View Full Version : How many shims is too much?

04-26-2010, 12:05 PM
Ok, last week I landed a little too hard and I had to replace my feathering shaft. No biggy, I got this bird used and I noticed that the parts used in the feathering shaft were not quite what I've seen in some pics. But, my bird flew great, no vibes, great blade tracking. So I replace the shaft and install all the washers, shims and bearings just like the 400 bible shows. It really hasn't been the same since I did it. It's got 6 shims on each side and it doesn't seem to be enough. The o-ring can come out a bit and that causes the blades to be woobly. The blades in one spot track, but if i look on the other side they don't track, what gives? Should I add enough shims to make it tight enough that it's not wobbly?

04-26-2010, 01:00 PM
I've looked at some pics and the ones I've seen there aren't many shims being used. What gives? Why do I have to use so many?

Also, I used the Align feathering shaft. I remember it came with little collars, I didn't use them, was I supposed too? And of so where?

04-26-2010, 03:48 PM
I believe the align feathering shafts need to be grinded down slightly to fit properly.

04-26-2010, 06:06 PM
I don't know about the align feathering shaft but I replaced my feathering shaft a couple days ago and did a lot of research on this matter. what it came down to for me was first determining if your orings need replaced, mine did so I just went to Lowes and got 10 of them for a couple dollars. these new orings coupled with 4 shims per side really seemed to do the trick. ultimately what I ended up doing was just adding shims one by one until I got the grips nice and snug, it took a heck of a lot of time but now I know the right combo for my heli. generally what I have seen around the web is people are using about 4 per side, but it really depends on the condition and stiffness of your orings. hope this helps

04-26-2010, 06:53 PM
do have the specifics on your o-rings from Lowe's? part number?

04-26-2010, 11:10 PM
go to home depot or lowes or similiar and get #60 orings in oring section, plumbing etc. direct replacement .... from Londo HF member.

I've never been able to find them myself but if you do, please ship some my way:-)

04-27-2010, 07:57 AM
ill go ahead and check when I get home after work, but I couldn't find anything at home depot (what a surprise) Lowes seems to never fail tho.

04-27-2010, 08:31 AM
If you're using 6 shims per side and still have slop the shaft must be too long. Get the proper B400 shafts and go from there. Four shims + the step washer per side should be plenty.

04-27-2010, 11:00 AM
yeah, that's my only conclusion, the shaft must be too long. I ended up putting one extra cup washer on each side and use just one shim next to the o-ring and she is good to go now. No notchy in the grips.

I know i'll get flamed for not using the right parts, but hey, it works. ;)

04-27-2010, 02:20 PM
No flame from me. As long as it's working and the heads not going to fly apart you're good to go. Just make sure you locktite the blade grip bolts.

04-27-2010, 09:14 PM
for future reference if you still need it, I got the orings at Lowes, brand is Danco and look for 1/4"OD x 1/8"ID x 1/16"