901 Transmission Bearings

[ix0ifan]

Does any one have any bearing numbers for the 901 Transmission or are they all OEM only.

The price of a bearing set is very costly and if they can be bought from FAG or similar it may save some money.

[304065]

Most of the retailers (Pelican, Sierra Madre) actually sell the product as an OEM, not as "Geniune Porsche." Stoddard has the 999-053-025-00, for example, slightly higher than the other two, but I still think it's an OEM part, not one in a factory bag.

Why have you concluded you need new bearings? Are the cages shot? Do you have Dr. Evil's DVD?

[ix0ifan]

The price of bearings does vary greatly.

Pelican list the Flywheel end Pinion Bearing for $498 as an example and Stoddard show it for $165.

For all other bearings Pelican are cheaper.

I am not sure the bearings are worn out it just seems a good idea to change them as they are nearly 50 years old.

At $1100 assuming Pelican prices and $900 from Stoddard I agree it needs some more investigation.

I would expect a Four-Point Contact (Angular) bearing of an appropriate size to cost around $50-60 from a supplier such as FAG or INA but I could be wrong, I just thought it was worth trying.

The rear wheel bearing on a SWB car is about $110. The bearing on its own is about $6.00 (FAG Branded - $3.00 each for unbranded assumed Chinese) but the extended inner sleeve adds to the cost.

I bought a batch of INA Inner sleeves of the correct OD and length but with too small a bore for $8.00 each and had them cylindrically ground to the correct ID for $10.00 each

Total price $24.00 per bearing set which is a decent saving and we only had to make 5 car sets.

I had hoped we could manage something similar with the 901 bearings but maybe I am being optimistic.

It is worth the effort in trying as we have about 10 - 901/911 transmissions that we need to refurbish.

I don't have Dr. Evil's DVD.

I am trying to locate most of the tools needed but struggling a little but have made a P37 using an old clutch centre.

I guess the hardest part to find will be the diff setting tool.

[911quest]

The difference is the way the outer part of the race mounts on the bearings that go into the intermediate plate. I can usually get the bearings for a pretty good price if interested. Everytime I have seen a "cheaper" bearing used there have been issues.

[ix0ifan]

Tony,

I agree with your basic comments but I am not trying to use 'cheap' bearings. I want to use quality branded parts to the correct standard in terms of temperture and clearance grades I just want to avoid mark ups on mark ups and spending $1000 per box.

An SKF N2207 which is a Cylindrical Roller Bearing with flanged inner tracks is about $45-50 depending on where it is purchased.

This is virtually identical to the Genuine Porsche Bearing for $498 with the exception of the circlip groove which is not present in the standard component.

To grind a circlip groove to the correct dimensions has a cost of about $5.00 per bearing.

I will check all of the dimensions and flange sizes before I decide but as I am sure you realise the bearings originally used would have been either catalogue parts or as in the case of the circlip grooves a reatively simple modification.

I have a very good local company that have specialised in modifying bearings for several years and I am confident that all will be well.

If we can't match 100% in terms of spec/fit than we won't make any compromises.

[Olivier]

i'm sure you already know that, but, be very carefull when you have a standard bearing ground or machined... Bearing steel is very capricious. Hard and brittle, very heat sensitive.. 100Cr6 begins to loose his quench short after 200°C. in the same way, sharp edges in the bottom of a grrove is not a very good idea...

O.

[ix0ifan]

Olivier,

Thanks, I appreciate the comments and I am aware of the issues.

The company that will modify the outer race do this type of work all the time and are very experienced.

We have two or three old cages as samples so we can grind - lots of coolant- and then check the groove profile with a Shadowgraph.

I have spent a number of years working with high speed bearings - mostly angular contact and am aware of most of the pitfalls.

I would have thought that the cage was more likely to be a 1C-1.5Cr or an AISI 52100 but these are very similar to 100Cr6.

I agree that the tempering temperature of these alloys is normally 150/160degC and that they will soften after prolonged use at 200degC, which tends to be the limiting service temperature, but short term exposure to temperatures as high as 225degC will cause little change in property.

[Olivier]

My apologize!

You seem much more skilled than me in the bearing land!

My experience is that there is very few company which will do this work the proper way. Your seem very pro! I wish I could find the same here in France, but this is a nightmare.

I wanted to have custom made needle bearing inner race, and up today, I havn't found anybody willing to do this seriously for a reasonable price...

Maybe you could help me? Right material, rigth treatment, and right dimensions...

By the way, if you ever need to have custom bearings made, let me know, I hava a good address, but they are not cheap and there is a minimum order. I havn't worked with them, but I believe they know their job...

Regards

Olivier.