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Old 09-11-2006, 12:56 AM   #151
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Hey Aussie Bob!!!
Just wondering what voltage you are testing at? and also what gear ratio or roll out you are using?I run 4.6 most guys at my club run at a lower ratio 4.1 to 4.4. Sounds like you ar fast so any help would be appreciated
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Old 09-11-2006, 02:25 AM   #152
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At our local track in Christchurch, New Zealand, the top guys are all runing betwen 3.7 and 4.0. The track is very big (designed mainly for gas cars). Im sure you could run around 4.0-4.2 easily on a tight track.

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Old 09-11-2006, 03:31 AM   #153
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we usually run a rollout of between 39 & 44 depending on the layout,its not the biggest track you will find,usually has 1 long straight (approx 30mts) & the rest is technical a little bumpy in places with average grip level(concrete surface)average lap time is about 13.5 sec using rubbers foams only get chewed up on this surface
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Old 09-11-2006, 04:23 AM   #154
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Thanks Professor, suggestion for people... seeing we are all using the same motor lets stick to using rollout ratios instead of internal ratios, as these vary from car to car, and rubbers to foams. At Castle Hill a rollout of about 40 is about the optimum, whereas at the Narrabeen/St Ives track which is VERY open with two LOOOOONG straights I ran a rollout of 50, which was with my largest available pinion.

Rollout, for those who arent sure, is how far the car moves forward in mm, per revolution of the motor. So it takes into account all the drive train variations. check out www.gearchart.com
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Old 09-11-2006, 04:46 AM   #155
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Thanks for all the tips!!!!

My roll out is 43, it seems if i go any higher the motor feels like its laboring a bit, is this normal???? do i need a fan?
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Old 09-11-2006, 04:52 AM   #156
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I wouldnt go any higher in that case, I rule of thumb i use is this... you want to hit top speed by about 1/3 of the way down the straight. there is no point gearing right up, only to hit top speed just before the end of the straight, and then you lose your momentum and cant really get it back through the infield...

if your motor is getting really hot (too hot to touch) the heat will damage your motor, get a heat sink and fan.

just my 2 cents worth...
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Old 09-11-2006, 02:04 PM   #157
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Anyone actually try acetone to clean a motor?
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Old 09-11-2006, 03:54 PM   #158
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Quote:
Originally Posted by gazza726
i was recenty in the mid north coast owtlaw challenge.. i ran stock but i had to have a look at the 540 class and there was an old guy runi a bmi tc3 in the 540 class and i never seen a 540 car go so fast.. so i asked him wat he was doin to his silver cans and he told me cleaner is faster.. he was syin he dips his motors in water to clean them out then sprays wd40 in them then dips them in water with the wd40 in the motor then dips again in fresh water to rinse and bench runs it for 5 mins then cleans the com with metho.. i have tried this on an old johson 540 i had and it is notacbly faster and its leagal coz u dont open the can but just remeber cleaner is faster...
Like just dip the motor? Or dip it while conected to a battery.
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Old 09-11-2006, 05:15 PM   #159
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Water dipping is where the motor is immersed in water while running on a low voltage, say 1 or 2 volts.

two ways you can do this, either get a charger with a run-in feature (I can set my charger to deliver anywhere from 1v to 8v, for upto 99 hours), or solder up an old pack in PARALLEL, ie 1.2v x 6 cells - +ve to +ve to +ve.... to motor positive and -ve to -ve to -ve....to motor negative, which will deliver 1.2 volts for the whole pack for about 15 min, then put the motor in a glass of water until the pack is dead.
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Old 09-11-2006, 05:31 PM   #160
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Quote:
Originally Posted by MK_Arbiter
Like just dip the motor? Or dip it while conected to a battery.
No, use a set voltage, i use a dyno with 7.2 volts, so if you make a change the same voltage is used all the time. By the way Proffessor, if that is the case wouldnt it be that 99% of the field would be out, or maybe i am doing something and everybody is driving far better than me with less revs and i am point ond squirt trying to catch them. Also, i have a brand new 540 silver can straight from the mini, nothing done, 17300 before anything was done, a bit more now but. PS, have they ever used that rule ?????. If the guy still has a 30,000 motor, maybe 12volts, PM me with a price, or put it on Ebay with a confirmation of 7.2v at 30,000, like to see that (BS)
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Old 09-11-2006, 06:19 PM   #161
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I've recently noticed that cleaner is faster (was wondering why the guys at the track suggested cleaning out motor after every meet). Also noticed that the motor runs so much smoother and quieter after a good clean and lube.

I've still to try the water dipping, but wanted to check if you dip the hole motor in, including the taps which the "power" wires are attached to? My guess is that you'll need to get it that far into the water to keep the comm and brushs immersed. But what stops the water conducting power between the wires etc and shorting out the battery?
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Old 09-11-2006, 06:32 PM   #162
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I think that water only conducts electricity at above 20v or thereabouts, which is why a car battery wont short underwater, but for example if your mains power gets in the pool it will conduct. I was a bit iffy aswell about electricity and water, but it is just as safe as touching both the terminals on the battery with your fingers, it doesnt conduct. where as if you touch +ve and -ve wires from the mains you get a shock (DO NOT MESS WITH MAINS POWER, IT IS VERY DANGEROUS!)
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Old 09-11-2006, 06:35 PM   #163
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Hey, has anyone else noticed how many Aussies (especially Sydneysiders) there are on this thread...

we should get together in someones garage for a cleaning and maintainence session some rainy weekend...
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Old 09-11-2006, 07:04 PM   #164
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Quote:
Originally Posted by PeteB
I think that water only conducts electricity at above 20v or thereabouts, which is why a car battery wont short underwater, but for example if your mains power gets in the pool it will conduct. I was a bit iffy aswell about electricity and water, but it is just as safe as touching both the terminals on the battery with your fingers, it doesnt conduct. where as if you touch +ve and -ve wires from the mains you get a shock (DO NOT MESS WITH MAINS POWER, IT IS VERY DANGEROUS!)
Impurities in water conduct electricity. Pure water will not conduct electricity. This is how they know when to change filters ona water purification system; two electrodes are placed in the purified water and when a crrent passes through it, it is time to change the filters
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Old 09-11-2006, 10:26 PM   #165
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Quote:
Originally Posted by koinonas
I've recently noticed that cleaner is faster (was wondering why the guys at the track suggested cleaning out motor after every meet). Also noticed that the motor runs so much smoother and quieter after a good clean and lube.

I've still to try the water dipping, but wanted to check if you dip the hole motor in, including the taps which the "power" wires are attached to? My guess is that you'll need to get it that far into the water to keep the comm and brushs immersed. But what stops the water conducting power between the wires etc and shorting out the battery?

I dunk my motors upside down, as that is where the brushes are.
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