input shaft bearing? - SR20 Forum
 
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#1 (permalink) Old 06-03-2004, 02:58 AM
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input shaft bearing?

Ok, I installed my my clutch and stuff a few days ago. Everything went fine and the car drove fine with no funny noises whatsoever. Today though, I noticed a subtle whirring noise coming from the transmission that goes away when I press down on the clutch pedal: the more I push down on the clutch pedal, the softer the noise gets, until it disappears when the clutch pedal is to the floor. It makes the noise while in neutral, and even in gear it's noticeable--the noise changes with acceleration too until the engine noise drowns it out. I can hear the whirring coming from under the pedals while in the car, and even outside the car with the hood closed; it's easy to hear.

I'm thinking it's the input shaft bearing(s), so I think I need to replace them asap. I have a few questions though:

1) When changing the bearing, do I need to take off the entire bellhousing as if I am changing the clutch? Or can I just take off the transmission case itself?

http://www2.hawaii.edu/~jescasa/tranny/tranny.jpg

2)do I need to replace both the front and rear input shaft bearings? Or just the front bearing? When I looked at my FSM, the front bearing looks like the part that would make the noise that's coming from my tranny: the front bearing is a ring with ball bearings in it, so I'm guessing the ball bearings are making the noise, and thus this would need to be the only part to be replaced...? Oh, and it looks like all I have to remove off the input shaft in order to get to the bearing is a c-clip and an input gear spacer... right?

you can check out a pic of the input shaft here to see what I'm talking about:
http://www2.hawaii.edu/~jescasa/tranny/inputshaft.jpg

the front bearing is #6 in the picture, and the rear bearing is the left most piece.

3)what problems can a bad input shaft bearing cause if left unchanged?

4)what causes an input shaft bearing to go bad in the first place?

Hopefully you guys can help me out here. Any answers are appreciated.
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#2 (permalink) Old 06-06-2004, 07:35 PM
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Re: input shaft bearing?

I was thinking of how my input shaft could have gotten damaged while doing my clutch job, and I remembered something: when we were reinstalling the transmission back onto the block, we slid the input shaft properly into the clutch disc/pilot bearing area, but we let the weight of the tranny hang on the input shaft for moments at a time--we did not support the weight of the tranny underneath, while trying to align the dowels on the block to the tranny. I think that might have bent/damaged something on the input shaft... what do you guys think?
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#3 (permalink) Old 06-07-2004, 07:59 PM
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Re: input shaft bearing?

Replace the input shaft bearing on the bell housing side of the trans. This is a common nissan problem guys.


I need to do the one in my ga16de 5 speed soon. I did my buds 200sx SER last year.

95 200sx SE-R
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96 Sentra 1.6(B13)
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#4 (permalink) Old 06-07-2004, 08:10 PM
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Re: input shaft bearing?

you dont need to replace the input shaft bearing. I dought it was damaged. what you probably need to replace is the throwout bearing. You should replace it with a oem nissan TOB. About half of the aftermarket TOB's give that noise or go bad. All you do is drop the tranny, pull the TOB off the input shaft, reconnect the little metal clips from the old TOB to the new TOB, slide it back on the shaft, make sure the little clips connect to the lever arm, put tranny back on.
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#5 (permalink) Old 06-07-2004, 09:17 PM
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Re: input shaft bearing?

thanks for the suggestions, my car is in the shop right now and I'll have them take a look at the throwout bearing. I replaced my TO bearing with a brand new OEM unit though, so I don't think that's the problem; when a TO bearing goes bad, it'll make a noise when you press down on the clutch pedal (that's when it's doing its job). My problem is just the opposite: the tranny noise is present only when the car is in neutral/in gear, and goes away when I press on the clutch pedal. However Greg Vogel also suggested taking a look at the TO bearing, can't remember what he said, but yeah I'll have the shop take a look. But yeah, the owner of the tranny shop said that the noise is definitely coming from the transmission case, not the bellhousing.
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#6 (permalink) Old 06-08-2004, 12:52 AM
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Re: input shaft bearing?

let me know what you find out.
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#7 (permalink) Old 06-09-2004, 09:10 PM
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Re: input shaft bearing?

so far the shop replaced both input shaft bearings. Apparently they said the front bearing was indeed bad. Unfortunately, new bearings didn't remedy the problem with the tranny noise; they said the noise from the tranny is now alot quiter, but it is still present (it'll go away when you press down on the clutch pedal).

