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BitHed
04-23-2005, 02:05 AM
...ok...i have a theory that i needed to get out there before i started on it, plus i just needed to look like i was busy for about an hour ;)

...The motor is getting very hot...both brushed and brushless are getting very hot...

...this is what i think...

...The slipper is creating a fraction too much friction...The shaft revolves in two bearings...with the tension spring tightened we are preventing the 'free rolling' of the shaft...thus the motor is getting hotter than it should...

...I thought the car might be underpowered as Graphix mentioned on one18th but i dismissed that when people were saying that their MAMBAs were even slow...THAT just doesnt make sense...If the car was underpowered then the esc would be getting REALLY hot etc and i just didnt see enough fingers on my car as pointing to that as the possible culprit...

...i also felt that my car was getting MUCH hotter than everyone elses because i was complaining most...And what did i do that many people HAVENT done yet? I shimmed the shaft at the front...i wanted to get rid of the 'play' in it...i succeeded at that but i think that is one of the factors of my cooking incidents...

...SO..this afternoon, its saturday but i have morning classes, I will be removing the shims, swapping in the titanium shaft, CA-ing the two gears, the idler and whatever the other one is called, thus making it a solid single unit...replace the bearings that hold the shaft at either end, something with a few more 'balls'...Let the spring tension ALL THE WAY OFF but just keep enough on to keep everything aligned...basically the shaft will have ZEROpressure on it, the slipper will NOT function as a slipper, merely as a gear-changer for the motor to power the car as it SHOULD be doing...Obviously all other diffs wiill be re-lubed etc...

...I think this will make the heat problems MUCH better...Your comments ?

mOOsE
04-23-2005, 02:37 AM
Your it...I compare my half eight to the mini quake. It uses the same motors and is close to the same weight. However, the kyosho heavier with the 8 cell setup. I don't have the exact figure but it is definately heavier. I think you have something there with the slipper shaft. I believe it is also the drivetrain. On my touring car, I test the drivetrain resistance by unbolting the motor and free-rolling the car. I did the same procedure with the half eight and you mind as well have the motor attatched. Their is too much "crap" for the motor to run through. Although the center diff works, it is rather novelty for a mini. The slipper is also kind of novelty because their have been no issues with previous mini's without slippers...at least not big issues. Hopefully, I can find a way to remove the center diff the create a free motion. Then its on to the slipper clutch just as you are doing.
Keep us posted...

BitHed
04-23-2005, 02:55 AM
...you're IT...BARRIER !!

...i agree...too much stuff for the motor to do...we tighten the slipper to make the motor work HARDER to spin? That makes no sense...get rid of the middle diff? I disagree, but making the slipper a NON-option is the go i think...basically castrating the H8...I am pretty sure it will reduce the heat ALOT...

...small change in plans...Part ONE: Loosen nut, let off spring...CA slipper fore and aft...do up nut, let try and harden...loosen nut and spring...drive away..

...if that all turns to sh!t THEN replace with titty shaft and start again...Easier to do it all in ithe setup it is now plus i have my motor mesh in its g spot...had it sounding like a smooth onroad car last night...it was kinda cool watching my K4 arc in the darkness though...

...Cant wait to get rid of all this tension and 'let my hair down'...

...Olly Olly Oxen Free!!

jatetu
04-23-2005, 10:23 AM
good investigation work, keep us online.

I think that this problem is because the high grip of the mininferno. The center diff balances grip between front and rear drives, so always extreme gripping.

May be with a alu chassis, an alu motor mount and/or a fan. Like the gas powered cars (not the fan).

