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and now im looking for the bad boys...


sone

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after taking a little look and cleaning out the crank shaft of my 1977 280z my mechanic showed me the crank shaft bearings were good but were a little worn down, he pulled out 2 and showed how'd the (inner half pipe looking) side looked like it was sanded down a little on the edges, its not a job i was planning to do anytime soon but wanted to know who was selling these things and how much? i might end up doing it mid 09 but im trying to stay focused on the necessities first, thanks to JSM i should be able to check anpther part off my z wishlist. anywho... they look kind of like the ones on #3 in this picture squared on one side with a half moon cut on the other.

http://www.atlanticz.ca/zclub/techtips/explodedviews/280z/77fsm/main%20bearings.gif

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Yeah The Main Bearings Are Easy To Find But What I Meant Were The Pieces At The Bottom Of The Picture, To Be More Specific, The Big Block Of Aluminum Where The Main Bearings Go Flush Inside. (in Other Words The First Piece Right Over The Number 3) Lol. Thanks Again.

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Yeah The Main Bearings Are Easy To Find But What I Meant Were The Pieces At The Bottom Of The Picture, To Be More Specific, The Big Block Of Aluminum Where The Main Bearings Go Flush Inside. (in Other Words The First Piece Right Over The Number 3) Lol. Thanks Again.

 

That's not aluminum... its iron, and its called a "main cap". You're saying you wore into a main cap? :hs:

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Yeah, the inner surface of the main caps isn't a mirror finish. I can't see any way for the main bearings themselves to wiggle about much because they are keyed on one end to prevent movement and torqued down at the same time. You'd probably have to show us some pictures of the "wear" for us to see what you're talking about.

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If you wore down to a main cap, you would have more than likely spun a bearing inside the main cap and screwed it up that way. If a bearing is good, it should protect the main cap - unless of course, you spun the bearing and the crank and main cap started making friends. You'd hear that as an obnoxious knocking noise when the car was running.

 

I'm with Paul - you can get a used motor/bottom end cheaper than rebuilding the one you have.

 

I used genuine Nissan bearings, and those alone for rods and mains were $150.

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I don't know squat about nissan engines, but it seems to me that the only way it would be possible to get wear on the sides of the main caps would be to grind through the thickness of the thrust face on the number four main bearing( in the illustration.) If that were to happen, the flywheel would take out the rear main seal, or the harmonic balancer would destroy the seal in the front and the engine would, at best, leak oil faster than it could be poured in. Either way, the bearings would be more than a "little worn down". IMHO. The mechanic is trying to stick you for a major repair. Just mic the crank and install new bearings.

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whoa you guys are scarring me here, i see what you mean about the bearing protecting that side of the cap, and now im questioning why he never mentioned the actual bearing being there, he showed me main cap (in which i made the mistake of calling a bearing) but he never showed or even mentioned the actual bearings. im going to have to go see it again and take pictures, thanks for the replies

btw- the onyl noise i had was the cracked first header that made a irregular bursts , but i never heard that knocking noise so i doubt i spun a bearing.

 

I LOVE THIS FORUM! lol

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