DDK - Die Deutschen Klassiker

I am rebuilding my alternator, do I use standard bearings or do I need C3 type extra clearance ones for high temperature?

Thanks.

Well, if nothing else I’ve learnt that the 38 people who have looked at this don’t know the answer to my question.
I wonder if anyone does?

I too am curious for the answer.

Ask Simply Bearings who supply many types for many applications?

Yes. Extract what’s in there, measure them (or even check the number engraved on the side) then ask Simply Bearings.

If it’s not worn off (I’m guessing it is) the C3 would be marked.

Thanks for the replies chaps.

I'll explain where I am with it.

Firstly, the alternator is for a 993, though I'm sure the information we need would be equally relevant to the 911.

The front bearing in it is a specific alternator bearing, so I can't go wrong with that. (It's a NSK B17-99DW8 by the way.)

The rear bearing is a 6201 2RS, which is just a standard sized bearing.

The one I removed has NTN 6201 CS20 printed on the outside and 6201LU on the rubber seals.



I have found that LU means that it is a contacting seal and that CS20 means 20 microns clearance but I have not been able to discover what the standard or C3 clearances would be.

Ideally I would just buy exactly the same NTN bearing but I have been unable to find any, hence my original question.

The old bearing has noticeable movement in it but that could just be because it is worn out.

I may just have to take it to a bearing specialist (when I can) and see what they say.

Again, Simply Bearings would be a good first call as you have all the info they will need.

911hillclimber wrote:Again, Simply Bearings would be a good first call as you have all the info they will need.

Cheers Graham, I’m awaiting their reply.

Had a reply from simply bearings, they offered an alternative bearing which was totally the wrong type, so I’m awaiting their next suggestion, though I must say I don’t know how confident I feel about what they may offer me next time...

Yes, that's dissapointing.
They sorted two bearing issues on my 1950 France crankshaft bearing issues which were quite high speed but lubrication by petrol/oil 2 stroke mix.
Fingers crossed for their next suggestion.

I just gave my alternator to my local guy who rebuilds them .. he had access to all the correct bearings. Do you have an alternator reconditioner near ?

I’ve used these people before and they were helpful, may be worth a call to ask them. https://www.burghfieldstarterandalternatorcentre.co.uk/

Not sure if you've seen this? 964 but must be close.
Well played to the original poster - it's an impressive technical write up.
http://forums.pelicanparts.com/porsche- ... build.html

inaglasshouse wrote:Not sure if you've seen this? 964 but must be close.
Well played to the original poster - it's an impressive technical write up.
http://forums.pelicanparts.com/porsche- ... build.html

Thanks, that’s a very helpful write up.
It’s basically the same except mine has a different front bearing.

I’m still waiting for simply bearings second suggestion, he said it might be a C3 bearing but needs to look into it.