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Old 01-14-2002, 08:56 AM   #1
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Default Rollout what is it for?

Hi all.
What's rollout used for?

Bryan has a guide to it:
http://www.balakracing.com/rollout.htm

But I have no idea how to apply it on the track. Right now I usually run a Yokomo 23T stocker, geared at 6.8:1 FDR.

It is geared so that it hits top speed 1/2 to 3/4 the length of the longest straight. Why 1/2 to 3/4 - different batteries.

If the "fast" guys run mod am I supposed to adjust my FDR to match the same rollout as theirs?

Thanks in advance!

Regards,
Alvin
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Old 01-14-2002, 09:08 AM   #2
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You would adjust your FDR to match - so your guess is right - but you would only do it if your tire size is different. Rollout is a method to adjust gear ratio to match varying tire size.
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Old 01-14-2002, 09:11 AM   #3
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Does this matter in say an informal "chase session" where tons of ppl using like 23T with silver brush, 27T stockers, 14x2 mods etc. is there any point in finding out the rollout, or is rollout more for say, a race where everyone is more or less running 9x2s/27t stockers, so as to achive the optimal gear ratio?
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Old 01-14-2002, 08:00 PM   #4
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rollout is just another way on how u calculate the gear ratio....
people who use rollout are those oval racers who run on foam ( pan cars )
the use rollout as a ratio cause the foams wear down and the ratio would be different cause the Diametar of the tire would be smaller when it wears off.......

so asuming ur 6.81 FDR ur roll out would be 33.49mm per rev which means that ur tires move 33.49mm if ur motor makes 1 full 360 turn
and from there u could calculate the speed of ur car if u know ur motor speed under load say its a stock motor and under load its 16000 RPM ur speed would be 29.27KPH
and if ur tires is smaller the top sped would be less bigger more


well for ur question ... i would say it depends ... cause if u gear the stocker right to the roll out a mod motor is going teorically u will be of the same speed but it depends on the track ... and the motor itself

heres a plain example ... i wont calculate i m LAZY figures are all made up

say a 14 turn is geared at 9.6 FDR and a 27 turn is geared at 4.8 FDR and asuming that the 27 turn the rollout is 32mm and the 14 turn the rollout is 16mm with the same tire diameter of 60 mm and the motor speed under load of the both motor is say 18000 for the stock and 36000 for the mod
teorically it will be of the same speed but then it depends on the track. say all tires driver etc etc being equal except the track well the mod might have the edge over the stocker cause it WILL have better acceleration.....
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Old 01-14-2002, 08:38 PM   #5
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Rollout is a calculation to determine the best possible gear ratio to a track for a certain motor. Say you went to a permenant track that you never raced on before. Rather than going to each hometown track racer and asking him what motor, tires, internal ratio, spur size, pinion and what pitch he's using and then go calculate up the final gear ratio they're running for each racer, it's alot easier to say "what is a good rollout for the 19T class?" After you know that, you know where to start on gearing your car for their track. It saves alot of ink, paper, time and frustration. Rollout is almost the same thing as asking what final gear ratio everyone's running, except that tire size is calculated into the equation which results in whats called rollout.
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Old 01-14-2002, 11:17 PM   #6
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Thank you both! I now get the idea.
Right now, I have several sets of tires, and all of them have different diameters. What I do is calculate the rollout, and based on each tire, calculate the appropriate FDR for use with them. Thus it theory the car *should* perform the same since they will move at the same distance for each revolution!!!!!

Woohoo now to take out my calculator

Thanks again!

Regards,
Alvin
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Old 01-15-2002, 02:06 PM   #7
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Quote:
Originally posted by Alvin
...Woohoo now to take out my calculator

Thanks again!

Regards,
Alvin
Why do that? This will do the math for you:

http://www.arroyoc.com/gear.asp

Bryan
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Old 01-15-2002, 06:50 PM   #8
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yep it will save lots of time and fingers punching the calculator
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Old 01-16-2002, 01:04 AM   #9
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One reason - no web access at the track
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Old 01-17-2002, 02:31 AM   #10
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no no do it first then ... make it into a table and PRINT it ... anytime u can see at the track
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Old 01-17-2002, 02:36 AM   #11
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Rollout is for the anal racer. Who uses rolllout?
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Old 01-17-2002, 09:36 PM   #12
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lol rccadet ... u r calling urself a anal racer??? whats that LINK under ur name !!!
LOLOLOLOLOLOL
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