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Old 04-27-2006, 10:45 AM   #196
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By allowing you to gear down to reach the same speeds, it puts less of a strain on the motor allowing it to run cooler.

Tony
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Old 05-25-2006, 08:34 PM   #197
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Tony-My experience with brushed motors is that the lower winds always pull more average amps, run hotter and destroy the comm faster in spite of lower gearing. It may be different with the brushless. I would love to hear an actual report of a thermal shutdown problem solved with a 5.5 or 3.5 (anything other than to gear the 6.5 motor so that it is slow as molasses on our track).


GTB 6.5 Hot weather test with motor cooling fan.
Track temp 132 F air temp 93 F. Good day for this test. Thermal shutdown after about 3 to 4 minutes. There was little improvement with the motor cooling fan.

GTB 6.5 Speed control Glitch
I had an additional problem. I was getting an unusual glitch with the GTB system. It would go to full throttle all by itself. This caused me a lot of grief and broke the car 3 times while I tried to trace it down. I replaced the receiver and it worked good for about 2/3 of a pack and then the glitch returned. I unhooked the motor fan. It was not the problem. I unhooked the receiver fan, it was not the problem. I took out the GTB 6.5. That was the problem. Must be an internal speed control failure. The harness is in good shape. Back to brushed.

I did a preliminary test of the custom flat wire and round wire arms to get the gearing right and to heat stress the comm. More to come.
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Old 05-26-2006, 10:39 AM   #198
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Quote:
Originally Posted by John Stranahan
Tony-My experience with brushed motors is that the lower winds always pull more average amps, run hotter and destroy the comm faster in spite of lower gearing. It may be different with the brushless. I would love to hear an actual report of a thermal shutdown problem solved with a 5.5 or 3.5 (anything other than to gear the 6.5 motor so that it is slow as molasses on our track).


GTB 6.5 Hot weather test with motor cooling fan.
Track temp 132 F air temp 93 F. Good day for this test. Thermal shutdown after about 3 to 4 minutes. There was little improvement with the motor cooling fan.

GTB 6.5 Speed control Glitch
I had an additional problem. I was getting an unusual glitch with the GTB system. It would go to full throttle all by itself. This caused me a lot of grief and broke the car 3 times while I tried to trace it down. I replaced the receiver and it worked good for about 2/3 of a pack and then the glitch returned. I unhooked the motor fan. It was not the problem. I unhooked the receiver fan, it was not the problem. I took out the GTB 6.5. That was the problem. Must be an internal speed control failure. The harness is in good shape. Back to brushed.

I did a preliminary test of the custom flat wire and round wire arms to get the gearing right and to heat stress the comm. More to come.
The 5.5 is not fast enough to run in Open Sedan Mod so guys would gear it up to get more speed and it would thermal. The 4.5 is plenty fast enough to run in Open Mod. You can gear the 4.5 lower and still have the necessary speed to run with 7T brushed motors without thermalling. However, it is getting hot enough now in the south that ALL BL systems are thermalling. When the track itself is 150deg you are pretty screwed...lol! Brushed motors are coming off the track over 200 deg...but they keep running.
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Old 05-26-2006, 05:01 PM   #199
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Adrian-Thanks for the report. If somebody knows, are the GTB thermal shutdowns because of motor overheating or speed control overheating. Those that have unplugged the tiny blue wire previously mentioned on this thread would know.


Here is a link to a well vented aircraft motor. I don't know why we don't have vents.
http://www2.towerhobbies.com/cgi-bin...?&I=LXLWW1&P=7

Here is a link to a photo of a vented aircraft motor that also probably has an internal fan.
http://www2.towerhobbies.com/cgi-bin...?&I=LXHEW2&P=7

There is a better picture of a fan cooled motor in the most recent tower hobbies sales catalog for aircraft.

Last edited by John Stranahan; 05-31-2006 at 09:35 PM.
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Old 05-26-2006, 06:15 PM   #200
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John, congratulations on the thread ( one of the most informative on RCTech ).
I have learnt a lot from reading this (even though I run a BD), and read with interest each new post you make.
Keep em coming!!
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Old 05-26-2006, 06:43 PM   #201
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Quote:
Originally Posted by John Stranahan
Adrian-Thanks for the report. If somebody knows, are the GTB thermal shutdowns because of motor overheating or speed control overheating. Those that have cut the tiny blue wire previously mentioned on this thread would know.


