angle you give the upper arm, the higher the roll center will be.

I'm very confused.
Jim.....quit worrying about the roll center. Leave it at stock and go practice your driving. You have more to worry about than something that's very overrated
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Old 04-22-2006, 07:31 PM   #6117
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Originally Posted by JustRace
Jim.....quit worrying about the roll center. Leave it at stock and go practice your driving. You have more to worry about than something that's very overrated
Worried... who me? I'm just looking for knowledge. The more I understand about this stuff the better-off I will be, besides, my car is excellent. If I could drive like you and Robert I would be the champ! You are right, practice is what I need.
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Old 04-22-2006, 08:42 PM   #6118
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Originally Posted by tommi
KNN...this one chim or not?

... this statment i catch the ball liao
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Old 04-22-2006, 08:44 PM   #6119
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Originally Posted by nismo46
hi all

ive been training today for the meeting of tomorow and i find out that my car has much less bottom speed then the other cars with the same motor. i already changed my clutch, it helped a bid buth not enough, i find out that the other drivers drove with a lighter gear ratio, i still have the standard gears:

pinion 16/21
spur 61/56

wich gear do i need? pinion gears 15/17 - 21/22/23

spur gears: 59/60 - 55

its not a very big track, with a couple of short corners. i don't want to lose to much top speed.

thnx
Pinion 15/ 20

spur 60/ 55

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Old 04-22-2006, 09:01 PM   #6120
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Originally Posted by JustRace
Jim.....quit worrying about the roll center. Leave it at stock and go practice your driving. You have more to worry about than something that's very overrated
Hey Mr.Lee hope everything is well...I need my juice for this weekend...remeber the old blend you were giving me......also please dont forget that motor mount i need......Ohh and by the way Jim thanks for the compliment and Jims car is very good right now francis....crap load of steering...and wasnt trac. rolling at royal palm and all the other cars were...
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