Help me I'm an idiot!

[Mac]

I was reading Tantrum's website about the Zerk fittings in the swingarm and I have a question. I really like the Idea but am confused as to how the grease gets from the pivot bolt to the bearings. It seems to me that the grease has to go from the pivot bolt through a 1/8 inch hole into the sleeve (race) which also has a 1/8 inch hole then into the bearings. Thats all great but dont the holes have to line up?? How do you ensure the holes in the pivot bolt line up exactly with the holes in the race to pass the grease. And even if you did line them up carefully during installation won't they spin relative to each other when riding? I'm probably just missing the obvious but could someone clue me in.:think

 

[Fred T]

Ya

Me too. I was thinking the same thing, so I'm missing the obvious also.

 

[Kaw_Boy_5]

The holes do not have to line up. There is a little clearace between to two pieces through which the oil will flow and make it into the hole and to the bearing.

 

[Hucker]

My Pivot Works swingarm kit has the same setup (just installed it yesterday) I was also wondering the same thing! I guess I got my answer....

 

[Mac]

Originally posted by Kaw_Boy_5
The holes do not have to line up. There is a little clearace between to two pieces through which the oil will flow and make it into the hole and to the bearing.

If there's a gap between the bolt and the race wouldn't the grease just squirt out the sides?

 

[Tantrum]

Ok,
The concept will seem simple when explained using the pressurized lubrication system of a internal combustion motor.

If you open up any car motor and look at how the rod bearings are bolted over the crank journal, you will notice that the crank has holes in it. Keep in mind that the tolerance between the bearing and the crank journal is literally thousandths of and inch, the oil still manages to get in there and lubricate.

In the case of Zerking a Swingarm, the concept is the same, but without the tight exacting tolerances.

The grease goes in the pivot bolt and thru the hole into the inside diameter of the sleeve, or race. This area is blocked off from the outside by the seal at the frame rail and the pivot bolt hole that is actually part of the motor case itself.When you tighten the pivot bolt, it creates a solid mass of metal from one side to the other. Starting at the frame rail at either side, you have the rail itself, then the seal, the seal is against the sleeve (or race), then the race itself, which is against the next seal. That seal is against the engine case and then to the other side of the swingarm. There you have the next seal, the race, the seal, and finally the opposite frame rail.

So you see, once the grease is introduced into the system, it cannot leave the confines of this area unless it travel thru the hole which you have drilled. Yes, the area in which it travels is a tight area, but when you are pressing on the handle of your grease gun you are appling quite a lot PSI to the system.

When you pressurize the system with the grease, as with most physics based theories, it will follow the path of least resistance. The least resistance in this whole system is the rubber seal. When you see grease slowly spooge out the edges of the seal, you will have sent the grease thru the whole system infiltrating every nook and cranny.

If you look at the site again and see the last pictures of the job, you will see how the grease filled the bearing area better than any hand greasing job could do. Prior to installing the bearings, I brake cleaned the inside of the bearings to remove any existing grease. I did this just to prove the effectiveness of this mod.

I hope that I explained this well and have answered any of your questions.

At your KDX service,
B.

 

[Mac]

Thanks Tantrum that was a very good explanation. I didn't think the seals would hold up to that kind of pressure but I guess the proof is in the pictures.
Would you recommend using a lighter grease instead of a thicker one?
Also do think the pivot bolt strength was reduced by drilling the four holes, I know there is alot of strain on this bolt and would hate to break it when overjumping a double?