Here is a link to a well vented aircraft motor. I don't know why we don't have vents.
http://www2.towerhobbies.com/cgi-bin...?&I=LXLWW1&P=7

Here is a link to a photo of a vented aircraft motor that also probably has an internal fan.
http://www2.towerhobbies.com/cgi-bin...?&I=LXHEW2&P=7

There is a better picture of a fan cooled motor in the most recent tower hobbies sales catalog for aircraft.
On the GTB its 60/40 motor/speedo. The Novak motor temp sensor setting is a bit conservative. This is why some unplug the blue wire. The Reedy motors do not have a temp sensor in them. This is why they seem to thermal less often.
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Old 05-26-2006, 07:19 PM   #202
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Quote:
Originally Posted by John Stranahan
Adrian-Thanks for the report. If somebody knows, are the GTB thermal shutdowns because of motor overheating or speed control overheating. Those that have cut the tiny blue wire previously mentioned on this thread would know.


Here is a link to a well vented aircraft motor. I don't know why we don't have vents.
http://www2.towerhobbies.com/cgi-bin...?&I=LXLWW1&P=7

Here is a link to a photo of a vented aircraft motor that also probably has an internal fan.
http://www2.towerhobbies.com/cgi-bin...?&I=LXHEW2&P=7

There is a better picture of a fan cooled motor in the most recent tower hobbies sales catalog for aircraft.


the links posted are of outrunner brushless motors. they work kind of backwards, the can spins and the arm stays in place. fewer rpms, but massive tourque. not sure if that has anything to do with how BL motors work, but outrunners are the only BL motors i have seen vented
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Old 05-26-2006, 08:14 PM   #203
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lopedeloop-thanks. Adrian thanks. I agree that the motor temp sensor is too conservative, but then I don't do warantee work on the beast. Our stock motors run at 210 F without a problem. At 240 they are short lived.

OK here is a link to the brushless motor in the catalog that is advertized as the first to have a built in fan. This would help our motors a lot. Double fans on the speed control helps blow a lot more air. Maybe there is hope for the next generation. At this point I'll have to say, save this brushless for winter racing in the south. I have not tried a cloth sock saturated in alcohol on the motor. This might work good with the fan. Unless the speed control Thermals. They might need to run the electronics in a cooling but non electricity conductive liquid if that is the case.

http://www2.towerhobbies.com/cgi-bin...=++&search3=Go

go the manufacturers product web page link to see the inner details of the fan.

geeunit1014-I see some rimfire motors at tower that look like the case turns, but they don't have a shaft that extends from the front?

http://www2.towerhobbies.com/cgi-bin...?&I=LXJTU6&P=C

Last edited by John Stranahan; 05-26-2006 at 08:43 PM.
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Old 05-31-2006, 08:43 PM   #204
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Alcohol?? Hot motor, electrical leads, alcohol... Brave.

Incidentally, i suppose an alcohol fire would be fairly invisible so you wouldn't know until the car itself caught fire or the shell started melting right? LoL..

Sorry to hear of your ongoing BL system troubles.. Perhaps the track will let you use a 5.5? Just maybe?
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Old 05-31-2006, 09:32 PM   #205
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No sparks near the motor to cause a flame. Rubbing alcohol 70%. Reasonably high flash point. No problems. It will be less corrosive than using water and have a better cooling effect from the lower boiling point. The motor will dry out better at the end of the day. I'll try alcohol if I get my GTB back from service. Not brave at all. Don't use Methanol Neet! Aside from the fact that it will probably melt all the plastic in the model it would burn with a blue almost invisible flame. The rubbing alcohol (isopropyl or ethyl) burns yellow and is actually difficult to ignite because of the water content.

Also it would seem a 4.5 might be in order. I plan to get one. Note that the blue wire will unplug at the speed control end similar to a receiver plug wire removal. There is a tiny tab. Don't cut the blue wire. I'll suggest the track go to open mod if one of these faster motors works. It would be nice if the motor had a built in fan here in Houston, Though. The motors by themselves are actually similarly priced to a brushed mod. You could stand to run it a little hotter and reduce its life slightly.

Last edited by John Stranahan; 05-31-2006 at 10:20 PM.
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Old 06-03-2006, 01:22 AM   #206
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Quote:
Originally Posted by John Stranahan
No sparks near the motor to cause a flame. Rubbing alcohol 70%. Reasonably high flash point. No problems. It will be less corrosive than using water and have a better cooling effect from the lower boiling point. The motor will dry out better at the end of the day. I'll try alcohol if I get my GTB back from service. Not brave at all. Don't use Methanol Neet! Aside from the fact that it will probably melt all the plastic in the model it would burn with a blue almost invisible flame. The rubbing alcohol (isopropyl or ethyl) burns yellow and is actually difficult to ignite because of the water content.

