I have had about 10 Pilot crankshafts in my hands over the years not ONE could I see
any machine marks that would indicate the crank was balanced, I post a pic of one
of PB covers that had the balance washer on it dunno where the pic is its here some
place, here is Power Bloc web page http://www.cvtech-ibc.com/lang.html maybe someone
can call and ask if they balance their clutches and how, here is the HRD number maybe someone
can call and ask harry how they are balanced them HRD Racing 909-875-4150 http://www.hrdracing.com

The manufactures balancing marks will be much different than a performance shops balancing marks. Manufactures tolerences are not nearly as stringent when it comes to balances. Many manufactures crankshafts are balanced roughly with chamfers, matched grooves, and flat edges. Two of which I can see in the pictures of the pilot crankshaft. If you take a crankshaft out of any Engine you will find that it there is quite a bit of machining that can be done to make it run smoother, especially at higher rpm. You can balance each part individually then match every part and balance the rotating assembly. Once you change any part of that rotating assembly with an aftermarket/different part the assembly is going to be out of balance, creating a frequency vibration that you will never feel, hear, or see. A few of the power bloc clutchs that I saw had a washer that was attatched and that was supposed to be the balance weight. The two units I bought for mine had the same weights on them, A mass produced balancing act. (Returned them because of the washer/rivet deal) The P-85 unit I decided to run was balanced on the inner "pulley" on the OD by drilling a series of holes were needed. THe rivets on the pilot bearings are probably coming loose from a vibration caused by an imbalance in the rotating assembly, (clutch, overboaring a cylinder and using a larger piston).

I don't think the rivets are coming apart because they vibrated apart, the metal around
them is discolored, I think the heads poped off because of tension from expanding metal
OR they were not installed properly, heck maybe they have a material quality problem,
the age range on the bearings that failed in my Pilot were 12 years old to 2 years old,
the orignal bearings on my Pilot failed after I had almost completly worn out my first
Power Bloc, I used it on my Pilot for 6 years, thousands of miles on it, soon after I
installed macdizzy top end (way more power) then my factory orignal clutch side
bearing failed.


Stoneman had a clutch on his Pilot you could see it wobble because it was bent,
some mutt tried to use a 3 jaw puller to remove it? he drove it for 2-3? seasons
before the crank bearings got loose (unkown age on bearings) but the rivets never
came apart..

Save those bearings! I am going to call back to Nachi tomorrow and get an address to send these to. Mine would not come off the crank so I had to cut mine in 2 pieces. So, mine may not be all that good for evaluation. I cleaned up the crank where it was stuck on and checked runout. Everything is within specs. For fun, I chucked up the Powerblock clutch in the lathe to see how it spun. My movable face spun true and didn't seem to have any vibration at 3000 RPM. The fixed face was the same. I would like to find an old clutch half of a pilot crank to check it as an assembly, anyone got a wasted crank? I am gonna try to check the weights of the cover and pucks and see what I find there.

Balancing the Engine as a whole would be next to impossible becasue of the counterbalancer. The bottom end would have to be assembled as well as the jug/piston. It could be done but I still don't know if it is the issue.

I still think the bearing just can't handle the added horses we are squeezing out!

This was taken from a post on Dizzys board.

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Plastic cages should have less inertia-they allow the balls to accelerate more agressively (while revving up the Engine)without shattering the cage itself-the heat isn't an issue at all if we're talking about crankcase bearings.
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Perhaps that is our problem, acceleration and deceleration I am on and off the gas constantly, constant RPM is only when I am WOT (Wide Open Throttle), I use my Engine with my suspension.

More
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As the crank accelerates and decelerates, the parts (balls and cages) have to do the same. The light cages can do so easily, but the heavier balls have more trouble- inertia. Hence, the balls hammer against the cages. As crank speed rises, the loads against the cages rises to rpm squared- double the rpm, the load increases four times. At normal street rpms, the cages won't suffer. Start revving the Engine's guts out (like in racing!) and the cages will be battered to death.
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Snip form another board.

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I heard something interesting from a guy in our rotating equipment group the other day. He's big buddies with another dude who's some sort of Harley Davidson rep. It seems Harley was having bearing problems (main bearings, I believe) that were causing a lot of warranty claims, and they traced the cause to the synthetic oil they were using in their crankcases. The balls in the bearing were actually skidding instead of rolling, and they were poorly suited as journal bearings! After doing the mechanical repairs, they then started using a mineral based oil, and the problem was solved. Interesting - An instance where you DON'T want to use synthetics - it's too slick!
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Well I was running Golden Spectro in mine both before and after it went poofkaboom (a Stoneman phrase used with permission) and I believe it is a synthetic blend rather than pure synthetic.

So I guess my question is, do I need to put my 4 gallons of Amsoil on Ebay as it is the "slickest stuff for main bearing failure" and leave out the word "prevention" at the end?

Pilotman

I was using Golden Spectro in both of my bearing failures as well! Could we be onto something here?

Golden Spectro is a semi synthetic..