Rod Bearing Controversy

[manbridge 74]

I believe I read on early s that Porsche uses a different factory still in or near Germany to supply their bearings. The other larger factory is in a former eastern bloc country and has had some quality issues. So two factories both making bearings labeled Glyco.

Why not buy from Porsche? Is it that much more? I believe they inspect/measure every set. Or used to.

[Tom_in_NH]

I had read this thread through. I thought I remembered reading within this thread, that the Glyco issue was only with the 3.2, 3.3, and 3.6 rod bearing shells, but not the 3.0. I can't find that data point now. Was I imagining that?

Thanks,
Tom

[911pcars]

The only answer is to measure everything.

Glyco vs clevite rod bearings - with data

Does everyone realize that mistakes are made in manufacturing, packaging and that returned parts can be recycled to other buyers?

Assuming anything in a box is the correct part is foolish, especially when it involves engine parts. Would one assume the same with pistons, rings and other parts? Play it conservative and check everything. Otherwise, it's a crap shoot.

As for poor manufacturing and/or quality control, if the manufacturer doesn't respond, move on. Their loss.

S

[Henry Schmidt]

We've given up on generic Glyco bearings. Whenever posible we use Porsche GT3 bearings but we also have a huge supply of Clevite 77 rod bearings in stock.
Standard and first under (.25mm) for every air-cooled engine model.

[911pcars]

Henry,
Clevite 77 bearings have been around a long time. When I used them in an engine rebuild years ago, they had a reputation of being a harder bearing (for heavier loads). Is that still the case?

Thanks,
Sherwood

[Henry Schmidt]

Originally Posted by 911pcars

Henry,
Clevite 77 bearings have been around a long time. When I used them in an engine rebuild years ago, they had a reputation of being a harder bearing (for heavier loads). Is that still the case?

Thanks,
Sherwood

I'm not certain what "heavier load" means. I use them because the precision I find in the manufacturing gives me confidence in the product we build.
The slightly higher cost is out weighed by to success we experience.

Caveat: we are seeing some main bearings manufactured by Glyco coming out of So. Africa that seem to show a better level of consistency. Too early to tell but perhaps we're seeing a new factory with slightly higher QC standard.

[911pcars]

Here are a couple of papers on Clevite 77 series bearings:

http://www.stealth316.com/misc/clevite-77-rod-main-bearings.pdf
http://www.mahle-aftermarket.com/media/local-media-north-america/pdfs/eb-40-14.pdf

Sherwood

[chris_seven]

I have just opened up an old 901/01 engine that we have had hanging around for a while now.

The crank has had the rod bearings ground by 0.75mm and this size of bearing is now NLA.

I don't really want to change the crank so any ideas about bearings?

[911pcars]

If you can find these undersize rod bearings, it might be more cost effective to source a standard crank.

It's also possible to build up-weld the rod journals, then machine to standard. You'll have to research and weigh the pros and cons of each option.

Crankshaft Welding

Methods of repairing crankshaft journals - pros/cons

S

[onevoice]

Originally Posted by stownsen914

I, for one, will not be using Glyco bearings in my upcoming rebuild. But I do have a question about the measurements that onevoice did above on rod bearings that were installed. Could a contributing factor to the large various noted in bearing thickness have been the very fact that they were installed? I understand that bearings squish a little when installed and everything is torqued down. It seems reasonable that this may result in a some distortion on the ends of the bearing shells where they touch when installed (and where it appears onevoice measured) ... I am speculating here, and have no idea how much if any distortion is to be expected due to squishing.

Scott

Plain bearings like rod and main bearings are meant to have an interference fit into the rod or crankcase journal. It makes sense logically that there would have to be some distortion from installation, but I have measured used bearings from other engines and never been able to measure such distortion. I would therefore assume that any distortion from installation, if actually present, is smaller than the capabilities of my measuring tools.

The variation I measured was HUGE, and didn't even allow the rods to spin on the crank.

That said, I have seen all manner of parts with problems when building engines.

MEASURE AND CHECK EVERYTHING.

[NICE 69 S]

"In an engine where we have the variables described above, it has been determined that a slightly oval bearing ID with the minimum diameter oriented in line
with the maximum load is the most desirable. To produce this type of profile bearings are made with what we call an eccentric wall. In nearly all cases the bearing wall is thickest at 90 degrees to the parting line and tapers off from that point toward each parting line by some specified amount."

From the Clevite Tech Paper referenced above. Exactly opposite what people were seeing with the Glyco bearings in the "Glyco vs Clevite" post and what "onevoice" was seeing.
Bob B

[Trackrash]

I'll add another data point. I have just finished assembling the bottom end on my '78 SC motor.

I used Glycos (standartd) made in south Africa.

I measured every shell to make sure they were not defective. They all measured the same at each end (near the parting line) and at the center. I measured each bearing shell in three places, at each end and the center. I also measured some of the original, used bearings that I removed. They measured the same as the new bearings, taking into consideration some very slight wear.

I confirmed the fit of my rods on my crank using plastiguage. Each rod exhibited no noticeable play, but moved freely.

I figured that if they did not measure correctly, I would return them. However they fit fine, from what I can tell.

[KTL]

I totally agree with what's said about measuring and checking to be sure the clearance specs are where they should be. But I think what's also the issue here is the bearing material itself failing, even when they measure in spec.

[Trackrash]

Originally Posted by KTL

I totally agree with what's said about measuring and checking to be sure the clearance specs are where they should be. But I think what's also the issue here is the bearing material itself failing, even when they measure in spec.

Has anyone experienced flaking or delamination of the bearing material? Have these type of failures been blamed on defective bearings?
Is anyone sure what caused the failure in post#4?

[KTL]

Originally Posted by Trackrash

Has anyone experienced flaking or delamination of the bearing material? Have these type of failures been blamed on defective bearings?

Yep Walt Fricke did in post #3 of this thread and he also contacted Automobile Associates to get their take on what that material failure is.

Glyco rod bearing wear

[TurboKraft]

onevoice -- excellent thorough job documenting this, thank you. It confirms what we, too, measured
3-4 years ago, that Glyco's QC was worthless.

TurboKraft will not assemble an engine with Glyco aftermarket bearings, either. Like Henry at Supertec, and Steve W at Rennsport: GT3 bearings, Clevite bearings, or Genuine Porsche.
Everything else is a crap shoot. Bearings are not a job any sane person wants to do twice. It's senseless to take the risk just to maybe save a few hundred when buying bearings.