John, more details. That's awesome.

Also, anyone see an issue with replacing an S2 torque tube with a NA torque tube?

 

 

No issue with using an "early" TT. I put a torque tube in my 89S2 that came from an 86 turbo. Lengths are the same and splines are the same. And to refernece earlier reference to the "slit" in the S2 TT, I had heard is was put in for a "crumple zone" and allows the engine to submarine the body (after the motor mounts break) to absorb more energy in a head-on collision. That aluminum tape will fail if not checked, and will allow road debris up into the tube (water, dirt, etc.) and accelerates the failure of the TT bearings. I went through a trans rebuild because I listened to everyone who said my noise was all pinion bearing, rebuilt the trans and same noise existed, nasty TT bearing failure. So my thought was the early TT is a more stout unit, and better protected from the elements. If you can find an early TT with low mileage (say, under 70K), you will have many miles of worry free operation. I scored mine for $120.

 

No such luck in Australia - there isn't enough of a parts base, and importing from the UK or US is very expensive due to freight charges - and then you may end up with a dud anyway.

PS My S2 TT failed at 85,000 miles.

I will need to rebuild mine, so I am currently trying to procure the C4 clearance bearings and delrin bushes. Jager has the bushes for around $20, but their bearings don't specify clearance, so presumably they are C3.

Does anyone know of a (cheap) source for the C4 bearings?

I've also read where the bearing are installed and removed using PVC pipe to bang them in and out. Not sure if this would work terribly well. Other options are the Clarks threaded rod option or using a jack and some tubing which can be coupled together in sections.

Any ideas on what is easiest?

 

There's a 928 vendor here that's make a really nice rebuild kit for the 944 TT including the rubber damper rings. I'm not sure if they are in production yet and the price looks to be pricey but it's worth a look. There are many here that have used a good C3 bearing with no ill effects including dedicated track cars. Finding the right C4 is like searching for the Holy Grail, the OE C5 can only be found in Heaven. I have the VBX C3 and the delrin bushings and am not concerned about longevity since they are rated for 15K rpm and we never see half of that. They aren't exactly taking any serious loads; they just help keep the shaft centered for balance. The OE C5 bearings don't exactly have a stellar track record anyway.

 

New poll - what's the best way to replace the TT bearings?

 

buy a good unit from an old wrecked turbo and save yourself a bunch of time, bloody knuckles and $$ understanding you are in Australia so it may not be an option. The S2 TT is much more difficult to take apart compared to the older style TT. Much more difficult to take the shaft out, there is a coating on the shaft (kind of like a thick powdercoat) that makes it near impossible to slide the shaft from the carrier bearings. It would be recommended to set up a rig with a hydraulic ram to press it out if you are going to rebuild the S2 TT.

 

Thanks for the advice... Does that mean that even if I get the shaft out, I'll have to hone out the bushings to get more clearance for reinstallation?

Starting to sound like a crap job.

 

I had done an older style unit about 2 years ago using Clarks instructions and it went rather smooth (except for the machine shop I used to mke the delrin bushing). Then I got involved with this S2. Went through a complete driveline overhaul from the rear main seal all the way through rebuilding the drive-axles. Started to pound the shaft out before I could get the threaded rod set-up working, it wasn't moving nearly as easy as I remembered the first one. I mushroomed the heck out of the brass drift block I was using to get it started (barely marked it when I did nthe service on an early TT) I think it has something to do with the coating on the shaft. And most places here in the states will not take an S2 style TT as a core for thier rebuilt units (944online.com as an example). But also here in the states, you can find wrecked older 944T's and 944's all over the place. There is no reason that an S2 TT cannot be rebuilt, but what is your time worth? I would like to see someone do a detailed description of how they tackled an S2 TT rebuild, as I have (1) extra S2TT that could use a rebuild.

 

Cool. I have one out of my wrecked '85 that's fine, so when I decide to pull the S2 TT, I have a bolt-in replacement.

 

If I succeed I'll post a method. I'm thinking about a method using a steel tube over the pilot bearing end (1/2" galv tube will hopefully be rigid enough - if not will need to run in a guide made from timber), chocking each end against opposite walls and using a scissor jack (or cheap bottle jack if that doesn't work) with multiple blocks of wood to form spacers at the jack end. At the other end use a built up piece of timber (to form a large "tube" for the driveshaft to pass between) at the other. Getting it back in should be easy.

I'm a civil engineer - I'll make something work, getting the time is the more difficult part.

 

Using a jack that way is a great idea. When I rebuilt my TT I used Clark's method and it worked great. I improvised on the rod thickness and I think I went one size up. Also, I had to go buy more washers as mine kept bowling. An air gun is a MUST, and with it it's a simple job.

 

Got the trans out today. The rear no. 4 bearing looks like it has lost some grease, and the inside of the tube is quite black and greasy. There is also shavings of rubber in the base of the tube and in the lip of the steel carrier. I know that no 2 is also cactus.

Is this the "normal" failure mode for the TT bearings?

 

Darren, I put an '86 951 TT into my 968. Yes, I gave up the 2-piece driveshaft. But the TT fits and works perfectly.

Eric, I haven't heard of many true failures, but it does make sense to see the rubber debris. When the rubber bushing fails it would allow shaft vibration and deflection which could seriously hurt the bearings.