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Jshwaa
2015.01.30, 06:24 PM
OK, so I'm finally a Mini-Z owner. Just confirmed a purchase on eBay, for a "Kyosho MINI-Z MR-03S SAUBER Mercedes - KYO32207S-B" and an 8-pack of eneloop pro's.

Haven't even got it yet, but can anyone tell me what I'm undoubtedly going to want to purchase next(ie bearings, etc.)? I don't plan on doing as much 'driving' as much as dissecting it to analyze the electronics, but I would like to get the 'must have's' out of the way as soon as possible.

Thanks in advance.

arch2b
2015.01.30, 07:26 PM
ball bearings. until you know what your racing on, hold off on tires. other than that, the LM runs fairly well right out of the box. you don't want to dump a lot of money into something that isn't going to provide the returns with little track time.

Jshwaa
2015.01.30, 09:39 PM
Good to know, thanks.

Went ahead and got the Boca LBT ceramic hybrids. That should work, eh?

herman
2015.01.31, 09:51 PM
any bearings would do... I'd throw in a carbon fiber t-plate, just in case the stock plastic plate breaks... and that's it... :D

When you start to get serious, there's a whole lot more to think about...

Welcome to the forums...

Jshwaa
2015.02.01, 09:06 AM
any bearings would do... I'd throw in a carbon fiber t-plate, just in case the stock plastic plate breaks... and that's it... :D

When you start to get serious, there's a whole lot more to think about...

Welcome to the forums...

Thanks, Herman.

Looking forward to sharing my thoughts when I get my wheels! Picked up some Si4562's from Digikey to hopefully make running a 32T survivable.

Would anyone suggest cramming 2 more cells (ie. 6-cell) in them, or is 4-cell good enough?

arch2b
2015.02.01, 09:33 AM
if you want that kind of power, look into kyosho's Li-Fe cells.

Jshwaa
2015.02.01, 11:44 AM
if you want that kind of power, look into kyosho's Li-Fe cells.

Cool! Will those drop in with minimal hardware modifications? I don't want to cut up anything if I don't have to. Thanks again.

arch2b
2015.02.01, 03:18 PM
they plug in with a battery wire harness. no modifications necessary.

Jshwaa
2015.02.01, 10:58 PM
they plug in with a battery wire harness. no modifications necessary.

OK, cool. I was just curious about the holders. I take it that the shape and volume of one of the Li-FE's is very close to 2xAAA's?

ilove599xx
2015.02.02, 08:28 AM
I ve changed my tires. metal bearing. metal wheelnuts, and run for about 10 hours on the track in my local shop,

after 10 hours i broke my first thing that's the t plate, so i changed it to the x-power fiber t plate. i also changed FRONT STEERING KNUCKLE to 1 degree

I have every spend written in my excel file. I am trying to use every parts from the original as long as possible.

this is only my 4th month to own mini-z 03mm

and i am so addicited to it. whenever anything in my car goes wrong i will keep thinking it whole day.

Jshwaa
2015.02.04, 07:26 PM
OK, so I got my mini-z....

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/IMG_5768.jpg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/IMG_5768.jpg.html)

Didn't even put batteries in it before I gutted it...

So, let me get this straight...

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/IMG_5771.jpg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/IMG_5771.jpg.html)

They actually provided a spot for 2 more FET's and just DIDN'T put them there??? LOL. Talk about marketing. How many mini-z's have been destroyed in the effort to put 2 FET's there, I wonder...

So, another question... Do people stack FET's on either side of the PCB(ie 6 FET's or greater), or does simply installing the extra 2 FET's in the empty slots (ie 4 FET's) provide enough drive for hot motors/Li-FE cells?

I bought a 10-pack of these bad boys...

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/IMG_5772.jpg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/IMG_5772.jpg.html)

However, I think there may be a new FET on the block...

Went perusing through Digikey's selection of FET's and found these...

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/new_fet_body.jpeg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/new_fet_body.jpeg.html)

They are a different package style, but this allows for a little more power dissipation.

I'm sure you've all heard of the almight Vishay Si4562. Pretty decent FET for use with mini-z's. Low Vgs, low Rds, and decent power dissipation (2W). Here is the Si4562 stats...

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/4562_stats.jpeg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/4562_stats.jpeg.html)

Here's the stats of the 'new' FET...

