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  View original topic: input shaft center divot-- use case?
charleslabri Sat Nov 14, 2020 11:24 am

Anyone have a good idea why the center divot is there in the input/main/etc shaft coming out of the trans?

The outer chamfor makes sense- so it guides it into the pilot bearing.

But why this center carve out?




MarkWard Sat Nov 14, 2020 11:28 am

So it could be chucked up in a lathe. Normal and not required if you are considering cutting it back.

Zeitgeist 13 Sat Nov 14, 2020 12:32 pm

It might also be a recess for a reserve of grease to keep the pilot bearing lubed over time.

charleslabri Sat Nov 14, 2020 12:44 pm

Thanks for the insight. Y’all are great

MarkWard Sat Nov 14, 2020 12:55 pm

Zeitgeist 13 wrote: It might also be a recess for a reserve of grease to keep the pilot bearing lubed over time.

I hope this advice was tongue and cheek. Don't pack a bunch of grease in there. Grease shouldn't be flowing. If it did, centrifugal force would throw it on the clutch disc.

Howesight Sat Nov 14, 2020 1:12 pm

Zeitgeist, shame on you for that fake news! That space is NOT intended to hold grease.

Originally, the centre was carved out to give Vanagon owners a place to hide their weed. VW realized that with the Splitty and Bay vans, there was no secure place to hide your weed, so they ensured the Vanagon generation would not suffer this ignominy. Now that increasingly liberal laws on weed are popping up in many states, that space has been re-designated as a place to hide your ecstasy, although you will only find this information in the darkest corners of the interwebs.

https://www.youtube.com/watch?v=eFktbuhAyLM

Zeitgeist 13 Sat Nov 14, 2020 1:18 pm

MarkWard wrote: Zeitgeist 13 wrote: It might also be a recess for a reserve of grease to keep the pilot bearing lubed over time.

I hope this advice was tongue and cheek. Don't pack a bunch of grease in there. Grease shouldn't be flowing. If it did, centrifugal force would throw it on the clutch disc.

I was trained to pack the pilot bearing with Bosch distributor grease, and to fill the divot with the same. I'm not talking about filling that entire crank cavity, 'cause that would be a recipe for hot spots on the wear surfaces.

Vanagon Nut Sat Nov 14, 2020 1:24 pm

My vote is also for lathe work. Morse taper part at tail piece?

edit: both my ABA swaps with cut input shaft, no divot at end, work fine.

I added a little extra grease (IIRC a "sticky" synthetic grease) at the new pilot bearing on my first ABA swap and possibly too much Moly at input shaft splines. I'm not certain but I think it was Moly from input shaft splines that ended up on my FW. Regardless, in hindsight, (edit: in my less than educated opinion) I should not have added grease to the new "sealed" type pilot bearing.

Neil.

15º ABA FW, early days. Looks like excess Moly from input shaft splines. Clutch still worked fine though and little wear was seen at disc after some years use.


charleslabri Sat Nov 14, 2020 3:58 pm

I ended up doing a very gentle cutting wheel method and adding a slight campher.
The original campher was 5mm deep, i went about 3.5mm. After these pics i polished it with 400-600 grit sandpaper
Sounds like this divot in question is non-essential




MarkWard Sat Nov 14, 2020 4:04 pm

Do yourself a favor and bolt the transmission to the engine with no clutch. Select a gear and turn the engine through. Make sure the cv flange does not turn. You can also leave your string to see how deep the shaft engages the pilot bearing.

revolution337 Sat Nov 14, 2020 6:17 pm

MarkWard wrote: Do yourself a favor and bolt the transmission to the engine with no clutch. Select a gear and turn the engine through. Make sure the cv flange does not turn. You can also leave your string to see how deep the shaft engages the pilot bearing.

I did exactly this. Although I used an o-ring instead of string to help determine the depth of the insertion into the pilot bearing. A was able to get a pretty clear shot of the whole package through the starter hole. I had a friend spin the engine over by hand while watching the trans input shaft. I could easily verify that the crankshaft was turning and the input shaft was not, indicating no binding.




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