gongshow71

iTrader: (1)

Background: all 25,000 miles ago: T56 was rebuilt with a Stage II build, new Monster Stage II clutch, Monster 28lb flywheel, new GM slave cylinder, new pilot bearing, new GM clutch master cylinder, eBay speed bleeder.

Last night I made a 25 mile highway drive smooth as can be. No hard driving. When I pulled into my destination and pressed in the clutch I heard a strange grinding noise and knew something was wrong. Had to work 2 hours and then drove it home which was 25 miles.

The noise was only present while the clutch was disengaged and it sounded like a bearing noise because it was consistent and seemed to oscillate. Had a hard time shifting and heard clunking noises from the bell housing area. But power is delivered normally through the clutch with no slipping. Every gear in the transmission works properly aside from the hard shifting issue.

Today I put it on blocks and the rear wheels were still spinning in 1st gear while I had the clutch disengaged (aka clutch pedal pressed in).

Tore it apart today and discovered that my pilot bearing is absolutely trashed, and the input shaft of my T56 may be trashed as well.

Here is the advice I'm seeking:

1) What is the best pilot bearing replacement? I read something about a solid bronze pilot bearing for older hot rods?

2) Do I need a new input shaft for my T56 based on the picture below?

3) What could have caused this failure?

4) Does my clutch, flywheel, and pressure plate look okay in the pictures below?

5) Is my GM slave cylinder okay? The reason I ask is due to the rear wheels still spinning while clutch pressed in. It seems to depress properly by hand.

6) What are the essential repairs I need to do while having the transmission out? Seals, sensors, spark plugs?

Pictures:
















Thanks!

Centerforce

1) There's no clear winner. We've had issues and successes with both pilot bearings and pilot bushings, but we include bearings with our clutch kits.

2) We'd need to see it in more detail, but usually if the surface is uneven and rough after some polishing with an emery cloth its better to replace it now.

3) Bad quality bearing, loss of grease, damaged when trans was installed

4) Looks like the clutch was mating unevenly based off the scorch marks. We'd recommend resurfacing the flywheel and replacing the clutch, or bare minimum just the pressure plate.

5) The problems you describe also sound like something is also up with your slave. Replace that, pilot, and most would suggest installing a tick bleeder while you're there too, but that's completely up to you.

SNLPerformance

iTrader: (15)

Give us a call, so we can go over all of your questions. (817-750-2000)

ElQueFør

I would stay away from pilot bearings. Had them fail before, NEVER ONCE had trouble from a bushing. Usually when the bearing fails it takes out the input shaft pilot tip also. I lost a T56 input shaft to a pilot bearing failure.

I once had a clutch disk fail catastrophically when it ejected about half of the friction off the disk itself. This caused enough vibration that the input shaft beat up the bronze bushing to the point that when I pulled the trans off the pilot bushing just fell out. But, the bushing took the beating and the input shaft was still perfect. All I did was put a new clutch in and a new pilot bushing and it was good to go again.

Bushings were used for a long time, sometime maybe in the 70s pilot bearings started to become more common.

Here is a couple pics of one of my pilot bearing failures




No matter if you install the pilot bearing properly, grease it suffieicntly, and install the trans without banging it up, eventually the grease will dry up and the little needle rollers will fail and it's never pretty when they do.

PB656HD is the part number for a true bronze bushing. If you elect to go back with a bushing MAKE SURE it's bronze. You DO NOT want the pilot bushing to stick to a magnet, that means it's iron and you don't want that.

Take that bushing, pop it in the freezer for a bit and then quickly and carefully tap it into the crank while it's still cold.

I have read alot of people saying that a bearing is "smoother" and also last longer. From my real world experience I can say that neither one is "smoother" than the other and if anything the bushings last much much longer.

Once the bushing is installed I like to put a little bit of molybdenum grease on them as the molybdenum burnishes itself into the bushing providing long lasting lubrication.