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HomeAircraftHelicopterHelicopter Main Discussion › This is why Align 700N clutch fails
09-20-2013 04:27 AM  5 years agoPost 21
3dgimble

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Rochester

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red_z06 that was some brilliant explanation of why align clutches fail, thank you.

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09-20-2013 04:54 AM  5 years agoPost 22
Scott1115

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Greenwich, CT

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Excellent Benny!

Compass 7HV, Trex 550E
RCRCC

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09-20-2013 04:56 AM  5 years agoPost 23
dragonflya

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Evergreen Aviation RC Club, Flyaway RC Club Oregon

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I had run the quick uk clutches but with the high cost and similar failure rates am back to the stock clutches. Would be nice to figure this out, great analysis red_z06! It's a pain with the frequency of replacement lately for our 700's, not so much on the 600n


AMA #909110

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09-20-2013 04:57 AM  5 years agoPost 24
Paul Woodcock

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Dubai - United Arab Emirates

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Hi guys

I found the Lynx Gasser liner was perfect. It is thicker than stock liner and reduces the gap nicely.

Your motor needs to be properly tuned and setup. With a smaller gap, the clutch starts grabbing at anything over a slow idle.

My first Heli, Raptor 30, had this clutch issue. You could buy 'performance' clutches that were slightly bigger. Nothing special, just the correct size.

I have to laugh at guys at our field that think 4 or 5000 rpm to get the clutch to grab is ok..... But complain when the clutch brakes in a few outings.

Regards
Paul

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09-20-2013 05:06 AM  5 years agoPost 25
red_z06

rrProfessor

Dumont, NJ

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Yes, as for the clutch liners, I have used the Lynx liners and ended up with exactly 0.007 gap. This in conjunction with the stress lowering clutch mod, both the clutch and the liner should last a long long time.

www.JustinJee.com

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09-20-2013 05:08 AM  5 years agoPost 26
jschenck

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La Vista, NE.

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I don't break clutches on my 700's that I've been flying for 4 years. I make sure my clutch gap is. 008" and the clutch is centered within .001" and I have had great service from the stock clutch. Breaking clutches is an issue with any brand if the gap isn't right or if the shoe is off center.

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09-20-2013 05:22 AM  5 years agoPost 27
red_z06

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Dumont, NJ

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I don't break clutches on my 700's that I've been flying for 4 years. I make sure my clutch gap is. 008"
Can someone get 0.008 with stock clutch and the stock bell housing with liner? If yes, please share.

www.JustinJee.com

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09-20-2013 05:28 AM  5 years agoPost 28
Paul Woodcock

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Dubai - United Arab Emirates

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Hi

On my 1st Trex700, when I built it, I removed the stock liner and glued in a new stock one with a thin shim.

It's called the coke can mod.....

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09-20-2013 05:30 AM  5 years agoPost 29
red_z06

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Dumont, NJ

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I know that mod to the clutch or liner or both will prolong the life of both. But, one should not have to do that, which is my point.

Also, the current design has the limited range of wear. This is much like replacing your break pads after you wore down 10% of the thickness.

www.JustinJee.com

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09-20-2013 05:36 AM  5 years agoPost 30
red_z06

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Dumont, NJ

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However, if I was Align, I would leave things exactly as they are.

www.JustinJee.com

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09-20-2013 05:38 AM  5 years agoPost 31
BobOD

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New York- USA

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Nice work Benny.
I'll offer a couple thoughts for you to consider.
1. Increase the length of the pivot. Instead of a simple hole forming the pivot, make that an egg shape. This will reduce the stress concentration. The Lynx clutch employs this feature.
2. Change the hardness. If the material is soft enough to yield, it will close even a large gap. Done right, it will still have enough spring to disengage. I've always suspected the reason Align clutches are so variable in failure rate is due to poor control of the heat treating process. I have annealed Align clutches that never failed...albeit they were a little grabby but nothing you couldn't hold against.
3. The clutch should not be round in the free state, it should be round in the expanded state.

Team POP Secret

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09-20-2013 05:44 AM  5 years agoPost 32
red_z06

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Dumont, NJ

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Bob, I agree on both.

Egg or even larger hole at the pivot works. Lynx missed this with a careless addition of larger than needed corner radii on inner hub and at the outer wall. This necessitated spot facing to clear around the screw hole leaving very sharp inside corner where the stress would be infinite under load.

