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Old 07-11-2008, 09:53 AM   #46
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don't you start getting into 'too much' grip that makes you scrub hard or just flip?
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Old 07-11-2008, 09:56 AM   #47
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don't you start getting into 'too much' grip that makes you scrub hard or just flip?
I think proper Droop would fix that....
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Old 07-11-2008, 10:00 AM   #48
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my head hurts now
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Old 07-11-2008, 10:18 AM   #49
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don't you start getting into 'too much' grip that makes you scrub hard or just flip?
only with bad setups. among other changes, as grip comes up, d/r goes down (which takes the "scrub" out) and yields better lap times. i've never known anyone (competent) pleading for grip to go back down. at least not at the levels we're currently seeing (or have seen).
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Old 07-11-2008, 10:44 AM   #50
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only with bad setups. among other changes, as grip comes up, d/r goes down (which takes the "scrub" out) and yields better lap times. i've never known anyone (competent) pleading for grip to go back down. at least not at the levels we're currently seeing (or have seen).
You ever seen carpet with a 3 foot wide black groove laid down? Paragon was sprayed on the carpet at the beginning of our regionals this past year, and it was so tacky that you would stick to the floor after marshaling a car. It was way different than what I am used to, and I was wishing for less grip. I could not get my car setup right, even with help from some sponsored guys. I will say one thing though, if you didn't spray your tires out with motor spray after every run, you would be flipping in the corners.
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Old 07-11-2008, 11:31 AM   #51
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You ever seen carpet with a 3 foot wide black groove laid down?
nope. never. can that really happen?



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Old 07-11-2008, 11:28 PM   #52
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Old 07-12-2008, 12:05 AM   #53
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For a long, long time I had absolutely no clue how to set droop and was basically running 3 to 6mm droop in a Cadillac type drive that required ‘throwing’ the weight to one side before hitting a corner. I was trying to race a boat. Eventually I actually got it to kind of work like that and figured out how to make it set and hang a line. After a couple friendly wrench beatings, I am down to 1 or 1.5mm. So, I’m no expert, but,,,,,
Droop for rubber asphalt I would guess is much different than foam carpet 13.5 in both setting and performance. Also, unlike full scale where grip is always sought after, carpet foam produces more traction than you’d ever really want and so some of the chassis dynamics operate in reverse…… right?

“Another thing I want to briefly mention is weight transfer. There are two components, one is dynamic and caused by the acceleration, deceleration and cornering forces on the car, the other is static and is caused by the movement of the CG as the car pitches and rolls. Static weight transfer has much, much, much less effect than dynamic, so much so that it can be safely ignored - however a lot of people mistakenly give it a lot of consideration.”

If I take the static and dynamic forces and place them on an x and y axis, isn’t the motion of the car using both at the same time? As you dive into the sweeper weight is transferred forward and driver side. I would think that the dynamic would act as and exaggerating factor on the static forces?

“got one for you:

the popular *opinion* is that more droop tranfers more weight (f/r, pitch direction). how is this possible, when droop itself, is there to allow the unloading tires to maintain their contact pressure (force) on the racing surface?

(essentially, droop reduces the unsprung weight from taking part in the total of that which is transferred).”

I think/guess it does allow more weight transfer, but running less droop would produce a faster transfer of weight. So it may not be as much weight being thrown into the chassis, but it would get there quicker. So conversely, more droop would allow for more weight transfer, but it would take longer to get there. That’s the experiences of a rook running crazy droop anyways…

“The main problem I have with measuring droop the way we should with the wheels coming up is that for me its not real exact "until the wheels start to lift" wish there was a better way than to eyeball the moment of lift or at least a way to use the guages we have to give you the same droop effect.

Rod”

For foam, I place a ride height gauge under the chassis plate in the spot right before it bends towards the bulkhead at 4.5mm and then lift the plate to 5.5mm on the ride height gauge and turn the droop screw until the wheel comes up. I do the rest of the corners and then go back to the first and measure again. On the second go, I apply just enough upwards pressure to feel the screws hit the plate while holding down the wheel. It’s kind of finger acrobatics, but with gentle pressure I can usually get a very accurate reading.

This brings up another question though. I have always had issues with the graphite wearing away under the droop screw. I hear that some pro drivers and putting flush screws in from the underside of the arm at big events and just changing out tires to maintain droop setting. I’ve thought about putting a piece of metal onto the chassis, but can’t ‘hack’ the reality of it.
Thin stainless steel pads glued to the graphite under the droop screws. You can even make them look pretty nice.

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Old 07-12-2008, 02:24 AM   #54
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Last night using foams on carpet on a small 10x15m track was challenging, considering I havnt raced sedan on them for a long time.

They mixed in 13.5 brushless on rubber with 27t on foam into the same group and there is very little in it, either can make the A main.

And yes, even on a track that small you still see the groove, if you stepped off it, you found yourself with a car that pushed... straight into the board
It didnt help that I was racing with tyres of an unknown shore rating (found out before the main they were all 37's, far from ideal 37/35 or ideally 35/32 seems to be the ticket so I heard from the regulars).

All good fun though, but with foams, I found them to be very sensitive to droop. So much so that in practice the back end was very responsive.... So responsive that as soon as I turned the tiniest amount, the front of the car was head on with the apex of the corner,ooops!

Oversteer? Just a little!!! Still, with a few things changed here and there it was getting better every run

Moral of the story? NEVER underestimate Droop and how it can change the handling of the car. Especially on high bite tracks
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