'59 A in the Swiss Alps

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George Krompecher
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Re: '59 A in the Swiss Alps

#91 Post by George Krompecher »

I saw the groove, it eludes me so far. Am I supposed to fold the retaining plate into the groove? Seems half useful if it is only to hold the broken head in place and not prevent it from loosening in the first place.
I'll remove the diff. Prevention, and solves the ring bolt tightening question.

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Vic Skirmants
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Re: '59 A in the Swiss Alps

#92 Post by Vic Skirmants »

Yes, fold the plate into the groove. It seems that Porsche gave up on the idea of "locking" the bolt. They tried several different approaches; none worked perfectly. The later bolts with increased tightening torque helped.

George Krompecher
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Re: '59 A in the Swiss Alps

#93 Post by George Krompecher »

Vic Skirmants wrote: Thu Feb 09, 2023 9:35 am Yes, fold the plate into the groove. It seems that Porsche gave up on the idea of "locking" the bolt. They tried several different approaches; none worked perfectly. The later bolts with increased tightening torque helped.
What torque do you suggest? I won't be going by the factory manual, '59 vintage...

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Martin Benade
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Re: '59 A in the Swiss Alps

#94 Post by Martin Benade »

I’ll need that torque number myself next week. And red Loctite?
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Re: '59 A in the Swiss Alps

#95 Post by Vic Skirmants »

I use 65 ft-lbs; you'll have to convert that to your measurements.
Yes; red Loctite.

George Krompecher
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Re: '59 A in the Swiss Alps

#96 Post by George Krompecher »

:)
Many thanks.
I'll follow up as time allows.

Edit: 88Nm

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Re: '59 A in the Swiss Alps

#97 Post by George Krompecher »

I got the differential out today and put it on the bench. It is not cracked, yay!

My luck stopped there. I found a piece of bolt broken in the ring. Oh well. Put the Schäublin 12 mill to work. After setting the ring up securely, centering the hole with the broken bolt, I managed to machine it out without damaging the threads, at all. 3rd time the Schäublin saved my bacon. It paid for itself twice over already.

Now the new (12.9 grade) bolts and locking plates are in for a trial fit, seems OK.. Loctite and torque wrench are up next.
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Joris Koning
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Re: '59 A in the Swiss Alps

#98 Post by Joris Koning »

George, share some pictures of the Schaublin. That’s a sweet mill
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George Krompecher
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Re: '59 A in the Swiss Alps

#99 Post by George Krompecher »

Here it is:
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Re: '59 A in the Swiss Alps

#100 Post by Jon Bunin »

George Krompecher wrote: Sun Feb 12, 2023 8:41 amNow the new (12.9 grade) bolts and locking plates are in for a trial fit, seems OK.. Loctite and torque wrench are up next.
George, you should fasten the bolts directly to the differential cover, without any plates, tabs or washers under the bolt heads.
Insert three 741 locking plates (741.332.281.00) into the grooves in the bolt heads, and secure them as described in the factory 911 manual...
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Martin Benade
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Re: '59 A in the Swiss Alps

#101 Post by Martin Benade »

The correct latest locking plates only go in the grooves to hold the pieces if the bolts break, not under the heads as a locking device.
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Re: '59 A in the Swiss Alps

#102 Post by George Krompecher »

That is unfortunate. I have the oler style locking plates, and it is now all done. Loctite, torque and bent plates...

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Re: '59 A in the Swiss Alps

#103 Post by George Krompecher »

This a no-no?
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Re: '59 A in the Swiss Alps

#104 Post by Jon Bunin »

George Krompecher wrote: Mon Feb 13, 2023 4:26 am This a no-no?
George, those plates are not hard enough for the torqueing and clamping forces involved. They'll deform and compromise the clamping force.
The bolts are best applied directly to the differential surface, without any plates, tabs or washers under the bolt heads.
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George Krompecher
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Re: '59 A in the Swiss Alps

#105 Post by George Krompecher »

OK, good to know.
Next question: the factory workshop mentions a rubber o-ring in addition to the paper gasket for the aluminum side plates (bearing covers). I can't sem to find it on the usual sellers' websites?

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