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I'm rebuilding an 86 944 torque tube, and I discover the clutch end of the shaft, that goes into the pilot bearing, is quite worn. Some call this the input shaft "nub".....OK, I'll go with that. The bearing has an ID of 15mm, so I would expect the "nub" to measure very close that that. But, it's a tad below 14mm, and is a VERY loose fit in the bearing. It doesn't look worn, it's just small. I have another one and it measured 14.9mm. Are there 2 sizes?? I checked the bearing and the same one fits all 944, 951, 968, so I don't think there are 2 sizes. Is this common?? Any comments on a way forward? I've got a bit of a hobby shop (mill, lathe, mig/tig so we have some capability.
I'm rebuilding an 86 944 torque tube, and I discover the clutch end of the shaft, that goes into the pilot bearing, is quite worn. Some call this the input shaft "nub".....OK, I'll go with that. The bearing has an ID of 15mm, so I would expect the "nub" to measure very close that that. But, it's a tad below 14mm, and is a VERY loose fit in the bearing. It doesn't look worn, it's just small. I have another one and it measured 14.9mm. Are there 2 sizes?? I checked the bearing and the same one fits all 944, 951, 968, so I don't think there are 2 sizes. Is this common?? Any comments on a way forward? I've got a bit of a hobby shop (mill, lathe, mig/tig so we have some capability.
Thanks as always!
Gord.
All the same size. Should be a snug fit into the pilot bearing. Anything else is junk. Ask me how I know.
I'll echo 931guru. Should be snug. Absolutely zero play. And I'll echo his "ask me how I know" on that.
Constantine at Black Sea R&D builds these back up with new material and machines them to original spec. Absolutely outstanding work.
Both my nub and my splines were toast... below is the "mine vs. what it should look like" before my rebuild. No saving my splines... I had to get a new shaft. Your nub looks/sounds done for... but your splines look better than mine did.
Last edited by Millermatic; 01-27-2022 at 10:47 AM.
Here's mine when I did the v8 swap, not the best pics as I don't have one not partially inserted. Everything ended up working fine, I inserted it a but more than the pics.
If you have a shop with a tig and a lathe... I’d be inclined to try and build up the nub and machine it down if you aren’t interested in getting another or shipping it to have it built up by someone else. You probably can’t make it any worse than the 1mm difference you have now.
It’s a bit of a pain to get the shaft out once everything is back together. I’d be worried about my shaft rattling around and having to redo the job in the not too distant future. Come to think of it... a worn nub may be why my old shaft has the abrasion below the splines you can see in my picture above.
My driveline was a mess... I absolutely had the difficulty with the clutch that T&T describes. Among other problems. Tough to tell what was ultimately responsible (search TT treads and you’ll find at least one by me). I ended up rebuilding it _all_.
Last edited by Millermatic; 01-29-2022 at 12:16 PM.
Done. Now measures 14.94mm, nice snug fit in the bearing. There are a couple of "pin holes" where I built it up, but nothing serious. I can understand why so many people said to just use it, since it sucks to throw out a whole TT because of a worn nib. But fixing it is the right thing to do.
01-26-2022, 06:20 PM
TT input shaft "nub"
