Do "NOS" gears have lapping compound on them?

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Weak440

Weak440

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So, I was telling a local junk yard/collector about how I would like to find a set of 3.23 gears. Well, supposedly He found a "NOS" set. I was skeptical because they claim to be "coated with the factory yellow lapping compound "... That sure looks like the marking compound used to set up the gears. Also, the threaded portion of the pinion looks like it has rust above where the nut would set if it had a yoke tigthened down on it.

What do you guys think... are these NOS gears or... have then been setup before and never used? Does that look like red loctite in the threads on the ring gear?
 

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Are those photos something they sent you, or do you have the set?

If you have them post a better pic of the ring gear teeth. The pinion sure looks pretty clean. As for the compound I haven't a clue.
 
I have to say (looking at pictures on my phone) it looks to me like there has been a race on the big end of the pinion by the gear there appears to be lateral markings like a race has been removed. Also looks like a yoke has been on it. But again little screen old eyes.
 
They are pictures they sent me. I have them on my phone. I am working on getting them uploaded right now.
 
I believe these are all the pics I have of them.
 

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Dubob said:
I have to say (looking at pictures on my phone) it looks to me like there has been a race on the big end of the pinion by the gear there appears to be lateral markings like a race has been removed. Also looks like a yoke has been on it. But again little screen old eyes.
Click to expand...

I would say you see pretty good, lol.
 

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The gears look new to me. I would have to see them in person before I could make a final decision on the bearing area. And yes, I know General Motors put the marking compound on replacement gears from the factory as I replaced a good many when I worked at the local chevy dealer. They came lookin just like that.
 
RustyRatRod said:
The gears look new to me.
Click to expand...

They sure don't look like they have been run at all to me as well. There are some marks there where it looks as though there was a bearing race slid on and off, but that could be tooling marks too.
 
They are cut as a matched set, look for the matching numbers on each piece. Even if its painted like the 42. The +1 may be a shim designator. Look ok to me.
 
I agree that they don't look like they were run but it does look like someone pressed a bearing cone onto the pinion. Maybe they started to use them then decided on using a different ratio? Looks like rust on the pinion threads, not Loctite. That'll most likely clean up with a wire wheel. I'd run a thread tap into the ring gear bolt holes cause they also look rusted. Their 3/8-24 left hand threads. As Pishta said verify that they are a matched set by the numbers and date code on them. The +1 is a designator that the factory used. They had a specific factory pinion depth and that designator is how much to vary from it.
 
Does it matter if they are Nos or not?
You were looking for a set, he has them so I don't see the problem.
Unless he's charging big bucks for his Nos set, I would buy them from him.
 
The yellow is not lapping compound, but gear paint for checking the pattern on the teeth. (maybe someone didn't like what they saw):dontknow:

It looks as though it had bearing race on the pinion, and the red stuff is a form of loctite that the factory uses.

I say someone bought it and changed thier mind for some reason.

If you get it take a look at the ends of the teeth on the pinion gear closest to the bearing side.
It's really easy to take a chip off of one of the teeth if you have to remove a bearing race after it's installed.

I would catagorize that as "installed but never run" but somebody doesn't know anything about it if they called that lapping compound.
 
i have been a machinist for a LONG time. but have never ran a lapping machine. but have talked to guys that have. i think the lapping compound would NOT be left on the gears. what is on them is marking paint, for testing the grind on the gear. gust my idea.
 
The 'wear' pattern on the paint on the ring teeth in particular sure looks like a normal mesh pattern, as if these had been set up and spun around some.
 
moe7404 said:
i have been a machinist for a LONG time. but have never ran a lapping machine. but have talked to guys that have. i think the lapping compound would NOT be left on the gears. what is on them is marking paint, for testing the grind on the gear. gust my idea.
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nm9stheham said:
The 'wear' pattern on the paint on the ring teeth in particular sure looks like a normal mesh pattern, as if these had been set up and spun around some.
Click to expand...

Exactly, on both counts.
It's just what was told to the OP was obviously someone who didn't have a clue.
They were painted, spun and they decided against them for whatever reason.
 
Lapping compound, marking compound, marking paint. WTF ever. People call the same things by different names a lot of times. Really don't know what the guy means without asking. Most people who know anything about gears know what the yellow paint is for, regardless of what they call it.
 
lapping compound is NOT the same as testing paint. some times its just paint for "oil painting". or Prussian blue. if lapping compound was left on the gears it will add more wear to the gears, when in use. lapping compound is the way the gears are finished. on a very special machine. the lapping takes off only a few thousands. add makes the surface way smoother that a milling machine could do.
 
moe7404 said:
lapping compound is NOT the same as testing paint. some times its just paint for "oil painting". or Prussian blue. if lapping compound was left on the gears it will add more wear to the gears, when in use. lapping compound is the way the gears are finished. on a very special machine. the lapping takes off only a few thousands. add makes the surface way smoother that a milling machine could do.
Click to expand...

Who said it was the same? I been lapping valves in since I was a kid. I was merely saying that sometimes people call things by different names than other people. While they may know what they mean, they sometimes get the terminology wrong. You don't lap gears in anyway. Anyone who sets them up knows that. So it's a moot point to argue. It's marking compound. Pretty obvious. Gonna be purdy stupid for it to take up three pages arguing about something that doesn't amount to a hill of beans. That was my point.
 
There are a lot of things on here that don't amount to a hill of beans, but people still go on for pages and pages.

Which isn't the point either :)
 
Those are new, OEM take-out gears. In other words, they came out of an NOS 8.75 third-member.
 
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