Also it would seem a 4.5 might be in order. I plan to get one. Note that the blue wire will unplug at the speed control end similar to a receiver plug wire removal. There is a tiny tab. Don't cut the blue wire. I'll suggest the track go to open mod if one of these faster motors works. It would be nice if the motor had a built in fan here in Houston, Though. The motors by themselves are actually similarly priced to a brushed mod. You could stand to run it a little hotter and reduce its life slightly.
John- Agree with your point.
I think alcohol (not methanol..) evaporate very quickly and take the heat out of the subject, back in the old day of history, Hitler's V2 rocket engine using the same principle, they have to use alcohol spray outside the rocket nozzle to keep those ol' days material at certain temperature or being deteriorate without proper cooling to enormous pressure and heat from burned fuel jets inside the nozzle,
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Old 06-08-2006, 11:56 PM   #207
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I know this isn't the right thread to post this but I'm going to go ahead and ask anyway since I was told to post this here. I get understeer (on power) and wide turns. My car feels lazy when it turns. How do I approach this problem? What should I change first?

Equipments: (FT TC4)
M8 w/ spektrum system = capacitor installed
Airtonics 94758z
GTX
CO27
CS27 tires premounted

Here is my current FT TC4 setup: Asphalt Track (Med High Traction)
Front:
Droop = 5
Ride height = 5.5
Springs = blue
Pistons = one hole
Oil wt. = 35
Camber = -1
Caster = 4
Toe = 0
A-arm = outer hole
Where the camber linkages go = inner most hole with one shim under it.
Shock tower = outer hole

Rear:
Droop = 4
Ride height = 5.5
Springs = blue
Pistons = one hole
Oil wt. = 35
Camber = -1.5
Caster = 0
Toe = 3
A-arm = outer hole
Where the camber linkages go = inner most hole with one shim under it.
Shock tower = second to the last outer hole.

Edit: Sorry, I forgot to mention: No stand offs and no spine plate.

Thanks in advance,
Mark

Last edited by bukil; 06-09-2006 at 12:08 AM.
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Old 06-09-2006, 04:57 AM   #208
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Quote:
Originally Posted by John Stranahan
lopedeloop-thanks. Adrian thanks. I agree that the motor temp sensor is too conservative, but then I don't do warantee work on the beast. Our stock motors run at 210 F without a problem. At 240 they are short lived.

OK here is a link to the brushless motor in the catalog that is advertized as the first to have a built in fan. This would help our motors a lot. Double fans on the speed control helps blow a lot more air. Maybe there is hope for the next generation. At this point I'll have to say, save this brushless for winter racing in the south. I have not tried a cloth sock saturated in alcohol on the motor. This might work good with the fan. Unless the speed control Thermals. They might need to run the electronics in a cooling but non electricity conductive liquid if that is the case.

http://www2.towerhobbies.com/cgi-bin...=++&search3=Go

go the manufacturers product web page link to see the inner details of the fan.

geeunit1014-I see some rimfire motors at tower that look like the case turns, but they don't have a shaft that extends from the front?

http://www2.towerhobbies.com/cgi-bin...?&I=LXJTU6&P=C
i believe that is the motor that is pre-modded to work with a variable pitch prop
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Old 06-09-2006, 09:12 PM   #209
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Mark

The setup change that gets you more steering traction on power is affected some by the front diff you are running. I did not see this in your posted setup.

For a standard ball front diff making the front end softer will give you more steering traction generally and thus more steering traction on power. Move the Front blue spring inward on the tower or the rear spring outward. Having a supple shock in the front will help as well. Go to 30 weight in the front. Not sure what a 1 hole piston is, but I think the Associated pistons are numbered. Check Christian Tabush's setup earlier in this thread for some more clues.
http://www.rctech.net/forum/showthre...up#post2068840
He had the same problem. One thing he tried that was succesful is going to the more flexible plastic front arms from the TC3.

I keep adjusting my car until on power the car drifts pretty much sideways all the way to the boards when I give it too much power.

Also your rear toe may be a bit high for running a stock motor. Try 2.5 degrees. This will loosen the rear effectively increasing apparent steering traction. Make this change first, then springs, then shock.
John

Gunit1014, Faiz- Thanks for the posts.

Last edited by John Stranahan; 06-09-2006 at 09:35 PM.
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Old 06-10-2006, 08:53 AM   #210
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Sorry. I forgot to mention I'm running spool in the front.
Thanks John! I will try it.

Mark
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