Replacement B Grips Arrived Today

[uberbania]

Originally Posted by prillernut

shit, y'all are right - no excuses here, I just f'ed up - and it looks like HH did also... There actually doesn't appear to be any improvement to keep from tearing the outboard bearing in half.

Yeah, there isn't any load transferred to the inner bearing but the added material in the middle does seem to overlap the inner race, saving it from flying off like beachman said. What will probably happen is a crap-ton of vibration and loss of most control, a throttle hold, and a few minutes of swapping bearings

[ahahn]

Originally Posted by TomC

The trex250 also uses much larger bearings than the mcpx. Bearing for trex250 are 2.5x6x2.6mm versus 1.5x4x1.2mm for the mcpx.

Short of going to thrust washers, I think that Eflite should look at going to larger main grip bearings.

Cheers,
TomC

Tom,
Well of course I know that! The 250 blades are a lot bigger! But the 250 tail did originally use two of the 1.2mm width bearings per grip, the same ones we have been using as replacements for the Blade stock bearings.

But the point I was making is that there are heli's out there without thrust bearings, and blades aren't flying everywhere!

I am beginning to think that maybe HH was right that there were a bunch of substandard bearings in the original shipments. And it probably is true that crashes will destroy the bearing too, and that what we have been hearing over the last month or so has been a combination of both issues.

But at least now the blades shouldn't go flying--unless we forget to locktite the screw!

[Ampdraw]

Got my B grips and head.

Bearings are not moulded in....only difference is the central plastic comes toward the feathering shaft more and supports the inner race of the bearing.

Loktite was used on the feathering screw but not enough that I couldn't take it apart...ie screw head didn't shear off.

Interestingly mine came with the outer bearings brass shield toward the blades, ie facing outward and the inner bearings were the other way around with the brass facing the head??

Anyway, b grips, spectra 50Lb tether (incase the screw head shears) and all good for indoor inches from face inverted imo. If I dumb thumb it I may get a crazy 2g blade gash. I can blame myself and point the finger toward the mirror. Been running a tether from day one though as I like to fly this heli close and well...things can happen.

Crashed my Spek 2s 4g6 into myself before spinning 4800 rpm and sure it stung like an angry bee and broke the skin but no big deal.

Good job HH. This is the perfect lounge cp for me.

Amp

[tracknoob]

Thanks for the info, Ampdraw. Yup, I'll be keeping my tether too -- just cheap insurance at this guy's pico fastener-size combined with high headspeed. I had a feathering screw back out even on the Airey shaft with longer screw in this application, so there is a lot of stuff going on in there.

[bradharvy]

Originally Posted by Ampdraw

Got my B grips and head.

Bearings are not moulded in....only difference is the central plastic comes toward the feathering shaft more and supports the inner race of the bearing.

Loktite was used on the feathering screw but not enough that I couldn't take it apart...ie screw head didn't shear off.

Interestingly mine came with the outer bearings brass shield toward the blades, ie facing outward and the inner bearings were the other way around with the brass facing the head??

Anyway, b grips, spectra 50Lb tether (incase the screw head shears) and all good for indoor inches from face inverted imo. If I dumb thumb it I may get a crazy 2g blade gash. I can blame myself and point the finger toward the mirror. Been running a tether from day one though as I like to fly this heli close and well...things can happen.

Crashed my Spek 2s 4g6 into myself before spinning 4800 rpm and sure it stung like an angry bee and broke the skin but no big deal.

Good job HH. This is the perfect lounge cp for me.

Amp

Good ta know you can reuse grips if you were ta have a bearing problem. Thanx for lookin.

[ScotY]

I can't quite tell from the pic, but assume there is clearance between the plastic and the outer bearing's inner race on the B grips?

I wonder why they didn't mold the grips to have both bearings inserted from the outboard (blade) side? That way, with a tiny washer between the bearings, both bearings could share the load. From memory, most older plastic non-thrust bearing helicopters were designed that way. Puzzled...

[mejmea]

Originally Posted by Ampdraw

Got my B grips and head.

Bearings are not moulded in....only difference is the central plastic comes toward the feathering shaft more and supports the inner race of the bearing.

Loktite was used on the feathering screw but not enough that I couldn't take it apart...ie screw head didn't shear off.

Interestingly mine came with the outer bearings brass shield toward the blades, ie facing outward and the inner bearings were the other way around with the brass facing the head??

Anyway, b grips, spectra 50Lb tether (incase the screw head shears) and all good for indoor inches from face inverted imo. If I dumb thumb it I may get a crazy 2g blade gash. I can blame myself and point the finger toward the mirror. Been running a tether from day one though as I like to fly this heli close and well...things can happen.

Crashed my Spek 2s 4g6 into myself before spinning 4800 rpm and sure it stung like an angry bee and broke the skin but no big deal.

Good job HH. This is the perfect lounge cp for me.

Amp

This seems logical to me. These bearings only have a 1/2 cage, i.e. the cage does not totally surround each ball. Picture a tiny little crown that sits in the bearing and each of the eight balls is captured in one of the valleys of the crown. The bearing cage is inserted from the opposite side as the brass colored seal.

With the old grips I think one of the potential failure modes was that the bearing cages could come out which leads to bearing failure (I had this happen with two bearings, one brass side out and one silver side out - I happened to catch both in the act before they blade actually went flying). This could happen due to impact or possibly in conjunction with the centrifugal forces as well. The original recommendation was thus (IMO) to have the brass/shield side of both bearings face the blades so that the cages were not exposed to both possibilities at the same time.

In the ideal world, however, the brass seals would face outward for each bearing just as you say that they are in the new grips. (They are intended to keep junk out of the bearing so why would you have them face the inside of the grip, right?) With the new design the additional plastic in the middle retains the inner race and the bearing cage of the bearing closest to the hub so that bearing can now be flipped and put in the proper orientation with the seal facing the hub. The outer bearing retains it's original seal facing out orientation because that makes sense both from a "retain the cage" as well as a "keep the dirt out" perspective.