RAPTOR 30 TO 50 shim or no shim

[ILIKERC]

Hello

I am upgradeing a Raptor 30v1 to a 50v1 i am using the mavrikk metal fan and the stock raptor clutch.
can anyone tell me if i need to install the clutch shim:?

[capebob]

I'm not sure that they ever did any good. The V1 clutch was just bad no matter what fix they came out with. Since the shim comes with the V2 clutch I am using it. It's kind of like the Jewish man who was about to undergo some serious surgery and was caught crossing himself. When asked why he crossed himself he replied "It cant hurt". :wink:

Bob

[HelicopterJohn]

ILIKERC

I "think" the reason for the shim to provide clearance on the clutch shoes so they engage and disengage freely without dragging on the fan hub. I have attached below some ideas that may help the longevity of your clutches and provide a smooth running helicopter.

Just something you might want to consider. Whether you machine the lining or not the "ENGINE ALIGNMENT" is VERY important. In "my opinion" engine misalignment has broken more clutches that anything else.


Raptor Clutch Liner Replacement

I have made some modifications to my clutch setup that have been a real help to "me". In "my opinion" the clutch shoe to liner clearance is way to wide on the Raptors 30/50/60/90. The original clutch (the piece that bolts to the engine fan) at it largest point is approximately 1.417 on the Raptor 30/50 V1 and 1.495 on the Raptor 30/50 V2. I find that if I make the clearance between the clutch and the liner .012 (that is .006 on each side of the shoe it works fine. I have found that gluing a new lining in the old bell will not provide a good fit and break in time. I have seen some last a long time and others break in just a few flights. This first thing I do is remove all the bolts from the engine to the motor mount and clean all the holes of any excess loctite that may have accumulated in the holes. I would also clean all the bolts with a wire brush to get any buildup off the bolts threads. Furthermore, I would also clean the bolt holes in the side frame where the motor mount is attached and also clean the bolts of any excess loctite. By cleaning all the holes and bolts it will provide some room for alignment of the (engine with the clutch and one way bearing attached) to properly align itself into the "start shaft" during the reassembly process. ALIGNMENT OF THE MOTOR TO THE CLUTCH ASSEMBLY IS VERY IMPORTANT. You should be able to rotate the Start Shaft with the piston off the compression stroke and have minimal drag. During the reinstallation process watch the fan blade. Turning it one direction will drive the engine for starting purposes. Turning it the other direction is where you want minimal drag. The SECRET is gradually tightening all of the (8) bolts (4) on the engine to the motor mount and (4) on side frames to the motor mount. By gradually tightening all the bolts (and moving the engine as necessary from front to back and side to side) will create minimal drag on the start shaft. The other part of the SECRET is the proper clearance between the clutch and liner as stated above. I remove the old liner material by putting the bell in my metal lathe and turning out the old liner material. Then I a place a (piece or two) of .005 brass shim stock (depending of the clearance needed) in the clutch bell gluing the pieces of brass shim stock and the liner material into the bell assembly. You may have to remove a small piece of the end of the liner material to allow for the JB WELD and associated shim stock. I let this assembly dry over night. At this stage the clutch will either fit very tight or not fit at all into the clutch bell with the new liner installed. I then turn the ID of the clutch bell (the liner surface) to a dimension of 1.429 which gives it the .012 clearance. I have really good luck with this setup. I know it sounds like a lot of work but it is really worth the effort. Most likely you don't have a metal lathe and this method may not work for you. P.S. Make sure you remove the shim washer (located behind the drive washer) on the front of the OS engine it you have one. This will eliminate any drag that may be induced by "to tight of a fit" between the clutch and clutch bell support bearing.

[alexander]

the clutch shoe to liner clearance is way to wide on the Raptors 30/50/60/90.


On the bigger raptors like the 90SE the clutch clearance is .015" per shoe for a reason. The larger clutch means the same bend radius yeilds more shoe travel. If you go low in clearance like with the 50/30 at .006"-.008"(ideal) you may well have a engine dragging the clutch bell at idle. We've got a case of fuel through our 90 and it engaged as new correctly and stayed that way. Granted the clearance may be lowered but not that low IMO.

stephen

[HelicopterJohn]

stephen.

You could be correct. The only one I have any experience with in the 90 size engines is a Raptor 60 with a Thunder Tiger 90 engine with the standard clutch. It runs super smooth with my setup and no clutch drag.

I am sure that you have tried many different engine/clutch configuarations and each one could be different.

As I said before "engine alignment" is very important and a misaligned engine can easily cause drag at low speed idle and can also lead to clutch breakage.

Thanks for the heads up.

[WillJames]

Once the clutch has gotten hot from dragging it becomes very brittle and develops cracks at the thinest part. If you have a clutch that is dragging bad at idle speeds, chances are it has been hot and is broken. If it is brand new, chances are it is mis-aligned. Ask me how I know... :oops:

[HelicopterJohn]

Isn't if funny how experience teaches us.

[WillJames]

Your right John. your also right about clutch clearances, at least form my bad experience. I'm learning though. Thanks for the tips!!