JD 870 Pilot Bearing-Shaft fit

[Jim1934]

Greetings.
My 870 has a 6203 pilot bearing which has a bore of 0.669 inches, or 17 mm.
The shaft that goes into that bearing measures 0.664.
Zero.005 is a lot of slop.
Can one tell me if my shaft is in spec.? I am aware it cannot be a wring or press fit.
Thanks, Jim.

 

[Partspring]

I would not be concerned with a .005 loose fit input shaft to pilot brg.

 

[Jim1934]

I would not be concerned with a .005 loose fit input shaft to pilot brg.

Thanks for your response. I am wondering why you would not be concerned. Is that JD's intent?
Jim

 

[Mysfyt]

I don't know what JD's specs are, but that would be more slop than any pilot bearing I've dealt with. Does the end of the shaft look worn?

 

[Jim1934]

I don't know what JD's specs are, but that would be more slop than any pilot bearing I've dealt with. Does the end of the shaft look worn?

I didn't inspect it very close.
I will mike the dia. all around and see if the measurements are consistent.
Tractor not at this site so will take a day or two to do so.
Perhaps JD used a special size bearing. That's why I am looking for shaft specs.
Thanks, Jim

 

[Mysfyt]

Let's for the sake of argument assume it's worn. You can have a custom bearing machined out of bronze that would work just fine for the application and it wouldn't be expensive. My old 1953 Jeep had exactly this for a pilot bearing.

 

[Jim1934]

Let's for the sake of argument assume it's worn. You can have a custom bearing machined out of bronze that would work just fine for the application and it wouldn't be expensive. My old 1953 Jeep had exactly this for a pilot bearing.

Don't think shaft is worn. Pilot is 0.666 -.0000,+.0005 all around.
Perhaps the shoulder behind pilot pushes up against inner race and rotates same?
Otherwise pilot spins in the 0.669 inner race.
BTW Mysfyt, beautiful lathe.

 

[Winmac]

In the first post the shaft measured .664 and now it's .666, is that a typo? Or is it a error in your measuring equipment?

 

[Mysfyt]

Don't think shaft is worn. Pilot is 0.666 -.0000,+.0005 all around.
Perhaps the shoulder behind pilot pushes up against inner race and rotates same?
Otherwise pilot spins in the 0.669 inner race.
BTW Mysfyt, beautiful lathe.

I did a little research and .001-.003 is the tolerance for a slip fit on a 17mm bearing. So I'm thinking your good to go with what you got. Maybe somebody with a JD manual will come along and confirm this.

Thanks for lathe compliment. I refer to it as my 27 inch hobby lathe. Saved it from going to the scrap yard.

 

[Mysfyt]

Don't think shaft is worn. Pilot is 0.666 -.0000,+.0005 all around.
Perhaps the shoulder behind pilot pushes up against inner race and rotates same?
Otherwise pilot spins in the 0.669 inner race.
BTW Mysfyt, beautiful lathe.

I did a little research and .001-.003 is the tolerance for a slip fit on a 17mm bearing. So I'm thinking your good to go with what you got. Maybe somebody with a JD manual will come along and confirm this.

Thanks for lathe compliment. I refer to it as my 27 inch hobby lathe. Saved it from going to the scrap yard.