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Old 04-22-2007, 11:31 AM   #1156
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Mathijs-I see now where they have all ceramic bearings available at Boca even the cages.

My bearing was a ceramic hybrid. Balls ceramic, races steel. This one was from MurdockRC. The cages on the Novak bearings don't seem to disintigrate, but the bearing fails about as fast. It just develops excessive friction from wear and then runs very hot.

TallyRC-Please ask. I had a metalurgical engineer diagnose a ring and pinion failure on a full size vehicle. I ended up with a reimbursement from poorly labeled lubricant.

I did a search at Boca Bearings for a .1875 x .5 x <.2 bearing which fits the outer Novak Bearing. Quite a few are listed with several seal types. Complete bearing data including the RPM limit is also listed. Many of the bearings fall below the RPM I calculated for the 3.5 motor on a long straight which was about 63,000 RPM. This bearing in a non contact seal had good specs. SR3C-YZZ-#5-NB2. RPM specs with oil are about 7,000 higher than with grease. Interestingly of the seals that will go to this high RPM, the rubber seals seem to be the choice also in a ceramic hybrid SR3C-2YS-#5-NB2, both ABEC #5. ABEC #7 (more precisely made) are only suitable for uses where no shock is present and the environment is clean.

Now that I have been reeducated on bearings, I don't think that I will run that $1. bearing. The consequences of failure are about $270 if it locks the motor up. I am sure it is not rated for the high RPM.
John

Last edited by John Stranahan; 04-22-2007 at 02:39 PM.
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Old 04-22-2007, 12:44 PM   #1157
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well unfortunately my father had little opinion of which bearing to recomend between the given choices (ceramic/stainless) as he built bearings before ceramics existed (think just post WWII).. his one nugget that i did find interesting was that he said far and away the number one cause of failure was poor instalation.. even slightly off axis and the wear rate will be horrific.. maybe reseating even the factory bearings could be bennificial.. when i told him the RPM range were were dealing with he said "how long you expect them to last at those speeds"? i laughed.. his opinion was that a higher rated bearing with the best seal possible might be the way to go, keeping it clean is key..

is your first option listed there supposed to be yZZ? the shielded equivelant of the other? also when you calclulate your rpm load is that under load or free based on volts/rpm? never mind i just did the math and using a 2.2in tire thats about 82% efficiency under load.. impressive..
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Last edited by tallyrc; 04-22-2007 at 01:39 PM.
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Old 04-22-2007, 06:49 PM   #1158
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Yes ZZ

I did some more searching. This time for 1/8 x 3/8 bearings that are likely to come on the Trinity N60 motor. (note the Trinity actually comes with the large bearing front and back; I learned this after receiving the motor) The RPM capability for a similar bearing to the one I posted the part # is about 25,000 RPM higher due to the lower surface speeds that a smaller bearing runs at. Load capability is less. But if RPM is what is killing the bearing then the 1/8 shaft size may hold up better.
John

Last edited by John Stranahan; 04-27-2007 at 10:27 AM.
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Old 04-23-2007, 05:31 AM   #1159
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Quote:
Originally Posted by John Stranahan
. I used a socket that would contact the outer race to hammer in the new ones with Permatex High Temperature Red Threadlocker.

Don't hammer! Not even on the outer ring!

The trick is simple: put the alu end piece in the oven for a minute or so. (when the missus is not looking) Doesn't even have to be that hot, 70C was enough for mine. The bearing will literally fall in.
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Old 04-23-2007, 08:26 AM   #1160
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I imagine putting the bearing in the freezer for a little while would give similar results with less questions from the better half.
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Old 04-23-2007, 09:20 AM   #1161
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I used a screw and nut (and some washers to spread the load) to gently push it in..
This always worked for brushed motor bearings.
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Old 04-23-2007, 09:37 AM   #1162
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That sounds much more like the way bearings are supposed to be "pressed" in.

Hey John - what about taking a small piece of foam and using a piece of servo tape (with a hole punched in it) to stick it over the bearing area. . . to work as an air filter, kinda sorta.

