Topic: 1975 cb550f

[Oddjob]

Yeah, that brake pivot shaft has to go in first with cb750's also...

It’s taken a while, but I did it in the right order on my last two! I like to drill and tap the pivot tube for a grease fitting. Surprised Honda never provided an easy way to lubricate that spot…..

The availability of parts makes the 1969-76 cb750 a good choice. A word of caution: start with a very complete bike, preferably with a running engine. It’s very easy for the “sum of the parts” to well exceed the value of the completed project!

And here's me thinking I was the only one fitting a grease nipple on the brake pivot tube, I also do one on the headstock so I can lubricate the head bearings without dismantling the front end, on my 500 I fit the 550K swinging arm as that still has the removable blocks for rear wheel removal and it also has a fitted grease nipple, I fit one on the centre stand, doing the side stand next and I've also done the front caliper brackets so I can grease that pivot. I prefer to spend a little time beforehand so it saves me time and money later in the bikes life. There may be more but that's all I can think of right now.

[calj737]

I also do one on the headstock so I can lubricate the head bearings without dismantling the front end…

I don’t understand how a fitting will inject grease into the stock bearings as the races would be on the “grease side” of the nipple. The balls for the top sit on a race, and the balls for the bottom sit below a race. The steering stem rides within the races, so where’s the benefit of this?

[Oddjob]

I use taper rollers, it works fine.

[calj737]

I use taper rollers, it works fine.

And they still have square-edged races covering the bearings. I’m not persuaded that any of the grease you’re adding is actually making it to the bearing instead of filling the neck. Those tapered bearings should last years without greasing under daily riding. How much use does that bike actually get annually?

[Oddjob]

Are you sure you're visualising how the setup works? The rollers face up and down, the headstock stem is not a tight fit inside the outer race, so grease travels along the stem, through the gap between the stem and the outer race, around the rollers and finally forces it's way out of the ends of the headstock. When I pump grease in it comes out of both ends of the headstock the same way it does on the swinging arm.

Annual use, 10K approx, the 500 none at the moment as it's not finished. Grease goes hard over time, it moves away from the surfaces as it's compressed away, it's way most headstock bearings are surrounded by a wall of hard grease with little left on the bearings themselves. A quick squirt of new grease just helps keep them well greased and working as they should. No idea why this idea seems to upset you so much.

[RAFster122s]

It is the grease breaking down into oil at the moving parts that does the real work, the grease merely a carrier for the oil that does the lubrication. Any wear particles gets distributed out into the grease surrounding the parts of grot doesn't remain in the wear surfaces.
The grease serves as a viscous barrier to dirt getting to the moving parts being lubricated.
 Isn't that how it works?

[calj737]

No idea why this idea seems to upset you so much.

It doesn’t upset me at all, I’m just dubious as to the application. By your description, the grease is traveling between the neck and the outer race, and out the tube at either end. As I posit, the grease never actually passes over the bearings, making the introduction of a nipple into the neck tube pointless.

Between the race shape and the bearing cage, there is no pathway for new grease to be introduced by my analysis. Sure, the grease will travel down the stem between the race, cage and tube and exit the neck at either end. But there’s little reason to believe it’s actually displacing the grease in the bearings.

I believe you believe you’re improving the situation, but my assertion is you’re not and that you’re mistaking the nipple for an upgrade akin to the pivot bolt which is a completely different scenario.

The pivot tube allows the grease to pass between the bushings and the rod since there is not a stock bearings there. Wholly different. And tapered bearings have a dust seal, washer and square races to compress the cage making the bearing pretty much “sealed” from debris.

But do as you wish if you feel more comfortable with that solution.

[seanbarney41]

Lord help the mechanic that has to clean up that mess next time it's apart.  Those bearings survival, whether balls or tapered rollers, depend much more on proper adjustment than the presence of dirt and/or grease.

[Oddjob]

As in most things, time will be the judge.