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/new_fet_stats.jpeg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/new_fet_stats.jpeg.html)

Si4562's dissipate 2W, while this new FET dissipates 2.3W. This is a marked difference, and should show itself in cooler running, and less thermal resistance when running hot motors. Haven't GOT them yet, but I ordered them right after I ordered the 4562's, and got the 4562's today, so they should be here tomorrow or next day. Plan to install 4 of those and a heat sink to one of the pairs.

Just wanted to check up and ask about the mysterious 'missing FET's'. I plan on losing tires here really soon! :D

DMALMAD
2015.02.04, 07:31 PM
The standard 03 comes with 4 fets, two on bottom two on top. 8858 fairchild fets is the normal upgrade ones so you can use those for comparison for specs. I am not certain about this but I think that because it is a sport you only get two fets.

Jshwaa
2015.02.04, 07:45 PM
The standard 03 comes with 4 fets, two on bottom two on top. 8858 fairchild fets is the normal upgrade ones so you can use those for comparison for specs. I am not certain about this but I think that because it is a sport you only get two fets.

Hmmm...interesting. So the ONLY difference is the number of FET's included? Why the heck would they not put 4 FET's on a MR-03S?? I feel like I bought an inferior mini-z now :mad:

Anyway, here's the specs for the 8858...

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/8858_stats.jpeg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/8858_stats.jpeg.html)

Looks like they are 'about' as good as the 4562's. They require a 10V Vgs to achieve the minimum resistance, which the mini-z does not provide. This is a stat many people overlook in their search for FET's, as they are only looking for a low R(ds) and a high I(d), not knowing that the FET requires a proper gate drive to achieve those parameters. And the 8858's are also 2W power dissipating...

DMALMAD
2015.02.04, 08:38 PM
no the sport uses a different radio system and is not compatible with the higher end ko propo radios. It uses the cheaper flysky radio system which kyosho probably integrated with the esc unit previously used.

Jshwaa
2015.02.05, 06:44 AM
no the sport uses a different radio system and is not compatible with the higher end ko propo radios. It uses the cheaper flysky radio system which kyosho probably integrated with the esc unit previously used.

So how do the differences between the ko-propo design and the 'flysky' system translate to the power end of the mini-z? Do they all run on the same FET circuit as far as the motor is concerned?

Does anyone know if installing the extra FET's on this MR-03S board will work? I did not take a close look to see if the locations are actually connected to power/signal for possible use. I will be upset if I can only use 2 FET's on this thing....

mleemor60
2015.02.05, 08:33 AM
I'm not sure I understand the fascination with additional fets. The car right out of the box is too fast for most to handle on the standard RCP layout. Until you learn the small quirks of the chassis speed and power is anything but your friend. Once you have consistently run the same laps for a given time you can add a tooth to the pinion and learn all over again. These are not like touring cars that haul butt down the straight and lock up the brakes so you can walk it around the corner and then repeat the process to the next one. It is more about momentum and maintaining it. One of the most discouraging things encountered by most "noob's" to the scale is letting or forcing speed to get ahead of the operational learning curve. Unless you have access to a banquet room sized sea of carpet free from any barrier or obstruction, slower will almost always be quicker. The thing to focus on for you is the fact that virtually all of our events are time specific so it matters how far you went in the time allowed. Not how fast. Think about it.

imxlr8ed
2015.02.05, 10:39 AM
I have asked that myself, but in all honesty it is not an inferior product just more open to marketability.

Yes, you can put fets on the empty spots but if you have never done it before... be prepared to fry a board. First time you do a fet job, you will more than likely miss something or forget to do something. I can't remember how many fried boards I had when I first started out, and I was lucky!

Technically, you do not need to fet it. Just drive it and enjoy it, learn to handle the cars at their stock speeds and then step it up. Consistency wins over speed everytime.

Jshwaa
2015.02.05, 12:18 PM
Thanks for that input. Much appreciated....

I understand your objective viewpoints on mini-z modifications with respect to lap racing, however right now I am about hardware maximizing, so that I have a ceiling for power that's insensitive to me throwing any motor I would like without fear of circuit failures. The ability for my FET's to handle 10A does not mean that will be my operating point.

I find it hard to believe that the inevitable need for more power leads people to fry FET's before they consider upgrading them. I would rather govern down a system that is too powerful, than to wish I had more power and couldn't reap it. Wouldn't you agree?

