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Home✈️Aircraft🚁HelicopterHIROBOOther › Evo 50 clutch breaking
05-21-2007 09:08 PM  13 years ago
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R/C Speed Nut

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Galesburg, Michigan USA

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Evo 50 clutch breaking
Is anyone else having a problem with the Evo 50 clutch breaking frequently?
I can't seem to get mine to last more than three or four months, even on a fresh clutch liner.
The liner has about 0.2mm worn off. Is that considered worn out?
Is there a heavy duty clutch available for the Evo 50?

Mike

Funky Chicken?!!..........I thought this was how you do a piro flip!!
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05-21-2007 09:18 PM  13 years ago
MRC-Hirobo

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Edison, NJ

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Hi Mike,

Are you learning to fly, doing an excessive amount of Autos, stuff like that? On and off the power a lot? That will wear out a clutch pretty quickly.

From my experience under "normal" expected flights, the shoe has held up well.

Are you replacing the clutch liners with OEM thickness Hirobo sutff, 0400004?

Where are you at now with the liner life? Did you just replace it?

Give me a shout at jeff@modelrectifer.com with your address and We'll help ya with the problem. Clutches sell, and people do have them break, but not widespread as far as warranty requests go.

let me know.

Thanks
Jeff
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05-21-2007 09:38 PM  13 years ago
R/C Speed Nut

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Galesburg, Michigan USA

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I've been flying for several years, but am learning some mild 3D. I usually end each flight with 3 or 4 autos.
I am using the the 0400004 liners
The liner was replace with the last clutch change last fall and has about 4 months of flying on it (no flights over the winter), and 0.2mm worn off.

Mike

Funky Chicken?!!..........I thought this was how you do a piro flip!!
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05-21-2007 09:41 PM  13 years ago
z11355

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New England

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that seems like alot of wear in a small amount of time.
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05-21-2007 09:46 PM  13 years ago
R/C Speed Nut

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Galesburg, Michigan USA

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Would you consider 0.2mm of wear to be worn out and in need of replacement?
Mike

Funky Chicken?!!..........I thought this was how you do a piro flip!!
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05-21-2007 10:55 PM  13 years ago
Dalieo

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SW FL

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Is it starting to spool up rather quickly or are you almost at half throttle before the clutch really starts to engage?
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05-21-2007 10:57 PM  13 years ago
MRC-Hirobo

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Edison, NJ

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Is that .2mm a side or total wear. I recall that the tolerance was .5mm a side (1mm difference total) per the liner instruction sheet.

Same clutch bell?

Your flying description is well withing normal I would say.

So if it .2mm a side, no you are within tolerance.

Is the shoe sitting flat on the fan hub surface? Did you have excessive tip runout?

Are you using the OS black thrust washer between the hub and the front bearing?

Like I said, send me your address so we can get you some parts to help. Definitely not normal wear and tear by your descriptions so far.

jeff
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05-21-2007 10:57 PM  13 years ago
R/C Speed Nut

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It engages at probably about 30% throttle.
Mike

Funky Chicken?!!..........I thought this was how you do a piro flip!!
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05-21-2007 11:07 PM  13 years ago
R/C Speed Nut

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Galesburg, Michigan USA

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Same clutch bell?
I have two clutch bells that I have been rotating in and out of service with new liners.
Is that .2mm a side or total wear?
It is .2mm on each side (liner thickness is 1mm, worn liner is .8mm).
Is the shoe sitting flat on the fan hub surface? Did you have excessive tip runout?
Tip runout is approximately .002 and clutch is setting flat on hub.

Mike

Funky Chicken?!!..........I thought this was how you do a piro flip!!
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05-22-2007 12:00 AM  13 years ago
skwidd

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NOLA

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Yes, I have had the same problem. Shortly after I bought the heli, the clutch broke. One of the shoes broke off and locked up the clutch, i.e., lodged between the clutch liner and the clutch and wouldn't disengaged.

I replaced the clutch (but not the liner) and shortly thereafter I broke another clutch.

I then replaced the bell, liner and clutch a few months ago and am waiting to see how it holds up.

But so far 2 clutches have not held up well, breaking within a short period of time on my Evo50. I posted about this maybe 8 months ago, but no one had a resolution or any advice.
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05-22-2007 12:43 AM  13 years ago
Leif

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USA

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When's the last time you replaced the engine bearings? I went through a bunch of clutches last year when my Hyper bearings went south. I should have caught it sooner but didn't expect such quick failure of ceramic/stainless bearings. When the engine vibrations started breaking clutch shoes every other flight I finally caught on.

