Condition of Rear End Gears

[Charlie Stephens]

A friend purchased a set of rear end gears from a fellow club member. The gears had been described over the phone as in “nice shape” and since it was a fellow club member that was trusted no photos or details were given. How would you describe the condition of the gears, would you run them, would they make noise or be short lived? Also they appear to have been media (not sand) blasted from their patina. Would this cause a problem?

Pictures show the worst teeth, others are probably "ok".

Charlie Stephens

[Kurt in NJ]

Ok for a doodlebug
Ok if you think---"it's just an old car, it won't matter"
Ok if you don't mind the noise

[Russ/40]

Lots a noise and a short life.

[MikeK]

Why doesn't your friend just tell the other club member that upon fine inspection, some of the pinion teeth have rust cavitation/pitting on their thrust surfaces and this is not considered "good shape". I belong to two clubs, and I've never heard of anyone 'sticking' another member with a part they didn't like, even if it was perfect.

[billwill]

Junk

[SeaSlugs]

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yea, pits in teeth ar enever good, that means you now have half the surface area in contact with the tooth it connects with and those pits act like a rasp to the ring gear. Will wear rather fast to the bottom of the pits and who knows how much to the other gears teeth.

even my AA's worm drive didnt look like that. still had shiney contact surfaces and it sat outside for 60 years...

[H. L. Chauvin]

FWIW:

In my humble opinion, this situation could be regarded as a "time" related decision.

1. It will take "time" to put the differential back together the first time; and,

2. If it makes noise & your friend does not like the noise, it will take "time" to dismantle it; & it will take "time" to buy & receive new gears; & it will take "time" to reassemble the differential a second time; ............ or possibly,

3. If it does not make noise initially with the indicated visible pits on some gears, but with "time", it later makes noise in the very near future, figure spending "all" of the same extra "time" as that indicated in the above paragraph 2.

4. Now, if "time" is not valuable, maybe try it; however, if "time" is precious & valuable, think about considering new gears; but, please warn your friend that if he tries the gears & they make noise, and if he attacks his fellow club member who sold him the gears, he will have to do additional "time".

Hope this helps.

[Flatout]

Junk. Installing them will add wasted time to your wasted money. These gears appear to have had SERIOUS rust, removed by blasting. Are they even a matched set?

[tbirdtbird]

NG
who could think they are good?

[Charlie Stephens]

Originally Posted by Flatout

Junk. Installing them will add wasted time to your wasted money. These gears appear to have had SERIOUS rust, removed by blasting. Are they even a matched set?

The pinion gear has a number on it that looks like it was put on when it was at the factory. The ring gear has the same number put on by a 5 year old with a vibrator etching tool. Does this mean they are a matched numbered set, maybe? I sincerely appreciate the comments so far and look forward to more.

Charlie Stephens

[Bruce Rossiter]

It looks to me that the drive side of the gear is smooth and the coast side is the rough side. If this is the case, the smooth side of the gear is in contact going forward and the rough side of the gear is in contact going backward and it should work fine.

[Tom Endy]

Originally Posted by Charlie Stephens

The pinion gear has a number on it that looks like it was put on when it was at the factory. The ring gear has the same number put on by a 5 year old with a vibrator etching tool. Does this mean they are a matched numbered set, maybe? I sincerely appreciate the comments so far and look forward to more.

Charlie Stephens

I think this was the practice at the factory as I have seen countless R&P sets numbered in this manner. I suspect the routine was to pull a numbered pinion from stock and scribe the same number on the flat side of an un-numbered ring pulled from stock with a vibrating tool. In this manner they became a matched numbered set, and were such when they ran together for a few thousand miles.

Tom Endy

[Tom Wesenberg]

Originally Posted by Bruce Rossiter

It looks to me that the drive side of the gear is smooth and the coast side is the rough side. If this is the case, the smooth side of the gear is in contact going forward and the rough side of the gear is in contact going backward and it should work fine.

From what is pictured I see the same thing as Bruce. I wouldn't be surprized if the went for years, but if you're set on 4.11 gears and could find a better set, I'd opt for the better set.

I have a tranny with some lightly rust pitted gears. Some day I just might blast them clean and run it in my own car to see how it does.

As Kurt said, they'd be fine in a doodlebug.

[H. L. Chauvin]

Hi Charlie,

One point on the bright side is, no doubt they will work just fine mechanically & the only drawback in my opinion is that these pitted R & P gears could possibly be noisy.

If your friend is not a senior citizen, and/or is not a little on the deaf side like most of us, he could buy a good set of ear muffs from Cabello's for about $20.00 if he rides alone; but if these gears are going on a (4) door with 5 passenger capability, 5 sets of ear plugs would be cheaper.

Another good point is people riding bicycles out front could hear him coming from a good distance & they could move to the side of the road in plenty of time to be safe; plus his horn would last longer if he never had to use it often.

Others will probably advise of other good features to add "just in case" these gears may be noisy -- life appears to always be full of gambles.

[tbirdtbird]

haha H.L. LOL on that one!

[SSsssteamer]

The pitting is on the reverse drive direction of the pinion gear in the first photo. I never use gears that are pitted as the pitting weakens for teeth for breaking off. The gear teeth are hard like glass. To break glass, you scribe a line across the glass to break the glass on the line. The same is true of a gear tooth. With pits lined up on a tooth, it gives it a direction break the gear tooth off on. For today's street travel, 4.11 is a too low of a gear ration. 3.78 or 3.54 are a lot easier of the A motor. The model A motor should never be ran at a too high of RPM because the babbit bearings just won't take it. 4.11 works if you don't plan on driving much over 40 mph. On our roads out west, 60 mph is the safe Model A top speed for keeping up with today's traffic.

[Growley bear]

Originally Posted by billwill

Junk

Ditto

[Rowdy]

I agree with "JUNK". Rod

[Charlie Stephens]

Originally Posted by SSsssteamer

The pitting is on the reverse drive direction of the pinion gear in the first photo. I never use gears that are pitted as the pitting weakens for teeth for breaking off. The gear teeth are hard like glass. To break glass, you scribe a line across the glass to break the glass on the line. The same is true of a gear tooth. With pits lined up on a tooth, it gives it a direction break the gear tooth off on. For today's street travel, 4.11 is a too low of a gear ration. 3.78 or 3.54 are a lot easier of the A motor. The model A motor should never be ran at a too high of RPM because the babbit bearings just won't take it. 4.11 works if you don't plan on driving much over 40 mph. On our roads out west, 60 mph is the safe Model A top speed for keeping up with today's traffic.

Actually the gears were to be run with an overdrive but that is another story.

Charlie Stephens

[Growley bear]

Each one of those pits is a stress riser, leading to a weakened condition of the gear. Even though the pits are on the coast side, that side of the gear will contact the ring gear and the very fine particles of steel will act as a grinding compound on other very expensive internal parts.
The manufacturers used to lap the ring and pinion gear sets and checked them for tooth contact and noise, that is how they come to be matched. One manufacturer that I know of used the smoothest and least noisy gear sets in convertibles-roadsters-drop head coupes.
When installing parts that are marginal at best, there is always that bit of doubt concerning reliability. Remember that if any thing can go wrong, it will and at the worst possible moment.
However maybe if time of no consequence then ????

Chet