And as far as the skill required to solder FET's.... well, don't let the fact that I just bought my first mini-z fool you. I got the skills and tools necessary to desolder a FET and keep it intact. Back in the xmod's hayday, I had mini-z owners sending me their cars for FET jobs. No cold-solder joints here. :p

The only xmod board that I ever fried was due to electro-static-discharge, not a short circuit, and I never fried a mini-z board yet. *knocking on wood-like substance*

DMALMAD
2015.02.05, 12:33 PM
You can stack as many as u like. I had an Mr-02 which only has two fets initialy and only has the solder points for those two fets but I stacked 3x3. As long as you solder the fets together u are good.

Jshwaa
2015.02.05, 01:05 PM
You can stack as many as u like. I had an Mr-02 which only has two fets initialy and only has the solder points for those two fets but I stacked 3x3. As long as you solder the fets together u are good.

No, I don't plan on stacking. I was concerned with the ability to 'at least' add the additional 2 FET's in the empty slots. I will do so with superior FET's and replace the stocks with the same superior FET's....which circuit-wise is a 2x2 stack, but I will not be physically mounting a FET on top of another FET. If everything works out, I will be tacking a heat-sink on the pair of FET's that faces up, to help dissipate heat and keep the thermal resistance down.

To be honest, any additional set of FET's in parallel (definition of stack) does have diminishing returns. It takes a requisite amount of charge to turn on/off a FET, and additional FET's in parallel increase that requisite charge. If you increase that requisite charge beyond the mini-z elec's ability to provide it, then the FET's do not fully turn on/off, which creates cross-conduction and your FET's will be shorting power, heating up, and thus NOT delivering power to the motor.

This is why the 8858 is not actually an ideal choice for FET upgrade, because the R(ds) and I(d) specs that people drool over are not achieved, as they require a 10V Vgs signal to open the channel enough for the advertised current flow. Look at previous post for those numbers...

DMALMAD
2015.02.05, 01:13 PM
I was giving an example not saying that that is neccesary or the best. Most racers where I am at just upgrade the 4 stock fets with 4562 or 8858's as that is enough. We race lipo batteries so the upgraded fets are pretty much a neccesity. We also upgrade the steering fets as they blow due to the lipos too.

Jshwaa
2015.02.05, 01:35 PM
I was giving an example not saying that that is neccesary or the best. Most racers where I am at just upgrade the 4 stock fets with 4562 or 8858's as that is enough. We race lipo batteries so the upgraded fets are pretty much a neccesity. We also upgrade the steering fets as they blow due to the lipos too.

Gotcha. Didn't think about the steering FET's. Thanks for that. After bearings and FET's I'm gonna mess around with just straight 4-cell eneloop pro's and see about this 32T motor I bought. Don't live near a track, but got plenty of straight-away at the college.

I'm more interested in analyzing the dynamics of the mini-z and breaking down the physics and electronics behind it. I'm developing a dynamometer for use with 2mm shaft motors (mini-z motors) and I plan on trying to translate the data gathered from a motor on the 'dyno' to a prediction of speed and acceleration of the car through the gearing used and the mass of the car, and the radius of the wheels used. To go even further, I will eventually expand on the dynamometer design to include testing the entire mini-z assembly by bolting on a 'speed checker' (for the wheel tumblers and holding the mini-z) and thus give NOT ONLY real time speed readings, but torque and power as well, something I've noticed the hobby has been lacking for some time now from my perspective. There are people that are impressed by high numbers on a speed checker, but real racers know that what really matters is how fast you achieve that speed (ie acceleration).

arch2b
2015.02.05, 03:11 PM
i replace the stock fets almost immediately after purchasing a car. i've had a long run of bad luck burning up fets so just preemptively replace them now unless class rules prohibit it.

i don't do this myself mind you, i gave up that effort long ago. much easier and willing to pay someone skilled a fair fee to do it for me. :p

Mike Keely
2015.02.05, 03:20 PM
Some of the dyno's that I have seen in the past used a weighted disk that was bolted onto the motor shaft. They had holes in the disk that some sort of eye would read through the holes to know how fast it would turn. They also checked the torque by how fast the disk would spool up. All of the numbers would show up on a graph.

