T-rex 450 pro V2 serious tail bearing problem

[Jamison816]

Originally Posted by trexpro

+1 sounds like a reverse problem. check your setup

Yes it is the 3gx and it's correcting and moving in the correct direction. I just took the tail apart one of the 6x3 bearings is really crunchy... I'm headed to the local shop now I'll let ya know.

[trexpro]

Originally Posted by Jamison816

Yes it is the 3gx and it's correcting and moving in the correct direction. I just took the tail apart one of the 6x3 bearings is really crunchy... I'm headed to the local shop now I'll let ya know.

Please do, I'm curious

[Jamison816]

The local store didn't have the bearings. Anyone got a good link for the boco's or something proven I'd appreciate it.? Thanks

[suresharp]

RC bearings .com will have a complet set of bearings for your helli or buy individual size. Good quality worth changing over all your bearings.

[bdr529]

I went through 3 bearing failures early on, maybe between 10-30in flights. Second one happened soon after the first, should have replaced both when the first one failed. I switched to boca and have not had a failure in about 50+ flights. I realize that the tail blades i was using at the time of the failures were slightly heavier than the stock, which probably aggravated the poor design. Now i am using KBDD blades which are even lighter than stock, so far so good.

Here is a link to the 10 pack sets, http://www.bocabearings.com/bearing-...-cent-bearings

If you look there are probably coupons too. When I ordered mine I used a 25% off coupon as well.

[Jamison816]

Originally Posted by bdr529

I went through 3 bearing failures early on, maybe between 10-30in flights. Second one happened soon after the first, should have replaced both when the first one failed. I switched to boca and have not had a failure in about 50+ flights. I realize that the tail blades i was using at the time of the failures were slightly heavier than the stock, which probably aggravated the poor design. Now i am using KBDD blades which are even lighter than stock, so far so good.

Here is a link to the 10 pack sets, http://www.bocabearings.com/bearing-...-cent-bearings

If you look there are probably coupons too. When I ordered mine I used a 25% off coupon as well.

Awsome thanks bud! Where do you buy your KBDD blades?

[BadboyR6]

I got my set of kbdd from ebay

[bdr529]

I got mine from HeliDirect because I was ordering a few other things as well. I am not saying KBDD is the answer to this bearing problem, but they are lighter which can't hurt. The reason I got them was for the neon yellow.

[Jamison816]

Originally Posted by trexpro

Please do, I'm curious

It was the tail bearings! Shes dead on point now!

[grabsomeozone]

not really sure if it would fit but maybe try a blade 450/450x tail grip hub and tail grips. they have thrust bearings in them. not sure of the dimensions though. just a thought.

[airmanthesixth]

Are you guys flying with a positive or negative tail pitch angle of attack?

When I have my tail servo at 90 and my pitch slider right in the middle my blade angle of attack is positive, is not counteracting the torque of the main rotor, is actually increasing the torque, that just don't look right, even if you're flying in heading hold, the geometry of the tail is not right, then if you have an under power servo like the stock one, a sloppy tail, and low quality bearings on top of that, well, that's pretty much all you need to have a catastrophic failure.

[erdocdan]

All of a sudden a real bad tail wag. I could not corrected with the gain. I saw the tell tale gap between the hub and grip. The inner shoulder of the bering had disinagrated. I don't know if this is a metallurgy problem or just a piss poor design.
The helicopter doesn't even have 10 minutes on it I was just finishing setting it up and fine tune it. All I've done is hover so far. What's the best fix? Tail upgrade? Or just replace the bearings?
Sent from my SAMSUNG-SGH-I777 using Tapatalk 2

[Raydee]

So far Align is ignoring the issue with the tail so there is no real fix. All I can say is replace the bearings with Boca and get as many flights in as you can before they fail again. Some guys are reporting that when you reassemble the tail dont torque down on the grip screws to much.

[erdocdan]

Maybe the hub is a tad too short and the screw/washer squashes it. I would'nt think that this would be a high stress area. I mean how much load can be on a tail rotor? There has to be a flaw in the design or real crappy metal.

[Bodge]

another one here. happened yesterday. Changed my edge tail blades over to some cheep plastic ones, and then there was a little bit of wag. i thought i was just from changing to different blade so tweeked the gain and that was it. spinning round wagging hard, couldn't turn right.

In the end after 3 packs of trying to adjust the gain I saw the gap between the tail grip and hub. worse thing is somone was watching me though the hole thing trying to get it to fly. Random people always seem to enjoy watching more if your struggling to get it to fly or they think its going to crash lol.


anyway changed the bearing and it flys GREAT again. It seems like its been defective for some time and the vbar was doing a great job of getting it to fly with no wag. first time i thought something was up was on spooling up on the ground the tail would be very sensitive to inputs before it was off the ground.

[Raydee]

Make sure you guys vote in my tail problem pole.
https://www.helifreak.com/showthread.php?t=414274

[erdocdan]

All they need to do is lose the outer radial bearing and replace it with thrust bearings. That way the load is on the ball bearings and not on the sides of the races.

Sent from my SAMSUNG-SGH-I777 using Tapatalk 2

[ryem3]

Originally Posted by erdocdan

All they need to do is lose the outer radial bearing and replace it with thrust bearings. That way the load is on the ball bearings and not on the sides of the races.

Sent from my SAMSUNG-SGH-I777 using Tapatalk 2

Could you imagine the precision of an Align 5mm thrust bearing? Or anyone's for that matter? it is just too small. Problem is that the tail RPM is just too high. THe tail should probably be regeared like they did with the 500 pro. This bearing design just can't handle the pro RPM. I think running it at 3200 plus RPM is the problem. The outer race facing the grip screw is only 5 mm in diameter. Anyone good with the gear math figured out what the tail RPM is at 3500 RPM headspeed? Must be scary.

[SeanM]

I want to say that the tail rotor makes something like 3 or 4 revolutions for every one revolution of the main rotor. So that would make it around 12,000 RPM...

[mamartin]

Originally Posted by Jamison816

It was the tail bearings! Shes dead on point now!

If your LHS has Blade heli parts you can get the bearings for the flybar cage of a blade 400 or blade 450 3D and use those to repair your TREX tail blade grip bearings. They are the exact same size and rating.
I did this on mine when I had this same problem arise.
It was on a Sunday and all of the stores were closed due to it being Sunday and I didn't want to wait. That was 2 months ago and still flying now with no issues