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Old 07-15-2007, 10:21 AM   #2416
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Originally Posted by Lewd Skywalker View Post
Hi, I'm running a Losi JRX-S (1.83 IR), GTB with a 4.5R motor. My problem is thermal shutdown.

Here's what I noticed in different runs:

GTB + 4.5R with non-sintered rotor
used FDR of 10.2 - thermal shutdown after 5 minutes and 1 lap (23 secs)
used FDR of 9.76 - thermal shutdown, did not finish the 5 mins. heat

GTB + 4.5R with sintered rotor
used FDR of 10.2 - thermal shutdown after 5 minutes + 2 lap
used FDR of 9.76 - thermal shutdown after 5 minutes + 1 lap
used FDR of 9.37 - did not continue feeling I might be overgeared as it seems acceleration is mushy and car slowed down after 2-3 laps
temperature measurement ranged for the motor from 68-81 degC after shutdown, ESC is about 48-55degC (measured after each test run)

Am I undergeared with the above set-up? Also with the sintered rotor, I notice sometimes there is a point after braking, the motor wont run (cogged?).

Does undergearing could also cause the brushless system to overheat?

One more thing, I think my radio is set to 50/50 electronic thown and not the 70/30 recommended, will this have anything to do with the overheating/shutdowns???

Many thanks to all for the help. Regards..

Ludwig
make sure that your drivetrain is smooth and i would replace the rotor
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Old 07-15-2007, 10:30 AM   #2417
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Quote:
Originally Posted by Lewd Skywalker View Post
Hi, I'm running a Losi JRX-S (1.83 IR), GTB with a 4.5R motor. My problem is thermal shutdown.

Here's what I noticed in different runs:

GTB + 4.5R with non-sintered rotor
used FDR of 10.2 - thermal shutdown after 5 minutes and 1 lap (23 secs)
used FDR of 9.76 - thermal shutdown, did not finish the 5 mins. heat

GTB + 4.5R with sintered rotor
used FDR of 10.2 - thermal shutdown after 5 minutes + 2 lap
used FDR of 9.76 - thermal shutdown after 5 minutes + 1 lap
used FDR of 9.37 - did not continue feeling I might be overgeared as it seems acceleration is mushy and car slowed down after 2-3 laps
temperature measurement ranged for the motor from 68-81 degC after shutdown, ESC is about 48-55degC (measured after each test run)

Am I undergeared with the above set-up? Also with the sintered rotor, I notice sometimes there is a point after braking, the motor wont run (cogged?).

Does undergearing could also cause the brushless system to overheat?

One more thing, I think my radio is set to 50/50 electronic thown and not the 70/30 recommended, will this have anything to do with the overheating/shutdowns???

Many thanks to all for the help. Regards..

Ludwig
lewd, you are definitely overgeared specially with our local temperature.
try working above 10.2 fdr... maybe 10.5 to 10.75 should be a good gearing. I have geared mine @ 10.2 (bonded rotor) with no thermal issues but my set-up was strictly 5mins run night race.

Btw, just some advice specially for non sintered rotor as much as possible avoid thermal issues as it will weaken the rotor and eventually damaged the magnets. Don't make hard brakings as this too can damaged the rotor.. It happended to me
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Old 07-15-2007, 10:32 AM   #2418
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this might help a little

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Old 07-15-2007, 12:05 PM   #2419
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Quote:
Originally Posted by BrainTeased View Post
the 13.5 without sintered rotor will thermal at approx 200 F

Everytime you thermal the motor the rotor gets weaker and will thermal again at a reduced tempreture (for example 190F)

so try to be cautious or better yet get a sintered rotor if the track does not allow that, then be cautious and ask your fellow club members what ratio they are using.
Correct, though I have had some bonded rotors that will do their first thermal shutdown at a lower temp than that. I think because not all of them are equal, different ones will go at different temps. I've had one that first thermalled at about 170 degrees, & one that first did it at more like 155, & yet others that were closer to the 200 mentioned by BrainTeased. In general though, I'd try to keep the motor from getting any hotter than 150 after a run, just to be safe.....
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Old 07-15-2007, 05:38 PM   #2420
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Default Thermal

Need some help.