https://www.youtube.com/watch?v=Zox7EnafQmE

Jshwaa
2015.02.05, 08:46 PM
Some of the dyno's that I have seen in the past used a weighted disk that was bolted onto the motor shaft. They had holes in the disk that some sort of eye would read through the holes to know how fast it would turn. They also checked the torque by how fast the disk would spool up. All of the numbers would show up on a graph.

https://www.youtube.com/watch?v=Zox7EnafQmE



That's exactly what I plan to do. I got a control and measurement system in development right now. I should receive the inertia wheel portion of it really soon.


i replace the stock fets almost immediately after purchasing a car. i've had a long run of bad luck burning up fets so just preemptively replace them now unless class rules prohibit it.

i don't do this myself mind you, i gave up that effort long ago. much easier and willing to pay someone skilled a fair fee to do it for me.

I used to do that... Just finished the FET job on my new mini-z..

Here's the clean-up on the top-side(missing FET's). Had to remove the beads of solder that the manufacturer leaves on the pads so that the new FET's will seat correctly.

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/IMG_5773.jpg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/IMG_5773.jpg.html)


And then the removal and clean-up of bottom-side FET's. One of the FET's was lost in the effort, but I was able to remove one intact. Ah well, they are the old crappy FET's, right?

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/IMG_5779.jpg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/IMG_5779.jpg.html)

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/IMG_5777.jpg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/IMG_5777.jpg.html)

And now the replacements...

These new FET's have a different package style and includes two extra connections to the drains that protrude out the sides..

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/new_fet_body.jpeg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/new_fet_body.jpeg.html)

However, there are no 'extra' pads to solder FET's to on the mini-z pcb, so I filed the extra legs off so as to prevent them from touching each other due to their close proximity on the board.

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/IMG_5781.jpg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/IMG_5781.jpg.html)

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/IMG_5776.jpg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/IMG_5776.jpg.html)

And now to test...

I would be willing to bet that the biggest culprit to people frying their mini-z boards is not correctly checking their work...

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/IMG_5782.jpg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/IMG_5782.jpg.html)

I connect a meter across the motor connections, and then throttle in forward and reverse while monitoring voltage. If I get a positive and negative voltage on command, we are heading in the right direction...

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/IMG_5783.jpg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/IMG_5783.jpg.html)

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/IMG_5784.jpg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/IMG_5784.jpg.html)

No problem.

So now it's time to reassemble

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/IMG_5789.jpg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/IMG_5789.jpg.html)

Oh, and I dropped the dead-weight of the power switch and wiring. I just soldered a header lead across the connection that the switch connects when you turn the mini-z on, so now my mini-z turns on when i put in the 4th cell. No biggy...

Jshwaa
2015.02.05, 09:19 PM
Yea, this thing rips with some old energizer Ni-MH's and stock everything (except for FET's, of course). Losing the rear end very easily. I can tell right now that I'm going to want some wider rear rims and tires. Any suggestions?

*Update* Put the 32T in, now this thing is pretty fast.

DMALMAD
2015.02.05, 10:19 PM
pn 15 fronts and 6 rears or kyosho 30 fronts and 20 rears are the starting point for tires. These are rubber tires, you want to stay away from silicon tires. For just running in your house it doesn't really matter what tires you go with whether you get pn or kyosho but usually you don't mix and match. ie you don't use pn 6 in the rear with kyosho 30 in the front. Also you should look into tire tape if you don't want to glue your tires, securing your tires makes a big difference.

herman
2015.02.06, 01:39 AM
pretty cool upgrading the fets... to 4562...

here's probably one more thing that you could do.... click me (http://mini-zracer.com/forums/showthread.php?p=386341#post386341)

it's about lowering the body (the clearance of the rear wheel well and tires look really huge) by relocating the body clips... don't lower it too much though as the gear diff and tires may rub the inside of the body...

Jshwaa
2015.02.06, 07:05 AM
pretty cool upgrading the fets... to 4562...

I did not use the 4562's. I ordered some, and got them, but right after ordering them I discovered this 'new' FET. I was reluctant to publish the part number because I wanted to be sure they worked so as to not give out bad information, but....

Now that I'm fairly certain they are adequate upgrades for mini-z, here's the part number...