So bit żdo you know if there is the alu motor mount available? :D

BitHed
04-23-2005, 12:00 PM
...Jatetu...KYOSHO has a blue (YUK!) and a silver one which arent out yet...CAW is working on one or two, and we have talked about getting a fan 'mount' on one of them...My mate Nick at CAW is working double time on the mill trying to get everything done..Big shout out to Nick who i am SURE sleeps less than me which wont be much at all...GPM will also do one or two and when they do TopCad usually does too so in couple of months there will be lots to choose from...

richh
04-23-2005, 02:02 PM
not sure i understand...

the slipper spring adjusts how the two idler gears behave. when loose, the two gears can spin independently, when tight (or glued :) ), they act as one gear. there is also a flange on the idler shaft to key the larger gear and also back it up against the force of the spring. so unless the spring is so tight tha it is bending the shaft, i don't see how a tight slipper would make the idler harder to spin in than a loose slipper. can you take the motor and center diff out, the see how freely the idler spins when tight and loose to see if there is any drag when it's tight?

WhoMe
04-23-2005, 03:12 PM
Mine rolls pretty good without a motor in it. I think the car's ability to roll free has nothing to do with the complexity of the driveline; it has more to do with notchy action the stock diffs have. Granted the slipper on the H8 is alittle faulty but the need for a slipper is no oversite. Ive torn up many a gear diff on an offroad car because my slipper was too tight. Ive actually blown up spider gears in other cars because of that. In addition I think the only reason brushless guys havent been blowing up spider gears is because of the three diff design. But again, I still havent had the motor get that hot on me. When my X-speed gets in and I have some different pinions to work with Illl report back. But so far my motors both stock and K4 running on six cells stay pretty cool. And for those running more than six cells...make note adding voltage will really put the HEAT..in these motors. Ive seen well wound and put together 280 motors move out like a brushless beast in 1/18th scale trucks with six cells. 7.2 volts can move this car...the right motor and gearing is needed.

mOOsE
04-23-2005, 03:30 PM
the free rolling of the car has a lot to do with the drivetrain. Having three diff's and a heavy topshaft/slipper assembly creates a large amount of rotating mass for the motor. Especially the slipper assembly. That thing is heavy if you take it out! its mostly because the shaft and two bushings though. Hopefully I can locate some plastic bushings and a titanium shaft to reduce it. The "notchy" diffs don't have anything to do with the car rolling. Diffs don't even do anything unless you are turning or have less traction on the left or right side. As for the center diff, I don't care for it a whole lot because its extra weight and it causes to front tires to get most of the power in loose conditions.

WhoMe
04-23-2005, 03:55 PM
Well weither you like it or not..the car is built as such. And the diffs DO contribute to how to car rolls. Take the diffs out..hear the click..roll the car hear the click. Those clicks are the clicks of resistance that DO play a part on how freely the car rolls.

P.S. The casing to the center diff and slipper assembly is cocked...it causes the gears to catch. There is another point of resistance. But again...like i said before, despite its "complex" driveline my motors dont overheat on six cells.

OneTimeCRX
04-23-2005, 04:19 PM
I don't think that tightening the slipper makes the entire unit any harder to spin. The tension of the spring is contained within the shaft, so nothing is pressing up against the bearings.

There is quite a lot of frictional losses in the drivetrain, more than necessary. I think much of the problem is due to poor quality gears that don't mesh very well. If it's possible to make the gears mesh better plus reduce the overall rotational mass of the drivetrain I think things would get a lot better.

Using a bigger pinion might also help.

The Huckleberry
04-23-2005, 04:23 PM
Hi,

I've been reading a lot of threads on this forum because I like the H8 a lot.
When I saw the hothothot-thread, I must admit I said to myself; there you go. I was very impressed with al those transmission parts, right from the start, but I was afraid of friction. As Moose said, that's a whole lot of parts to move before the car has actually run an inch. A small motor like that on should have a minimalistic transmission with 64dp gears. Come to think of it, I don't know of any 1/10th el. rc car that has a center diff. Just a thought...

richh
04-23-2005, 04:40 PM
I think much of the problem is due to poor quality gears that don't mesh very well. If it's possible to make the gears mesh better plus reduce the overall rotational mass of the drivetrain I think things would get a lot better.


yup... i keep going back to the example of my miniquake and minizilla who's front and rear diffs feel like butter compared to the mini inferno. i have to think that something is out of tolerance and or out of alignment. i can't believe this is how kyosho designed the diffs to feel. in my opinion, probably production start up issues.

