Do grooves in thrust bearing matter?

[304065]

There's an old article in Velocity, the POC magazine, by Gregory Brown, that claims that if you get your thrust bearing from Glyco, the aftermarket supplier, it has different grooves than if you get it from Porsche.



He claims:

If you
look at the pictures of the thrust bearings, you can see that the aftermarket supplied rear thrust has straight grooves that pass the oil onto the thrust surfaces
and allow the oil to escape without any resistance. Now look at the Porsche thrust bearing. Note that the oil grooves are cut notches that do not communicate
with the outer edge of the thrust area. This keeps the oil more captive and thus keeps more oil heading towards the rod bearings. This is the same thrust bearing
that is recommended for all of the Porsche race engines, the only difference being that Porsche pays no attention to the size of the rear thrust bearing for
street engines. The race engines have three different size rear thrust bearings that can be used, depending upon what size the crankshaft is. You had better get
these the correct size, with the engines turning over 8,500 rpm.

The original article is here: http://www.porscheownersclub.org/pdf/2002/winter.pdf

Now, here's what PET shows. The grooves look pretty big to me, much like what's in my Glyco set.



Thoughts? Important or no?

[efhughes3]

John: I saw the reply you had to my thread, that you must've deleted to start this thread. To answer your question, I've seen that article, but I also have the Glyco bearings with the large groove.

[Eagledriver]

The only significant effect I could see is how much oil gets to the thrust surfaces of the bearing. The notches that don't go all the way through will cause more oil to get onto the thrust surfaces. The loss of pressure in the crankshaft galleys will be insignificant. The oil pressure is mostly contained by the tolerance of the bearing on the crankshaft journals. Think about the other end of the crankshaft. The number 1 bearing that feeds that end of the crankshaft has no thrust surfaces to contain the oil there. The thrust surfaces of the number 8 bearing don't seem to be a problem area of the engine so I think this bearing difference is irrelevent.

-Andy

[efhughes3]

Andy, I think you have your numbers backwards....

[Steve@Rennsport]

FWIW,....We do not use aftermarket Glyco bearings,............its a dimensional QC issue.

The ONLY bearings we will use are either dealer-sourced main & rod bearings or specially-made ones due to FAR better concentricity and overall dimension control.

[304065]

Steve, I understand, it's all about the dementia, er-- dimensions.

Well, I have a ball tip for my micrometer, basically a sphere of radius smaller than the bearing's radius, that I can use to measure the thickness at various spots, including the taper at the ends. As far as surface finish goes, any irregularities will be noted.

It's interesting that so many professional engine builders have noted the poor QC of the Glyco bearings. A well-known expert here on the East Coast who shall remain anonymous but whose initials are Peter Dawe said he prefers to use a NASCAR bearing due to the high quality coming out of North Carolina.

Here's a reference to a good thread on the subject for anyone interested.

Glyco bearing quality