'Diodes Incorporated - DMC1017UPD'
Digikey Part #: DMC1017UPD-13DICT-ND

And you want to know the best part?? They were only $0.72 a piece!

pretty cool upgrading the fets... to 4562...

here's probably one more thing that you could do.... click me (http://mini-zracer.com/forums/showthread.php?p=386341#post386341)

it's about lowering the body (the clearance of the rear wheel well and tires look really huge) by relocating the body clips... don't lower it too much though as the gear diff and tires may rub the inside of the body...

Nice work! Lowering center of gravity is important, especially when the body is as heavy as it is. I'm sure whatever you did was noticeable in handling. The body seems like it's as heavy as the rest of the car.

*Correction*

Well, not quite...

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/IMG_5792.jpg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/IMG_5792.jpg.html)

http://i83.photobucket.com/albums/j314/Jshwaa/Mini-Z/IMG_5791.jpg (http://s83.photobucket.com/user/Jshwaa/media/Mini-Z/IMG_5791.jpg.html)

But still, the body makes up...

(38.0/(38.0 + 142.1)) * 100% = 21.1% of the mini-z's mass

Theoretically, you could accelerate that much faster without it, and have that much less inertia to deal with in corners. So not only lowering the body mass, but getting rid of it is key. These mini-z bodies look sweet, but race-wise they are a lug.

cowboysir
2015.02.06, 09:30 AM
You did happen to pick the heaviest asc in your sports 03.

A lot of the sports car asc are much lighter (McLaren 12c is in the 20 - ish gram).

Jshwaa
2015.02.06, 09:40 AM
You did happen to pick the heaviest asc in your sports 03.

A lot of the sports car asc are much lighter (McLaren 12c is in the 20 - ish gram).

Thanks, cowboysir. That was going to be my next question...

Also, I've seen complete remakes of chassis using slabs of carbon fiber. Are there rules specific to custom chassis? Looks like there are several opportunities for lightening the mini-z's mass while maintaining the same mechanical profile.

cowboysir
2015.02.06, 10:37 AM
If it were me and I was planning to document motor capability I would have a result catagory based on stock motors (70t and the like) and PNWC weight restrictions for chassis/cells/body which is min 170g. That would keep the chassis stock for the opening data collection.

X power seems to be the most popular chassis conversion.

Jshwaa
2015.02.06, 11:13 AM
If it were me and I was planning to document motor capability I would have a result catagory based on stock motors (70t and the like) and PNWC weight restrictions for chassis/cells/body which is min 170g. That would keep the chassis stock for the opening data collection.

X power seems to be the most popular chassis conversion.

Not sure what you mean.

If you were referring to my earlier comment about using a motor dynamometer...

The motor data collection will be done outside of the mini-z. The data set can then be applied to a conversion equation using any given mass, radius of back tires, and gear ratio to compute a 'theoretical' acceleration and speed of a mini-z at any point in time. Regardless of chassis composition, it all washes out to some mass. Therefore, the same data can be applied to any mass (m) to compute a 'theoretical' performance profile. I say 'theoretical' because it would assume frictionless transmission and perfect friction to the ground, but those are also things that can be optimized.

Jshwaa
2015.02.06, 10:52 PM
*Update*

Just ordered the tires DMALMAD recommended, and some motors...

Kyosho Parts X-Speed Mini-Z MOTOR-V

PN Racing Mini-Z PNWC 70 Turn Official Stock Motor

PN Racing 123243 Mini-Z PNWC Ball Bearing Motor 43 Turn

Atomic MO-033 Mini-Z Dual Ball Bearing ASF Spec. Motor



And some pinions...

PN Racing Mini-Z 7075 Alloy S3 Pinion 64P 8T

PN Racing Mini-Z 7075 Alloy S3 Pinion 64P 11T

PN Racing Mini-Z 7075 Alloy S3 Pinion 64P 14T


And just for insanity sake...

Kyosho Mini-Z R246-1802 Li-Fe 3.3V Battery 2pcs

Kyosho Mini Z R246-1803 MINI-Z Li-Fe Mount Cord

Kyosho Mini Z R246-1804 MINI-Z Li-Fe Charging Cord


Question....

Where's the nearest help group?

mleemor60
2015.02.07, 06:31 AM
Help group? Too late for you. You have chosen to partake of the Kool-Aid.

Jshwaa
2015.02.07, 08:54 AM
Help group? Too late for you. You have chosen to partake of the Kool-Aid.

