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Discussion Starter · #1 ·
I was chatting with a friend of mine today about the 2V belt engines when he commented that his old Pantah’s swingarm bearings were lubricated by the engine oil.

Huh?

i was incredulous, as I see nothing in the way of oil seals on the bearing ends of my 93’ 900ss.

He claims to have read about it somewhere a long time ago. Well, I searched online and found a Cycle World article saying the Alazzurra did just that.

I still don’t believe it. Anyone know anything about this?

Article link:
 

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Early motors did not have bearings in the cases like your 1993. It was a bronze(iirc) bushing and as the swingarm pivot wore the bushing you went to the next size larger swingarm pivot pin. Look at most 1980's and older pantah based motors and you will see a much parger pivot hole with no bearings.

I have some pantah 500 cases I can check to see if grand-daddy pantah had them as well but I know many in the 80's did as I used to change them at work.
 

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Discussion Starter · #3 ·
Interesting. I put bronze bushings in the swingarm of a rd350 racebike I built, oh Jeeze, 20 some odd years ago. Thanks for the info.

So, any veracity to the claim that the engine oil somehow lubricated the pivot?
 

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I would need to look at a set of the cases apart. some early motors did allow engine oil to spray onto the pivot in the case IIRC but I do not know if that was for bushing lube. Looking at the microfiche for a 88 750 sport there are 4 different pin sizes and a seal at the case.
 

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True. Pantah's had bronze bushes fitted to the crankcases with oil seals fitted outside of them and the bushes ran in the engine oil. A brilliant idea when new, but the problem with all bronze bushes is when the time comes to ream them, because almost no-one has the equipment to do it properly, and in the case of the Pantah, the engine would have to come apart to ream the bushes to the next size of pin, due to swarf falling into the engine.

I don't know how other countries fare, but in the UK it is almost impossible to get swinging arm bushes line reamed. The Ducati factory used a line honing machine, which gave an accurate and smooth finish, but if the bushes are hand reamed they are always out of line and poorly finished. I had my 750's bushes reamed once, after a lot of searching to find someone who could do it, but they ended up no better than the bushes that I took out. Since then I have shied away from replacing the bushes, just replacing the pin, because that seems to be the part that wears. Oh, and being obsessive about greasing!

I think that if I had to replace swinging arm bushes again, I would carry out a needle roller conversion.
 
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