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safe
Joined: 18 Mar 2017 Posts: 631 Location: Sweden
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Posted: Wed Aug 28, 2024 4:52 pm Post subject: bent torque tube axle |
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I'm restoring a 931 car that is mostly in pieces right now. I checked the torque tube after re-rusting and painting it.
I noticed that its slightly bent on the engine side, the bearing doesn't sound very nice either.
I didn't notice anything when I drove the car before picking it apart, but I didn't drive it very much.
Shouldn't it have been obvious?
Has anyone straitened one?
I think it would be possible to unbend it in a press if removed. _________________ /Magnus, Stockholm Sweden
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Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe |
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morghen
Joined: 21 Jan 2005 Posts: 8947 Location: Romania
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Posted: Wed Aug 28, 2024 5:07 pm Post subject: |
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How much is it bent? Maybe it got bent during disassembly?
You can try to bend it back i guess...it may wear the needle bearing sooner if its not straight. _________________ https://www.the924.com |
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safe
Joined: 18 Mar 2017 Posts: 631 Location: Sweden
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Posted: Wed Aug 28, 2024 5:25 pm Post subject: |
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morghen wrote: | How much is it bent? Maybe it got bent during disassembly?
You can try to bend it back i guess...it may wear the needle bearing sooner if its not straight. |
Haven't measured it yet, 1-2 mm maybe at the tip. Its enough rotate back to its preferred resting place if I turn it 90 degrees.
Other TT I have are dead straight.
It could have been bent on disassembly. If I had to guess I would think that the shaft would be of pretty flexible steel and be hard to bend... _________________ /Magnus, Stockholm Sweden
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Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe |
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morghen
Joined: 21 Jan 2005 Posts: 8947 Location: Romania
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Posted: Wed Aug 28, 2024 9:00 pm Post subject: |
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maybe the shaft isnt bent but the bearings sleeves are deformed/crunched and the shaft sits at an angle ? _________________ https://www.the924.com |
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safe
Joined: 18 Mar 2017 Posts: 631 Location: Sweden
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Posted: Wed Aug 28, 2024 9:09 pm Post subject: |
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I think I have to pull out the shaft and have a look.
Probably need to replace at least one of the bearings.
From experience with my NA TT, the end bearings are probably the worst. _________________ /Magnus, Stockholm Sweden
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Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe |
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Mike9311
Joined: 14 Dec 2004 Posts: 1700 Location: Chicago-ish
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Posted: Thu Aug 29, 2024 7:10 am Post subject: |
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I'm wondering if the closest bearing is in the wrong position which allowed it to get bent? Like that unsupported section is now longer? This seems weird to me that it would get bent (see my final note below too)
I'll watching for what you find for sure
What I can tell you is that the tubes themselves have some bend to them. All that have been checked so far especially the longer S2 versions (Audi). One of my pet theory's on the carrier design was that it deforms to the position its at on first install as new. In this way the shaft stays as straight as possible (carriers are sheet metal). Its also why I think they used C5 clearance bearings, not C or C3 which are much more common. The deformation in the tube actually preloaded the bearing (common practice) or else why would there be C5 (more clearance)? Those bearings have to hate being spun up when cold especially on really cold days. I want preload of some kind on any bearing. Better for the bearing
These are the kind of thoughts I had when working the Alum tube project and why I know the tubes are typically bent (lots of testing). Some more than others. My thought there was that Porsche could just take raw tube straight from shelf and use it without much processing
also a bad bearing can cause you to think a shaft is bent. I see this almost every day in my work life. The farther away from that bad bearing only makes it seem worse _________________ 1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car |
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safe
Joined: 18 Mar 2017 Posts: 631 Location: Sweden
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Posted: Mon Oct 14, 2024 7:14 pm Post subject: |
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Small update.
I removed the axle from the tube, at first glance it doesn't appear to be bent. I'm waiting for a pair of v-blocks to be able to check it.
But it seams ridiculous that a 25 mm / 1 inch shaft will take a bend, I would also guess that its made from some kind of hard and "springy" steel making it even more unprobable.
I will remove the 1st bearing in the tube to check that out. Making a special tool to extract that... _________________ /Magnus, Stockholm Sweden
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Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe |
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Nobbi
Joined: 24 Aug 2006 Posts: 1380 Location: Germany
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Posted: Sun Oct 20, 2024 7:54 pm Post subject: |
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Bending the drive line happens when the car gets lifted under the gearbox.Even more, the older your rubber on the attachment of the gearbox is.So, never lift the car there, even when its really handy...
Nobbi _________________ NA 924 - april/1977- 4-speed-audi gearbox.
500.000 km with fun.....and new toy:Porsche 944 S2 Cabriolet.Other car Daimler c-class cabby,brandnew..Plus : DEUTZ 4005 tractor Built 1969 |
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barnwerks
Joined: 28 Oct 2022 Posts: 29 Location: Northeast and southeast US
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Posted: Sun Oct 20, 2024 10:25 pm Post subject: |
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In regard to bending the driveshaft, I will contend that, while there can be potential for damage to the transaxle or it's mountings, lifting the car from the transaxle will not introduce unusual forces to the driveshaft or support tube. |
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safe
Joined: 18 Mar 2017 Posts: 631 Location: Sweden
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Posted: Mon Oct 21, 2024 7:40 am Post subject: |
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Made a contraption to hook onto the first bearing and pull it out.
Yes, the bearing was crusty and sloppy...
Looks like I can save the inner plastic bushing and the the outer carrier too. Just need to find the right bearing. _________________ /Magnus, Stockholm Sweden
=======================
Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe |
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Raize
Joined: 18 Sep 2013 Posts: 236 Location: Scotland
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Posted: Mon Nov 04, 2024 4:43 am Post subject: |
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I remember reading a post once that the tolerance class of that bearing is extremely important and you need the tightest-tolerance version but I just can't find it... |
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safe
Joined: 18 Mar 2017 Posts: 631 Location: Sweden
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Posted: Mon Nov 04, 2024 4:47 am Post subject: |
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Raize wrote: | I remember reading a post once that the tolerance class of that bearing is extremely important and you need the tightest-tolerance version but I just can't find it... |
Not the tightest, the loosest, C5. 6006 2z c5
But it seems that bearings of standard tightness have been used as replacement by some. I think the bearings I got for my NA is C0, standard. _________________ /Magnus, Stockholm Sweden
=======================
Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe |
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