Pivot Bolt Question

[B4ndit]

Is it good practice to apply grease to the pivot bearing where the roller bearings will make contact with it?

I have done loads of reading on this subject and can't find anywhere this has been mentioned. But is it one of those things that mechanics naturally assume everybody knows you should apply grease in this area. Or is it left dry for a reason?

Hope somebody has the answer.

 

[MikeP]

It won't do any harm as it will help the next time you need to strip it again. The pivot pin doesn't rotate in the bearing, the bearing race does what rotating is needed.

It is worth separating the bearing race from the cage and re-packing the needle roller cage with grease. The races just pop-out but may not feel like it owing to grease "stiction".

 

[B4ndit]

Mike. Thanks for your reply. I've just re assembled everything following various instructions either from here or Adv Rider and also Haynes. Then after this I thought maybe the pivot pin should be greased, nobody mentions this, but half of me says it would be the right thing to do and the other half says it would be the wrong thing because every publication doesn't mention greasing the pivot bearing.

I am hoping Fanum or Steptoe comes on here and offers there wisdom.

 

[Fanum]

I am hoping Fanum or Steptoe comes on here and offers there wisdom.

Wisdom from me




I'd grease it up, but then I do have 76 tubes of ex miltary heavy duty grease to get rid of

Oh, and 'cos Mike says so

 

[B4ndit]

The plot thickens.

I phoned up BMW this morning to see if I could get a definitive answer.

It would appear that the Pivot pin comes out of the factory dry. The BMW technicians when replacing the pivot pin lightly grease the pivot pin thread. The part the bearing sits on is left dry. The thread is greased so as to aid later removal. Apparently they get corroded in!

This must have some effect on the torque settings on reassembly.

 

[Beemerman59]

Assuming they're similar to those on my K1100 - when I took these off for the first time, the pins were dry and the threads were loctited in (no grease and required a fair amount of heat to undo including the use of a breaker bar). Now I tend to put some moly on the pins ( HondaMoly 60 same as used in the bearings themselves) to stop corrosion but leave the threads dry. I torque these up but don't bother with loctite - I just dab a bit of paint on them so I can tell if they are coming loose or not - never have done so far.

 

[MikeP]

The plot thickens.

I phoned up BMW this morning to see if I could get a definitive answer.

It would appear that the Pivot pin comes out of the factory dry.

Here are four, the two Paralever pivot pins and the two swing-arm pivot pins from a bike with less than 1,600 miles from new, that I removed them past few days and I haven't got around to cleaning yet.

They have not been disturbed since the bike was assembled and they clearly have some grease on the bearing surfaces of the pins.

Now it might be excess grease from the bearings but as the pins sit in the bearings and any over enthusiastic greasing of the bearing surface of the pins will surely get squeezed out on assembly, putting a smear on them won't cause any harm.

As for the threaded sections, the BMW advice is to use thread locking compound on clean threads and then tighten to the specified torque.

Neil (Steptoe) advises that he yearly removes the pivot pins of his bike to re-grease the pivot bearings but does not use a thread locking compound on reassembly.

I suspect that Neil has vastly more experience than any staff in any BMW franchise (given their apparent turn-over of staff - he's also one of those BMW-trained escapees who spent years working for 'Da Man').

I'm just an enthusiastic amateur so I pick the middle ground: I do remove and clean them and re-grease the bearings but I use a less strong thread locking compound than BMW recommend when I reassemble everything.

I will grease the bearing surfaces of the (above) pins when I put it back together because it can't do any harm and it may aid future disassembly given that the pivot pins are not sealed from moisture.

 

[B4ndit]

They look pretty bad. Has that bike been in lots of water?

My theory behind the question is as follows.

The Dry option.

The pivot pin is made out of titanium which is naturally strong and corrosion resistant. The bearings are greased and held captive within the shaft on the outer race and the inner face sits on the pivot pin with a little bit of friction holding it in place. Both outer contacts are dry which tends to make the bearing do its work. IE the needle bearings move around acting as a bearing.

The greased option

With a layer of grease on the pivot pin I am thinking that any wear between these two surfaces will be reduced. However this will increase the chance of movement of the inner race which leads to the downside of this option. If the inner race moves at the same rate as the needle bearings surely pitting will start which will ruin the bearings.

BMW say dry but I haven't been able to work out what the reasoning behind it is yet. Maybe when I can get down to BMW at the weekend I might get some more info.

 

[MikeP]

The bearings don't do much rotating, they move perhaps a few degrees at most and as the pivot pins don't rotate at all and neither do the bearing cages, the only rotation is between the inner race and the needle rollers. Damage occurs when the lubrication in the roller cage is insufficient. Having a smear of lube between the pivot pin and the inner race can't do any harm.

The inner race isn't held in place by friction, it's held in place by the correct adjustment that restricts lateral movement.

They're your bearings, I'll leave you to grease or not as you choose.

 

[B4ndit]

They're your bearings, I'll leave you to grease or not as you choose.

Cheers mate. Just airing my thoughts in public. Might help someone in the future.

 

[MattW]

As Mike says, the pivot bearings don't really move more than a couple of degrees and the danger is that if the adjustment slips, they can tend to brinnel through suspension impact and lock solid. The only option to accommodate suspension movement is for the bearing to spin on the pin, thus knackering the pin and the bearing - one of mine on my 1100 (unlike the 1150's has one steel pin):

<a href="https://picasaweb.google.com/lh/photo/und9WHfa013kBdJx90CVoNMTjNZETYmyPJy0liipFm0?feat=embedwebsite"><img src="https://lh5.googleusercontent.com/-07rIc2N9oaM/ScfFWDxp2WI/AAAAAAAABhU/kFvumQLXV60/s800/IMG_4363.JPG" height="600" width="800" /></a>

<a href="https://picasaweb.google.com/lh/photo/_IDpW2PXmpLymykdWUN0PtMTjNZETYmyPJy0liipFm0?feat=embedwebsite"><img src="https://lh4.googleusercontent.com/-ZrvOUece7kE/ScfFmLwwBvI/AAAAAAAABhc/T5TItRwd1n4/s800/IMG_4352.JPG" height="600" width="800" /></a>

I guess the question is, would grease on the pin make this more likely?... My gut feeling is that it might. Grease belongs on sliding surfaces or as an anti-corrosion measure - neither of which apply here - you don't want the pin to be a sliding bearing and the difficulty in removing old pins isn't due to corrosion but the high strength thread lock used by BMW.

So I'd say, keep the grease where it belongs (in the actual bearing - definitely not on the pin threads- the last thing you want is for the pin to start backing out), don't use thread-lock on the pins and make pin removal, bearing degrease and adjustment a part of your maintenance regime (a la Steptoe).

But that's just my humble opinion - each to their own

 

[Steptoe]

. Might help someone in the future.

They've all managed quiet well without any help or problems about greasing the pins since 1994.

 

[Black Rooster]

the wise one has now spoken thread closed

 

[Steptoe]

the wise one has now spoken thread closed

It's a non event. You grease them, or you don't. The outcome is the same.