Turns out most seals and bearing are available for very little money. For example, the two bearings in the 4 speed torque converter cover are the same 6008 bearings used in the throw out bearing. The throw out bearings from 928 Specialists is between $312 to $183. Yet the 6008 bearing Porsche uses is a very very common bearing coming in many styles - even ceramic. Further the inside bearing is only about $4. The bearing is rated for 5800 RPM and for a few dollars more you can get the same bearing sealed rated a 10,000 RPM.
Dan the Pod guy
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Recently I rebuilt the torque tube. I bought the original kit for Jaeger Engineering. It as a nice kit and after severely modifying the instructions I ended up with a rebuilt torque tube for a fourth of the rebuilt cost. But after finding that the bearing supplied were common bearing I looked around and found bearings for $13 each or less than half Jeager's price. So a rebuilt torque tube comes down from $450 to $39. Multiply that one a few times and you can buy another 928.
Dan the Pod guy
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With my engine out, of course I'll rebuild the TT. So I decided to take a look at bearings available online. Hey, I don't know jack about bearings, but I found a joint out in Cali that sells TT bearings (6006ZZ, double shielded, 16k rpm - I think that works) at 10 for $39.99.

Bearing 6006ZZ 30x55x13 Shielded http://www.vxb.com/page/bearings/PROD/6006ZZ

High Quality 10 Ball Bearings ( 6006ZZ ), the inner diameter is 30, outer diameter is 55 and the width is 13, this is a popular size that could be used in many applications, Bearings are made of Chrome Steel and can rotate up to 16000 rpm, each bearing has Double Shielded to protect the bearing from dust or any possible contamination. Bearings are packed 10 bearings in one plastic tube.

Item: Double Shielded Ball Bearings 6006-ZZ
Material: Chrome Steel
Closures: Metal Shields
Size: 30mm x 55mm x 13mm
Type: Deep groove ball bearings
Lubrication: Self Lubricated (Grease)
Quantity: 10 Bearings
Packing: 10 bearings in 1 plastic tube
Equal: 6006-2Z

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TBelt crank idlers - 6201 bearings pressed into old shells
TB Idler pulley -'87> ........6905
- '85/'86.....6004
-'80 ( early 16v) ...... 6303,
- all press into old shells.
These bearings average $7 for top grade double sealed.
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Flappy bearings for late intakes:
HK1012RS are the right size and have a seal like the originals.

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Considering the amount of work involved changing them, I'd rather spend the few extra $ on name-brand premium bearings for the torque tube. Ditto the alternator, torque converter, front wheel bearings, power steering and air pump. In fact I can't think of a ball or roller bearing in the car that I'd consider replacing with cheap. $4/each for name-brand non-Asian/Central American 6006 high-speed grade 6 or higher with high-temp grease, sealed and shielded (not just shielded) is an impossibly good buy. Advice-- confirm place of manufacture, and inspect the bearing for manufacturer's name before you buy. I've purchased bearing sets that were boxed identically but had all different sources inside. Kinda like buying the aftermarket motor mounts from Rock Auto. Ya just don't know what you are getting until you get well past the name printed on the box sometimes.
__________________
Bob Fuelleman
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I'm with Dr. Bob on the TT bearings.
To big of a job to use cheap bearings with the risk of having to do it all over again.
My original bearings where made by FAG Germany and marked 6006 C5 and had a metal shielding on them and clearly had leaked some grease over the Years.
(C5 is the bearing tolerance and I believe they are a little looser than C1, C3 or nothing marked for tolerance, guess it is to compensate for heat expansion) The best alternative i could find was made by SNR France and was rubber sealed and packed with a high temp grease 6006.FT150.

https://www.snr-bearings.com/catalog...l&id=6006FT150

Maybe the 6006.FT150ZZ is even better with a higher max rpm?

Just my 2 cents.

/Peter
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1 Smog Pump front bearing 6203RS
4 Smog Pump vane bearings J-65 (2 per vane)
1 Smog Pump rear bearing B-188

NSK #6909VVCM NS7S 211 worked great on my AC clutch. About $40 each.

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Just some bearing pullers...

Watch the slide hammer to pull using a sliding weight that knocks to the upper stop causing a pull and not a push.

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Torque Tube Bearing Info for Rebuild

I am going to replace the bearings on the rattling tube I took apart last year, and found some interesting things when sourcing the SKF replacements.

The SKF part number I have for an 87 tube is 6006 2Z C5 HT51

This bearing is a Metric (6006) Double Metal "Z'" Shielded (2Z) Highest Clearance between the balls and race (C5) and Hi temp greased= HT51(-30 to +150 DegC).

Now the standard running clearance is CN to C3. The standard grease and clearance are good for quite a temperature range.

