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Old 06-26-2009, 07:46 PM   #736
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Thanks for the posts guys. Two good ideas.

Motor cooling. I possibly reached the limit of my motor cooling today. It was 108 F in the shade and the track reached 150 F. The newly installed speed control fresh from LRP ran 3 and then 4 minutes before some kind of shut down. I say possibly because this was a used only once LRP TC edition that I had returned for warantee service after its very first service. The complaint was that in my pan car at 3 minutes and then 2 minutes or so the car would run fine and then the speed control would gain a mind of its own which included full throttle periods as well as short off periods. I could steer, but I had no throttle control. I was up in the drivers stand by myself. You can imagine my histeria. Finally in ever tightening circles I parked it in the ditch that was created by maintenance of the track, it hit a pipe and stalled wheels spinning wildly until I got down to it. The second test I had changed the receiver. No better. The third test I had changed the speed control to an identical model. Back to normal. No thermal shutdowns no glitches no problems at all. There is only one conclusion for me. Bad speed control; it was brand new. I cannot say this was a thermal shutdown as you don't normally get full throttle with one. I sent it back. They put it in an off-road truck with a milder motor; it worked fine; they sent it back. Took six weeks. Here I am again with a milder version of the same problem. I approach the car and it is not full throttle but the lights on speed control are going on and off irregularly as are the fans. Same timing after start of the heat. Much hotter air temp though. I plan to send it back and request some kind of exchange.

Better cooling- In extreme temps you may have to take more extreme measures than I had previously. I made some changes to have better chance of success tomorrow. Firstly I notice that if you plug 3 more fans into the Battery Eliminator Circuit (BEC) at the receiver, the velocity of the speed control fan is reduced quite a bit. You can tell by unplugging and replugging your auxilliary fan. That is not so good at 108 F. The fix is to plug the auxilliary fans direct to the battery. Here is a preliminary install. If I get the correct white plugs from SMC it will be neater and more rugged. In the meantime I used a servo extender harness and removed the outer cover on the female plug. This leaves three tangs exposed. Move the red out, remove the white and leave the middle blank. Now it plugs in like a male plug into the white plug. Cut and solder the auxilliary fan pigtail to the red and black wire. On my TC4 fans the black with white stripe wire is positive and solders to the red wire. I put two zip ties on the plug leads so the plug would not undo itself in a crash. Now I have full speed on the speed control fan and faster speeds on my other fan, than are possible from the BEC circuit, from the higher pack voltage. If you leave this fan plugged in after a run you will ruin your LiPo.

I swapped to an X12 4.0 which I purchased previously for just such a case. I aimed my auxilliary fans into the front motor vents.
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Old 06-27-2009, 05:31 AM   #737
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I know it will spoil the aerodynamics a bit but a large (35mm) hole in your front windscreen and a smaller hole in the rear window (30mm) in line with your esc/motor will reduce your running temps by quite a bit. I tested this indoors at my club (tc and mardave on carpet with foams, stock motors, ~20'c hall temps) about a year ago and have run it ever since. I was looking at a couple of degree ('c) drop with one hole at the front or back but with both open it dropped the temps by about 5'c.

This was without any extra passive or active cooling on the motor, just the extra airflow through the body. If you feel the rear window of your shell before you remove it from the car it will be quite warm Ok this solution isnt the best as its not legal for running in big races but we do allow it at our club and its easy to tape up the holes when running elsewhere.
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Old 07-01-2009, 12:29 AM   #738
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John,
I have through time read your whole thread. You have done a great detailed job. I have seen the new exotek tc5 bits and I was wondering what you think?
Thanks and God Bless


http://www.exotekracing.com/EXOTEK_N...6/29_TC5X.html
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Old 07-01-2009, 06:59 AM   #739
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Conrad-Thanks for the cooling tips. At this point we have a dictum from above to stay ROAR legal in case a big race is won in the bidding. In this case it is better to practice exactly how you will be required to race in the big one. No need to find out your closed winshield now makes the car unusable in warmup for the big race.

I did have outstanding results on a single duct that cools the speed control and motor on my wide pan car. it creates a 60 mph blast of air each lap. I reported the results recently on my CRC, Battle Axe, Gen X 10 thread. I don't even need a fan on either in 105 degree weather. Truly outstanding. On the touring car I was thinking of a NACA duct on the side which is allowed by the rules. It is a flush fitting duct and if it is of the proper shape it will pull in the boundary layer of air very efficiently with little drag. One of my buddies has a model one to show me, but I have not seen it yet.