I think it was mentioned a few posts ago. . .thought I'd repeat it.
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Old 04-23-2007, 12:25 PM   #1163
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The expensive bearings that come pre assembled from Novak fail in the same time frame. This indicates there is more wrong than assembly. A press would certainly be better if you don't want to tap it in. This can be done in the vise or a small arbor press. The main goal is to have the bearing bottom completely in its recess without bending the aluminum endplate. I think that rubber sealed bearing with oil in it would be the way to go. If your 3.5 is not getting the car up to about 60 mph then you probably don't have this problem. Thanks for the tips. I am aware of these methods as the Nitro guys use them on the motors. It really does not take much force to put one of these bearings in. You need the loctite to hold it securely.

Boomer-It was mentioned but it needs to be stuck on as you suggest or it will just move away from the bearing.
John

Last edited by John Stranahan; 04-23-2007 at 07:41 PM.
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Old 04-23-2007, 12:29 PM   #1164
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My pan car is on the way thanks to Mr. Stranahan!
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Old 04-23-2007, 12:39 PM   #1165
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RCLocos-Good luck with it. Post us a pic when you get it put together.
John
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Old 04-25-2007, 07:37 PM   #1166
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Mamba Max Speed Control

Yes We have Mamba. No motor yet.

It is suggested not to shorten the motor wires. The fan is a Trinity fan which I added. The kit does not come with a fan. This fan is a nice fit. The controller looks good there. The fan will draw air from the top of the cockpit vents on some bodies. I deleted the on off switch which is not that good of an idea with LiPo batteries anyway. This way you have to unplug it to turn it off and kill the fan. This might save you from leaving it on and killing a battery one day. More to come.
The kit comes with a USB cable and software to tinker with the speed control parameters.

There appears to be no weight penalty. The car is actually .3 ounces lighter with the mamba (no switch) and a Novak 3.5R motor.
John
Attached Thumbnails
Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-mamba-max-speed-control-003-resized.jpg  
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Old 04-25-2007, 08:43 PM   #1167
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I installed the Castle Link Software. It was easy to use. First I did a Web update that it requested. This updates the Castle Link Software and also downloads any new firmware revision for the speed control. It appeared that a firmware revision was available so I installed it.

Settings were way easy to change on the computer. Here is what I selected.

proportional throttle with reverse lockout
100 % brakes instead of 50% (brushless tend to have weak brakes I will see if this is still true)
Start Power High (it is best to roll on the throttle slower with the trigger finger as the power required changes daily and even from heat to heat)
Cutoff Voltage 6.0V for a 2 cell LiPo.
Drag Brake 20%
Motor Type Brushless
Linear Throttle and Brake curves. You can actually shape these to your desires but I think linear is going to work fine.
Pic is of the other side of the controller. Very pleased so far.
John
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Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-mamba-max-speed-control-lead-wire-side-resized.jpg  
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Old 04-25-2007, 09:20 PM   #1168
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Quote:
Originally Posted by John Stranahan
I installed the Castle Link Software. It was easy to use. First I did a Web update that it requested. This updates the Castle Link Software and also downloads any new firmware revision for the speed control. It appeared that a firmware revision was available so I installed it.

Settings were way easy to change on the computer. Here is what I selected.

proportional throttle with reverse lockout
100 % brakes instead of 50% (brushless tend to have weak brakes I will see if this is still true)
Start Power High (it is best to roll on the throttle slower with the trigger finger as the power required changes daily and even from heat to heat)
Cutoff Voltage 6.0V for a 2 cell LiPo.
Drag Brake 20%
Motor Type Brushless
Linear Throttle and Brake curves. You can actually shape these to your desires but I think linear is going to work fine.
Pic is of the other side of the controller. Very pleased so far.
John
John- I think you will want to turn your brake down when you do get to drive it. I've run the Mamba in my TC and used 50% and it was lots. I also used 25% drag brake but with the pancar you will probably not need as much. Which motor are you going to run? I know a guy that's been testing the Trinity N60 but it's blowing up the Mamba ESC cause the motor is wye wind and the Mamba is delta wind. This is a quote from his email I got:

Joe Ford and the Castle guys have been helpful so far, so hopefully we can find a solution. Unofficially, I have been told by one of their beta testers that they are having software problems with wye wind motors (which the N60 is). I guess the Mamba motors are delta wind, and it is significantly easier to get a senorless controller to detect back EMF on a delta wind motor. I'm probably throwing the worst case scenario at it - low turn Wye wind.