The C5 - which is a special and rarely specified, has excess clearance so when the bearing heats up it will not bind I suppose.

Clearance or play on the front bearing is what creates the tube rattle. The tube I took out was fine except for a lot of play. The tube I replaced it with (60K miles from an 87) had much less play, but still would rattle if the shaft was struck with a rubber mallet. I also let the front bearing soak up some synthetic grease before installation.

The converters operate at high temperature (~700 DegC), so I am wondering is the temperature inside the tube above 110DegC in normal operation?

Also a clearance spec of C3 would certainly reduce the tube rattle.

Paul Jager


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I thought this might be some help to 928 owners. The bearings in my torque tube were INA 6006-z-c4, but I had a lot of trouble trying to get these. In the end I spoke to a technical engineer at INA who told me the following:

Porsche's IF tolerances for the bearing is 10-35 microns
6006-zz-CN= 5-20 microns
6006-zz-C3=13-28 microns
6006-zz-C4=23-41 microns

I know that in the tip above, the author mentions the CN to C3, but I thought it might be useful to know the exact tolerances. I've ended up using C3 bearings as this is in Porsche's tolerances that INA had (original bearing supplier). He did go on to say that his blueprint was dated 1989 so this might explain why my bearing was a c4 (my car's an 87 s4 auto) and the bearing within the tolerances is the C3. Hope this helps fellow 928 owners

Russell
United Kingdom

======

Thanks for the article. For your info, the torque tube bearings on my 89 S4 were type 6007.

Russell Croxford

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FAG 6006 C5 FB
===========
Heat-resistant bearing 6006-2Z/VA208
Structure: Deep Groove
Type: Ball
Brand Name: FAG, NSK, NTN, SKF, THK, NBAY
Bore Size: 12 - 1000 mm
Outside Diameter: 26 - 1000 mm
Model Number: 6006-2Z/VA208 6206/VA201 6206-2Z/...
Precision Rating: P4 etc.
Seals Type: ZZ,RZ,2RZ,N,NR,RS,2RS,Z,
Number of Row: Single Row
Place of Origin: Shanghai China (Mainland)
Brand Name: NBAY
Model Number: 6006-2Z/VA208 6206/VA201 6206-2Z/...
===========
I used the 6006ZB C4 as that was what came out of my tube, I simply took the bearing in to my local supplier and the hunt began, It looks like a standard bearing but is quite rare, I can't see the grease getting that hot in a torque tube.
Here is what I wrote below.

To recondition a Torque tube:

Order 4 of 6006ZB C4 Bearings, they are an odd size and can be hard to locate (at least in New Zealand) so get them first.

Remove the Torque tube from the car, this can be done without disconnecting the brake lines or cables, but it may be easier to do so (the transmission must be removed first).

Measure how far into the tube each of the end bearings are located from the end, mark the tube or write it down.
Get a piece of steel pipe that fits over the drive shaft, the thicker the pipe the better.
I added a flat piece to the end that pushed evenly on the bearing housing so as not to deform or twist it.

Remove the shaft by belting the hell out of it, I held the tube in a vice and had an assistant steady the end of the pipe while I hit it with a sledge hammer (this can be done with threaded rods as a puller but is not necessary)

After the shaft and bearings are out I put the end of the shaft against a block of wood and belted the bearings down the shaft with just the weight and impact of the steel pipe.

After the bearings are removed press the plastic sleeve out of the inside of the bearing (a socket and a hammer will do this) do not throw these away as they are reused.

Next drill the six rivets out of the bearing retainers (5mm drill bit) and separate the two halves, later cars do not have riveted bearing carriers (easier).

Throw the old bearings away and reassemble the new bearings in the housings with new rivets if necessary, I ground part of the rivets away so it would fit in the groove (this is obvious when you can see it), I also used a small spacer between the rivet gun and the rivets so they would pull in evenly.

I then pushed the shaft in from the gearbox end with the bearing closest to that end fitted to the shaft, the shaft goes in until it is 49mm +/- 0.5mm from the edge of the gearbox end bellhousing (specs from factory manual).

Next I put the assembly hard up against a solid wall with a piece of wood jammed between the driveshaft and the wall, this stops the drive shaft sliding back out when fitting the other bearings.

Next I installed the bearings by pushing the housings down to there appropriate position with the steel pipe, I put marks on the pipe so I wouldn't push the bearings too far.

After installing all four check the shaft end is still 49mm +/- 0.5mm from the edge of the gearbox end bellhousing.

The new bearings are quieter than the old ones but not silent.

Total cost was 110$ NZ (including shipping the bearings from Japan) about 55$US. Not too difficult but time consuming.
__________________
Martin Taylor


Material: Bearing steel
Precision: P4
Seal: Open RS,2RS,Z, etc.