Problem with #4 Bearing

356 Porsche-related discussions and questions.
Message
Author
User avatar
Albert Tiedemann
356 Fan
Posts: 1246
Joined: Thu Apr 03, 2008 2:46 pm

Re: Problem with #4 Bearing

#16 Post by Albert Tiedemann » Fri Apr 09, 2010 12:33 am

Alan Klingen wrote:Alan,
What has happened is that the main bearings have been line
bored and they also did the #4. This bearing is not usually
done but yours has been. I will look at my stash of bearings
to see if I have one and there might be people out there
that might also have one. I usually don't do this bearing
since most kits came with standard and this one was not
damaged. First are all your other bearings line bored?

Alan


Original Porsche bearings had 4 bearings in a set. These were available in various combinations of standard and oversize on the OD and standard and undersize on the ID. However, the number 4 bearing only came in the standard size for the OD regardles of the size you ordered for the other two interfaces. So, do not bother looking through your stash of bearings for a Porsche number 4 bearing with an oversize OD.

Post generated using Mail2Forum via email.[/quote]
Albert Tiedemann, C356C
"The Hermit"

Jack Staggs
356 Fan
Posts: 1059
Joined: Wed Jun 11, 2008 5:01 pm

#17 Post by Jack Staggs » Fri Apr 09, 2010 1:45 am

VW 36hp most certainly used a #4 main bearing. In fact the picture in the first post shows a couple of pictures of one. It is true that align bore main bearing sets from Porsche came with standard O.D. #4 bearings, but high quality aftermarket sets with oversize #4 were available, as well as 36hp parts. While I have never had a third piece cut for oversize, I have had a number of engines for repair that have been resized due to cutting or just slightly oversize due to plain wear. If I cannot find the exact bearing needed, a larger O.D bearing is turned down to the size needed for any size bore, standard, worn or otherwise. Finding reasonable solutions to seemingly impossible situations with 45+ year old stuff is what experienced experts are facing every day. If it was easy, girls would be doing it.

User avatar
Alan Winer
356 Fan
Posts: 299
Joined: Wed Mar 26, 2008 8:45 pm
Location: St. Augustine, FL

Problem with #4 Bearing

#18 Post by Alan Winer » Fri Apr 09, 2010 8:46 am

Even though the topic has taken an additional direction, the solution to correcting (resolving) the problem is to use a nose bearing from either a VW36HP std/std bearing set or a nose bearing from a VW 1200-1660 std ID/.50case. Both will give me a 40mm (39.82)ID and an OD of 50.50mm. The 1200-1600 with required some machining for oil holes and bolt recess.
Thanks for all your input.

Alan Hall
356 Fan
Posts: 1078
Joined: Wed Mar 26, 2008 12:06 pm
Location: Orinda, CA

#19 Post by Alan Hall » Fri Apr 09, 2010 11:29 am

Alan,

I think you mean a +.020 (.5mm) OD for the 36hp bearing also, I think that line bore bearing sets for 36hp VW motors are available at Vintage Parts, in Valencia CA, 800-898-8684. I think they run about 75 to 100 for a set.

Alan Hall

User avatar
Alan Winer
356 Fan
Posts: 299
Joined: Wed Mar 26, 2008 8:45 pm
Location: St. Augustine, FL

Problem #4

#20 Post by Alan Winer » Fri Apr 09, 2010 12:15 pm

Alan,
I have been told, from VW informants, that the VW 36HP std. nose bearing(#4) has an OD of 50.50mm. For some reason nose bearing sizes are difficult to find specs on.
Alan

Alan Hall
356 Fan
Posts: 1078
Joined: Wed Mar 26, 2008 12:06 pm
Location: Orinda, CA

#21 Post by Alan Hall » Fri Apr 09, 2010 1:06 pm

Alan,I am almost 100% sure that you have been mis-informed. I am almost positive the std 36hp small bearing has a 50mm OD. I think I have some around and will check later today.Alan

Peter Reagan
356 Fan
Posts: 72
Joined: Tue May 05, 2009 6:08 pm

#22 Post by Peter Reagan » Fri Apr 09, 2010 1:37 pm

I used to rebuild 36hp VWs. I have new sets of bearings stored away in the garage. Let me know if you would like me to find them and measure them to see if you can use them.