J-Saves- Thanks. I looked at the XOTEC web site.

I like the chassis for carpet as it looks stiffer than stock. For asphalt not so much. I like the battery cutouts and in fact made two additional battery shaped cutouts on the other side. For asphalt their lightened top plate looks good. I would have to study it closely to find differences from Associated increased torsional flex (ITF) top plate.

I liked the kit up until it said tape slots, then not so much. Then I read farther down about the new battery strap and posts. Back to OK then.

I like the way the weights protect the corner of the battery and also the way they are offset more to the right. That seems to be what we need at this day in time, until ROAR is enlightened and sheds 5 ounces or so from our required minimum weight. This may not take that long. Conversion to Lipo is finally happening at a rapid pace.


I have lots to report on the TC5 including a new setup for virgin asphalt. I am not quite through with it yet. It gets faster every session as I nudge things a little. I also have a motor gearing setup for 105 F and 150 F track temps. Stay tuned.

Pic-Extremely effective little duct on my wide pan. No fans are needed at 105 F


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Old 07-01-2009, 09:42 AM   #740
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[QUOTE=John Stranahan;6009356]
J-Saves- Thanks. I looked at the XOTEC web site.

I like the chassis for carpet as it looks stiffer than stock. For asphalt not so much. I like the battery cutouts and in fact made two additional battery shaped cutouts on the other side. For asphalt their lightened top plate looks good. I would have to study it closely to find differences from Associated increased torsional flex (ITF) top plate.

I liked the kit up until it said tape slots, then not so much. Then I read farther down about the new battery strap and posts. Back to OK then.

I like the way the weights protect the corner of the battery and also the way they are offset more to the right. That seems to be what we need at this day in time, until ROAR is enlightened and sheds 5 ounces or so from our required minimum weight. This may not take that long. Conversion to Lipo is finally happening at a rapid pace.

Actually the new chassis allows for additional and more consistent flex than the ITF chassis. The chassis is specifically designed for rubber tires as well as to minimize tweak which has been a problem for a fair percentage of TC5 owners (Especially while using the top deck washers and O-rings).
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Old 07-07-2009, 10:01 AM   #741
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Just incase you didnt know John, but Hot Bodies have brought out an LCD driveshaft for their cyclone in the same style as the Losi LCD. I managed to get some sizes from a standard cyclone cvd, xray t2 cvd and schumacher mi2 cvd so i could compare them, let me know if you want the numbers.

https://www.hotbodiesonline.com/products/en/67699.html
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Old 07-07-2009, 10:05 AM   #742
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Please give these numbers
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Old 07-07-2009, 10:45 AM   #743
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Certainly Kajman, [Click Me]

I didnt have a hex pin for the cyclone driveshaft when i measured it and they dont come with blades. The shoulder i mention in my sizes is the shoulder on the stub axle where the the face of the inside bearing sits. These are sizes for the standard driveshafts on the three cars not the LCD versions but the basic sizes should be pretty close to the LCD's. Perhaps you could add the sizes for the LCD's John?

From a personal standpoint the Xray ECS shafts should fit my Mi2 or Mi3/Mi4 with only a little modification to the diff halves to allow for the fatter blade and perhaps some material removal on the c-hub for the ECS unit. The Mi2 c-hubs are 291" at the widesest point compared to 274" on the T2 007 front hubs.
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Old 07-08-2009, 01:16 PM   #744
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Conrad-Thanks. I will post the LCD joints diameter later.

I took a rough measure of the X-ray ECD without dissasembling the car. It looks to be about .200 inch in diameter at the inboard side of the ECD barrel. This barrel does taper to a smaller size as it goes inboard. It is quite a bit smaller in OD than the Losi (from memory).

Finally a company , HPI, giving this constant velocity joint the proper name. The Double Cardan Joint (DCD)
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Old 07-10-2009, 07:22 AM   #745
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TC5 setup for Hot Conditions 107F air Temp, 150F track temp.

I demotored slightly to a LRP X12 4.0. I ended up with 8.75:1 overall ratio. I installed 3 fans. The two in front of the motor draw in air from 2 home made slots in the frame.

