420 crawler final drive bearings

danny · Post by **danny** » Fri Nov 28, 2014 7:05 am

Hello
I have found spherical tapered roller bearings on both ends of the drive shafts leading out to the sprocket but regular tapered bearings on the upper pinion shafts. My question is: Has anyone that has rebuilt their final drives gone to the Timken 390A regular tapered roller bearing? and has it worked out OK over the years? I understand that the spherical bearing would help in self alignment but I don't see any need for that.
I guess someone before me many years ago may have installed the spherical bearings in error.
I need your input. I am a very capable mechanic but new to final drives. The regular tapered bearings are less expensive as you know.
One other question: What method have you found best to build up the output shaft seal area? Mine are in need as grit and father time have worn them to the point that a new seal probably will not do the job.
Thanks a lot for your experience.

Post by **Lavoy** » Fri Nov 28, 2014 10:11 am

The spherangular bearings are obsolete and superseded by regular bearings, you won't have a problem.
Lavoy

Ray III · Post by **Ray III** » Fri Nov 28, 2014 10:24 am

To repair the seal surface get the correct size repair sleeve, fill the holes with JB Weld and slide it over. Be sure the outer seal lip ends up facing outward to keep dirt out.

danny · Post by **danny** » Fri Nov 28, 2014 11:05 am

Thank you very much for that info.
Have you ever built up the seal area of the output shaft?
I was thinking spray welding. What are your thoughts?

thanks again

Paul Buhler · Post by **Paul Buhler** » Fri Nov 28, 2014 5:20 pm

You may find this link helpful. See page 2 for using speedi-sleeves in a similar situation.
http://www.jdcrawlers.com/messageboard/ ... c&start=15

JimAnderson · Post by **JimAnderson** » Fri Nov 28, 2014 9:01 pm

Danny,
I am doing a pair of final drive shafts now.I have welded the worn area with 7018 and remachined the seal area to size.It may not be the most popular way to do it but it has worked for me.Spray welding ,done right is a good option but in my area no one does it that I trust.One of the shafts I am doing now shows evidence of having this very way of repair in the past,stick weld and machine.Speedi sleeves are a good option on the pinion shafts,jmho.Luck,JimAnderson

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