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Thunder Tiger Raptors 30-90 - Imperio > RAPTOR 30 Tempering the Raptor clutch?
 
 
pgoelz
Senior Heliman
Location: Rochester MI

Anyone tried to heat treat their clutch? Mine started grabbing bad enough today that I can't get it to idle. A replacement is several days away so I decided to try heat treating the living hinges.

For my first attept I heated the living hinge area to a barely visible red and quenched it. I then sanded it so I could see the natural metal color and re-heated it until it started to barely change color and let it cool naturally. The result was a hinge that seems to spring and not take a set. Unfortunately, it also toasted the one way and no amount of solvent or lube would get it going again.

So for my next attempt, I tried heating the hinges with the clutch standing on edge in a pan of water so only the hinge area was above water. When it got hot enough I simply tipped it over to quench it.

We'll see how it works tomorrow. Worst case it grabs or a shoe breaks off and I'm back to where I started and I install the new clutch (and liner) in a couple days. Best case is the hinges actually flex without bending or breaking.....

Paul

Paul Goelz
Rochester MI USA
http://www.pgoelz.com
08-10-2008 03:41 AM
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JuanRodriguez
Elite Veteran
Location: Rochester, New York

Paul,

My understanding is that the metal has to be the proper composition to accept heat treating..... don't know what the TT clutches are made of....

I can tell you that most of the problems with this setup is that there is too much gap between the clutch and liner....that's in the "stock" configuration..... We've measured over 30 thou clearance..... the clutch shoes have to travel too far and wind up getting "sprung" like yours....

A better solution (IMO) is to "fix" that problem.....We glue in thicker liners and then turn them down for a TOTAL clearance of about 12 thou between the clutch and liner/bell.... So that's about 6 or so thou per side......

Since we started doing that (many yrs ago), problem solved..... and no more broken clutches.....

Hope this helps....
08-10-2008 02:53 PM
 
 
T-Rex-Flyer
Key Veteran
Location: Panama City, Fl

Quote 
We've measured over 30 thou clearance..... the clutch shoes have to travel too far and wind up getting "sprung" like yours

JuanRodriguez could you go into a little detail on the process and equip used to turn down the thicker liners. Sounds like you might be on to something here.

If the wings are traveling faster than the fuselage, it's probably a helicopter.
08-10-2008 03:30 PM
 
 
JuanRodriguez
Elite Veteran
Location: Rochester, New York

Sure,

BTW, this problem was identified shortly after the Raptors first came out....

What we've done from almost day one was to throw away the "stock" liners. They are too thin, thus the huge clearance between the clutch and liner which causes the problem described....The stock liners are about 40 thou whereas the Gerlok material is about 66 thou....



We then glue the liner in place as usual and then after the glue dries overnite, the clutch bell is mounted in a lathe and the liner is turned down to achieve the desired clearance.....

While I realize that many (if not most) do not have a lathe or measuring equipment, this method might not be practical to many....

A second and easier method that I have HEARD works well to achieve the same result is as follows....

Prepare your clutch by wrapping it with a couple of layers of electrical tape...... Then mix your 2 part epoxy (I like JB Weld) and glue in your liner while being careful not to get any glue in the clutch bell bearing...... Then stuff your clutch into the bell and let the epoxy cure overnite..... After the epoxy cures, pull out the clutch and remove the electrical tape. The tape serves two purposes..... it "sets" the proper clearance we're discussing while preventing the epoxy from sticking to the clutch....

Hope all of this helps....
08-10-2008 04:56 PM
 
 
pgoelz
Senior Heliman
Location: Rochester MI

Well, the tempering didn't work. So I stripped the clutch and did some measuring. It's been a while since I had it apart.... I've just been replacing broken / bent clutches. And the clearance issue is at least as bad as you describe... maybe worse!

I ended up cutting a strip of 0.010" aluminum flashing stock (comes in a roll at Home Depot) and forming it to a circle so it fits the bell snugly. I then formed a stock liner into a circle and trimmed the end until it just barely popped into place. The ends are in contact with each other and provide some force that helps seat the liner and shim. Looks like the resulting clearance (allowing for some glue thickness) will be about 0.004" to 0.006". The trick will be to use very little epoxy and get the clutch into the bell with just the right amount of tape wrapped around it.