Now they want $400 more to replace the "cluster bearings"??? I'm thinking they're referring to the bearings on the mainshaft or something. I'm not down with this trial and error/shotgun approach, so I'm taking my car out of the shop today--I'll just have to eat the cost of the parts/labor. I am awaiting a tranny from soko, and I'll just bolt that one in if my current tranny noise turns into a bigger problem.

I'm thinking it just might be the throwout bearing after all...? The shop didn't even check the bellhousing parts.
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#8 (permalink) Old 06-09-2004, 09:33 PM
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Re: input shaft bearing?

it is the tob, thats why it goes away when you push the clutch in. Did you grease it? maybe it was defective. It happens sometimes. but it is definetly the TOB. Been there done that.

Nick McCollom
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93 Nissan NX2000 14.027 @97.98 (N/A) I wish I had time and money again, this little car has sat for 2 years now. I do miss driving it bad. It will be back soon though faster than ever.



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#9 (permalink) Old 06-09-2004, 09:42 PM
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Re: input shaft bearing?

There was no need to replace the imput shaft bearing and i doubt what the shop told you was even true. Sakerocket1 is right, you should have just had them install a new throw out bearing. With that said there is still a pretty good chance the the TOB will still make noise even after you replace it. I havehad 3 different ones in my car and all made noise no more than 50 miles after install.
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#10 (permalink) Old 06-09-2004, 09:46 PM
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Re: input shaft bearing?

Throw out bearing is not the problem the input bearing is. I see these posts about once a week.

93 SE-R- Former BBDET with T28, 13.1 @ 112mph. *SOLD*
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#11 (permalink) Old 06-10-2004, 06:06 PM
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Re: input shaft bearing?

guys i see these problems all the time. I was right when i said it was the input shaft bearings. Now the little bit of noise left could be the mainshaft bearings. The differential bearings only make noise when driving. Also the cv joint support bearing on the pass side can crap out, those are when driving though.

of course it could have been the tob, but probably not since it is new. The inputshafts etc.. all get pressure applied to them when the clutch is pushed in. It could be any of them.

95 200sx SE-R
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#12 (permalink) Old 06-10-2004, 06:41 PM
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Re: input shaft bearing?

well I got the car back yesterday, and honestly the noise has not changed at all in my opinion. The shop probably thought the tranny noise became quieter after they replaced 2 bearings, because they only listened to the tranny when it was cold; they started the car up and didn't really drive it around long enough to warm up the tranny. When the tranny warms up however, the noise becomes much more apparent, and I can just barely hear it over the radio while in neutral. The new bearings did nothing.

I'm not exactly sure which bearings they replaced, one for sure is the front input shaft bearing. The other one looks exactly the same as the input bearing, but it has a line thru it. The owner of the shop spun one of the bearings on his fingers and told me to listen to the noise it made. I didn't notice any difference in the rolling sound of both the bearings he replaced. I'll take a pic of them later. The only other culprit bearings that the shop can replace are:

32273 m
32264

I'll have to check the Nissan FAST program to find out which bearings these are.

Anyway my car is perfectly drivable, except for the tranny noise. I noticed that downshifting feels a little more difficult, and regular upshifting doesn't feel much different. It's still notchy as it was before. I reverted from Redline MTL to just X-brand GL-4 (MTL made NO difference in shift feel in my opinion). Oh, and my pedal effort is difficult again--the shop put "Never Seez" lubricant on the input shaft where the TOB slides on. Never heard of that brand, but it definitely makes the pedal effort alot crappier. It doesn't feel JWT-ish anymore
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