WhoMe
04-23-2005, 04:46 PM
Somthing definatly isnt right in the gears. Thats why is as loud as it is. But i still hold to the fact that i think the center diff thing can work well.

SSS
04-23-2005, 10:16 PM
Somthing definatly isnt right in the gears. Thats why is as loud as it is. But i still hold to the fact that i think the center diff thing can work well.

I also do agree about the drivetrain on the HalfEight, it`s noisy and far away from smooth. BUT, it is working very vell, especially on loose dirt.
It is almost impossible to loose traction with this car. It has so good traction , it`s boring to drive in standard setup.. I have a Mini-T with 6-cell and Losi
speedmotor (ball bear., oil shocks etc.), it behaves much more nervous - and therefore more exciting to drive :D. I`m still awaiting a 8 cell pack, even a Mamba kit. I do believe though, that Kyosho should do something about the diffs...(sealeable, new material for the slipper maybe :confused:

My H8: ball bearings, oil shocks, X-speed with 12t pinion-nothing without 8 cells :(

RURC
04-24-2005, 02:07 PM
BITHED

You know before my stuff was taken I do remember a large differance in temperture in the 2 of my brushless units (both with 6800 motors) one of the units had the pined (locked) slipper and the other had just had the slipper assembly adjusted (tightened). I did not get the opertunity to check into this further due to problems many here are already aware of. I do think that you have hit onto something that really needs to be fully investageted. Upon arrival of my replacement units and the Mamba systems I will delve into this. Good job everyone. :D

jatetu
04-24-2005, 05:42 PM
RURC, do you remember which was the one with lesser temp, the locked or the other?

I'm getting serious temp issues with my mamba 8000 & h8.

cheers

TNB
04-24-2005, 11:32 PM
SSS,
I was confused by your earlier post. Do you prefer to drive the Losi Mini-T or the Kyosho Mini-Inferno? My Losi Mini-T handles like dog do-do compared to my Kyosho Mini-Inferno on the 1/8th scale dirt track. Of course, I used better shocks on the Kyosho Mini-Inferno, but even on the street, the Kyosho Mini-Inferno seems to handle high speeds better though I'm running the 8000kv brushless in the Kyosho Mini-Inferno and only a brushed in the Losi Mini-T.

BitHed
04-25-2005, 01:31 AM
...ok...my slipper diff is now ONE PIECE...so its not a slipper anymore; more a big boot :D ONE metal bushing remained and one was removed, also CA'd to the shaft and the FRONT end of the shaft was glued INTO the slipper gears...Spring and washers and nut have been removed...its naked...

...BTW the FRONT bearing on the slipper was a little rough so i wil swap that out for something better..It was a little 'grindy'...Rear one was fine...

...nothing really changed with this setup...I may have slimmed down a TINY little bit in the weight department but still lots of friction and an extremely hot motor...

..BUT..all is not lost...

...it was WhoMe who made this comment and it was in my mind as i hacked and bashed...Quote "P.S. The casing to the center diff and slipper assembly is cocked...it causes the gears to catch. There is another point of resistance." End quote...

...SO this is what i found...The casing / gear BOX itself is a major player in all this...tighten it TOO much and the slipper gets harder to turn...try it and see...the LOOSER you can get the 3 screws holding the gear box together the better...You are a little dictated to on this by the 5 or 6 screws that go into the gear box from UNDER the car but set it (the gear box) loose and this helps ALOT!!

...I also removed the pillow ball and LONG torque rod that goes from the front assembly to just in front of the gear box with no negative affects...Little bit of weight saved...No real difference in flex or roll or power transfer or anything...

