What's the point of the pilot bearing?
 

The only reason I could find for installing it was to make the clutch alignment tool happy. I always though the end of the input shaft goes inside the pilot bearing...I was wrong (in least in our application):

http://www.ericj.org/maxima/img/engi...t_bearing1.jpg
http://www.ericj.org/maxima/img/engi...t_bearing2.jpg
http://www.ericj.org/maxima/img/engi...gine_crank.jpg

Why even have one?

the pilot bearing/bushin supports the outer end of the trannys input shaft also by doing that it helps to keep the clutch disc centered in the pressure plate.

How so? The input shaft doesn't go into the pilot bearing at all, as the first picture above indicates.

It keeps the shaft from banging against the crank.. the pilot bushing is always made of copper (or has copper in it), which won't ever bind up against steel. brass and copper are both used for dry bearings like that so they don't require lube..
to the end of the input shaft rests on the end of it, but only if the shaft starts moving around.. keeps it from hitting the crankshaft and causing $$$ damage.

So it doesn't really act as a bearing? Does it in other cars (ie - input shaft goes into the pilot bearing)?

yes the bearing goes on to the shaft in everycar ... just like Matt said its basic purpose it to support the shaft

Not every car. The input shaft does not go into the bearing in our cars...hence the point of this post.

Maybe this will clear things up...the outer diameter of the pilot bearing is exactly the same as the outer diameter of the tip of the input shaft. The bearing isn't made to fit over the input shaft.

When I did the tranny conversion on my car I encountered the same situation as you. I thought that maybe the wrong size pilot bearing (bushing, really) had been included in my ACT clutch kit. I didn't know what to do with it so I left it out. Others in this forum have also left it out. So far, no problems (15000 miles later).

I talked to a transmission specialist about it and he said not to worry about. With FWD cars, the transmission input shaft is so short that it doesn't need the extra stabilizing that the pilot bearing gives.

I thought so at first too, but I compared it to the stock bearing in the old motor, and they were the same. I put it in, because I had no real reason not too. Plus the clutch alignment tool kinda needed it to function properly.

Makes sense. I figured the pilot bearing (bushing is a better term, you're right) was used incase the input shaft had excessive latteral (in and out) movement...which wouldn't be a good thing.

I just don't see why Nissan would bother with it.

Re: What's the point of the pilot bearing?
 

:laugh:
It turns with the clutch plate, when press on the clutch it lets the tranny spin while you change ratios in the box.

Re: Re: What's the point of the pilot bearing?
 

No, the pilot bearing, not the throw-out bearing.

Re: Re: Re: What's the point of the pilot bearing?
 

Eric, can you tell if the input shaft even contacts that bushing with it installed and the transmission bolted up to the engine? I'm pretty puzzled about it, too. Maybe it is just for the clutch centering tool. I had to center the clutch plate by eyeball when I installed my clutch because the centering tool wouldn't work without the bushing.

Re: Re: Re: What's the point of the pilot bearing?
 

Eric, can you tell if the input shaft even contacts that bushing with it installed and the transmission bolted up to the engine? I'm pretty puzzled about it, too. I'm thinking maybe it is just for the clutch centering tool. I had to center the clutch plate by eyeball when I installed my clutch because the centering tool wouldn't work without the bushing.

Re: Re: Re: Re: What's the point of the pilot bearing?
 

I could try and take some measurements...it would hard to tell though. I'll see if I can figure it out.