Is a little play ok?

[DWill]

I just replaced the main shaft on my Trex 500 Pro DFC.

There is a very small amount of up and down play in the shaft. The amount of play is less than .3mm. This is with a .5mm shim in place.

I have a .3mm shim as well; I pit that on the shaft with the. .5mm and it causes too much pressure. So much so that the OWB will not turn freely. I take out the .3mm shim and the OWB turns smooth and free but I get the very slight vertical play.

I have KDE thruster main bearing on the 500. Those thrust bearings should take the force and not let it get to the radial bearings.

Is this small amount of slop a real problem? If so how do I get rid of it, the only shims I have are why came in the kit which is the. .5 and .3mm shims.

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[Diggiz]

I have a small amount of play in most of my helis. It should be fine.Its when you have a mm or more is when its bad.

[DCflyer]

Align sells shim kits for every size heli - they come in a bag ranging from 0.1 up to 0.5mm. I would shim it until there's no play. When you're in the air slamming the heli around, even the smallest amount of play will be causing the main shaft to be slamming up and down against the blocks - not ideal.

You can also try shimming above and below the upper bearing block as long as there's no pressure on the lower jesus bolt as you described.

[Spinnerdog]

I had some play in mine a few days ago. Swapping out the shaft with another new one fixed it. If the shaft moves it will affect pitch and you can imagine with higher head speed making pitch changes more sensitive it makes the bird's altitude more difficult to control. If it were me I'd try to find more shims and put 2 thin ones in. But, I really like to have the bird a close to perfect as I can get it almost as much as I like to fly it. Just nutty that way.

[DWill]

Deleted… double post

[DWill]

DCflyer, any idea where to get a shim kit?

I've been searching for them for a hour already this morning. A .1 mm or .2mm shim would likely be perfect; .3 is just a bit too much.

Anyway if you know where to get the shim kits that would be a big help.

[DCflyer]

I looked too - couldn't find the shim kit. Strange. I found the main shaft spacer kit but you already have that. Is there a local hobby shop you can visit?

If not, simply take a digital caliper and measure the inside diameter and outside diameter of the spacers you already have and go to a local hardware store and see if you can find them in the thickness you need. If not, you can find them online searching for them.

Amainhobbies has a ton of spacers/fasteners/washers/bolts etc. I'm sure they'd have something.

[treotraveler]

DWill

Check Discount hobby warehouse in Kearny Mesa, there in San Diego. They have rc car parts, and rc cars use a ton of different spacers. I'm sure John's rc car guy would be able to help you out. I have used various rc car spacers in heli applications.

Also, AMains hardware section has a ton of spacers listed in various sizes....

[DWill]

Thanks for the help guys; I got it sorted.

I was able to find the head spacer kit in stock at a LHS. Used two of the .3mm spacers and it fixed the problem.

It would be nice if Align would include a couple extra .5mm and .3mm spacers in the kit that way you could come up with a combo of spacers that will work without having to make a trip to the LHS or order parts.

[Gladius]

I had a little bit of play in my head, and it destroyed my thrust bearings after 4 flights! I could actually hear when it happened, but was able to land it safely.

[JohnCrashes]

I have some play in the main shaft of my Trex 500 pro DFC, where the head can shift up and down about 2 millimeters. I would like to shim it, but (dumb question) where do I place the shims? I'm afraid that I'm trashing my bearings.

[vtown nick]

Originally Posted by JohnCrashes

I have some play in the main shaft of my Trex 500 pro DFC, where the head can shift up and down about 2 millimeters. I would like to shim it, but (dumb question) where do I place the shims? I'm afraid that I'm trashing my bearings.

Take the blades off, unhook the 2 front swash links and unscrew the elevator pin out of the swash, remove the jesus bolt from the main gear and lift the assembly out of the heli. You slide the shim on the shaft from the bottom of the shaft and put it back in the main bearings and put the jesus bolt back in the main gear and recheck till you are happy with it then reassemble

[JohnCrashes]

Originally Posted by vtown nick

Take the blades off, unhook the 2 front swash links and unscrew the elevator pin out of the swash, remove the jesus bolt from the main gear and lift the assembly out of the heli. You slide the shim on the shaft from the bottom of the shaft and put it back in the main bearings and put the jesus bolt back in the main gear and recheck till you are happy with it then reassemble

Thank you!

[Gladius]

Why do you have to take the blades off?

[Angelo A]

I have a similar situation. Just built my 500 Pro E and notice that the main shaft shifts upward as a complete assembly with the Jesus bolt on the main gear. I have both shims in place too so I'm confused. The movement is probably less than 1mm but I don't like it.

I took it apart to examine and noticed that the two spacers are actually lodged onto the main shaft above where it meets the top bearing block. Tried like heck to remove them but they are jammed on pretty good. Is that normal. I have 0 flights so there was no real loading on the head. I don't understand. Feels like it may need one more spacer. Sound familiar to anyone? Any ideas?