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-

I couldn’t find any new old stock under the 916 prefix number. I’m machining a fixture to hold the new bearings and turn them down to the size my old bearings measure.

Depending on my outcome, and I feel 99.9999%, I’ll offer to the community to machine anyones bearings to the older dimensions.

Granted a little neanderthal, but since the shoulder height of the bearing is relatively non-critical, would it be acceptable to remove .8 mm or whatever the correct amount is, using a belt sander (very carefully of course)?

You could grind the edge on a rock until it fits. THAT would be Neanderthal. The edge of the thrust face isn't critical.

Just measured the layshaft bearings I acquired recently, and they are 5 mm. I think the video mentions this is the "old" measurement and would be OK.

That is the smaller of the two. What number is on the box, and where did you say you got them?

I am getting ready to assemble a 3.0L SC engine and read this post. I had just purchased the latest Glyco IMS bearings.
http://forums.pelicanparts.com/uploa...1707099604.jpg

I did not have the same issue with them sitting high mine were flush.

http://forums.pelicanparts.com/uploa...1707099716.jpg

I decided to check some of the other cases I have to see if there would be a issue. I found Porsche factory bearings in the two I checked. One had 916 series (86 930 case probably factory installed) and a previously rebuilt 2.7 with 993 prefix bearings. I tried the new Glyco in each case and found it fit the same as pictured.

http://forums.pelicanparts.com/uploa...1707099928.jpg

http://forums.pelicanparts.com/uploa...1707099977.jpg

When I compared the 3 bearings the 916 and 993 appeared identical. And the bearing surface is .9 inches wide.

http://forums.pelicanparts.com/uploa...1707101265.jpg

The 996 version has a couple differences I can see so far. There is no hole drilled in the bearing, the thrust face is a little wider and the bearing surface is wider at 1.05 inches.

http://forums.pelicanparts.com/uploa...1707101426.jpg

All three bearings appear to be the same height at .68 inches from table to highest point on bearing. Left to right 916.993. 996.

http://forums.pelicanparts.com/uploa...1707101591.jpg

http://forums.pelicanparts.com/uploa...1707101692.jpg



Based on what I have measured so far I would prefer the 996 version for the wider bearing surface.
http://forums.pelicanparts.com/uploa...1707101781.jpg

I purchased some NOS 916 bearing and will measure to see if there is any difference in clearance when they show up.

John

I got mine from a friend who is an engine builder, and they came without a box, so no part number. Here’s a picture though in case that helps. Both flanged bearings measured 5.1-5.2 mm. Perhaps noteworthy that they appear to have a 2020 date code.


http://forums.pelicanparts.com/uploa...1707102583.jpg

Well after spending some undisclosed hours, ok I’m retired… doesn’t really matter…

I machined a lathe fixture to hold an IS thrust bearing to machine it to fit early engines.

http://forums.pelicanparts.com/uploa...1707279919.jpg
http://forums.pelicanparts.com/uploa...1707279919.jpg
http://forums.pelicanparts.com/uploa...1707279919.jpg
http://forums.pelicanparts.com/uploa...1707279919.jpg

I wish the interchange would get straightened out across the board. Not much chance of that since the central authority (Porsche’s parts manuals), has it wrong in all there manuals, (1965-1969), (1970-1973), (1974-1977), (1978-1983). They all show the 993-101-137-01 as compatible and the superseded part number. Vendors look at that as the gospel. What are the chances Porsche will correct this?

Mods:
Maybe a sticky note is in order

Hi
Looking at the very first photo:
How can you be sure that the bearing shell is seated correctly in the case ?
(You cannot see because of the shell thrust faces.)
Suggest you fit both bearing shells and carefully assemble case halves and watch what happens as the adjacent case bolts are torqued up.
Do the two bearing shells seat correctly ?
Is the inside bore diameter of the installed bearing shells within limits ?
Best regards

Magyar Kiwi, read the whole thread. There is a problem with the later bearings, with respect to flange diameter, in the engine cases prior to the 996 engine. If the bearing half is sitting proud.015” and the same for the second half, that’s .030”, the case will not close and that .030” is way off any intended bearing crush. After I machined the bearing outer flange diameter to the diameter of my removed bearing, they nested where they should be. I researched the part numbers in all the current porsche parts manuals that are available on the Porsche website all the way back to 1965 year model and the 996 part number shows up. It seems to me that the manuals are living manuals, meaning Porsche updates them from time to time. The problem started throughout the parts network because Porsche made an error with supersedure. One gentleman had unfortunately assembled his engine and had a leak because of this bearing causing a gap in the case.

Hi
Thank you for the clarification.
The key information is in the youtube link at Post 14.
I have now watched it.
Best regards

Porschedude996, I disagree with you conclusion that all the 996 int shaft bearings are an issue.

"There is a problem with the later bearings, with respect to flange diameter, in the engine cases prior to the 996 engine."

I have the same part number 02 8005 Glyco bearings (996 part number on box). They appear to be made 12 of 21 (not the best picture).

http://forums.pelicanparts.com/uploa...1707801765.jpg

I did not find the same issue you did. I installed the 996 bearing in a 3.0, 3.3 and 2.7 case and none had the issue you experienced. The bearing was flush in all the cases I tested.
Maybe it was a limited production issue or there is a difference in how your case was machined.

I purchased a set of NOS 916 bearings.

http://forums.pelicanparts.com/uploa...1707802619.jpg


I measured the bore diameter with a bore gauge after bolting down the case halves comparing the 916 and 996 bearing. I found they were almost the same (the 916 bearing was .0005" smaller), which given the clearance range is nothing.
Based on my case fitting and my measuring as saw no issue with using the 996 bearing. With the wider bearing surface of the 996 bearing (measured in earlier post) I would prefer the 996 bearing to earlier 916 or 993 bearing.

john

Huh, I took a look at my original bearings and they are stamped with a porsche number of 916.137.00. They fit my case perfectly, the superseded to the 996 number didn’t fit. I find no reason to measure the inside bore, I know it’s going to be good when the bearing doesn’t sit proudly above the case mating surface. My .015” height surely was not going to allow the case to close.

http://forums.pelicanparts.com/uploa...1707856509.jpg

This post and the Breitworks video really freaked me out!

I'm getting closer to closing up my 2.7 case, so I ordered a set of bearings from our host. They were not marked where they were made. I put them in to see how they looked, and they seem fine to me. I can barely catch a fingernail across the tops.

http://forums.pelicanparts.com/uploa...1708205236.jpg

http://forums.pelicanparts.com/uploa...1708205236.jpg

My brain is scrambled at this point…;)

I dunno... he didn't torque both sides of that bearing down.. so that dichem test isn't valid is it?

http://forums.pelicanparts.com/uploa...1708424633.png
https://i.imgur.com/h8PchgY.png