Transmission input shaft

[sierraspider]

The Fiat fun never stops. When I bought it, it made a whining sound in the trans area. Thought it was TO bearing and since I was doing clutch, no big deal. But alas, I was not a forum member and made the dumb ass mistake of not diagnosing input shaft bearing on trans. Car shifts great and doesn't make any noises or pop out of individual gears. So it looks like I'm doing another trans yank (not bad really if you have 12 extensions) to do input shaft. (saw video on you tube and since I have access to a shop I'm not too daunted by it) While I'm there, without significantly ripping into trans, are there other maintenance tasks I should do?

[bradartigue]

If the thing is working then I'd only replace the bearing...but it is always worth inspecting the guts without fully disassembling, and then replacing any of the forks or syncros that look bad (if they look bad). The rear needle is often overlooked - if it makes any noise at all then replace it.

[vandor]

To replace the input shaft you have to nearly completely disassemble the trans - only the main shaft will still be installed.
Another 3 minutes of work and one can pull that out too and be able to inspect the synchros and their springs. Those are what fail most commonly, so I'd inspect at the very least. I usually put all new into any trans I take apart. Also inspect the shift forks and replace if they have any wear.

[Nanonevol]

I didn't consider springs in my rebuild. How do they fail, do they lose their springiness or do they actually break?

[bradartigue]

To replace the input shaft you have to nearly completely disassemble the trans - only the main shaft will still be installed.
Another 3 minutes of work and one can pull that out too and be able to inspect the synchros and their springs. Those are what fail most commonly, so I'd inspect at the very least. I usually put all new into any trans I take apart. Also inspect the shift forks and replace if they have any wear.

I don't know why I read this as a thread on the throwout bearing - re-reading its about the input shaft - sorry.

Curious to know, Csaba, once you reach this level of disassembly would you inspect the wearable parts or just replace them? I've been inclined to replace all of the wearable parts when I get the thing disassembled.

[vandor]

> How do they fail, do they lose their springiness or do they actually break?

They break, then get chewed up by the gears.

> would you inspect the wearable parts or just replace them?

It depends on one's budged, of course replacement gives peace of mind. In our reman'd transmission they all get replaced no matter what, except for the 5th gear parts, those only if needed. They are very rarely needed, plus the synchro ring and sleeve can be flipped over so their unworn side is used.

[sierraspider]

Csaba

I'm not talking about the input shaft, just the bearing. I did the clutch about 2 yrs ago (4k miles) and opened up the trans and changed gaskets. It all looked very good, with no unusual wear and everything turned smoothly. I'm not sure I'm ready or have the tools to rip into the thing at this point, so I'll probably just do the shaft. In another post someone mentioned the input needle bearing. Is this fairly easily done? I'm planning on checking clutch and possibly doing the lightened flywheel. Thoughts?

[vandor]

> I'm not talking about the input shaft, just the bearing.

You may be able to get it out without removing the shaft, depending on how tight it is in the trans case.

> someone mentioned the input needle bearing. Is this fairly easily done?

The input shaft has to be removed to change it, so no, not easily done.