Relay Arm Bearing Maintenance (2015 FJ-09)

[piotrek]

I noticed last year, that the inner plastic cage in relay arm bearings is becoming brittle, i.e. chunks were breaking off as I tried to pack the bearings. I have been a bit more gentle with them this year, but still... several more tiny pieces broke off. The rollers and races are in good shape, so I will leave it alone and check again next year.

I have been using Corrosion Block grease (recommended to me by a local bike shop), which has been excellent elsewhere on the bike. Hoping it isn't the grease that is swelling/degrading the plastic on these bearings. These aren't expensive parts, and they are all the same in the assembly, but still... at 67K kms these should not be falling apart like this.

I would be interested to know if others have observed the same.

Edited December 13, 2021 by piotrek

[skipperT]

I’ve run into it too. I believe it’s because you’re trying to “pack” or force grease in/around the bearing pieces and the part of the cage that surrounds the bearing (yellow in your picture) isn’t designed to have grease forced through it, like a timken bearing would…. Just a theory as I’m no engineer. Since ruining a set years ago, I now just wipe in a heavy coating and whatever is extra oozes out after the bushing is re-installed. 

interested in others’ experiences/opinions. Bueller?

-Skip

[2and3cylinders]

Last time I considered drilling, tapping and threading in zerk grease fittings into the swing arm bearing sections and linkage to facilitate lubing without disassembly, as I've done on other bikes.  The swing arm bolt gets very corroded making it difficult to remove because it's exposed in its middle portion rather than being protected in a tunnel like a lot of bikes. Next time I'm also going to epoxy an aluminum cover over the open swing arm bolt slot with a maybe its own zero fitting.

[keithu]

I don't have my service manual handy, but what does Yamaha recommend for lubricant and service intervals? One thing I've learned both with vehicles and in my job working on industrial equipment is that it's extremely common to damage bearings and other components due to following "sage advice" from an experienced mechanic rather than the manufacturer.

A current example: we have a linear bearing and car that is supposed to be lubed with CRC Food Safe Grease. Right next to it is a ball screw that's supposed to be lubed with a specific TriFlo food safe lubricant that is also labeled as "grease" even though it isn't. So what's happening is guys see the similar names and are just using the CRC grease on both. This is causing all kinds of expensive damage right now. 

These things are designed by engineers who test for wear and material compatibility. If they specify a certain lubricant it's probably important. Alas, it seems that mechanics are from Mars and engineers are from Venus.

[peteinpa]

I think I'd be changing those bearings.  But since I've never had my rear end apart and probably wont for awhile what do I know.

When it's assembled does the plastic have a job or is it just so the bearing is "an assembly" and not just loose needles? 

[bwringer]

Yes, the plastic cage keeps the needles at the proper separation. It is definitely needed, and if that's falling apart the bearing must be replaced. Otherwise you'll end up eventually with all the needles on one side. The same principle applies to ball bearings; they're assembled by adding the balls on one side, then they're spaced out and a simple cage maintains the spacing.

I've never seen this problem on any motorcycle, but I've never used that particular grease. Hard to say if the grease is the problem, but I have to say that I'd switch to a different waterproof grease. 

[piotrek]

Well... a little digging, and whaddaya know... I suspect these are maintenance free bearings (almost LOL). Roller bearings with solid grease.

1. RTFM (page 4-91 calls to apply grease to the race surface and the seal only)
2. NTN explains these in application notes on page 48 HERE, and another one HERE. The design isn't exactly as the one in the photo above, but the principle is there.

I will keep these bearings. I've clearly buggered up the maintenance-free features, so I will just keep an eye on these as I have been.

Thanks for jumping on this. 👍

 

Edited December 13, 2021 by piotrek

[piotrek]

13 minutes ago, bwringer said:

Yes, the plastic cage keeps the needles at the proper separation. It is definitely needed, and if that's falling apart the bearing must be replaced. Otherwise you'll end up eventually with all the needles on one side.

Ordinarily yes, but the rollers seem to be sitting in an indent, so once the race is in they can't move. I might have another peek at this before assembling, but I have not seen the rollers move or lift over the lase several years I've been checking this.

[piotrek]

12 hours ago, skipperT said:

I’ve run into it too. I believe it’s because you’re trying to “pack” or force grease in/around the bearing pieces and the part of the cage that surrounds the bearing (yellow in your picture) isn’t designed to have grease forced through it, like a timken bearing would

Thanks @skipperT. The yellow bits are super brittle, so I suspect it is not your ordinary plastic cage. I have updated the thread with some findings on this. I looked through failure analysis documents but could not find anything on plastic roller cages.

[piotrek]

I have double checked before final assembly on the bike. The yellow bits appear to be lubricant fill, and not structural. The rollers are set inside outer (black plastic) cage, and do not move.

So... when servicing these, do not clean with fingers/rag etc... and do not pack with grease. Lightly grease the shaft/race only, and pack the seal.

These are my findings and conclusions. YMMV.

[bwringer]

Good to know -- thanks for digging further and reporting back.

[2and3cylinders]

I found the OEM yellow grease had hardened and was ineffectual, same with the swing arm bearings.  I washed most of it out with Kerosene, low pressure air dried them, and repacked them with the prescribed I believe lithium waterproof grease. It was big PITA as the tiny rollers kept slipping out of their slots...

[piotrek]

5 hours ago, 2and3cylinders said:

I found the OEM yellow grease had hardened and was ineffectual, same with the swing arm bearings.

I am fairly confident that what appeared to look like "hardened grease" was actually part of bearing design. I flaked off small bits of that as I tried to work the rollers... clearly a bad idea. Intentionally removing all of it... priceless. 😛

[fr8dog]

On 12/13/2021 at 12:16 PM, piotrek said:

I am fairly confident that what appeared to look like "hardened grease" was actually part of bearing design. I flaked off small bits of that as I tried to work the rollers... clearly a bad idea. Intentionally removing all of it... priceless. 😛

Old thread with great info. I forgot to be gentle with those bearings. I stuck a rag and my finger in there and packed them. When the rollers started falling out I remembered this thread. Oops. Back together, but need new bearings.

How are these bearings removed? I had the seals out, but didn't want to delve deeper until i had the parts. 

Dan

[TomTracer]

I replaced the swing arm bearings on my R1100RT BMw. They are tapered and if you dont pay attention to installation you will chase your tail to correct problems from misassembly.