I've also taken apart a headstock with this mod done, sure it was a little messy but easily doable. The hardest part was filling the headstock with grease first off. I can say though that when the nipple is used grease mushrooms out all around the headstock, not just in one place, to get there is has to pass through the rollers IMO. Usually the grease coming out is discoloured from usage. Showing that it has been replaced by new grease. Again, time will tell.

Oh and I have needle bearings in my swinging arm, the normal 500 swinging arm spindle has to be changed as the grease nipples wouldn't work as the collar is not drilled to allow the grease through so you'd just end up filling the collar. I had to change the swinging arm to a 550K one to get the central grease nipple which feeds grease in outside the collar. Same principle applies as the headstock there, again my opinion.

[calj737]

Early 500/550 pivot rods had channels milled in them to route the grease to the bushing.

[Oddjob]

Yes but the needle roller conversion kit replaces that with a collar that doesn’t have any holes, fine on the 550 with it’s central grease nipple but not on the 500 which greases the bushes through the spindle.

[calj737]

All the bearing applications you cite have an interior cage that separates the bearings from the shaft about which they rotate. No grease from a nipple along the tube is going to displace the grease in the bearings.

Your neck nipple is undoubtedly pushing old grease from the tube, not from the bearing. But as I said, do what you wish but your logic is flawed. The races isolate the bearings from the tube and the seals separate the bearings from grease entering the cage. That’s the way bearings work.

And Sean is correct; bearing wear in the steering stem comes mostly from improperly tensioned bearings, not debris.

[Oddjob]

Seals? There are no seals on taper rollers. If it was pushing old grease from the tube it wouldn't be discoloured, when I opened one recently that had been done for a few years the grease inside still looked like new, only the grease in the bearing and around it looked different.

[calj737]

Seals? There are no seals on taper rollers. If it was pushing old grease from the tube it wouldn't be discoloured, when I opened one recently that had been done for a few years the grease inside still looked like new, only the grease in the bearing and around it looked different.

No seals? What the F do you call these dust seals pictured? Did you not install them in your steering tube?
And you’ll notice the captured race that faces downward for top bearing, and the captured race that faces upward for the bottom bearing. How grease can travel down then up is beyond me. Must be a southern hemisphere phenomenon. Just like polished ally cases from manufacturers I reckon.

[Fezzler]

Now back to regular programming . . .

More stuff:

(Seat, tank and exhaust just loosely positioned to see how it is shaping up.  On the "F", quite a feat of engineering integrating the right foot peg, kickstart lever and rear brake pedal! Oh, getting the brass swingarm bearings on the '78 and '71 was a chore.  On the '75 "F" the freeze/cold method worked perfect and I really like the rubber swingarm caps as opposed to the thin metal ones.)

Eating the elephant. 

[HondaMan]

Now back to regular programming . . .

More stuff:

(Seat, tank and exhaust just loosely positioned to see how it is shaping up.  On the "F", quite a feat of engineering integrating the right foot peg, kickstart lever and rear brake pedal! Oh, getting the brass swingarm bearings on the '78 and '71 was a chore.  On the '75 "F" the freeze/cold method worked perfect and I really like the rubber swingarm caps as opposed to the thin metal ones.)

Eating the elephant. 

About those swingarm bushings:
it sounds like you used the type with the 'top hat' bushing flanges on them? What brand are they (or where did they come from?)

Reason I ask is: I just finished re-rebuilding a 550 swingarm for a fellow Coloradoan, and his new bronze bushings that he'd installed left their outer width wider than the length of the collar inside by about 0.002". So, even if he could have inserted the collar, the arm would have bound up solidly when the long bolt got tightened. I've seen this often with the flanged bronze bushings out there. The bushings also 'accordioned' on their way in, almost 0.003" too small on one side and 0.002" on the other, so the collar wouldn't fit in. I had to pull them out and make new bushings for it (and replace the collar because the old one was egg-shaped on one side by 0.003", pretty bad.)