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Old 12-25-2008, 07:16 PM   #8731
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so in reality a lower roll center would help on traction if you had a loose car in the rear?? am i thinking right??
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Old 12-25-2008, 07:22 PM   #8732
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so in reality a lower roll center would help on traction if you had a loose car in the rear?? am i thinking right??
Nope...think of it as if you were pushing down on something. If you are above the tire pushing down (high roll center) you can put quit a bit of pressure on it. Now if you were closer to the tire or lower you wouldnt be able to put as much pressure on the same tire.
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Old 12-25-2008, 07:30 PM   #8733
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so in reality a lower roll center would help on traction if you had a loose car in the rear?? am i thinking right??
No, make the rear roll center higher.
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Old 12-25-2008, 07:54 PM   #8734
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Nope...think of it as if you were pushing down on something. If you are above the tire pushing down (high roll center) you can put quit a bit of pressure on it. Now if you were closer to the tire or lower you wouldnt be able to put as much pressure on the same tire.
i understand... thanks for explaining it more..
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Old 12-25-2008, 07:55 PM   #8735
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No, make the rear roll center higher.
thanks for the help!! gives me more of an idea on roll center!!!
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Old 12-25-2008, 07:57 PM   #8736
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i understand... thanks for explaining it more..

NP...just think of it as leverage...glad I could help.

Also if anyone knows this Fairtrace guy have him check his pm's...thanks!
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Old 12-25-2008, 09:52 PM   #8737
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Yea raising the pins will give you more side bite at that end of the car while on rubber tires.
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Old 12-25-2008, 10:03 PM   #8738
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Well the main reason i asked about the roll center is that i do run on rubber tires , from what i read Manufactures like xray and assocaited both claim that a high roll center decreases traction, maybe i read it wrong don't know, so i wanted to find out for sure..
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Old 12-25-2008, 10:23 PM   #8739
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Keep in mind that the roll center is not only adjusted by the pin height, that is only one aspect so you can't really compare.
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Old 12-25-2008, 11:37 PM   #8740
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Well the main reason i asked about the roll center is that i do run on rubber tires , from what i read Manufactures like xray and assocaited both claim that a high roll center decreases traction, maybe i read it wrong don't know, so i wanted to find out for sure..
I agree with what the Xray book says. Lower is more side grip. and puts more leverage on the wheels just like there diagrams say. Never had a car feel differant by changing roll centers. This was debated a few pages back.
It doesn't really matter though. Just set the front high and adjust the rear to you liking.

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Old 12-26-2008, 08:20 AM   #8741
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My car is loose in and loose out. Seems to be ok through the center, maybe a little tight. Right now I have Losi 30 with 17.5 springs in front and Losi 20 with 10.5 springs in rear. No sway bars. Maybe I have the car rolling too much?

I did drive someone elses car the other night. It is a Phi and it was stuck. I could not get it to break loose and I was a half second faster with it.
I would start with 15lb springs in the rear, there is such as thing as too soft, and underdampened. I drove a friends car that he had put together (his first rc kit build) and I neglected to go over his shocks, but had made sure the rest of the car was ok, it was on ice skates on 3 different sets of tires. Another racer came by and pushed on the front of the car and it was really light since he didn't build the shocks right, we re filled them with oil and bled them properly and the car was much much better. I only use this as an example that softer isn't always better, its a bit extreme.
You can also try running the top deck with orings under the 4 center screws, this will give a some more flex and may give you some more grip.
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Old 12-26-2008, 10:23 AM   #8742
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I would start with 15lb springs in the rear, there is such as thing as too soft, and underdampened. I drove a friends car that he had put together (his first rc kit build) and I neglected to go over his shocks, but had made sure the rest of the car was ok, it was on ice skates on 3 different sets of tires. Another racer came by and pushed on the front of the car and it was really light since he didn't build the shocks right, we re filled them with oil and bled them properly and the car was much much better. I only use this as an example that softer isn't always better, its a bit extreme.
You can also try running the top deck with orings under the 4 center screws, this will give a some more flex and may give you some more grip.

Agreed, just wanted to add, make sure you don't have too much oil in the shocks. The rebound should be slow and smootha and only about 50% of the shock length. If you have too much oil it will make the car twitchy and erratic and it won't matter what oil weight it is. The car will just do weird stuff all over the place.

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Old 12-26-2008, 11:40 AM   #8743
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Thanks for all the advice. Looking forward to Sunday so I can try these suggestions out.

Thanks again and have a Happy New Year!
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Old 12-31-2008, 11:20 PM   #8744
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What effect does diff height do? I've never had the option on previous cars, so I don't know anything about diff height through experience.
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Old 01-01-2009, 12:23 AM   #8745
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What effect does diff height do? I've never had the option on previous cars, so I don't know anything about diff height through experience.
I always use high upfront, and only tune the rear.

for flowing tracks with sweepers i set the rear at low setting, it should handle the long turns much better BUt if you want to free up the car then put the rear diff at the high position which is more suitable for small tracks

I am very sure that all of this is in the manual.
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