Does anyone use CA instead of Epoxy? Thin CA would be a lot neater and easier to control, but I'm not sure if it can handle the heat.

To ease future rebuilds, what do you all think about NOT using Loctite on the pinion where it screws into the clutch bell? I don't see any force in the direction that will unscrew it, and if it is not Loctited, it will be possible to remove it for rework without having to split the frames. ??

Paul Goelz
Rochester MI USA
http://www.pgoelz.com
08-11-2008 02:00 PM
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JuanRodriguez
Elite Veteran
Location: Rochester, New York

Hi Paul,

You're absolutely right......no loctite is needed on the pinion to clutch bell install for the reason you've mentioned..... In fact, a little dab of "never zeize" or other lube is beneficial, specially when you want to remove the clutch bell by unscrewing it from the pinion without having to split the frames..... That's what we do when it comes time to replace the liner.........

Good idea about the shim...... I forgot to mention that some do use that method..... they use business card stock to take up the gap.....

And yes, although I have never used CA, many do use it with good results......Your choice, I guess.......

That 4-6 thou clearance might be a little snug when its all said and done so you may need to spin the bell up in a drill (if you don't have a lathe) and shave some off with the careful use of some sand paper until you get the desired fit....
08-11-2008 02:15 PM
 
 
JuanRodriguez
Elite Veteran
Location: Rochester, New York

Take a look at this link.....

It talks about removing the clutch bell w/o splitting the frames and provides a pic of a tool you can make to help with the procedure....

http://www.raptortechnique.com/clutchbell.htm
08-11-2008 02:25 PM
 
 
pgoelz
Senior Heliman
Location: Rochester MI

Thanks, yes I did something like that when I removed the clutch bell.... I removed the pitch arm and then removed the screws holding the frames together but only split them enough to get the bell and bearing out. Before I reassemble, I'll remove the pinion and any Loctite and then reassemble. Unless I lose the bearing at some point, I should not have to split the frames again.

Paul

Paul Goelz
Rochester MI USA
http://www.pgoelz.com
08-11-2008 03:29 PM
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alvinrc
Veteran
Location: Mobile, AL, USA

A Crying Shame

that the factory bell with pre-installed liner and the clutch are so out with the clutch/bell clearance.

I am having to do the same thing. During recent rebuild, replaced clutch and bell, first flight, clutch sprang enough to be draggy clutch now.

Checked and clearance gap was way too much.
Will replace clutch and shim out liner to proper gap.

A friends Trex 600n has a nice high RPM clutch I like better.
08-12-2008 02:04 AM
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pgoelz
Senior Heliman
Location: Rochester MI

Hold the phone. I ordered a replacement clutch and a liner from a local hobby shop (didn't have time to drive across town and no one closer has Raptor parts). When the package arrived, instead of just the liner, they sent me a clutch bell with the liner pre-installed. This is the bell with a single line scribed around the outside as opposed to my original bell with no line.

I had my old bell all stripped, shimmed and the liner cut to fit snugly but was waiting to glue it until I had the new clutch. The new (and old) clutches measure about 1.416". My shimmed bell measured about 1.430, or a clearance of 0.007" (before shimming it was 1.450!). But the replacement bell with pre-installed liner measures 1.427, for a clearance of 0.0055... even better! It's all back together and I'll fly it tonight and see how it works. If my lighter throttle linkage and new throttle servo can keep my OS 37SZ-H throttle rotor from destroying itself, I'll finally have a reliable heli.

Paul

Paul Goelz
Rochester MI USA
http://www.pgoelz.com
08-13-2008 02:56 PM
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JuanRodriguez
Elite Veteran
Location: Rochester, New York

Sounds great, Paul....

Sounds like TT is listening !!
08-13-2008 03:13 PM
 
 
pgoelz
Senior Heliman
Location: Rochester MI

Well.... they may be listening but they don't have it right yet. The new clutch is a bit grabby at anything above an idle that is too low to run reliably. Probably understandable since the clearance was about 0.005" all around. So they went from too loose to too tight. I'll take it out and try to open it up a couple thou with a drill and sandpaper. Wish I had a lathe.....

