Is my pinion bearing worn too far?

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Mark Nunn
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Is my pinion bearing worn too far?

Post by Mark Nunn » Tue Sep 24, 2019 1:54 pm

I pulled apart my spare torque tube and was encouraged by what I measured. The front bushing had been replaced and the clearance between it and the driveshaft was less than .001”. The shaft had .001” of wear compared to the adjacent diameter that was not in contact with the bushing so I suspect the bushing was reamed to fit. So far so good.
Pinion gear2.gif
I cleaned and mic’d the bearing rollers. They should be .562” but .002” under is acceptable according to Glen’s book. The rollers measured .560” to .561” near the front but many rollers were down to .558” (.004” under) near the pinion gear where forces are greatest. I have not measured the spool I.D. yet. I still need to check the bearing fit with the cleaned spool over the bearing. If that does not reveal bearing clearance problems, does this bearing still need to be replaced?

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Re: Is my pinion bearing worn too far?

Post by Steve Jelf » Tue Sep 24, 2019 3:34 pm

If the car won't be driven much you could turn the bearing around with the big end toward the gear and probably get by with that. But for a driver I would ditch the stock bearing and install the FP version.
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Mark Nunn
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Re: Is my pinion bearing worn too far?

Post by Mark Nunn » Tue Sep 24, 2019 8:10 pm

I was planning to install a sealed bearing in my car's torque tube until I discovered the condition of my spare. It's better than the worn out junk in my car. I think I'll go ahead with the FP bearing in the spare and not regret a what-if.


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Re: Is my pinion bearing worn too far?

Post by wayne sheldon » Tue Sep 24, 2019 9:29 pm

I would definitely run that one! However, the FP version is no doubt the best way to go.


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Re: Is my pinion bearing worn too far?

Post by John kuehn » Wed Sep 25, 2019 8:56 am

I agree that the FP bearing set up is the way to go for a replacement. One of the best upgrades for a T you can do.


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Re: Is my pinion bearing worn too far?

Post by Mustang1964s » Wed Sep 25, 2019 9:08 am

I am going to ask a stupid question.
What is the FP version?

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Re: Is my pinion bearing worn too far?

Post by Steve Jelf » Wed Sep 25, 2019 9:50 am

The inevitable often happens.
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Re: Is my pinion bearing worn too far?

Post by Original Smith » Wed Sep 25, 2019 10:42 am

Your can't find out how much wear there is, until you mike the rollers. Just looking at it accomplishes nothing.


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Re: Is my pinion bearing worn too far?

Post by Adam » Wed Sep 25, 2019 10:56 am

He did mic the rollers. The info is in the original post. Read it and offer an opinion...

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Re: Is my pinion bearing worn too far?

Post by Mark Nunn » Thu Oct 03, 2019 8:27 am

I am going to replace my torque tube and driveshaft with my spare after some refurb and paint. Should I replace my driveshaft bushing? The only “problem” I see with it is that it is babbitt. Based on what I’ve seen in my spare rear axle and torque tube, they were rebuilt not long before they were taken out of service. The bushing-to-driveshaft clearance is like new. I can barely see any needle movement on my dial indicator when I wiggle the driveshaft. I believe there is no more than .0005” clearance. The machined diameter of the driveshaft measures .998” where it is not in contact with the bushing. It measures .997” at the bushing. That means the babbitt bushing is sized to the .997” shaft. Are the replacement brass bushings reamed for 1.000” driveshafts? I am afraid that I will end up with .003” shaft-to-bushing clearance. That is not bad but not as good as what I have now.

If my babbitt bushing is a later replacement, should I replace it or keep it. I have Glen’s rear axle book and it clearly states that a babbitt bushing should be replaced no matter how good it looks.

Thoughts on the subject?

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Re: Is my pinion bearing worn too far?

Post by Steve Jelf » Thu Oct 03, 2019 9:43 am

If my babbitt bushing is a later replacement...


These thirty-year-old NOS tires look brand new. These 90-year-old NOS cotton band linings look perfect. This NOS Babbitt thrust washer looks good to go.

Some materials are very stable for decades, or even centuries. Some are not.
The inevitable often happens.
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