Tom M'Guinn

I ordered a set of main bearings and found that the main full-loop bearing has a little lip inside where the joint is. Worried that this might scratch my crank, I sent them back and got a new set. The new set is exactly the same. I can feel the joint inside the bearing (where the two ends are joined together to form the loop) -- it is enough to catch with my fingernail for sure. Both sets were new Federal Mogul (gylco) bearings. Is this normal? Is there some way to smooth it out?

moliver

Probably wouldn't hurt to "break" the sharp edge with a file.....

toddk911

Should be polished smooth.

Rip It

I would contact the bearing manufacture if there's any doubt about it. That's not a easily rectified area should you discover later it to be a problem. My understanding about main and rod bearings is that they float the crankshaft and piston rods with oil and never actually touch the part. Someone correct me here if I am wrong.

Tom M'Guinn

That may be the understatement of the year! The vendor told me to smooth it out with emory cloth, which doesn't sound right to me.

ehall

Ask Chris Whit @ 944Enhancement.net, or Scott Gomes, err can't remember. Get the facts...not that I needed to tell you.

mark944turbo

It is not likely that your bearing will damage your crank. They are made of softer metal. If two sets in a row are the same, and this problem has never been reported before, then I say its fine.

There is supposed to be minimal metal to metal contact in the crank bearings, but at lower oil pressure situations (idle speed or startup) this "hydrodynamic" lubrication fails and you enter "boundary" lubrication where small amounts of oil molecules adhering to the valleys in the metal combined with oil additives still stuck to the metal are the only things providing a gap between the metals.

By the way, have you torqued the girdle down and seen if the ridge still exists? Bearings are intentionally sized too big, and they should only fit correctly when crushed by the girdle.

Helstrm

DO NOT PUT THAT IN YOUR ENGINE!!!!! It will damage your crank. The surface should be smooth. The first set I had for the 951 engine had the same issue. I ended up replacing the crank. the set i got from Paragon were perfect. You can use fine sand paper to smooth it out.

mark944turbo

Helstrm, more details please! This sounds odd.

Tom M'Guinn

Well, I took it down to my machine shop, since he's put together many a race motor. He didn't like the lip either, but did not think it would hurt the crank (since the bearing material is so much softer). He put the bearing on a little round mandrel thing, and tapped the high spot with a plastic hammer. Seems smooth now.

Helstrm -- do tell more! What happened to your crank? How bad was the bearing? Did you damage the crank installing the bearing, or running the motor with the bearing installed?

Zero10

My set was perfectly smooth there. I checked it, since that's one place I thought there might be trouble.

Tom M'Guinn

Zero10, do you recall what brand you used? Were they federal mogul/ gylco in a red and black box?

Zero10

They were Federal Mogul, I had never heard of them before getting the set of bearings. I found nothing alarming with my set. Everything seemed just right. Perhaps there was a batch made with this production error? And perhaps the place you bought them from ended up with a bunch of sets from the same batch?

Might be worth contacting Federal Mogul about, they would most likely be interested to hear about it.

I was most definately suspicious that there could be a problem there, since I knew it was 2 halves joined together, but it seemed just right on mine.

reno808

should be smooth as a babies bottom..

Tom M'Guinn

My machinist smoothed it out, but I'm going to order a new nose bearing from a dealer in a Porsche box. I've come too far to use a fixed-up scratchy bearing.