Just bought GTB 4 cell with 5.5 motor. Roll out was a little high 1.444, but perfect for 100 ft straight. The speed control kept thermalling off. Is there a way to keep this from happening or do you just have to keep going down on pinon and losing top end speed? If so that sucks I guess I should have bought an LRP.
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Old 07-15-2007, 06:05 PM   #2421
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Thanks for the replies, highly appreciate it.

Rcdy: Thanks bro, I ran the 4.5R with sintered rotor on 10.2 FDR and I finished the 5 minutes heat however continued to run the car for 2 more laps then it thermalled. Motor was hot 81 C (176 F). I'll try a 1 teeth smaller pinion.

Anyway, does the 50/50 and 70/30 electronic throw setting on the transmitter have anything to do with the performance on BL systems? The Novak BL required 70/30 but currently I figured out my 3PK was still on 50/50. Anyone?

Thanks again.
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Old 07-15-2007, 06:20 PM   #2422
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Looking into getting a 3.5 brushless system for my dragster, anyone have some feedback on the speed of it?
?
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Old 07-15-2007, 07:38 PM   #2423
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Originally Posted by fred kellner View Post
Need some help.

Just bought GTB 4 cell with 5.5 motor. Roll out was a little high 1.444, but perfect for 100 ft straight. The speed control kept thermalling off. Is there a way to keep this from happening or do you just have to keep going down on pinon and losing top end speed? If so that sucks I guess I should have bought an LRP.
get the sintered rotor
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Old 07-15-2007, 08:11 PM   #2424
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Default Thermal

Marcos I do have a sintered rotor. It isn't the motor getting too hot it is the speed control. I didn't temp either one, but the speed control is way hotter than the motor. Is this normal or do I have a bad speed control?
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Old 07-16-2007, 03:32 AM   #2425
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Quote:
Originally Posted by Lewd Skywalker View Post
Thanks for the replies, highly appreciate it.

Rcdy: Thanks bro, I ran the 4.5R with sintered rotor on 10.2 FDR and I finished the 5 minutes heat however continued to run the car for 2 more laps then it thermalled. Motor was hot 81 C (176 F). I'll try a 1 teeth smaller pinion.

Anyway, does the 50/50 and 70/30 electronic throw setting on the transmitter have anything to do with the performance on BL systems? The Novak BL required 70/30 but currently I figured out my 3PK was still on 50/50. Anyone?

Thanks again.
No prob pre... I also notice between fdr of 10.2 and 10.5 theres no speed difference. so to be safe 10.5 nlang.

I also don't think theres any effect on your radio settings. happy brushless racing lewd...
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Old 07-18-2007, 03:10 AM   #2426
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How do you turn off the cutoff in the GTB? I need to turn it off in case my batteries (for some reason) go too far and it wants to shut it down.
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Old 07-18-2007, 11:02 AM   #2427
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guys, my power cap became dented during racing so i removed it. I have since not run the GTB without the power cap and I like the look of it without the cap.

I run stock TC with a 13.5ss motor and sintered rotor with li-po. Do you think it will damage the ESC without a power cap or cause any issues?
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Old 07-18-2007, 12:00 PM   #2428
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Quote:
Originally Posted by B18C Turbo View Post
guys, my power cap became dented during racing so i removed it. I have since not run the GTB without the power cap and I like the look of it without the cap.

I run stock TC with a 13.5ss motor and sintered rotor with li-po. Do you think it will damage the ESC without a power cap or cause any issues?
i would put the powercap back!!
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Old 07-18-2007, 01:09 PM   #2429
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Quote:
Originally Posted by B18C Turbo View Post
guys, my power cap became dented during racing so i removed it. I have since not run the GTB without the power cap and I like the look of it without the cap.

I run stock TC with a 13.5ss motor and sintered rotor with li-po. Do you think it will damage the ESC without a power cap or cause any issues?
it's there to protect the speedo
so put it back (yes it does look better ) but don't leave it off
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Old 07-18-2007, 01:18 PM   #2430
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how does it protect the speedo? Cyclones didnt have one! What would be a good replacement because I refuse to drop $17 on an OEM novak one!
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