Thomas,
On the CNW that I was referring to, the material had to be relieved from the side facing the support plate, not front side - the clearance issue was with the raised bosses on the separator plate, and it would not center correctly until some of the potting was sanded away.
Agreed.
Yes - They are an odd nut - 5/16" UNF with 7/16" AF - I have made my own in the past in a pinch by drilling out a 1/4" nut and tapping it 5/16".
I may have a check for good measure. But I was getting zero oil leakage from that seal while it was running so I’m disinclined to believe it’s misaligned.
Yeah that’s not an area you can safely grind out the wax, as the stator wires are quite close to the surface. Learned that the hard way. The back side seems pretty safe to grind away though.
Nigel, The nuts with under sized heads you refer to are standard aviation items. See
Malcolm,That's a good idea!!! (see #4)
snipped
I missed that, as i did not click on your link in post #4.
Malcolm, thanks for pointing out the above. I have now edited that inane advice out of Section 34, step 34 in my edit of the Mk III workshop manual.
Just a though, but have you tried fitting the rotor without the woodruff key? I’m wondering if the key way may be too shallow causing it to bind and force the rotor over to one side. You may also want to try a test fit of the stator without washers under the nuts as they may restrict it’s range of adjustment.Hi all,
I'm running into a problem that seems fairly common on Commandos. My 3 phase stator/rotor upgrade has lead to a clearance issue between the two when mounted. So far fettling has not effectively resolved the issue. I can get it down to ALMOST a smooth .08mm clearance at the tightest spot, but the difference in gap from one side to the other is huge, and I have burned through one stator hoping what I got to previously was close enough. So I really want to make sure I do it right this time. The zone where it's tightest seems somewhat endemic to commandos:
I've done a lot of digging into suggestions for fixes, which have included:
the milk plastic shim method
bending the studs
hammering the stator
reaming bigger stud holes in the stator
grinding down the studs
removing material from the carrier on the right side where it closely follows the OD of the stator
milling down the OD of the rotor
...The list is long. But there doesn't seem to be a very clear consensus on best practices. My loosened assembly doesn't seem to have enough wiggle room for shims to work, and I don't understand how hammering or bending studs is going to move a part that is captured pretty tightly by the carrier plate (and the carrier plate in turn by the inner primary cover). Drilling bigger holes in the stator / grinding down the studs / modifying the carrier plate seem like they might potentially accommodate more movement, but what's the risk of stuff vibrating back into an interference condition? Milling down the rotor would be an interesting option if I had the setup to properly do that, but then the already large clearances on the left get even larger.
I'd appreciate any wisdom here because I'm a bit stumped as to the best fix for the problem.
Thanks,
Anthony
You really need to check that the inner case is sitting flat to the crankcase, and that the support nut is not holding things off. Even if it means stripping the whole lot off. A lot of rotor misalignment problems are down to this. Just because it isn't leaking doesn't mean its sitting flat.
I didn't think of how those washers might affect adjustability, that's an excellent observation. I also have not tried removing the woodruff key to see how that affects things. I'll give it a shot.