Note corner weights are perfect, but at a 49 ounce total weight. Diggety design .030 offset battery tray used with two home drilled holes outboard of the tape slots in the chassis. This allowed adjustment of this battery tray in and out in conjuction with this aftermarket battery strap that I was given (Brand anyone?); it is nice in that one screw removes the battery. The other end is a large pivot ball and pivot plastic. I did have to elongate the non pivoting side hole with the Dremmel as the strap was a hair short for this SMC battery.
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Old 07-13-2009, 11:12 PM   #746
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Quote:
Originally Posted by Conrad View Post
I know it will spoil the aerodynamics a bit but a large (35mm) hole in your front windscreen and a smaller hole in the rear window (30mm) in line with your esc/motor will reduce your running temps by quite a bit. I tested this indoors at my club (tc and mardave on carpet with foams, stock motors, ~20'c hall temps) about a year ago and have run it ever since. I was looking at a couple of degree ('c) drop with one hole at the front or back but with both open it dropped the temps by about 5'c.

This was without any extra passive or active cooling on the motor, just the extra airflow through the body. If you feel the rear window of your shell before you remove it from the car it will be quite warm Ok this solution isn't the best as its not legal for running in big races but we do allow it at our club and its easy to tape up the holes when running elsewhere.
Forced air cooling
We run on a long outdoor track in heats of 100 F with track temps 140 F or higher some times in the summer. Following up on Conrad's work but staying within the ROAR rules was my goal.

First the rules
6.1.10 Openings in the body other than those appropriate to full-size vehicle openings such
as grill, scoops, air vents, etc., must be kept to a minimum. Specifically servos,
receivers, batteries, and servo savers are not allowed to protrude through the original body shell.


8.10.5.7 Body rules:
No windows may be cut out.

You can put a scoop in, in other words, but not in the glass area of an electric car body. Other penetrations should be kept to a minimum. Typical scoops you see on Lemas race cars enter the grille, sometimes centered on the hood, brake scoops on the sides. You cannot exceed width limits with a tall brake scoop on the side.

I went to the auto parts store looking for blister packs of a suitable shape. The Dualist winshield wiper package provided the scoop almost fully formed. I trimmed it to fit the winshield so as to force air down through some penny sized holes in the top of the hood. The air enters a four sided rectangular smooth channel from a different brand of wiper blade. (These were in the garbage can outside). Some blister packages have four plastic sides this may work better inside the car. I used a plastic over cardstock package. I mounted the duct by bridging the hood to the deck lid. I used four tiny 2 x 56 screws to hold the vent and 2 to hold the scoop on. I sealed the very back end of the vent. It will be a maintenance hole to install some plastic shipping tube tops in the duct's exit holes.

You can see one of the exit holes above the speed controller in the pic. I plan to install a clear plastic tube from a machine tool shipping package. I will be using the press on tops (with new big hole) to push through my hole from the inside. Then my clear 1 inch tube will press on over this. Pic tomorrow. I tested with a hair drier and got a good stream of air out of my holes. On the track you will get some 55 mph air going directly to the motor and speed controller.

This system is working great on my wide pan car which is drawing an average of 50 amps during a run these days. I use no fans!

Our new asphalt and layout beg for a 3.5 in the TC5. I put the Novak Ballistic 3.5 motor back in the car. The high speed, cooler than track surface air, should help the car make the 6 minute mark.

I left one fan installed as I hated to cut the wires on a working LRP fan. It will help during periods when the car is stopped at the end of a run, at the beginning after a practice lap (and when the car is on its lid after getting punted into the wall)
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Old 07-14-2009, 09:36 AM   #747
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It did not take long to finish the duct. I sanded holes in the two plastic tube tops. I pulled these into place by expanding my LEXAN scissors inside of them and pulling them up into the tight fitting holes. They popped in place. I pushed my cylinders of plastic on while pulling up on the scissors. I put one drop of super glue on each side. I tested by blowing air in my hood scoop with a hair dryer. I got two good high velocity jets coming out my tubes. The short rear tube by intent has more of the flow. Especially important is to blow air at the solder tabs and wires as these can cool the core directly. Second important area on the Novak is under the trim ring where the stack is directly exposed to the air.

