Intermediate Shaft Fitment
 

In my current 1983 3.0L engine assembly process, I have concern with the intermediate shaft bearing inserts. Both the end-play and the insert sitting high in the case. The case has been had the line-bore checked. The engine has never been apart since initial Porsche Factory assembly, nor has it had a catastrophic event.

End-Play: With a new shaft assembly, the thrust clearance was undetectable value. I saw a video, from a well know guy, about tapping the shaft to force the bearing into the case to gain clearance. All my manuals don’t touch the subject. The little spec book does give a value, but nothing on how to accomplish the value. The bearings are Glyco brand made in Poland. I had higher confidence on the Polish made pieces. I’ve heard that the ones made in South Africa have had issues.

Bearing Shell Sitting Proud: I installed the shell half in the case and tapped it into the case. Both the bearing shell and the case were clean, free of burrs. The bearing shells sit proud by .015”. I have “Porsche OEM” bearing sets on order and will see how they fit. Any wisdom would be appreciated.

http://forums.pelicanparts.com/uploa...1706149638.jpg

.015" is huge. Something is wrong. Are you missing a zero? Even .0015" seems too much for "crush" to hold the bearings tightly in the case, for such a small diameter bearing. Didn't see specs in the tech specs book.

Hey Pete, no missing zero. If it were .0015” I would feel comfortable with that amount of bearing crush. This much more than a fingernail feel test. I’m looking forward to the Porsche branded version.

They compress. They're all like that. Relax.

It's called "bearing crush" and helps keep the bearings located in the case or connecting rod without spinning.

Tapping on the end of the intermediate shaft to gain end play is the way that it's done. Use a dead blow hammer and a brass drift.

Thanks reassured now. :) What was making me question, and I know about bearing crush, was that the non-thrust bearing doesn't sit proud like the thrust bearing...Hummmm.

I'll defer to John Walker. .015" still seems excessive to me, but he's built more of these engines than I ever will.

I asked in another thread, but I think it's relevant to this discussion ... are there any concerns with using "regular" Glyco intermediate shaft bearings? Or use the Porsche sourced ones? Or some other brand?

Yes, I read that. It was on rod bearings. The OEM was my next step. It seems a bit of bearing crush is good. Oh, just recalled that thread, part of the other thread was about bearing thickness taper as measured about the curve of the bearing. In that was the explanation about bearing crush. When the bearing is installed the opening around the main journal was round, whereas before the crush it was oval or racetrack shaped. The bearing crush forced the oval to round.

My original concern was what seemed like two much height above the case. It’s a pretty small bearing and a whole bunch of material to crush upon closure of the case halves.

I think i’ll remeasure now that the end play is set.

I'm suspecting that Glyco's issue isn't with rod bearings per se, but rather than whatever quality issues have crept in just surface in the most highly stressed bearings, namely rod bearings. And that whatever level of quality is sufficient for main bearings.

Not much discussion on the layshaft bearings though. They are highly stressed in a 911 engine, and I've heard they often show copper on teardowns. Just curious if Glyco's offering is acceptable. I'm not hearing too much discussion on it, maybe that's a sign.

To add one more data point, I can't remember the last 911/930 engine where the intermediate shaft bearings were NOT worn or showing copper somewhere. Dozens and dozens of engines at dealership level.

Yeah, it appears to me that the tin layer on the IMS bearings is very thin, like it's a thin plating, rather than a layer of tin. It also appears that it gets worn off quickly, and then the bearings work for several hundred thousand more miles. IMS bearing failures are also very rare in these engines, unlike the ball bearing IMS failures in 996 engines. The more robust Metzger versions of the 996 engines used plain bearings too.

Have not pulled a single one apart that did not show copper on those bearings... Thats over 20 years and plenty each year... :)

Cheers

Just watch this video from Breitwerks

https://youtu.be/U32-B-wS1GE?si=Ok5fQ-6MYHxXOIOp

Torque up the case with the bearing but without the shaft and measure the bore, quit guessing.


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Wow! I watched and investigated my engine and this is exactly what the problem is. Thanks, I really didn’t want to tear down for leaks…

Damn. So now we have layshaft bearings that don't fit 911 cases?! Glad I saw this. I'll check on my motor that's about to go together.

Damn! Another crappy Glyco part. I ain't buying anything Glyco ever again. .015" was way too much for crush allowance.

If I didn't want to go through the hassle and time of returning/ordering new ones, I would file down and chamfer the collar of the bearing so that it sits all the way into the saddle, then make damn sure it is't too short!

what's the answer here?? the breitwerks clip is alarming!- have new set of glycos due at my door tomorrow and guess i will be looking for little or no material proud of case- any leads on alternate manufacturer?

have plenty of files, and a healthy concern that engine will leak when i get it back together, too!- gonna leave the machine work to the pros-

have searched about a dozen parts suppliers- sorry, wayne- found a genuine porsche thrust set at auto atlanta-