I have been using the 7700 motor combo and it's pretty fast....as fast as 7x1 brushed motors. I usually run the timing normal and gear it from there. I think you'll be quite surprised how fast it is....I know I was.
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Old 04-25-2007, 09:41 PM   #1169
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Doug-Thanks for the note. That N60 was what I had planned sad to say. I can use the Novak 3.5 R if I get bearings for it.

I turn the brakes down at the radio. When traction is medium I use 85% on my two hairpins with the pan car and Novak Controller with a brushless. When traction is poor I can still set my Radio at about 65%. I also control brakes with the trigger. If I start the Mamba at 50%, I may not have enough. I know that on some layouts brake use is minimal. With our lap timer calling out lap times it is easy for me to tell the effect of hard braking on these two hairpins on our layout. I gain about .2 seconds on each turn going in hot and tight and adding as much brakes as I have traction.

I have a motor of about that Kv, the 4.5. There are some differences between this and the 3.5 that make the 3.5 faster in the pan car. One is it is geared lower and has a softer bottom end. This means fewer spinouts, better hookup, better front to rear weight transfer on acceleration. You can pull the front wheels on occasion with medium traction. The 4.5 is fast but is not quite as well suited to the pan car.
John

Last edited by John Stranahan; 04-26-2007 at 12:13 AM.
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Old 04-25-2007, 11:37 PM   #1170
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Mamba Max Continued
Bench Test-I installed the Novak 3.5 R. Here are some notes. When this system starts a motor from dead stopped, it is hard to tell which way your wheels are turning. Here is why I think. The motor turns for a small fraction of a revolution in a random direction. Back EMF is measured rotation is corrected to the forward direction. Anyway I found myself putting my finger lightly on the spur to see what direction it was going. I swapped two motor wires twice. Putting on the three wires to the motor is a trial and error thing. If it rotates backwards, you reverse two wires.

Setup is different than all other speed controls. Leave it to these speed control guys to find some new different way to do this simple task. You turn on the radio, apply full throttle, turn on the speed control (while full throttle is being applied; this is new and strange) wait for noise and red, apply full brakes, wait for noise and orange, go to neutral. It had trouble finding my neutral. Orange would stay blinking. I ended up moving the trigger slightly toward forward and then it found a neutral. Then I readjusted my throttle trim to have orange in neutral. (This may be a problem with my old and very tired twice rebuilt M8). Anyway I finally got a setup that would work.
(I put the dammed little switch back on, but it was not needed. It would not find neutral with the switch either)

I had one setup where brakes turned in to reverse. I had the setting proportinal with reverse lockout selected, I changed this to forward no reverse. Now I got just brakes. I'll read up on the difference between the two.

Brakes seem to be very strong like a brushed on the bench. Not terribly smooth though. Strong is good. I can turn them down at the radio. Drag Brake seems to be weak. I tried 10 and 20%. I may need more or a track test at 20%. Light drag brakes give you some forward weight transfer to enhance steering on corner entry without breaking traction on the back end.

Track Test Soon

Pic, Now where is that sensor harness? The system is .6 ounces lighter than GTB at this point. No switch. No Sensor Harness. Prototype II is at 40.8 ounce.

Center of Gravity and Weight Transfer
Now this has been addressed previously but you might wonder why I run my electronics back and up high. Well it has to do with 2 wheel drive. What I think makes this car really hookup is when you get good front to back weight transfer on acceleration and good back to front weight transfer on corner entry. Both conditions aid the 2 wheel drive pan car, but hurt the 4 w-d touring car. The pan car is so wide that lateral weight transfer is low. Here you are still helped by a higher polar moment of roll which slows down the roll and makes the car less twitchy and prone to spin. I noticed early on in my tests that the mostly stock wide pan car handled a lot better with the high Nissan 300z body than with the low GTP bodies. Now I put a little weight up higher with the GTP bodies and it is always helpful to put weight rearward on a 2 WD rear wheel drive car.

Anyway there are reasons why I put that stuff on the second deck.
Attached Thumbnails
Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-mamba-max-speed-control-novak-3.5r-002-resized.jpg  

Last edited by John Stranahan; 04-26-2007 at 12:24 AM.
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