Test today maybe. Weight is very modest. Body with duct is at 4.9 ounces.
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Old 07-14-2009, 11:39 PM   #748
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Track temp 146 F
Here is a pic of a Stratus race car with a hood scoop. Probably turboed. Looks like the kind of Stratus I would want to race, I don't know the series. Anyway there are other options for a cooling air intake. The hood scoop fed duct in the previous post did an amazing job today. It directs very high speed air directly at the speed control and motor. The air is just a little cooler than the track due to its being a couple of inches high. I removed the speed control fan. It was 105F today with the track at 146F. The speed control never got above track temperature. The motor peaked at 170 F after first a 4 minute run (150F) followed by a pause and then a second four minutes (170F). This was a Novak Ballistic 3.5 geared one tooth higher than I was able to previously on 90-95 F days. The LRP TC edition just loafed along at 149F. These duct fed coolers might be used to extend equipment life on these unusually hot days. They are free. I took the duct out of the garbage can at Auto zone. There was some critizism that this duct may not meet some unwritten ROAR rules that match the duct to those on the full size race car.

Now I looked for a hood scooped DNA3 full size race car body. Could not find any pics. It is just an imaginary body in someones mind. It could have an imaginary hood scoop for all I know.

The base of the windshield, although a very good place to draw cooling air, because of the high pressure there, is not the only place. Even the imaginary DNA3 must have an imaginary radiator. I can with more difficulty pull air through the grill. This air goes into a duct. It does not pollute your vacuum under the hood. It is nice to have several tools in your arsenal other than catching your speed control on fire and then replacing it when the weather gets unusually hot. I had not anticipated such a long string of 105F days.
You can't just make up the rules. You have to read and interpret what is written. Neither duct is expressly forbidden by the rules. If the grill fed duct is more palatable so be it.

Sorry for the disjointed post. I had a custom post written for this thread which the website ate. I borrowed most of this text from elswhere on RC-tech.

more pics and test of the grille fed duct to come. I wil start out by saying it is a lot more difficult this way than with the hood scoop. The reason is the shock tower is close to the body up front. I do have a custom short shock tower pictured earlier in this thread to resolve the problem. The third photo shows the installed duct and also a black diffuser. The diffuser will direct additional cooling air above the chassis. The duct follows closely the hood to create maximum clearance on the shock tower.

Another option for a duct is the corrugated flexible split wire loom. A couple of pieces might be snaked around a stock shock tower.

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Old 07-15-2009, 05:50 AM   #749
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Quote:
Originally Posted by John Stranahan View Post
TC5 setup for Hot Conditions 107F air Temp, 150F track temp.

I demotored slightly to a LRP X12 4.0. I ended up with 8.75:1 overall ratio. I installed 3 fans. The two in front of the motor draw in air from 2 home made slots in the frame.

Note corner weights are perfect, but at a 49 ounce total weight. Diggety design .030 offset battery tray used with two home drilled holes outboard of the tape slots in the chassis. This allowed adjustment of this battery tray in and out in conjuction with this aftermarket battery strap that I was given (Brand anyone?); it is nice in that one screw removes the battery. The other end is a large pivot ball and pivot plastic. I did have to elongate the non pivoting side hole with the Dremmel as the strap was a hair short for this SMC battery.

Nice job with the "hood scoop" we may see at body shell with this integrated.
One Day.

How do you like the LRP X12 4.0T, compare to the Novak 3.5T.

Alf
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Old 07-15-2009, 08:33 PM   #750
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Alf-thanks. A nice blow molded duct would be very nice and cheap insurance for the expensive electronics.
I can tolerate the 4.0. It is a bit punchy. I am having to gear it too low to keep cool. It would have better manners at 95F with another tooth on the pinion. I love the feel of the Novak ballistic 3.5 in the TC. I ran it today 90/20 x 2.0.

The hood scooped duct worked better than the grille scooped duct. The short length and positive pressure at the base of the winshield helps. I read an article on ram air locations in the front of the car. The location seemed to be a gamble unless you were able to test for positive pressure in that exact location. Anyway the car ran very well but thermalled at 5 minutes with 103F air temp with the grill mounted air intake. I have further improvements I can make on the back end. I have plenty of weight left over ROAR specs to add a couple auxiliary fans. Speed control measured 150F motor was at 210F. I need more air on the motor.
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