Kool-aid? It's not like I believe in 'turbo' or anything. ;) Pretty sure I'm blazing my own trail here, especially with a FET upgrade that's superior to anyone that uses 4562's or 8858's because a forum told them they were decent and not because they would happen to understand a datasheet.

Just thought I was getting up to speed here. Where did I go wrong? Li-FE's? The extra motors are more for my design project, to have a diverse test sample, but... other than that I'd say I'm still behind most of you as far as "investment into the hobby per returns". I didn't want to go brushless, because I won't have a test platform for brushless for some time. Probably months after I get a 'brushed' concept together.

Don't get me wrong, I wish I owned a track and could travel to other people's tracks and get into the tournament racing and all that, but without that all I can do is 'work in the garage'. I understand there must be a sense of pride that comes with being able to get record lap times and being very minimal about power upgrades, and that's great. I want to see how much power I can get to the ground, break something, and do it again. Maybe I'll get lucky enough to run into someone at a tennis court or at the mall...

It should all come together if/when I get the full dyno together though.

Mmmmm, Kool-aid... :rolleyes:

KWT
2015.02.07, 01:09 PM
First, Where are you located?

Second, You bought 64P pinions but you didn't get any 64P spur gears for an aftermarket diff since they are not compatible with the stock diff.

Third, there is more to FETs than just the paper specs. FETs with similar specs can feel different and have different throttle response.

arch2b
2015.02.07, 04:15 PM
Nothing wrong with wanting to go fast or favor upgrades, it's what keeps these shops open:)

As a general message, those of us who have been around for a long time try to caution against cannonballing in the deep end right out of the gate. Plenty have done so and ended up fire sale off the lot to those like us who are more than happy to scoop up stuff. It's nothing personal, nothing derogatory, just due diligence in cautioning not to go to deep, to fast. Sounds like your moving at a pace suitable for you and glad to have you hear to share the story :)

Jshwaa
2015.02.07, 04:21 PM
First, Where are you located?

Second, You bought 64P pinions but you didn't get any 64P spur gears for an aftermarket diff since they are not compatible with the stock diff.

Third, there is more to FETs than just the paper specs. FETs with similar specs can feel different and have different throttle response.

1) In a boondock town just South of Polo, Illinois. I don't get into the Chicago Area much...

2) Thanks for that info, now I'm going shopping. I was looking for pinions that I could lock on with a set screw as opposed to pressing them on.

3) Although what you said may be true, it comes from an experienced user perspective and there's no metric to put on that. The idea is to minimize resistance as much as possible so that the elecs are more survivable to higher current flows. If you don't change your cell composition or motor, you shouldn't notice a marked difference no matter what FET you choose(within reason). The FET's are just a switch and cannot add energy to anything, only take away. Thinking you can tune your throttle response based on your choice of FET's sounds like the same hokum as FETs being some sort of 'turbo'.

It really is as simple as:

Higher Resistance = More Energy Wasted At FET When Turned On
Lower Resistance = Less Energy Wasted At FET When Turned On

To say that you'd rather have a 'higher resistance' FET is like saying you'd rather run with rusty bearings, or a heavier chassis, or (insert your energy load of choice here).



Nothing wrong with wanting to go fast or favor upgrades, it's what keeps these shops open. As a general message, those of us who have been around for a long time try to caution against cannonballing in the deep end right out of the gate. Plenty have done so and ended up fire sale off the lot to those like us who are more than happy to scoop up stuff. It's nothing personal, nothing derogatory, just due diligence in cautioning not to go to deep, to fast. Sounds like your moving at a pace suitable for you and glad to have you hear to share the story

Thanks. No offense taken, however I'm kind of surprised at how much I'm assumed to not know based on a 'first-time' mini-z purchase. My questions are about things that I'm sure involve a level of experience that I don't have the time to achieve myself, so I gather shortcut information. For example, I was completely surprised by the missing 2 FETs on my MR-03S board so I immediately had to check in to see if you guys know why that is, or if that was typical. I could have just installed FET's to see for myself, but I decided to save the time and ask the forum if anyone has done this before. From the electrical standpoint....I know EXACTLY how mini-z's work to the equation level. Of course no mathematical models are perfect, but they all still adhere to the same ideals. So I know how to filter the 'tribal knowledge' for what's real and what isn't.

