The Stovebolt Site Forums The Shop Area Driveline PILOT BEARING QUESTIONS

Purchased a new pilot bearing and before installing it I slipped it onto the nose of the input shaft to make sure it fit.
I also measured the outter diameter to compare with the old one I had removed. I was within 0.001 "
When i went to install it I had to really beat on the seal installer to get it to fit.
I went to install the tranny and found that the nose of the input shaft would not fit into the pilot bearing whereas it had fit on before when the tranny was out. I presume that due to the difficulty of the pilot bearing install that by forcing it into the crank shaft opening for it that somehow it compressed inward by that 0.001" causing the fit problem I am experiencing now.
Questions:
1....can I ream open the pilot bearing by 0.001 " of an inch and do it while it is still in the crank hole ? The hole is deep enough but not sure what the tolerance should be between the input shaft nose and the inner diameter of the pilot bearing ??? What specifically is the amount of tolerance ?
2.... Should these pilot bearings be that tight going in ??
.......If I have to remove the pilot bearing to open it up a bit I might as well buy another one.
I just hated to remove the pressure plate and if I do is it ok to use the same grade 8 bolts and washers ???

Yes you could ream the bushing with a hand reamer of the correct size, however the cost of the reamer would be more than a whole box of pilot bearings.
You deformed the bushing installing it.
Make sure the crank hole is free of burs and brake the outer edge if there isn't a chamfer. The bearing should have a relieved edge as well.
The trick is to start the bearing perfectly straight to the hole.
If you have to tap it more than 4 - 5 times, it will deform.

ok Jim...that is what must have happened, I deformed it going in.
I will order a new pilot bearing and remove the pressure plate.
Questions:......can I reuse the same pressure plate to flywheel bolts & washers
They are or were new ????

also what should the tolerance be between the nose of the shaft and the pilot bearing?

I used an old clutch alignment tool with a heavy washer to drive in my pilot bushing. Lube up the pilot bushing and as Jim stated make sure there are no burrs at the crankshaft hole. The clutch alignment tool I have is metal and it has a nipple on it that will fit the pilot bearing hole. Place the heavy washer over the nipple and tap the pilot bushing home. You should not have to bang the pilot bearing in. It should install with a few good taps. If the bolts and lock washers are new that you installed, you can re-use them. If not, I would get new ones.

Tim

Good morning Zoe.

One thing I would try before replacing the pilot bushing is placing some abrasive like valve grinding compound or even paint polishing compound on a transmission main drive gear nose and rotating that into the hole to enlarge the hole. I have used those abrasives to ever so slightly polish carburetor metering rods in my lathe to make tiny changes in diameters. An interference fit of even a fraction of one thousandth of an inch will cause the interference you are experiencing.

If you search "BFH" on this forum you will see how often the damaging brute force you used is actually recommended. Yellow metals are very malleable and any brutality changes their shapes. If there's any trouble removing the bushing you can thread it then pull it out with a piece of allthread or a bolt. Every problem has a solution!

If you go with a new bushing, in addition to the advice already offered you might want to put the bushing in the freezer for a couple of hours before immediately installing it.

I second the freezer method, it makes a difference. I made the mistake of installing one in my cold garage after having the bushing inside my warm house. That is the opposite of what you want to do!

There are great ideas on this subject and I thank everyone for there suggestions.

Here is what I ended up doing.....I removed the pressure plate and clutch disk to make an easy access to the pilot bearing....I use a medium grit sanding tube from my drummel set and proceeded to grind away slowly ......when the plastic line up tool was able to be inserted into the pilot bearing with out having to push too hard I then tried installing the tranny without the pressure plate installed and using pilot pegs in the upper bellhousing holes I was able to push the tranny onto the pilot pegs to help keep the tranny at the right angle as it is tough laying on your back pushing this small but heavy tranny by hand and it dosent help being over 70.
Tranny went in nice.
So now I am planning to try a tranny install with the pressure plate installed and hopefully all will go well.....thanks to all.

An update....installed the pressure plate and disk and the tranny went in and now is installed....thanks again to all ...

IMO: Sanding/grinding/or using compounds on a bearing or on a part that goes in a bearing or a part that the bearing goes into, is a NO NO. I advise not to that next time. It would be near impossible that some of the fine particles did not get in. Sealed bearing or not. Usually pilot bearings are only sealed on one side. You can't clean the bearing afterwards because you will vacate the pre lube. The most dangerous of the above sanding comments would be sanding on the bearing itself.
Fine particles= "dust" from the sander/wheel and/or "dust" from the bearing metal.

The pilot bearing I used is a solid bronze block of metal, no moving parts. I did not use an actual bearing for which your advise is right on...thanks

Unfortunately, the engine/drive-train was not designated, and, nobody asked?

Most likely you are referring to a stovebolt 216/235/261 which has a sintered bronze/metal pilot bushing.

As Tim says: It's called a pilot bushing, not a pilot bearing. Big difference.
"We have here is a failure to communicate, boss."

I meant to say bushing and i said bearing........sorry and thanks again for all the help.

If the bushing / bearing were mine. I would not SAND or REAM it.

Here's some basic info on oil filled bronze bushing lubrication.

http://www.lm-tarbell.com/machining_sintered_bronze.htm

Here's the GM NOS sintered bronze clutch pilot bushing I used and it's original GM box.

http://i669.photobucket.com/albums/...ze/Crankshaft_bushing_2__zpsmaaeww4i.jpg



George
'54 3600

I think Zoe is OK now. He didn't do anything wrong. The bushing CAN be called a bearing in the auto world. I should have asked about it.