Glyco Rod Bearing Issues

[Mitch1]

Began checking rod bearing clearances after cleaning storage oil off crank and rods. Opened bearing package and bearings do not look good.













This one I actually used to check clearance. The shiny wash boarding at the edge was not there before I torqued the rod bolts.
These are not normal, right?

[KTL]

Not normal at all. Send 'em back for a refund.

Seems to still be some issues with the aftermarket bearings. Lots of people choose to get them direct from Porsche dealer for ~twice the price.

[Mitch1]

Thanks Kevin.

If something doesn't look right, stop. Took them back. Hopefully the new set will be OK.

[jhg41977]

I hope you have the packaging. Send them back.

[JFairman]

If 997 GT3 rod bearings will fit your rods I've heard they are a better quality choice than the common Glyco 911 replacements. I think they usually go for around $250-$275 instead of around $150 for Glyco 911 rod bearings.

I've also heard that as of a year or two ago new stock 911 rod bearings you buy from a porsche dealer are no better than the lower cost glyco replacement ones you get from the usual worldpac auto part sellers like pelican parts and most others.

Then again all that's hearsay... who knows.

[KTL]

GT3 (996, 997) rod bearings are only good for the SC rods because they share the same journal size and width.

[JFairman]

Originally Posted by KTL

GT3 (996, 997) rod bearings are only good for the SC rods because they share the same journal size and width.

Someone told me they also fit 911 turbo rods but
I don't know.

FWIW, here's a copy and paste of the regular 911 rod bearings from pelican parts.
It lists them to possibly fit 911 motors from the SC through the 1994 964.
That makes me think that if the GT3 bearings will fit SC rods they might fit rods from these other motors too.

Product Information: 930-103-147-15-M41

Part #: 930-103-147-15-M41
Brand: Glyco
$152.25

Other Brands Available
Glyco $188.25
$52.75

Rod Bearing Set
Brand:
Glyco
Applications:
Quantity
required

Price

Rod Bearing Set 6 $152.25
This part may also fit in the following categories:
911SC / Turbo (1978-1983) (TURBO) 12
911 Carrera / Turbo (1984-1986) 12
911 Carrera / Turbo (1987-1989) 12
964 C2/C4/Turbo (1989-1994) 12
Quantity in Stock: 36
Pelican Sales Rank: 3167
Time to Ship: Ships Today!
Weight: 0.5 lbs.
Warranty Info: 24 Months / 24,000 miles

[Mitch1]

Thanks guys, that's great information, especially considering my options are limited.

[KTL]

Actually that info is incorrect by including the SC. The part number 930-103-147-15 is the STD rod bearing for 78-89 930, 84-89 Carrera, 89-94 964. Not the SC which is 930-103-148-00.

Maybe you were thinking of early 930 (3.0L 1975-1977) along with 2.4, 2.7 rods that have the same big end diameter as the SC rod, but the rod thickness/width is larger. But those rod bearings also aren't the same part number as SC bearings because the 2.4, 2.7, Turbo 3.0 bearing shells themselves are wider to fit in those engines' wider rod bore.

SC bearings are a sort of unique bearing only applicable to the 78-83 SC crank. Then when the GT3 came along, Porsche decided to bring back the SC rod journal dimension in its crank. That's why you can use GT3 rod bearings for the SC rods but not any others.

The confusion may lie in the main bearing usage. Main bearings are the same from 78-98 and also are used in the GT3. GT3 bearings (both rod and main) however have different part numbers because they have a different coating on them. I've seen & used a few of the GT3 bearings myself on SC sized rods.

[H-viken]

So, are the GT3 bearings the best option out there at the moment, when rebuilding an SC engine? If so, What is the correct article number to use? Part #: 996-103-121-94-M100?

Johan

[KTL]

Originally Posted by H-viken

What is the correct article number to use? Part #: 996-103-121-94-M100?

Johan

Yes that part number is std GT3 rod bearing & they are very nice bearings. Work just fine in SC rods on the SC crank.

[brighton911]

I just received my Glyco 3.2 rod bearings from our host and they were perfect, no scuffs, weird marks etc The fit was also good, .001 clearance on a midrange crank. Hopefully your next set will be in the same good condition as mine.

[jpilcher]

I have mine on order, hoping to see them next week. Fingers crossed that they are okay?

[bpu699]

Originally Posted by KTL

Actually that info is incorrect by including the SC. The part number 930-103-147-15 is the STD rod bearing for 78-89 930, 84-89 Carrera, 89-94 964. Not the SC which is 930-103-148-00.

