fan shroud

[syn-]

ok, straight to the point:

Steps completed:
- Mounted pinion block that the start shaft goes through to set tension on the main gear
- Set engine height to allow for slight vertical movement of the clutch bell
- Trimmed fan shroud so it would not catch on the engine head (wonder why that isn't in the instructions?)

Problem:
- Fan shroud constantly rubbing on fan regardless of position when fan shroud mounting screws are loosely in place
- Removal of the mounting screws does allow the shroud to clear the fan, BUT the bottom of the shroud then contacts the tail drive gear (crown gear?) and does not line up with the holes in the frames for mounting the shroud.
- Raising the engine would seem to help with this problem, but then I will have no play in the clutch bell.

Questions:
- Got any clue how to resolve this???
- Can the fan be left to rub the shroud hoping it "wears in" on the first few flights


Thanks guys, and I apologize for blowing up the forum with my trivial questions


-syn

[Chuckie]

Here is my Synergy Engine Alignment Procedure

My steps can be followed when you get to page A8. You should reset the motor alignment if you have any of the following after page A8: The fan rubs the shroud, the main gear is tight on the pinion, you don't have any up and down play in the clutch bell, or your clutch shaft is not centered in the frames (you need to remove the pinion block to check).

1) Install the engine, engine mount sides, engine mount center block, engine shims, fan shroud, and pinion bearing block with all screws and bolts. Do not tighten screws and do not install the hex adapter. Lightly tighten only the screws mentioned at each step.

2) Lock pinion block. With the engine in position so the pinion and main gear are tight, press down and tighten the screws in the pinion bearing block.

3) Set the height of the engine. You want the engine as high as possible but you also want 0.25 to 0.5mm up and down play in the clutch bell. Snug up 4 engine bolts to engine mount sides and 8 engine mount sides to engine mount center block.

4) Fan Shroud. Tighten the fan shroud screws and check for the fan rubbing by rotating the clutch shaft. Move the shroud forward and back and if necessary set height by moving as much as the screw holes will allow. You might have to reset the engine height to prevent fan from rubbing. Install engine exhaust header/muffler and check shroud clearance. Have some gap between the shroud and muffler.

5) Pinion to main gear play/back lash. Loosen the screws holding the engine mounts to the side frame, without changing the height adjustment set in step 3, and set main gear back lash. While holding the clutch bell move the main gear and set so there is a very little back lash throughout the entire gear. Rotate the gear every 30 degrees and check for some back lash. If the gear is out of round set a tight condition at the high point and allow the gear to wear in the first few flights.

6) Clutch shaft in frame alignment. Remove the pinion bearing block and check distance on both sides from inside side frame to clutch shaft. The measurement should be about 0.4inch or 10mm or the same on each side. Loosen 4 screws for ONE engine mount at side frame and move engine to set same distance. Tighten 4 engine mount and recheck gap.

7) File down a little bit of the surface of the clutch shaft on the right side of the funnel shape hole. This will make removing the hex adapter easier at a later date.

8) Install pinion bearing block and Hex adapter. Hex adapter M4x6mm set screw (100-466) should have a taper on the end so it fits into the funnel shape hole. If height of engine has changed set position of pinion bearing block so the clutch bell has some up and down play. See step 3.

9) Add locktite to the appropriate screws shown in the manual and fully tighten all screws.

Regards,

Charles

[cricket]

I fought my shroud and got it to work. JK and I had discussions about the problem and he said I had not properly trimmed to clear the head on the SZ and that was why it was hard to set up. I looked over the fan shroud and cylinder head and found it did not clear the head in one spot. I had to pull the engine at a later date, I trimmed the shroud after that and the alignment was much easier the second time.

John

[syn-]

gotcha. I tried to get it all trimmed out and the shroud will easily move forward and backward, just won't stop rubbing... well unless I unbolt it from the frame and shift it down a little, but this it hits the crown gear. :(

-syn

[Chuckie]

syn,

I know it’s long but did you try my method? Sounds like you need to move the motor up. Loosen the pinion block and push it up as high as it will go then tighten. Then move the motor up as high as it will go. Center and tighten the fan shroud and test for rubbing. Then move the motor down unit the fan clears, tighten motor. If clear when you rotate the fan it only takes a little pressure on the outside of the shroud to cause it to rub. The gap is like 0.25mm above and below the fan blades so the motor and shroud have to be mounted before you won't have any rubbing. If set correctly you should have a very little play in the clutch bell. At this time if the bell is tight I move the motor down a very little bit. Too much and the fan will start rubbing.

Charles

[TMoore]

syn-,

Long build eh?

TM

[syn-]

Charles,
Your method was the first thing I tried before even making this post. :( The problem is that if I move the engine up any I lose all play in the clutch bell and I still can't get the clearance needed on the shroud.
Maybe I'm not understanding something correctly (been known to happen), when you mention the pinion block, are you referring to the block that the start shaft goes through or something on the main shaft? I've been working it as if it were the block that the start shaft goes through, so I hope that is correct... I certainly can't get that joker to move up very much though.

TMoore,
With the exception of the drive train, everything else builds pretty quickly. I've just been spending almost all of my time attempting to get the engine, fan assembly, and shroud setup. At this point, it seems like trying to get all the planets and moons to align may be an easier task. Am I the only one that finds this part of the build to be particularly painful?


-syn

[ISSUES]

You've obviously gotten this problem fixed by now, but I just thought I'd add, that I took a small endmill to the shroud mounting locations on the frame to enlarge the holes lower just a tiny bit. Seems to align fine now.