input shaft

[kkjb4x4.0]

I'm in the process of installing a new clutch and slave in my 97 4.0 m5od 4x4..Before the slave blew out the trans whinned in all the gears but 4th . Could that be caused by the input shaft bearing? And if it is can it be replaced without splitting the trans?

 

[Bruce]

The whine could be from the pilot bearing between the input shaft and main shaft,or it could be the counter shaft bearings which is internal and trans has to come apart to fix.

 

[AllanD]

I was once left nearly speechless by an otherwise technically savvy woman to whom I was strongly attracted.

what she said was that she'd rather have a Mistusishi trans than
a Mazda because the Mitsubishi burned up bearings while the
Mazda burned up gears.

the magnitude of the fundemental misunderstanding that this revealed
was what left me speechless...

The bearings in a Mazda are just so overkill for the loads on the trans...

I have yet to see a really bad countershaft bearing, but I'm always on the lookout for it and those flaming monkeys that will be flying top cover for it...

the Pocket bearing (the little bearing that centers the mainshaft in the input gear)
can easily fail, but usually due to oil starvation.
the input bearing can go bad, usually from thermal conduction
from a MELTED input gear.

But if the transmission is "whining" I'd atleast check the input shaft for sideplay

This is NOT an indicator of a failing bearing but of excessive mainshaft end play.

AD

 

[kkjb4x4.0]

AllanD, there does seem to be some sideplay! When I spin the input shaft it does not turn smoothly. It feels rather rough, like turning a wheel with a spent wheel bearing

 

[Bruce]

I was once left nearly speechless by an otherwise technically savvy woman to whom I was strongly attracted.

what she said was that she'd rather have a Mistusishi trans than
a Mazda because the Mitsubishi burned up bearings while the
Mazda burned up gears.

the magnitude of the fundemental misunderstanding that this revealed
was what left me speechless...

The bearings in a Mazda are just so overkill for the loads on the trans...

I have yet to see a really bad countershaft bearing, but I'm always on the lookout for it and those flaming monkeys that will be flying top cover for it...

the Pocket bearing (the little bearing that centers the mainshaft in the input gear)
can easily fail, but usually due to oil starvation.
the input bearing can go bad, usually from thermal conduction
from a MELTED input gear.

But if the transmission is "whining" I'd atleast check the input shaft for sideplay

This is NOT an indicator of a failing bearing but of excessive mainshaft end play.

AD

Wow then i guess them bad counter shaft(another term used cluster shaft) bearings i have seen where just an illusion .

The pocket bearing you refer to has also been referred to as a pilot bearing between the input shaft and the main shaft(also called output shaft for Allens sake)

Either way trans has to come apart to repair the noise.

 

[AllanD]

The only "Bad" countershaft bearing I have seen didn't count.
someone had installed a much weaker (Inferior) bearing in substitution.

this bearing was at the input end and instead of a full set of rollers
had a sheet metal cage taking up half the space.

What bothers me is that in all likelihood someone removed a servicable bearing
during an overhaul and installed an inferior piece.


I have also seen bearings filled with fragmentary material in a trans that
suffered a full meltdown but the bearing wasn't so much "bad" (as in
"failure" as in CAUSE of the trans being removed from service and
disassembled) as it was collateral dammage to a total UNREBUILDABLE
transmission failure.

So your saying one is "Bad" when you have the trans apart is different from
my meaning of the term "Bad"

finding JUST a bad countershaft bearing (in an isolated failure) is something
I simply don't or won't bother looking for because it basically doesn't happen.

It is not part of my diagnostic analysis of a transmission in the field.
Nor should you routinely consider it.

I keep seeing people mention a bad countershaft bearing as a source of a noise
and I'm tellin you it simply does not happen. and when it does it's like a spilled
martini in first class during an airliner crash.

The difference is about philosophical understanding of the term "Bad"
as opposed to "Failure".

Is the countershaft bearing WHY the tranmission was taken out of service?

Ok, does that meet your semantic sensibilities Bruce?



Now, as to the specific issue being discussed here (ignoring the contrarian gadflies) the problem is CLEARLY an input gear issue

your input bearing is in all liklihood not bad, but tapered roller bearings that are allowed to "float" tend to be rough and noisy

Even a new bearing built to NASA specs is less than smooth until it's properly preloaded.

Therein likes the issue with the noise, mos likely a gear mesh noise
when tapered rollers are "loose" they by definition have radial play as well as axial play and for gears to operate smoothly (and quietly) they MUST be maintained in a consistant relationship to one another.

Removing the front bearing retainer (just to clean out the trash that collects there is ample justification for doing it)
and reshimming the input bearing will probably stop the noise
and prevent the trans from the premature failure it might currently heading towards.

Yes you could replace the bearing, but that requires more or less complete disassembly of the trans

Simply standing the trans on end with the bearing retainer removed and rotating the shaft with one hand whole holding the bearing race down will tell you most of what you need to know.



AD

 

[kkjb4x4.0]

So it does seem to be the input bearing, someone was too liberal with silicone. Can this bearing be replaced without taking the tranny apart

 

[AllanD]

The trans needs to be torn down to replace it.

It's a tapered roller bearing and the reace is pressed onto the input shaft.

AD