Dynamo bearings - what number are they? (and mag ones while I'm at it...)

[t20racerman]

Hi all

I went to clean up my dynamo as part of the rebuild process and found that the biggest of the two bearings is seized solid, and that the whole bearing spins nicely in the alloy casting where it is supposed to be a tight fit!
Also, the three small threaded holes in the alloy bearing holder - the ones that the cork seal holder bracket screws down to - are stripped.

So:
I need a new bearing - what number is it please?
Anyone got a better condition bearing holder casting that they fancy punting out?

Thanks
 

[trevinoz]

Hi Racerman,
                       The drive end bearing is 6202 and the comm end 608. Use rubber sealed type and replace both.
I have plenty of end plates but am a long way from you.
The screws you refer to are 5BA which is close enough to 1/8".
Tap the holes to 5/32BSW or 4BA and it should be right. You may have to machine the diameter of the screw heads to fit but the cork gasket probably wouldn't care if you don't.
Loctite the drive end bearing into it's housing with a suitable grade.

  Trev.

[t20racerman]

Hi Racerman,
                       The drive end bearing is 6202 and the comm end 608. Use rubber sealed type and replace both.
I have plenty of end plates but am a long way from you.
The screws you refer to are 5BA which is close enough to 1/8".
Tap the holes to 5/32BSW or 4BA and it should be right. You may have to machine the diameter of the screw heads to fit but the cork gasket probably wouldn't care if you don't.
Loctite the drive end bearing into it's housing with a suitable grade.

  Trev.

Thanks Trev. I'll order some bearings tomorrow. Good idea to get the RS sealed type too.
I'm sure I can make the end plate work if I can't pick up another from somewhere, so thanks for the thread info.

All the best
Adrian

[t20racerman]

Just modified this thread - I might as well get some mag bearings too while I'm at it  - what number are they?
As always, thanks for the help guys. 

[trevinoz]

Racerman,
                   Depending on the age of your magy, the drive end is either E15 or E18. Slip ring end E15.
The number is the shaft diameter in mm.
I hope that you have a bearing puller.
  Trev.

[fido]

Remember you might have to shim up the endfloat on the mag if you fit new bearings.

[wilko]

And you'll need the special insulating cup washers. What a nightmare they are to fit. Be warned!

[MG]

And you'll need the special insulating cup washers. What a nightmare they are to fit. Be warned!

Coat the bottom and outside of the bearing race and one side of the star washer with a very thin layer of contact cement and press them together carefully, you got to get the bearing race centered over the hole in the washer properly!
Then bend up the ears of the washer and hold them in place with a strong rubber band, which will come off automatically as you press the bearing race home in the housing.
Heat the case before attempting to re-fit the bearing and use a drift of appropriate size!

Good luck, Markus

[t20racerman]

Thanks for the mag info - yes, I'd forgotten about the fiddly insulating washer. 

Perhaps a quick re-grease will do.. I hope so!