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Dear All,

We found some bits of chewed up brass loose in the differential housing of my 900 (Light Eight). I was thinking they were to make some extra noise, like cards in the spokes of a bike. Is this correct?

Just kidding. Really.

Seriously, anyone have a guess as to where they came from? All teeth on the ring gear and pinion gear look fine, as does the spline where they axles come in. The gears seem to rotate without any grinding. The bits are pictured below.

Thanks,

Tom

Edit: Pieces are close to 1/2" across.

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Looks like somebody was smuggling gold nuggets (you wish) ha ha

Thomas, I'm number 36 who is clueless viewing the nuggets.

Interesting, there is some commonality to the shapes. I did go down and take a look inside my spare Angelset rear and though I didn't take it apart, I saw no brass parts in it.

Was it possible that some component was brazed on in the past 79 years, and the chunks of brass are braze material that came loose?

Tom,

Most likely these came from the brass cages used to separate the rollers in the tapered roller bearings on each side of the ring / crown wheel carrier, or from the brass cages of the two ball roller bearings that support the front and rear of the pinion gear.

Some of the tapered roller bearings used steel cages, so my hunch would be they came from the ball bearings that support the pinion.

If the 900 differential is like the 901 it is easy to pull the carrier out that supports the pinion and check the front and rear pinion bearing. The front pinion bearing is a double row ball and about twice the size of the rear pinion bearing because it carries radial and axial load.

The rear pinion bearing is a single row ball bearing.
There may be some brass shims behind the pinion carrier.

Make sure to save these, they set the depth of the pinion relative to the ring or crown gear and make sure that you have the proper mesh / contact between the two gears.

I'd look into this before driving the car any more. Even though brass is soft if a piece gets caught in the gear mesh it could break a tooth on the ring or pinion gear.

Good luck,

Dave

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Some additional pictures of the bearings used in the differential.

Correction - the pinion rear bearing is a double row ball, not a single row.

Note - the brass cages have dis-colored because they have been attacked by the old gear oil that had sulfur in it, to give it EP properties. Over the years moisture combined with the sulfur to form sulfuric acid, which attacked the brass.

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The side carrier bearings shown both had steel cages, the brass is probably from one of the pinion bearings.

The titles to the pictures for the pinion bearings are reversed, the larger pinion bearing is towards the front, smaller to the rear.

Dave,

Thanks tons for the info. I have the differential apart, but have not separated the ring and pinion from the pinion carrier. I will do so tomorrow. Your close of of the bearings and bearing cages makes be think that you are onto something.

I will try to remember to report back.

BTW, the pictures of the 1930 differential are from my other car!

Cheers,

Tom