Press the bearing or not

G

Grampy

Member
A question came up in conversation today. In the 1930 transmission, does the bearing need to be pressed onto the main shaft, or should it slide on without needing to be pressed?
We've consulted two recognized authorities and have gotten conflicting answers.
It's been quite awhile since I built my transmission, but I seem to recall pressing the bearing on.
What do you guys think?
Thanks
 
If there is nothing to hold the inner race firmly to the shaft, it could creep and the shaft could get worn at that spot. Does the U-joint clamp the bearing in place?

Doug
 
Most all of the transmissions I have worked on I have had to press the old front bearing off and press the new bearing on. The rear bearing is a different story. Most seem to slip on and off. Occasionally I have had to press them on and off. I suspect they originally were a press fit but must have spun somehow. The stop on the mainshaft and installation of the U-joint holds ithe rear bearing in the proper place.

Tom Endy
 
Rule of thumb is that a bearing is always installed with a race fastened to the part of the machine that rotates. In your case the shaft rotates so the inner race of the bearing should be a press fit onto the shaft. If the shaft is worn so that the race is a slip fit, loctite can be used to secure the bearing race to the shaft.
 
I assume he was talking about the rear bearing. Doesn't that fit over splines, which might make a tight press fit problematic? I expect the front bearing to be a press fit.

Doug
 
I lay the bearing over a hundred watt light bulb for a while to heat up and expand, I then slip the bearing in place, no press needed. This method was published in one of the national club magazines many years ago and has always worked for me.
 
I use a bearing heater when I can. The light bulb works well too. 220 degrees bearing temp and it will fall right on.
 
It is the rear bearing we were talking about, and, yes it does fit over splines, which is exactly what started the conversation in the first place.

Thank you guys for your comments.
 
Neither bearing needs to be pressed on or should not be pressed off. Either might be a tight fit but, both are held on by a clip so, pressing is not needed. The front by a cup circlip and the rear by a small standard circlip.I have never had to press one on, just some light tapping with a hammer and pipe but, some are a bear to remove.
 
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