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T-REX 450 › T-rex 450 tail pulley bearing block ruined.
07-13-2008 05:26 PM  9 years agoPost 1
Tibo

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Montréal Canada

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I did a nasty thing today, I ruined the upper tail pulley bearing block trying to remove the tail drive gear/pullet assy. on my T-Rex se v1.5 (v1 with the new speedo and blue gears). Now, looking at Horrizon for the parts, I found out that I could buy the tail drive kit (AGNHS 121684, 9$) but the upper bearing block is part of SE alum. re-fit kit (AGNH 1207B, 52$) BTW, both turning out to be backorder... I don’t want to pay nor wait for the re-fit kit parts, what are my options?
Thank you...

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07-13-2008 05:41 PM  9 years agoPost 2
Sillyness

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Little Rock AR

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Get this:

http://www.readyheli.com/HS1121_CF_...et_p/hs1121.htm

Use the plastic bearing blocks instead. I took all of the aluminum bearing blocks out of my V2. I much prefer the plastic because:

1) Lighter than aluminum
2) Bearings last longer
3) Bearings are MUCH easier to change
4) Bearings can easily be greased before installation in the blocks (since they split into two halves).

Aluminum blocks just make you feel cool... that's about it.
For that matter, if I can find it, you can have my metal bearing block, though I think I might have thrown it out.

I replaced both the main shaft bearing blocks and the tail drive bearing blocks with the plastic ones in the kit, plus I now have an extra bottom plate from the kit. I didn't use the boom block, though I am thinking about it. Lighter is ALWAYS better!

Cheers

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07-13-2008 05:47 PM  9 years agoPost 3
Boidman (RIP)

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The Home Stretch

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I know of a few guys who have gone to that kit, for various reasons. Would you give your thoughts on why you believe the bearings last longer?

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07-13-2008 05:58 PM  9 years agoPost 4
Tibo

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Montréal Canada

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I know for one thing that the plastic parts offer a better way of getting the tail shaft pulley perfect in the frames to avoid chewing up the belt but also if they get loose for some reason they will destroy fast... I like the way the upper block split for servicing... I will give it a go...
Thanks'

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07-13-2008 05:59 PM  9 years agoPost 5
Sillyness

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Little Rock AR

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Aluminum is one of the hardest/harshest metals out there and it transmits vibration very efficiently.

I liken it to my experience with bicycles. Aluminum bikes have a very stiff and overly harsh ride. Steel bikes are very smooth, but are very expensive when light and can rust. My personal road bike is titanium: a sweet ride and no rust/wear.

Anyway, the plastic is compliant and should absorb some of the vibes rather than transmitting absolutely everything. I know folks in nitro helis find grip bearings last longer in plastic vs. metal grips.

One final benefit I have yet to test. If a bearing in a plastic block siezes, it should break free from the block and spin enough for you to get the heli down. If a bearing in a metal block siezes... good luck.

Cheers

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07-13-2008 06:07 PM  9 years agoPost 6
Heli 770

rrProfessor

USA.

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Boidman
I've have two SE.s, One of them I used the plastic on. It's needs bearing replacement more often then the alum. set up. I think the reason for it is, Alum. acts as a heat sink.

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07-13-2008 06:46 PM  9 years agoPost 7
USNAviationjay

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Houston Tx USA

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now that's entirely possible... plastic would not lose heat very easily.
but that said I do use the plastic blocks as well.

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07-13-2008 09:05 PM  9 years agoPost 8
Boidman (RIP)

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The Home Stretch

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Interesting thoughts, guys. Thanks.

I mostly think that lack of lubrication, from the factory, and then as regular maintenance, is the worst enemy of the bearings. Many of these little helicopters, at least in my corner of the world, never get any lube added, ever. Some guys end up replacing bearings due to damage after crashes often enough to never be really concerned about regular lubing. Can't hardly argue with what seems to work for them.

