I'm going to be doing a T56 conversion in a week or 2 and was wondering what are the pro's and con's of each one. And where should I buy it from, GM?

 

Bearings fail... bushings dont. You can get them at damn near any auto parts store but if i remember correctly I had to ask for one for an older chevy since it wasnt listed under LT1.

 

It's the same thing... It supports the tranny and provides a smooth surface when the input shaft and crankshaft are rotating at different speeds. If you have a summit magazine they have a roller pilot bearing you might want to look at, but most people usually don't have very many problems with these in the first place.

 

Do you have a part # for it, I can't find my summit catalog

 

SUM-G1700

 

Pilot bushings do not fail often, nor do bearings.

Obviously the bearing has more potential to fail as it has moving parts.

I use bearings in all my builds & have never had a failure. It should provide better shifting, but I'm not sure I could tell a difference.

You can get one from GM. It is listed for an 80's 6.2 diesel pickup truck. Cheaper than the aftermarket & tested for longevity by GM.....

Good luck in your choice.

 

The bearing/bushing shouldn't have anything to do with shifting - all it does is support the input shaft of the trans so it stays true. I used a bushing, just because there is (basically) no way a bushing can fail. I used to work for a clutch company and I've seen failed bearings before. Not pretty. I had a stock bushing, and it looked pretty good after 50,000 miles. I put a new bushing in anyway, since its only $5 or so.

 

While the bushing is primarily for the alignment & support of the input shaft to keep everything centered with the engine, the pilot bushing/bearing definitely can alter shifting characteristics. A bearing supposedly allows less friction, but as I previously stated, probably not enough to worry about.

When you shift, the trans intput shaft & clutch disk has to change speed to match the new gear you are shifting into. There is more mass to the driveline, so it wins (over the input shaft & disk) & causes the clutch to slow on an upshift until the clutch pedal is released. Then it matches the flywheel & accelerates the car. If it stayed at the same speed as the engine, pushing the clutch would do nothing.

If the input shaft is not free to spin at its own speed, it will somewhat act like the clutch is not disengaged by attempting to make the input shaft follow the flywheel speed. Poor shifting or at least increased syncro wear can result. If you have ever witnessed a galled pilot bushing, you would have thought the clutch is not completely releasing. I've only seen this once, but it is possible.

Furthermore, a car will actually function without one in place, but it may chatter on clutch release as the disk is trying to center itself on the flywheel. Trans damage can result as the input bearing is fully supporting the clutch disk.

I actually had a customer that could not get his car to stop chattering on initial engagement. On the 3rd try, he brought it to me to get it fixed. It chattered a little, but otherwise worked fine. I was rather surprised to see nothing in the crank when I pulled it apart. He was embarrassed to say the least.

Just trying to keep the facts straight.

 

You make a valid point, Lonnie Pavtis. It looks like what you are saying is that in rare cases, the bushing may provide too much friction, therefore torque is transmitted from the flywheel directly through the input shaft instead of through the clutch disc. Yes, I suppose that is possible, but I have never had that experience. I think if it is lubricated and installed correctly, a bushing will have no problems (given that the tolerances are not out of spec on the bushing itself).

 

Patroit..... you are 100% correct. Just explaining the theory behind it.