Dynamo Bearings

[MotorBikeLes]

Assuming this is a USA made Delco Remy from the '50's, I am having difficulty believing it is metric sized. Have you had a vernier in there to actually measure things up?
I don't know if it is just me, but I could not access Argus25's armature article.
Les.
Edit, seems my post crossed with a few others.

[Radio Wrangler]

No, not heat.

Rather than risk mushrooming the shaft, I grip bearing outers in a vice and grind almost all the way through the outer. (Com protected and after I've got the new part!) Do this in two opposite places and nip in the vice (wearing goggles and a rag over it) Ping! and the outer is off.

Then I grind the inner carefully to minimise the mark in the shaft. A tap with a BLUNT chisel and ping again.

No force on the shaft, little heat to the com if I don't rush, and let it cool between grinding sessions.

David

[Radio Wrangler]

I agree Les. Americans of that era thought the metric system was a commie plot! (many still do) I had to remind them that imperial units meant the Roman empire not the British.

All things are possible, but now the bearing is off, it would be a good idea to act suspicious and mike the shaft. It could save some messing around.

David

[Goldie99]

Not sure if it helps - I also came across some older Delco (generator, regulator) service data, possibly too old for a 50's unit, but maybe worth a quick look - various pdf's about half way down this page:

http://www.navioneer.org/riprelay/Th...les/navion.htm

[Station X]

Extract from a current MRC Bearings catalogue. This confirms the 201 type bearing as being 12 X 32 X 10 mm, but does not explicitly mention an extended inner race.

FFS is the code for two felt seals.

[Station X]

MRC 201 FFS is replaced by MRC 88501.

Possible UK source:-

https://www.thexmod.com/item_detail.asp?id=28393

[Station X]

Originally Posted by MotorBikeLes

Assuming this is a USA made Delco Remy from the '50's, I am having difficulty believing it is metric sized.

Originally Posted by Radio Wrangler

I agree Les. Americans of that era thought the metric system was a commie plot!

The US did use metric bearings, but they specified the dimensions in imperial units, often rounding up or down. This resulted in what looked like very odd sizes which did not reflect the true size of the bearing.

[barrymagrec]

Certain metric bearing size were used in the UK by motor manufacturers including Fracmo and Croydon, I think because they were convenient for certain shaft sizes, ie a small shoulder on a 5/16 shaft becomes 8mm and many 22mm OD X 8mm ID bearings were used even going back to the war.

[emeritus]

Re #22, the recommended way of removing one of the bearings in the official Rootes workshop manual for my Hillman Imp, was to remove the outer race and then to cut through the inner race using a cold chisel, supporting the shaft on a heavy vice or anvil. Fortunately it was something I never needed to do. A press was needed to fit the replacement.

[G6Tanuki]

Felts are not really seals; they're intended more to provide a reservoir of lubricant for old-style sintered bronze bearings.

[If you want easy seals for these sort of things then the traditional solution was a 'Nylos' ring - a sort-of pressed-metal tin-can-top with a sharp forward-facing part that cut its own channel in the soft facing of its abutment so providing a quick-and-dirty 'labyrinth' seal to exclude contaminants from the bearing itself]

[Sparky67]

So, would it be more sensible long-term to replace the original felt/steel bearing with a modern equivalent with say Viton rubber seals, or use a NOS part matching the original?

Martin