Some of us used to go over everything on a helicopter, right after landing, with a temp gun. Mostly just for fun, but sometimes looking for a clue about a problem. I don't think any numbers were ever written down, though.

The tail bearings were always the warm/hottest (ignoring the top motor bearing), and the front top tail drive bearing as measured actually just close at the aluminum fit, was next. Different belt brands, without lube, and pushing the limits of sane tension, got surprisingly warm.

The main shaft bearings had the lowest temps. I don't recall thinking that the temps were enough to believe that a viscosity change might cause any lube to be more inclined to exit the bearings, stage left.

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07-14-2008 12:13 AM  9 years agoPost 9
Tibo

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Montréal Canada

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So, after all, the plastic blocs should not be a problem? Those temps were not that high? On my heli, the belt produced a fair amount of "dust" in and around the bearings and bloc. So, to me, it looks like a ok idea running the plastics (since they separate in half) and cleaning things up a little once in a wile... Those V2 alum. blocs are the trick (they also separate), but 56$ ??? I buy 3 SA plastic kits for 18$ each and I’m good for 3 years...
I appreciate every one comments.
Thanks'

... I'm still talking about the tail shaft pulley bearing bloc...

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07-24-2008 04:03 AM  9 years agoPost 10
Tibo

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Montréal Canada

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Hey, sorry for reviving a old tread... just received my stuff (new tail shaft and pulley assy. plus plastic bearing bloc).

I was expecting having to press in the pulley on the shaft. Instead, the pulley slides up and down on the shaft by it's own weight, never mind trying turning the belt! Should I epoxy, green threadlock or Ca glue it to the shaft?

What is the proper distance between the pulley and the upper bearing? I'm asking because if I mock assemble it to the plastic bearing block, I find that the pulley could go all the way down the shaft right next to the upper bearing (there is a resess in the plastic block and the pulley does not rub on it). I remember seeing the old pulley/metal block set up (original metal unit) beeing close but not right on the bearing, am I wrong?

Need advice, thanks'

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07-24-2008 07:00 PM  9 years agoPost 11
TomRex

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West Palm Beach ​Join Date:​12-28-2005

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Sorry to you guys that didn't get the aluminum split bearing block.
Yes they make one! Makes life easier to change out the transfer shaft and or bearings. The better part by MicroHeli has bearings that have lasted me almost three years so far. Get one and you'll never look back. As far as plastic goes, ha! Good luck! Way lass rigid and less true.
imho

Ignorance is the absence of facts.Stupid is lacking the intellectual capacity to comprehend the fact

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07-25-2008 12:34 PM  9 years agoPost 12
Tibo

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Montréal Canada

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So, what is the best way to fix the pulley on the shaft?, Epoxy, locktite, CA... ?
I, since my last post, found the old shaft and pulley and it looks like the pulley is right next to the bearing, so, that at the least answers one of my questions.

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07-25-2008 03:40 PM  9 years agoPost 13
TomRex

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West Palm Beach ​Join Date:​12-28-2005

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Ok question, do you have the origional bearing block, if so is it aluminum 1 piece or split? Mine was split so I got the shaft kit with the pulley pressed on at 1 time, I now have the MH version. Are you speaking of the plastic pulley version? or metal pulley? Either way some use red or black locktight. J B weld works for some, epoxy will work but it needs to be the 45minute hard stuff not the spongy stuff. I'd seriously think on the MicroHeli version, pricey but it comes with set screws on the pulley and way better bearings. A 1 time purchase! imho

Ignorance is the absence of facts.Stupid is lacking the intellectual capacity to comprehend the fact

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07-26-2008 11:55 PM  9 years agoPost 14
Tibo

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Montréal Canada

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Thank you TomRex, I will use JB weld. I had the one piece alum block but killed it removing the pulley (dont ask, I do stupid things some times)... I bought the plastic one (450 xl kit) since it was cheep (450 v2 alum kit is 54$!!! crazy...)

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T-REX 450 › T-rex 450 tail pulley bearing block ruined.
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