I will be the first to agree with you that my recent purchases 'seem' kind of compulsive, but with the exception of purchasing eneloops before turning around and buying Li-FE's, I've been planning these purchases for some time, and I just found out I'm getting $5k back for taxes, so I'm putting those plans into action. I may just buy another mini-z and have a Li-FE and a Ni-Mh platform, so as to not be completely wasteful of the 8-pack eneloop purchase.

But so far, got the mini-z, upgraded the FET's, bearings, tires, pinions, cells, motor, and removed power switch...so far so good. Thanks for the words of caution though. No fried boards here guys, so you won't be seeing my Mercedes in the shop for sale anytime soon. :)

Jshwaa
2015.02.07, 05:31 PM
Ok, so I got these 64P pinions...

Can I just buy a 64P spur gear, or do I need to buy a complete ball diff, and if so...

Who sells the lightest and sturdiest 64P ball diff set to complement the 64P pinions?

Would getting the 'AR-286' and 'AR-269' be a good choice?

Sorry for all the added questions....

So it appears as if the gear ratios can range from (pinion/spur) 6T/54T to 14T/52T if I'm not mistaken?

What formula of motor and gear ratio do a fair amount of the experienced mini-z'ers use?

70T motor, 10T pinion, 53T spur?

43T motor, 8T pinion, 54T spur?

Thanks in advance.

DMALMAD
2015.02.07, 07:22 PM
Personally for 70t nimh I use 14 pinion and 52 spur. For 50 turn 12 tooth pinion and 53. 43-39 some where between 54/12 and 52/11 maybe even a 10 tooth pinion. And for 32 and 33 turn generally a 9 or 10 tooth pinion or even an 8 tooth if temps dictate. These are racing values and generally close to the edge as of motor temps after 8 min running. For the higher turn motors don't be afraid to gear to the moon but generaly start with a small pinion and see if the motor is too hot and go up. Only run what you can handle so don't start with the highest ratio and hottest motor first. As for determining what a safe motor temp is, if you can hold your finger on there as long as you like after you pull it off the track you should be good to go. If gets too hot to touch or to touch for say longer than 5 seconds its too hot. As for the Life batteries, they don't get much runtime, tried them a long time ago with almost all the motors (except 43 and 39) and they barely make 6 min regardless of what motor or gearing. So gear conservatively with the LiFe batteries.

In regards to the comments about sipping the kool aid, some people think that the bare bones, unmolested mini-z is the perfect and most divine creation ever imagined:rolleyes: There is no kool aid, get what you want or need, whatever the case it is just a hobby and about having fun;)

Jshwaa
2015.02.07, 07:49 PM
Personally for 70t nimh I use 14 pinion and 52 spur. For 50 turn 12 tooth pinion and 53. 43-39 some where between 54/12 and 52/11 maybe even a 10 tooth pinion. And for 32 and 33 turn generally a 9 or 10 tooth pinion or even an 8 tooth if temps dictate. These are racing values and generally close to the edge as of motor temps after 8 min running. For the higher turn motors don't be afraid to gear to the moon but generaly start with a small pinion and see if the motor is too hot and go up. Only run what you can handle so don't start with the highest ratio and hottest motor first. As for determining what a safe motor temp is, if you can hold your finger on there as long as you like after you pull it off the track you should be good to go. If gets too hot to touch or to touch for say longer than 5 seconds its too hot. As for the Life batteries, they don't get much runtime, tried them a long time ago with almost all the motors (except 43 and 39) and they barely make 6 min regardless of what motor or gearing. So gear conservatively with the LiFe batteries.

In regards to the comments about sipping the kool aid, some people think that the bare bones, unmolested mini-z is the perfect and most divine creation ever imagined:rolleyes: There is no kool aid, get what you want or need, whatever the case it is just a hobby and about having fun;)

Nice, thanks for that info. As far as upgrades, I understand there's a point when enough is enough. We had guys wanting to put nitro in xmods back in the day. Nice to daydream I guess.

One thing I've noticed about the motor situation is how cooped up it is behind the bulk of the chassis. Finding a way to channel air to the motor and heat sink would probably net some benefits I'd imagine. Anybody try venting their bodies in specific places I wonder?

But back to the 64P spur gear situation....

Would the 'AR-286' and 'AR-269' be a good choice for a differential and variety of gearing? Also, does the stock motor mount lend itself to these gearing adjustments? If not, which motor mount is the premium choice for allowing various gearing adjustments?

