PantyBuncher

i've got an 89 4runner v6/5speed 4WD with LOTS of miles.

(yes, i have searched and read many similar problems. i'm fairly experienced mechically, but no experience on toyota transmissions)

symptoms:
there is a fairly loud constant noise when the clutch is NOT depressed. for example, sitting in neutral with the clutch NOT depressed. once the clutch is depressed, the noise goes away. it is also somewhat difficult to get into first gear when stopped.


other's have posted sound descriptions like 'marbles in the tranny'. it seems like a pretty good description. i would say it sounds something like marbles but also with a bit of a rrrraaaarrwwhhh - rrrraaaarrwwhhh - rrrraaaarrwwhhh - it seems to have a bit of a cycle to it, not too fast. once the clutch is depressed, the noise goes away.


i anticipated that the throwout or the input bearing was going bad, so, i pulled the trans.


observations:
1. the pilot bearing is really rough

2. the input shaft is worn, it seems to have about 25 thousandths clearance between the ID of the pilot bearing and the OD of the input shaft

3. the throw-out bearing appears to be smooth with no slop


i removed the case from the transmission. so, now, the transmission internals are visible, but still installed in the intermediate plate, so i can't see the rear bearings. i'm a little hesitant to rip into it further without some thoughts from you experts.


4. the main input bearing appears to be smooth, with very little lateral slop.

5. the front countershaft bearing appears to be in good condition

6. the input shaft appears to have some lateral slop with regard to the output shaft, but then again, they aren't the same piece of steel, and with the way they are joined, and the case not in place to support the input bearing, it isn't too surprising. i'm simply not sure if this is normal.

7. moving the input shaft side to side results in the main shaft shifting a substantial amount. since the output-bearing/output-shaft are still installed in the intermediate plate, it seems like this shouldn't allow _any side to side deflection with respect to the intermediate plate(and hence, the shift rod and fork). at the point where the frontmost shift fork rides, it allows about 0.15" deflection. perhaps the output bearing is bad ? grasping the output shaft near the bearing and trying to feel the clearance, it doesn't seem too excessive, but there is some slop. just slightly more than i would expect. but without experience, i can only guess.


questions:

1. it seems to me that the bad pilot bearing could be responsible for it being hard to shift into first gear - yes ?

2. the input shaft is worn. are there options other than a new input shaft, like a bushing or pilot bearing with a smaller ID ? possibly this slop is the knocking that i can hear as the input shaft is allowed to bounce around a little ? how much is an input shaft $ ? any good sources for this part used ? how big of a problem is allowing the input shaft to continue to wear ? i did see this info, has anyone actually done this ? http://buzz.omgili.com/jmp/aHR0cDovL...BpYz0zOTk3OA==

3. it's hard to understand how a bad output bearing could make noise when idling in neutral. perhaps it may be a little sloppy, but not really the source of the noise ?

4. since it's noisy with the clutch engaged (pedal up), i can't see that the 'marbles' sound is related to the pilot bearing, since at that point, the pilot bearing shouldn't be turning, although there is the slop issue. yes ?

5. will an input bearing that is loud enough to hear feel obviously bad to the touch ?

6. all of this kind of leaves the throwout bearing as producing the noise, but it feels remarkably smooth to the touch, with no slop. perhaps at speed, inside the bellhousing it could give a sound like 'marbles'. i dunno.

i could put it all back with a new pilot bearing, throw-out bearing and input shaft, but as you know, this is alot of labor, so i'd prefer to only do the R & R once.

any insight would be greatly appreciated. TIA.

Andy

mr toytech

my old supra did the same thing. replace the pilot bearing. if the input shaft is too worn replace it too.

PantyBuncher

i hear ya. i mean, that's the obvious problem i see.

i just can't get my brain wrapped around how the noise is generated by a bad pilot bearing under conditions where the bearing doesn't need to turn. when the pedal is UP, the clutch is engaged and the bearing doesn't turn. right ?

maybe you're saying that the pilot bearing isn't making noise under these circumstances(clutch pedal is UP), but the input shaft is wandering around in there due to the excessive clearance ( in my case 25 thou ) and this is what is causing the noise ???

the noise goes away when the pedal is down....that's the point where the pilot bearing needs to turn, and at that point, it's quiet. it just doesn't make sense to me.