Maybe you were thinking of early 930 (3.0L 1975-1977) along with 2.4, 2.7 rods that have the same big end diameter as the SC rod, but the rod thickness/width is larger. But those rod bearings also aren't the same part number as SC bearings because the 2.4, 2.7, Turbo 3.0 bearing shells themselves are wider to fit in those engines' wider rod bore.

SC bearings are a sort of unique bearing only applicable to the 78-83 SC crank. Then when the GT3 came along, Porsche decided to bring back the SC rod journal dimension in its crank. That's why you can use GT3 rod bearings for the SC rods but not any others.

The confusion may lie in the main bearing usage. Main bearings are the same from 78-98 and also are used in the GT3. GT3 bearings (both rod and main) however have different part numbers because they have a different coating on them. I've seen & used a few of the GT3 bearings myself on SC sized rods.

Bringing back an old thread...

Do gt3 main bearing fit the crank of an 87 930? Never knew that was an option?

[KTL]

Yes the 996 GT3 main bearings are the same dimensions as the typical 3.0 SC, 3.2/3.3 and 3.6 air cooled engines. That's because the 996 GT3 engine case is based on the air cooled 3.6 case. So the crankshaft has the same size journals.

[bpu699]

Originally Posted by KTL

Yes the 996 GT3 main bearings are the same dimensions as the typical 3.0 SC, 3.2/3.3 and 3.6 air cooled engines. That's because the 996 GT3 engine case is based on the air cooled 3.6 case. So the crankshaft has the same size journals.

Cool, good to know. My understanding is that the GT3 bearings come in different thickness, correct?

Who sells the different thicknesses? Didn't see them on our hosts site?

The glyco mains I bought from our host are in fact .0005 thinner than the old bearing. Even went out and got another fancier micrometer accurate to .00005 and it shows the same. Found a bunch of threads back to 2012 that show the same.

I don't want to increase my clearance by .001 (which the glyco would do). In fact, would love to decrease it by .001 if possible.

As in my prior thread, I did have my original bearing coated at HM Elliot. The website says it tightens up the clearance about .0003 per shell (.0006 total). By my measurements, it tightened it up .0001-.0002 total... They somehow prep the surface prior to coating, and I suspect that eats away some material. May just send it back to them to get their "double coating" but if GT3 bearings come in different thicknesses that would be preferable...

Still don't understand why the new glyco would me manufactured thinner than before. The bearings are all the same, not like one's out of spec... And assuming its intentional, why wouldn't that be posted on the bearing packaging? Increasing clearance by .001 is somewhat of a significant detail...

[trond]

Based on advice from this forum I used the GT3 rod bearings when I rebuilt my 80SC this summer. Perfect fit and I particularly liked those QC marks that showed they had been measured....

[KTL]

Yep the GT3 bearings come in different color codings. I think you could get some good feedback from EBS Racing on these bearings, or other vendors like Steve Weiner @ Rennsport Systems or Henry Schmidt at Supertec.

What's your clearance at right now? If you run typical 20W50 oil, having a bit more clearance is a good thing to allow better flow. I'd assemble the empty case with the mains installed, bore gauge the mains, then check those measurements of the mic'd crank main journals. Then you'll know for sure what your clearance is going to be.

I can't answer why the new mains would be 0.0005" thinner. But given that the clearance spec is so wide on these engines, the 0.0005" doesn't seem like a huge issue. That is, unless the crank has been ground to minimum diameter?

[bpu699]

Originally Posted by KTL

Yep the GT3 bearings come in different color codings. I think you could get some good feedback from EBS Racing on these bearings, or other vendors like Steve Weiner @ Rennsport Systems or Henry Schmidt at Supertec.

What's your clearance at right now? If you run typical 20W50 oil, having a bit more clearance is a good thing to allow better flow. I'd assemble the empty case with the mains installed, bore gauge the mains, then check those measurements of the mic'd crank main journals. Then you'll know for sure what your clearance is going to be.

I can't answer why the new mains would be 0.0005" thinner. But given that the clearance spec is so wide on these engines, the 0.0005" doesn't seem like a huge issue. That is, unless the crank has been ground to minimum diameter?

The mains being .0005 thinner each, times 2, adds .001 to the clearance. Anything below a starting clearance with the old bearings of .0018 would then be out of spec (.0018 plus .001=.0028)

If someone starts out in spec at .0027 with the old bearings, with the new bearings you will be .0037... several prior threads of folks finding the same thing...

Bo

[KTL]

I agree with what you're saying. But starting out in spec at 0.0027" is at the far end of the spec. So in that case we'd have to be looking at closing up the clearance anyway, if there was going to be any work done on the crank? Coating the bearings seems like your best bet. I guess that's why bearing coatings are so prevalent?