Just something else to check.

Leif
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05-22-2007 07:21 AM  13 years ago
ripper

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Maryland

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Leif,
very interesting. I wonder if the start shaft runout was checked prior to installation? This as well could transmit vibes and start breaking parts.
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05-22-2007 12:26 PM  13 years ago
Leif

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USA

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Tip runout is approximately .002mm and clutch is setting flat on hub.
Sounds like it's within spec. The funny thing is when my bearings went I could still dial in the clutch OK on the bench since the forward bearing was centering the crankshaft. The rear bearing (when I finally figured it out) had greater than 0.5mm play on the inner race.

Needless to say this engine required a major rebuild. I just wish I hadn't gone through three clutches and one inverted flameout crash to figure out the problem.

Leif
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05-22-2007 03:19 PM  13 years ago
R/C Speed Nut

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Galesburg, Michigan USA

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When's the last time you replaced the engine bearings?
New set of ceramic/stainless last summer. Engine still runs smooth.

Mike

Funky Chicken?!!..........I thought this was how you do a piro flip!!
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05-22-2007 04:08 PM  13 years ago
MRC-Hirobo

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Edison, NJ

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Okay, have not gotten your address yet.

Please send to jeff@modelrectifier.com so I can help you with some new parts to try.

Something is wrong and needs some attention.

Thanks!

jeff
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05-22-2007 06:17 PM  13 years ago
R/C Speed Nut

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Galesburg, Michigan USA

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PM sent.
Mike

Funky Chicken?!!..........I thought this was how you do a piro flip!!
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05-22-2007 07:09 PM  13 years ago
Leif

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USA

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Engine still runs smooth
Please double-check your engine. Remove the crankshaft and check the play on the inner race of the rear bearing. Ceramic/Stainless bearings do not exhibit the same failure mechanism as steel/steel bearings. On my Hyper, there was none of the usual indications of bearing failure (rough idle, rattling, etc.). The symptoms, as seen over several weeks were:

1. A short period of RF glitching.
2. Some difficulty with engine tuning.
3. Engine running hotter than usual.
4. Clutch failure.
5. Flameout (only one, so I wrote it off).
6. Loss of power during flight.
7. Clutches breaking every flight.

This occured over a two month period, with the first symptoms appearing within a few tanks of the new ceramic/stainless bearings being installed. Symptoms 3-7 only appeared a week or two before I discovered the root cause. With ceramic/stainless bearings you won't get bits of metal departing the bearing. Instead, the ceramic balls just pound the heck out of the bearing races until they are oversized and you get lots of play between the races. Eventually you can get to the point where the play is so much that the conrod can hit the crankcase on the down-stroke. At this point you'll start blowing metal pieces from the conrod and crankcase through the engine.

In hindsight, my new ceramic/stainless bearings lasted about three tanks of fuel before failure symptoms began to show up. However, since these symptoms were not what I normally attribute to bearing issues it took much longer for me to actually figure out what was happening. When I finally determined the failure mode much of what I had observed over the previous weeks became crystal clear.

Leif
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05-22-2007 07:30 PM  13 years ago
hootowl

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Garnet Valley, Pa.

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Leif,

What the heck was wrong with the motor that it ate ceramic bearings so quickly?
Wolves don't lose sleep over the opinions of sheep
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05-22-2007 11:01 PM  13 years ago
Leif

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USA

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I'm still not sure. I sent the bearings back to Paul at RC-Bearings but I never heard back what the consensus was.

I personally think that stainless is too soft for the bearing races. They claim they can harden it to "close" to bearing steel, but I think "close" isn't close enough; especially when coupled with ceramic balls in an application that is probably over the limits of what a bearing this size is supposed to take.

With standard steel/steel bearings, the main issues are skipping and cold-welding. This is why you end up with bits of metal coming off the bearing. With ceramic/steel, you don't get cold welding of the balls and races, but rather end up pitting the races if the stress is high enough.

I've gone back to the standard steel/steel bearings. Still running strong after three or four gallons since I changed them. I would speculate that the best overall bearing is either a hybrid ceramic (mixed ceramic and steel balls) or ceramic balls and bearing steel races.

Leif
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