Paul

Paul Goelz
Rochester MI USA
http://www.pgoelz.com
08-17-2008 01:59 AM
HOMEPAGE  
 
 
JuanRodriguez
Elite Veteran
Location: Rochester, New York

Hummmm.....

That's a bummer, Paul....

You can do one of three things...... fly it like that for a while and the condition may improve.....

Or

You can start the motor, get a very firm grasp of the head and gun the motor so that the clutch slips a little on the liner.... do that a couple of times and that will probably make a difference....

Or

Do as you suggest..... take it apart and shave a little off the liner..... although you don't have a lathe, you can spin it up on a hand drill and use some medium sandpaper to do the job....
08-17-2008 02:39 PM
 
 
pgoelz
Senior Heliman
Location: Rochester MI

Yeah, I watched a buddy spin his up until it smoked and burn the liner down a bit. Worked OK but I am afraid of overheating the shoes and destroying any temper there is so I don't think I'll try that. I did do a mild version of it (no smoking and the bell wasn't too hot to touch) and it didn't help much.

In the mean time I'm flying it like that.... it isn't too bad but I'd like another 500-1000 RPM of idle before it engages. At least this time around it isn't because the shoes are sprung

I've gotten pretty fast dropping the engine and there isn't any more Loctite on the bell threads so it shouldn't be that hard to pull the bell and sand it down a tad. I have a pair of digital calipers so I can do it in a controlled fashion, a couple thou at a time. What is the current guideline for shoe to liner clearance (per side)?

Paul

Paul Goelz
Rochester MI USA
http://www.pgoelz.com
08-17-2008 09:58 PM
HOMEPAGE  
 
 
JuanRodriguez
Elite Veteran
Location: Rochester, New York

Quote 
What is the current guideline for shoe to liner clearance (per side)?

About 6-7 per side should do......
08-17-2008 10:26 PM
 
 
alvinrc
Veteran
Location: Mobile, AL, USA

Quote 
About 6-7 per side should do......
Is that like about two wraps of black plastic electrical tape around clutch?
08-17-2008 11:22 PM
HOMEPAGE  
 
 
pgoelz
Senior Heliman
Location: Rochester MI

Hmmmm.... I seem to recall it was about 4.5 to 6 per side when I installed it. Kinda hard to measure the inside of the bell accurately. I'll see if I can find some 0.006" shim stock and see how it fits.

The trouble with electrical tape is that it is compressible and you can also deform the shoes if you jam it in. I was never sure how tight it was supposed to be. This way (hopefully) is better... too tight and I'll try loosening it a bit.

Paul

Paul Goelz
Rochester MI USA
http://www.pgoelz.com
08-18-2008 02:23 AM
HOMEPAGE  
 
 
JuanRodriguez
Elite Veteran
Location: Rochester, New York

Quote 
Is that like about two wraps of black plastic electrical tape around clutch?

Yes..... as I stated in a previous post above, there are many out there using that "plug and play" method and experience great results.... I can't personally vouch for that method because I have never tried it myself.....
08-18-2008 01:23 PM
 
 
pgoelz
Senior Heliman
Location: Rochester MI

Reviving the thread..... the new clutch and bell were always a bit too snug.... the clutch grabbed just a bit even at a moderate idle. But the last time I had her out, it was worse so I tried some field troubleshooting. And discovered that the top two engine mount holes in the frame were cracked. This allowed the engine to vibrate more than usual.

Since this requires I replace the frames, I tore her down this evening. In the process I looked at the clutch again and discovered the in spite of the fact that it was always tight, with maybe 0.006" clearance (0.012" total), one of the shoes has bent outwards slightly.

I'm about to give up on this thing. I LOVE my Raptor and it has given me great service since maybe 2001, but the clutch is driving me NUTS. Can anyone direct me to a source for a V1 30 size clutch that is actually tempered and doesn't bend if you look at it sideways?

My new frames arrive tomorrow and I'll put her back together and try again. But I suspect that the clutch is going to be grabby because of the sprung shoe. I'm tempted to gently spring the other shoe to match so it will at least be balanced.... perhaps that is what cracked the frame in the first place?

Paul

Paul Goelz
Rochester MI USA
http://www.pgoelz.com
09-23-2008 02:18 AM
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Thunder Tiger Raptors 30-90 - Imperio > RAPTOR 30 Tempering the Raptor clutch?
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