...IN CONCLUSION: Loosen up your gear BOX, watch the bearings on the slipper shaft, stay lubed, wait for the titanium gears, pray for fine weather and never swallow your gum...takes 7 years to be digested :D

acsubie
04-25-2005, 02:13 AM
yea when i broke down my H8 i also noticed that the tightness of the screws in the gear box play a major roll on how smooth the slipper shaft spins

BitHed
04-25-2005, 04:09 AM
...i have mine pretty loose...i mean its not going to fall apart or anything but i tried to keep it as loose as i could...

mOOsE
04-25-2005, 04:28 AM
I also have my "screw pretty loose"...on the car too! One other thing I changed is I de-greased the center diff bearings and lubed them with some thinner oil. Wow...this made a large difference with friction. With the motor unbolted, my car rolls so free it may out roll my touring car

BitHed
04-25-2005, 07:00 AM
...hmm...so if that works with the center bearings then maybe we could de-lube ALL of them? The thought HAD crossed my mind but entailed a total tear-down which i didnt want to do until some other parts arrived...But if the Moose says its worth it then i might just have to crack open the de-lube equipment...

...Moose whats your favourite flavour to de-lube with?

acsubie
04-25-2005, 01:42 PM
havent seen any mention of the bushings insdie that gear in the slipper being a problem, wonder why kyosho couldnt fork over 2 more lousy bearings :rolleyes:

mOOsE
04-25-2005, 01:47 PM
I think bit removed one for wieght purposes. I would actually like some plastic ones to put in their but I cannot find any
I just use some automotive brake cleaner to de-grease that stuff.

SSS
04-25-2005, 02:11 PM
TNB,
I wasn`t clear on that one.. I meant that the H8 is extremely well driven. The Mini-T is a good car, but I think a brushed motor with a 6 cell battery is the limit of the Mini-T, at least if you want control... I do think that the H8 is the only car in this class that may be able to handle brushless speeds!

TNB
04-25-2005, 03:53 PM
havent seen any mention of the bushings insdie that gear in the slipper being a problem, wonder why kyosho couldnt fork over 2 more lousy bearings :rolleyes:
Kyosho does list the bearings as option parts and if you've ever owned a Kyosho Mini-Z, especially something like the Monster, you'd realize that the retail prices aren't cheap. However, Kyosho did later release a 40th Anniversary Edition which shipped with bearings--but for a price. It just seems like some people want or rather expect a "Pro" type RTR with a standard RTR price.

SSS
04-25-2005, 08:27 PM
Kyosho does list the bearings as option parts and if you've ever owned a Kyosho Mini-Z, especially something like the Monster, you'd realize that the retail prices aren't cheap. However, Kyosho did later release a 40th Anniversary Edition which shipped with bearings--but for a price. It just seems like some people want or rather expect a "Pro" type RTR with a standard RTR price.

Hi again!
I couldn`t agree more, having 7 Mini-Z`s, all with full options i found the H8 reasonably priced. I was even surprised that it had ball bearings in the driveline... (I did get that 40th Anniversary Ed. minimonster, and I think it was a bargain....30$ more than standard version :D )

half8 abuser
04-26-2005, 07:41 AM
What bearings will fit wear the slipper goes? I will buy that $hit and put it in there. Money aint no thing :)

SSS
04-26-2005, 08:02 AM
Look up in the manual that came with your H8, the dimensions should be there in one of the exploded views!

BitHed
04-26-2005, 09:24 AM
...740's...yup they be in the manual...Pge 35; Slipper Exploded...in more ways than one thinks ;)

mOOsE
04-26-2005, 01:50 PM
they probably didn't include bearings because their is no point in having them. That gear only turns on the shaft when your slipper is loose. Putting in bearings will do nothing but make the gear spin faster.

BitHed
04-26-2005, 01:53 PM
...and thats why i removed one...gave it a quick little nip and tuck ;) OUCH !! :eek:

TNB
04-26-2005, 04:03 PM
What bearings will fit wear the slipper goes? I will buy that $hit and put it in there. Money aint no thing :)
I can tell you that they are slightly thinner than the Losi Mini-T bearings since I tried those and one of the LHS I went to didn't have any in that size. I have yet to check elsewhere--Boca Bearings? If you go from store-to-store looking, I would take the manual since there is an actual size diagram.