Solo1
2015.02.07, 08:51 PM
i'm running a pn 70 t in a pn v4lcg motor mount in a 03s and like it very much i would think 1 of the pn 64p ball diffs would work well for you, i'm using a pn 64p gear diff and like that but understand it doesn't work well with the lower wind motors. Much quieter that stock. Just installed a double a arm also drives very good!!

DMALMAD
2015.02.07, 10:22 PM
A while ago we had an ingenutive racer who put a fan above the motor and vented it so that the air flowed down over the motor. It ran much cooler and allowed insane gearing but the airflow actually upset the handling as it pushed the rear end up. If you run into ovre heating you could probably do something simmilar if you werent too worried about wieght or handling.

Jshwaa
2015.02.07, 10:51 PM
A while ago we had an ingenutive racer who put a fan above the motor and vented it so that the air flowed down over the motor. It ran much cooler and allowed insane gearing but the airflow actually upset the handling as it pushed the rear end up. If you run into ovre heating you could probably do something simmilar if you werent too worried about wieght or handling.

Well I can't have my mini-z catching altitude, :p

Yea, that's one of those problems where adding the weight for cooling has the diminishing returns of also adding weight to further load the motor, not to mention robbing the little bit of current that could be used for immediate acceleration. I'm much more apt to venting and using some of the air drag for cooling. The mercedes body has all kinds of little 'fake' air ports that I may just take a dremel to and make 'real' air ports. There's so many opportunities to get rid of mass on that thing. Rear spoiler being one of them, but it does look cool...

Fans are probably not the best approach in my opinion.

LED
2015.02.08, 01:26 AM
Ok, so I got these 64P pinions...

Can I just buy a 64P spur gear, or do I need to buy a complete ball diff, and if so...

Who sells the lightest and sturdiest 64P ball diff set to complement the 64P pinions?

Would getting the 'AR-286' and 'AR-269' be a good choice?

Sorry for all the added questions....

So it appears as if the gear ratios can range from (pinion/spur) 6T/54T to 14T/52T if I'm not mistaken?

What formula of motor and gear ratio do a fair amount of the experienced mini-z'ers use?

70T motor, 10T pinion, 53T spur?

43T motor, 8T pinion, 54T spur?

Thanks in advance.

Welcome to the confusing world of mini-z after market parts and motors :D
You will need a complete aftermarket diff. The spurr of stock kyosho diff cannot be changed.
Secondly, you have an LM car, so if you want to keep the plastic motor mount you will also need an LM diff. I'm not sure if there even are LM aftermarket diffs anymore. Most people simply take a low COG motor mount wich works with a GT diff.

KWT
2015.02.08, 09:18 AM
There are still LM diffs or if you have a standard length diff you can always get a LM shaft to convert it.

You should probably try to make a trip up to Chicago to meet up with the mini-z group there. you will learn much faster with some first hand tips and being able to see other people's setups.

arch2b
2015.02.08, 09:55 AM
...Thanks. No offense taken, however I'm kind of surprised at how much I'm assumed to not know based on a 'first-time' mini-z purchase...

well, have to look at from the other shoe as well... in 14 plus years you see hundreds jump in, regardless of the proficiency of the inquiries, we've seen it all safest assumption is to start from bottom and work upward ;) again, nothing negative behind it.

don't read to much into the 'koolaid' comment, i'm not aware of any movement to push unmolested mini-z as a divine creation either. just people with varying interest and experiences all looking to help the best way they know how. :cool:

thanks for posting pictures of your fet work, it's always helpful to see how it's done.

PN an others make LM diff shafts. most prefer scratch building a 'perfect' 64p diff fom various parts vs. buying it. i myself enjoy the tinkering and build work myself. i used PN, RR and Qteq parts mostly for my diffs. there are some threads on building them.

LM motor mounts options are out there and opinions vary as one would expect. the stock pod is suitable but if your looking for optimal gear mesh, adjust ability is needed and you won't get that level of play with a stock pod. the Route246 R246-1202 pod is the most common one i see on the track. some will argue the counter points for screw down make it difficult to get a true parallel fitting however the counter is, these mounts sometimes have ever so slight movement in the arms or assemblies that cause them to shift under load. again, opinions will vary greatly as one would expect.

there is never any one right answer, only the one that best suits your style and need. good luck and i look forward to see this progress further.