Peter

User avatar
Alan Winer
356 Fan
Posts: 299
Joined: Wed Mar 26, 2008 8:45 pm
Location: St. Augustine, FL

#4 Bearing

#23 Post by Alan Winer » Fri Apr 09, 2010 3:56 pm

I believe that the 36HP #4 bearing OD is 50.50mm and that the 40HP OD is 50.00mm. Can any vintage VW guys confirm this?
Thanks

Alan Hall
356 Fan
Posts: 1078
Joined: Wed Mar 26, 2008 12:06 pm
Location: Orinda, CA

#24 Post by Alan Hall » Fri Apr 09, 2010 7:35 pm

Alan,

I checked a std/std 36hp bearing set (111.198.451) that I have, and the #4 bearing is 50mm OD by 40mm ID.

Alan

User avatar
Mike Klapac
356 Fan
Posts: 701
Joined: Thu Apr 03, 2008 12:41 pm

#25 Post by Mike Klapac » Sun Apr 11, 2010 9:29 am

Is the thrust width the same?

User avatar
Albert Tiedemann
356 Fan
Posts: 1246
Joined: Thu Apr 03, 2008 2:46 pm

#26 Post by Albert Tiedemann » Sun Apr 11, 2010 7:38 pm

Mike Klapac wrote:Is the thrust width the same?
This bearing does not take thrust loading. The #1 bearing at the flywheel takes the thrust.

The width of the bearing is all that is needed here and even if < the Porsche bearing, , it will likely be adequate since it only takes the residual imbalance load of the crankshaft pulley and the tension load of the fan belt. Small, compared to the torque load of a cylinder.[/b]
Albert Tiedemann, C356C
"The Hermit"

Jack Staggs
356 Fan
Posts: 1059
Joined: Wed Jun 11, 2008 5:01 pm

#27 Post by Jack Staggs » Sun Apr 11, 2010 9:47 pm

The #4 also gives support to the deflections of the crankshaft due to the camshaft gear loading.

User avatar
John Hawkins
356 Fan
Posts: 173
Joined: Thu Mar 27, 2008 6:38 pm
Location: Northern Colorado

Re: Problem with #4 Bearing

#28 Post by John Hawkins » Mon Apr 12, 2010 12:34 am

Albert Tiedemann wrote:However, the number 4 bearing only came in the standard size for the OD regardles of the size you ordered for the other two interfaces. So, do not bother looking through your stash of bearings for a Porsche number 4 bearing with an oversize OD.
Actually, Porsche did make an oversize for the #4 main bearing, it's just that they were rarely needed or used. I have three NOS #4 Porsche bearings # 539.146.70 (.25 mm OS x .25 mm US). See the Maestro's little spec book page 77. I haven't checked the PET to see if this size is listed there.

John

Image

User avatar
Albert Tiedemann
356 Fan
Posts: 1246
Joined: Thu Apr 03, 2008 2:46 pm

#29 Post by Albert Tiedemann » Mon Apr 12, 2010 8:51 am

In nearly 50 years of looking, I have never seen one--not even a picture until now.

Thanks for posting.

Did they make an oversize on the OD and a standard size for the journal as well? If not, then you would have to machine an otherwise good journal also. Perhaps the thinking was that if you needed an oversize bore in the third piece, the crankshaft was trash too. Lets see: 1) set-up & bore third piece, deburr and prepare oil inlet holes, 2) set-up and grind one journal--nah, they would do them all, 3) buy special bearing. or maybe included with a special bearing set of .25/.25mm

Interesting. I wonder how cost effective this would have been back in the day.

Maybe you could sell one of those bearings to Alan and he can get on with his life.
Albert Tiedemann, C356C
"The Hermit"

User avatar
Mike Klapac
356 Fan
Posts: 701
Joined: Thu Apr 03, 2008 12:41 pm

#30 Post by Mike Klapac » Mon Apr 12, 2010 7:56 pm

Sorry, should have clarified. I was speaking about the #1 bearing as far as the thrust cut was concerned. # 4 has the set screw.

One more question. Are the crank journals of 36hp VW mains the same width as 356 crank mains and if they are why would the bearings be narrower? I recall reading that a Porsche crank would fit in a 36hp case.

Post Reply