Mine actually cracked at base around the screw. Lynx was also more ductile than Align one.

More ductile steel will start to permanently deform as the gap widens while leaving enough gap. Raptor clutches were this way.

As for the clutch bell, putting a c#$k ring like band on the outside should reduce the flex when the motor is really revving.

Egg shape, however, is more difficult to produce properly unless you have a CNC mill. Holed clutches can be made easily on a manual lathe and mill.

www.JustinJee.com

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09-20-2013 05:58 AM  5 years agoPost 33
Paul Woodcock

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Dubai - United Arab Emirates

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Hi

I have seen you on RR for long enough to know you know the coke can mod...... And I agree, it shouldn't be necessary to do anything.

I just can't continue building a Heli when I can see an obvious problem.

On my Trex700, the clutch bell was the only thing I changed.... And spend a long time getting the clutch run out ok.

Regards
Paul

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09-20-2013 11:49 AM  5 years agoPost 34
Jeff polisena

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westpalmbeachflorida usa

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I think there are many things that can fail a clutch . Improperly setup of throttle mixing with a governor creates added heat ,gov pulling rpm back letting clutch slip . I used to manipulate governors to not fall too low letting clutch slip then switched to limiters and don't have to worry about failures .Yes ,re-lining clutch helps on deflection of shoe but if you can keep clutch locked in it will last .

I stole it ,flew it and gave it back ;)

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09-20-2013 12:31 PM  5 years agoPost 35
red_z06

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Dumont, NJ

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Jeff

Yes. All of that adds to the cyclic load count. But, ultimately, if the clutch was designed to work below the fatigue limit, parts will not fail.

Below shows Stress to Cycle curve. As the number goes infinite, the stress at which the part fails become asymptotic.

Below the horizontal tangent line to this curve is called fatigue limit of a material.

www.JustinJee.com

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09-20-2013 01:01 PM  5 years agoPost 36
Jeff polisena

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westpalmbeachflorida usa

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I agree , the problem is manufactures still look at these as toys and will cut cost with inferior metals to save money .
Something has to give so the Align clutch is good as it is . You can upgrade but then down the line something else needs beefed up.

I stole it ,flew it and gave it back ;)

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09-20-2013 01:06 PM  5 years agoPost 37
shinysideUP

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USA NJ, NY

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Wow, great.

However one may try switching to a TSA clutch/stack, or just switching to a TSA. I believe they solved it by making it manlier. Where as the Align is a little girly. Similar helis, its just TSA actually cares that we enjoy flying more reliably.
I never heard of anyone breaking G4 clutches.

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09-20-2013 01:06 PM  5 years agoPost 38
red_z06

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Dumont, NJ

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I agree , the problem is manufactures still look at these as toys and will cut cost with inferior metals to save money .
Most of the heli parts can be designed by empirical means through trial and error. But, some parts require in depth knowledge of the subject matter. I don't think they can or will hire analysts to solve these problems or commission a lab to run analysis as a typical FEA analysis will run thousands of dollars.

www.JustinJee.com

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09-20-2013 01:57 PM  5 years agoPost 39
red_z06

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Dumont, NJ

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However one may try switching to a TSA clutch/stack, or just switching to a TSA.
Is that a direct swap? If so, that is another option for the 700N users.

As for suggesting to switch to TSA, it is pretty rude.

I happened to like the 700N and HZ91 combo. I like it so much that I have 3 of them. The 0.7M original gear (updated) from 4 years ago is still on in and running strong. The links need to be replaced every 150-200 flight or so and the balls at 300-400 flights or so.

All the Chinese bearings are still functioning. So, with the clutch solved, it is a pretty bullet proof machine.

www.JustinJee.com

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09-20-2013 02:14 PM  5 years agoPost 40
fastflyer20

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N. Tonawanda, NY

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Constancy and Quality of the steel is critical too so the design parameters are realized in production.

It is one area where the USA and Europe still lead.

On a T700 gasser, I modified the clutch bell for a double clutch and ran low clearance on the liners. It held up much better.

Tom
CAUTION - my posts are based on my experiences, yours may be different.

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HomeAircraftHelicopterHelicopter Main Discussion › This is why Align 700N clutch fails
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