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Old 09-09-2014, 01:48 AM   #1
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Default Slow 21.5 speed..

Hey I've made the transition to onroad touring car racing with a modded Sakura Zero. Running a Turnigy 21.5 motor in the blinky stock class. Just having trouble with the cars top speed. It feels very slow. I watched the state titles the other week and the other 21.5 cars were a lot faster.
I've tried a few gear ratios but yet to really improve its top speed.
Currently running it with the stock spur and a 34 tooth pinion. The car just ambles down the straights and the motor/ESC (Speed Passion) are barely getting warm, its also not putting any strain on the 2S batteries that last for ages.
The motor is programmable but I'm just leaving it on default settings.

Is it all gearing related or am I doing something wrong?
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Old 09-09-2014, 02:04 AM   #2
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Quote:
Originally Posted by Coopz View Post
Hey I've made the transition to onroad touring car racing with a modded Sakura Zero. Running a Turnigy 21.5 motor in the blinky stock class. Just having trouble with the cars top speed. It feels very slow. I watched the state titles the other week and the other 21.5 cars were a lot faster.
I've tried a few gear ratios but yet to really improve its top speed.
Currently running it with the stock spur and a 34 tooth pinion. The car just ambles down the straights and the motor/ESC (Speed Passion) are barely getting warm, its also not putting any strain on the 2S batteries that last for ages.
The motor is programmable but I'm just leaving it on default settings.

Is it all gearing related or am I doing something wrong?
Your way under geared your fdr is very high at 4.71. Most people gear their 21.5t motors somewhere between 3.0-4.0fdr. Myself, I'm running 3.51fdr
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Old 09-09-2014, 02:05 AM   #3
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Hi mate, I suspect gearing is wrong. I was running the trackstar 21.5 for a bit and for my home track (IMCC in wollongong) we were gearing them around the 2.9 range. If your track is more technical you could go up to 3.1 or 3.2 fdr. I'm going to guess that the stock spur is in the 80s which will be way wrong. You will need something in the 50s to low 60s for the spur and a pinion in the high 30s.

Regards,

Simon
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Old 09-09-2014, 04:36 AM   #4
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Also check your timing. Most people are running 20+ degrees in timing depending on the motor - but make sure you keep an eye on temps.

Also in 21.5 there seems to be quite a large difference in motors. I used to run a SP esc/motor combo and was about 1 second off the pace for a 20 second lap. After switching to an LRP speedy/r1wurks, its a huge difference
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Old 09-09-2014, 05:08 AM   #5
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Ah cheers, yeah it's a 80t spur. Any pinions can I use without replacing the spur? Or is it better to just regear the whole thing?
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Old 09-09-2014, 06:24 AM   #6
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Depending on how much space you have to fit a pinion, go to a 45t pinion and see what temps looks like. That would put you at 3.56 fdr.

Please note that you could currently be geared correctly for YOUR track compared to the State track you saw. Different size/configurations on a track can make it go from tight/technical to smooth/high speed with different gearing needed for both.
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Old 09-09-2014, 06:52 AM   #7
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I run that motor and it's a monster down low but offers no rpm . So , advance timing all the way and gear it to 3.5for a base run and check temps after 2min keep below 130deg at 2min mark. You will love that motor once you gear it correctly
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Old 09-09-2014, 07:28 AM   #8
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This could be a stupid question......Are you running a motor sensor wire to your ESC? A bad (or missing) sensor wire could cause poor performance too.

I run a Hacker 21.5 with the timing cranked all the way up with gearing of 37/102 (5.51 FDR) in our USGT (Spec GT) class and the car isn't that much slower than the 17.5 cars running 4.0 FDR touring cars.

Motor temps do run in the 170 range with a motor fan, but then it's starting out at about 100+ degrees here in the desert, even racing at night.

Our GT class runs different gearing from most other GT classes for some reason, but with everyone running it it does make for some good racing. (We race on a relatively small track.)


You may want to re-gear your car so you can use 64 pitch gears, you can fine tune your FDR's a bit better. I tried to get away with using the stock spur gear but quickly saw the benefit to the 64 pitch gears and the wide range of possible ratios.
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Old 09-09-2014, 02:57 PM   #9
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Quote:
Originally Posted by mkiiina View Post
Depending on how much space you have to fit a pinion, go to a 45t pinion and see what temps looks like. That would put you at 3.56 fdr.

Please note that you could currently be geared correctly for YOUR track compared to the State track you saw. Different size/configurations on a track can make it go from tight/technical to smooth/high speed with different gearing needed for both.

