Bearing Help

[Buccaneer]

All the roller / needle bearings I need for my Firestone
Lower Unit have a "X" after the number.
What does X designate?
For Example, I have these Torrington Bearings I need to replace….
B-108 X
BH-812 X

I’ve found bearings online, but none with the X suffix.
Thanks, Clueless

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[foot_doctor]

The X suffix denotes EXTRA PRECISION. The B-108X is now GB108. I have not had any experience with the BH-812X, but I suspect that a GBH812 is not available. The origials were made by Torrington, and the company is now owned by KOYO. You may not use a B108 to replace a GB108. The B108 has a slightly larger diameter, and when pressed into the bore, it will shrink too small to accomodate the shaft it supports. The GB-108 is for a 5/8" shaft and is 1/2 inch long. The BH812 is for a 1/2" shaft and is 3/4" long. If I can locate my old Torrington catalog, I’ll try to find the specs for your bearings and post them here. R.T.

[Buccaneer]

Much appreciated Doc!
P.S.- Found the bearings on Amazon, Thanks!

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[Buccaneer]

Received my new GB prefix Koyo needle bearings today to replace my
old Torrington bearings with the X suffix as suggested.
The new bearings fit on the shafts okay, but I’m able to slide them
in the bores by hand. Presume I should have had to "tap" them in?
The old ones sure had to be tapped out. I put some locktite on the
bearing shells and installed them for lack of a better idea.
Will this work?

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[Mumbles]

Try and find the Torrington or Koyo PDF catalogue on line to check the sizing of the new bearings. They should be a press fit and if they fell in the hole, they might be metric.

[Buccaneer]

Worth a try, thanks Mumbles.

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[Buccaneer]

I have been studying up on the needed needle bearings for the Firestone.
Trying to replace the old Torrington bearings,
B-108X
BH-812X
The GB-108 and GBH-812 Koyo bearings I was steered to, are .002 to .003 too
small in the OD, and too loose on the shafts as well.
Never did find out for sure what the "X" suffix meant 65 years ago, but
evidently not "precision ground" as the G prefix series Koyo bearings.
Did find a handy Torrington Prefix and Suffix chart at……

http://www.ahrinternational.com/TORRING … ture.shtml

Interesting enough, they don’t have a "X" suffix in the list.
Some of the data says…..
G = Precision Ground
B = Regular Series, Inch Dimension
BH = Large Roller Series, Inch Dimension

From what I’m understanding, "Precision Ground" means your bearings
are going to have a larger ID, and smaller OD.

Interesting also, Amazon gives the same dimensions for Regular
and Precision ground bearings 🙁

I can see wanting the needles precision ground for hi rev shafts, but
couldn’t they make them so they’re standard size after they’re ground?
And why would the shell have to end up under size?

Tried looking on the KOYO site for actual bearing dimensions, found a
large PDF file, but my browser didn’t like it, and rolled over and died.

Think I’m going to order the standard bearings and hope for the best,
and try to sell the G series that are too loose.
Live and Learn.
Buccaneer

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[Buccaneer]

For the next person replacing their Torrington bearings with a "X" suffix,
I got a reply and figured out why my GB-108 Koyo bearing did not fit…..

The B-108X is the old call-out. New part number is B-108 and we have stock @ $6.78.
X does not mean extra precision which is why your GB-108’s were loose in the housing and shaft. You’ll be fine with the B-108.
Thanks,
Randy Faber
Impact Bearing

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[chinewalker]

Hmmm. So why did the X and GB series apparently interchange with my KF7? See my previous thread here. I had actually tried the B-series bearing first, and it was too tight. The GB series bearing worked like a charm…
viewtopic.php?t=237

[Buccaneer]

Yeah, I read that one before and left me confused as well.
Will report back when I get the next batch of bearings!

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[Author]

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