What is clutch "pilot bearing"?


#1

There was a discussion recently concerning a problematic clutch pilot bearing? Where is this part located? What does it do? I know the transmission input shaft goes through some splines in the center of the clutch disc. Is that where the pilot bearing is located? Or is it used to support the end of the transmission input shaft and is located at the center of the flywheel?


#2

Center of the crankshaft.

Keeps the input shaft of the transmission aligned with the engine so everything operates smoothly.

Tester


#3

Ah, so the input shaft goes right through a hole in the flywheel and into the center of the crankshaft, where’s there’s a bearing there to hold onto it but still allowing the two shafts to rotate independently, and keep the input shaft supported and lined up. Thanks.


#4

Sometimes it’s a bushing instead of a bearing.
Years ago I learned a clever trick for easily removing the old pilot bushing. It might work with pilot bearings.

  1. Fill the flywheel/crankshaft cavity, where the bushing is located, with soap from a bar of soap.

  2. Find a thick bolt whose diameter is the same as the tranny shaft that goes into the bushing.

  3. Insert the bolt in the hole, and begin hitting it with a hammer.
    The bolt will push against the soap, which will put pressure on the inside of the pilot bushing,
    causing the bushing to slowly “walk out”.

  4. Clean out the residual soap.


#5

Interesting. You mean you strike the bolt directly toward the crankshaft, but the bushing the bolt is attached to comes out in the opposite direction? Or do you mean you are hitting the bolt back and forth sideways, which rocks it out? It would never occur to me to hit it in the opposite direction you want it to move.


#6

I use grease from out of a grease gun.

Tester


#7

I’m with @Tester. I use grease from the grease gun to push out pilot bearings all the time. The good part is that it tends to stay in place once you put it there. And yes, @GeorgeSanJose, you strike the bolt towards to crankshaft. You need to fill the void through the pilot bearing hole with grease. The grease doesn’t compress, so the pressure from the bolt going in forces the grease to push against the back of the pilot bearing. I usually need to add more grease to the cavity a couple of times as the bearing works it’s way out. If you ever need to do it, the first time will be a ‘Holy Cow, It Works’ moment.


#8

I also use wheel bearing grease and the appropriate size wooden dowel from the hardware store to remove the pilot bearing (bushing).


#9

Sometimes there’s a bearing, sometimes there’s a bushing, sometimes there is neither. Those are my favorite ones.


#10

@Tester

I’m sure you misspoke . . .

You stated the clutch pilot bearing is in the center of the crankshaft

Not quite

The pilot bearing is pressed into the flywheel

This subject is fresh in my mind, because I did a clutch job on a C7500 last week. The shop that resurfaced the flywheel made a slight mistake. They didn’t press the new pilot bearing far enough into the flywheel


#11

Perhaps he meant coaxial to the crankshaft.


#12

"You stated the clutch pilot bearing is in the center of the crankshaft

Not quite

The pilot bearing is pressed into the flywheel"

Depends on the car, doesn’t it? Did a clutch this week on a Dakota, removed the flywheel and then changed the pilot in the crank. Some are in the flywheel, some are in the crankshaft, some don’t use one at all.


#13

Turns out we were all correct . . .


#14

Some of the older Subarus used a needle bearing as a pilot bearing. That bearing was pressed into the crankshaft and was a pain in the neck to remove after disentegrating or rusting in place. Hokey design.
Later models went to a sealed ball bearing pressed into the flywheel.

As to removal of old bushings, a thread tap will do the job also.