Ah it was the same track
Its this place so its fairly fast and flowing.
http://www.youtube.com/watch?v=at6NTUGGw-M
A 45T won't fit

Quote:
Originally Posted by OttoKrosse View Post
This could be a stupid question......Are you running a motor sensor wire to your ESC? A bad (or missing) sensor wire could cause poor performance too.

I run a Hacker 21.5 with the timing cranked all the way up with gearing of 37/102 (5.51 FDR) in our USGT (Spec GT) class and the car isn't that much slower than the 17.5 cars running 4.0 FDR touring cars.

Motor temps do run in the 170 range with a motor fan, but then it's starting out at about 100+ degrees here in the desert, even racing at night.

Our GT class runs different gearing from most other GT classes for some reason, but with everyone running it it does make for some good racing. (We race on a relatively small track.)


You may want to re-gear your car so you can use 64 pitch gears, you can fine tune your FDR's a bit better. I tried to get away with using the stock spur gear but quickly saw the benefit to the 64 pitch gears and the wide range of possible ratios.

Sensor cable is good, the motor and ESC are almost brand new.
I'll see if I can get a better spur/pinion ratio as I want to stay in the 21.5 class, 13.5 is to competitive for me
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Old 09-09-2014, 03:17 PM   #10
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Quote:
Originally Posted by Coopz View Post
Ah it was the same track
Its this place so its fairly fast and flowing.
http://www.youtube.com/watch?v=at6NTUGGw-M
A 45T won't fit




Sensor cable is good, the motor and ESC are almost brand new.
I'll see if I can get a better spur/pinion ratio as I want to stay in the 21.5 class, 13.5 is to competitive for me
COOPZ I don't run that motor but my buddy does and he has the timing cranked up to the max and runs a ~3.5FDR on a big flowing track. IF a 45T pinion doesn't fit, find the biggest pinion that will and crank the timing up. Care to watch the temps until you know the motor won't over heat. IF you still aren't fast, find a smaller spur gear. But even at 3.5 FDR and stock timing that puppy should fly.
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Old 09-09-2014, 03:44 PM   #11
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We run 21.5 in OVTA, with 92 spur and 51 pinion, we were at Tamiya track on Sunday. Timing is set at 40 on the REEDY Mach 2 motor, blinky and 5500mah 2S 60C wolfpak and the car was fast. Driving TC6.2 with J71 protoform body.
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Old 09-09-2014, 03:55 PM   #12
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i run 21.5 exclusively during the summer. 3.6 is a good ratio and up to 3.8 for smaller tracks. if its a large track i would suggest down to 3.3 to 3.4. monitor temps and adjust accordingly. run your timing up to between 35-40 degrees also. this will help with speed.
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Old 12-19-2014, 03:10 AM   #13
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Bump my old thread but I'm still having no luck with the cars top speed and its hurting my lap times.
I've changed the gearing to the smallest spur I could find for the Zero a 66T and I put a 38T pinion in it to give a FDR of around 3.3 and I've leaned the timing right out. The car still feels about 5-10kph slower in a straight line than the competition
I'm running 40c 2S Turnigy lipos if that makes much difference. Also using a Speed Passion Reventon Pro in blinky.

Starting to think my motor is a lemming. After a 5m run its up to about 60c so its getting warm but not too hot.

Maybe a different motor?
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Old 12-19-2014, 03:26 AM   #14
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I'm not a lot of help but have you tried any different batteries? I'm running a very different setup for offroad but noticed a fair difference in punch and speed between Turnigy 2s lipos (standard and nanotech) vs SMC factory spec batteries.
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Old 12-19-2014, 03:26 AM   #15
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Quote:
Originally Posted by Coopz View Post
Bump my old thread but I'm still having no luck with the cars top speed and its hurting my lap times.
I've changed the gearing to the smallest spur I could find for the Zero a 66T and I put a 38T pinion in it to give a FDR of around 3.3 and I've leaned the timing right out. The car still feels about 5-10kph slower in a straight line than the competition
I'm running 40c 2S Turnigy lipos if that makes much difference. Also using a Speed Passion Reventon Pro in blinky.

Starting to think my motor is a lemming. After a 5m run its up to about 60c so its getting warm but not too hot.

Maybe a different motor?
Generally the trackstar's are okay - they aren't the best but have some pace and with good enough driving, could possibly keep up with more expensive motors. I would say aim for lap times rather than top speed. Some people gear the shit out of their cars but their infield speed suffers greatly.

Play around with the gearing a bit more and try to run your motor between 60-70 deg celcius. Any hotter and it won't be good for the motor, any cooler and you won't be maximising your performance. With regard to spurs, maybe use some aftermarket ones? I'm not familiar with Sakura but I'm assuming they are just standard spurs? (So that you can use RW Racing spurs, etc)
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