Kasama T-Rex 700 Main Bearing Block

[rg686]

I just notice grandrc have the new Kasama main bearing block
http://www.grandrc.com/inc/sdetail/169717

[george0079]

Those look nice. But I haven't had any problems with the stock ones.

Must be a Bling thing

[gr8t1dini]

These must have the thrust bearing in them.

[Anthony.L]

Does not look like they have thrust bearing from the pics and normally GrandRC would label them as such.

[Tom Burgess]

Originally Posted by Anthony.L

Does not look like they have thrust bearing from the pics and normally GrandRC would label them as such.

they have

[rcmarty]

nice , will get these next season.

I noticed a difference on my 600n with the g-force units, far less bogging with my cyclic beating. lol

Martin

[nwolsink]

I like the stock ones better and I haven't heard any issues with them yet

[cbdane]

I'm confused on this. The 700 already has metal bearing blocks. I thought that what we really needed was metal blocks for the pinion shaft bearings?

[rcmarty]

They havea thrust bearing in them.

Radial bearings aren't designed to have side loads put on them. When your pitch pumping or hitting the pitch your putting side loads on the bearings.

With a thrust set the drag is reduced and the excess power is delivered to the head.

Martin

[Mercuriell]

Originally Posted by rcmarty

They havea thrust bearing in them.

Radial bearings aren't designed to have side loads put on them. When your pitch pumping or hitting the pitch your putting side loads on the bearings.

With a thrust set the drag is reduced and the excess power is delivered to the head.

Martin

All power to the head

Seriously though axial force isn't delivered to the radial bearing cos of the shimming and main mast step - as long as there is some lube I doubt whether much power is lost here otherwise the mast would be heating up! Be interesting to try out though ....

[Finless]

Well my .00001 cents. I have the Kasama main bearings on my 500 and 600n. I did not notice any performance difference flying BUT my god... The longevity is what I have noticed! Usually have to change the main shaft bearings after about 100 flights as they get wobbly or notchy even with no crashes. I have way more than that now on my 500 and 600n and have not had to change them yet! They are still butter smooth.

So the thrust bearings seem to be helping with radial bearings wear...

Bob

[DesertFlyer]

Had to change my 700 main bearings after only 5 gallons. Heli was making a heck of a noise. Thought it was my engine so I rebuilt that first. Finally checked the mains and the top beaing was dry and ratchety. Thrust bearing seems like a good idea. What a pain getting the bearings out and in. I'm going to open up the blocks a little with 600-1000 sandpaper next time. Installed RC-bearings and so far so good.

[rcmarty]

I didn't get a chance to see how long thay last .. lol
I crashed the heli , replaced the main bearings with align ones , align ones alow for some mainshaft movement , but i wasn't all that surprized that the align bearings did that.

I put the g-force bearing blocks and a QUK swash on my 600n basic. (hyper50/cp30/mp5/2100) and noticed an improvement. Even a fellow plank flyer noticed i wasn't bogging the head nearly as bad as before. Granted once i gain more collective management skills it may be less noticable.

The design of a radial bearing would allow for side loading being the bearing is set into a cup. With a normal load the ball will use the full cup to spread the loads out , where a side load will only use the top/bottom half of the cup for loads (in addition to the side loads - eg roll or flip). That would explain why a bearing lasts longer with the thrust sets installed.

The way some people tossing around the 700 i'm surprized the bearings are lasting long at all. I watched lucas doing his walls !! poor bearings , even the cameraman lost him. That's 10lbs+ being hammered to a stop and 1 bearing has to stop it.

They work for me i guess. I'll be getting them one day for sure. Maby one day i'll be good enough not to notice

Martin

[cbdane]

Originally Posted by rcmarty

They have a thrust bearing in them.

Got a set here on my desk. No thrust bearings.

Edit: I was wrong. Looked more closely. My bad.

[papatango72]

FYI....

I spoke with Garf at Gforce-Heli just a week ago, regarding some custom 700 parts; he's got a few new parts coming out, including thrust bearing blocks, 140 degree pro swash mod, tail grips and more.
He was good to deal with and very thorough in his product descriptions. Check his site for details in a few weeks.

[rcmarty]

Originally Posted by cbdane

Got a set here on my desk. No thrust bearings.

Edit: I was wrong. Looked more closely. My bad.

Sounds like there a bit captured or on the inside ..

I know the g-force blocks take a bit more care to get instaled without them falling out on you. I load the top ones on the mainshaft now and put the lower ones in the bottom block but with the heli on it's side , works well.

MArtin

[cbdane]

Originally Posted by rcmarty

Sounds like there a bit captured or on the inside ..

Okay, I've studied these and I'm confused (easily done). The top bearing has the thrust bearing sitting under it (mounted inside the housing). The ridge on the main shaft will come directly in contact with the center race of the radial bearing leaving the thrust bearing to do nothing. Vice-versa on the bottom, meaning that the top of the maingear assembly contacts the inner race of the radial bearing again. The only way the thrust bearing are taking any load is if the radial bearings are pressed in tight enough to compress the thrust bearing which puts an axial load back on the radial bearing where it shouldn't be.

The only way thrust bearings are going to work well is to place it outside the radial bearings like you are describing for the G-force setup. This would be a bad idea on the 700 since it would move the radial bearings even closer together. With only two bearings, they're really already too close to begin with.

Either a poor design or I'm missing something. Look at the photo to see what you think.

[Anthony.L]

See, that's what confused me. I looked at the pic on GrandRC's sit and saw the radial bearing on top and was like "ok, they don't have thrust bearings". Well I understand you description, the thrust bearing is behind the radial bearing and only works if they are basically pressed inward toward the thrust bearing. Seems backwards to me as well.

[stmpngrnd]

Originally Posted by cbdane

Okay, I've studied these and I'm confused (easily done). The top bearing has the thrust bearing sitting under it (mounted inside the housing). The ridge on the main shaft will come directly in contact with the center race of the radial bearing leaving the thrust bearing to do nothing. Vice-versa on the bottom, meaning that the top of the maingear assembly contacts the inner race of the radial bearing again. The only way the thrust bearing are taking any load is if the radial bearings are pressed in tight enough to compress the thrust bearing which puts an axial load back on the radial bearing where it shouldn't be.

The only way thrust bearings are going to work well is to place it outside the radial bearings like you are describing for the G-force setup. This would be a bad idea on the 700 since it would move the radial bearings even closer together. With only two bearings, they're really already too close to begin with.

Either a poor design or I'm missing something. Look at the photo to see what you think.

looks like they have added threaded holes on the blocks for cross bracing to stiffen up the frames more. Are they selling the cross brace as well?

edit----just google searched and found this, yes they are making a cross brace!

[Mercuriell]

I too can't see the point of mounting the thrust bearings on the inside of the radial ones