Yummybud924

Hey guys. I exchanged my pack of glyco rod bearings and the new one I got looks the same..... one of the bearings looks like it has some kind of scratches on the surface. the surface feels smooth. you can see the one on the left has a shiny spot I lightly dragged my finger nail on it and it looks as if there is a thin layer of tray pain and when you scratch it off it reveals shiny metal. Is this normal? I don't want to return them again.

Again, I can not feel any scratches with my finger but he surface looks like a thin layer of dull grey paint where it is screeching off and shiny in some spots. I have no idea if this is normal.

thanks.

william_b_noble

surface blemishes don't matter, it's the overall fit. if you are concerned, assemble and check fit with plastigauge.

PorscheDoc

Normal.

HICKS

+1

PerceptionProblem

This is good to know. I'm looking at doing my rod bearings here soon and would have freaked out if I didn't know that a little surface blemishing isn't a bad thing.

MB968

Yeah, you'll find that used ones have burnish marks from the mating member. As long as they have the right gap verified with plastigage they should be OK. The only other thing I would look at is the surface finish of the journal. They should be fairly smooth. Scratches that run across the width of the journal can be an issue. You can live with some roughness (though not ideal) that goes around the journal. But, there is an art to knowing what is too much.

Yummybud924

ok thanks guys. so what is that surface material that scratches off easily and reveals shiny metal underneath?

i just lightly scratches it with a fingernail and it comes off and reveals shiny metal.... you can see the shiny spot in the pic.


Also when I install new bearings is it okay to use synthetic oil? i've been using 25w50 redline.

And I also read somewhere that you need to drive the car easy for 1500km or so. i'm driving 500km back to university in a month and don't want it blowing up.

Roy Henneberger

The Babbit on the bearings it typically mostly tin which will form an oxide layer. It is probably best to let the oxide wear off since the oxide is harder than the base metal.

Unless you need to seat rings, I would recommend synthetic oil.

PorscheDoc

We install rod bearings in the race cars and then go hammer them on a race track pretty much immediately. No issues.

william_b_noble

the reason for driving easy at first is to let the bearings wear and adjust to the engine - and also more importantly to seat the rings properly. If you only changed the bearings, I'd say that after 10 or 15 minutes of running you are good to go. The bearings are a steel shell with a very soft material (babbit or aluminum) on which the hardened steel crank/cam/rod rides. In operation the hardened metal doesn't touch the soft metal unless you run out of oil - instead it rides on a film of oil a few molecules thick. The bearing must be soft to conform to any unevenness in the shaft and also to provide a "pillow" during startup if the engine has sat long enough for the oil to bleed out.