Type 741 Transmission Rear Pinion Bearing

[David Vellutini]

I am in the middle of rebuilding my 741 transmission again. I purchased all my bearings from a large, well known supplier of 356 parts. The newly sourced rear pinion bearing (Part # 915-302-399-06) is significantly different from the bearing which is coming out of the transmission. The newly sourced bearing is on the left, the old bearing (Timken made in Germany) is on the right in all 4 pictures.









The obvious differences are as follows:
- Right bearing (old) has 1 more roller
- Rollers in right bearing (old) are larger in diameter and longer

The part numbers stamped on the bearings are slightly different

I am a bit puzzled as to the differences between the two bearings. My gut feel is that the Timken bearing is more robust and will handle more load. I have sourced another Timken bearing and intend to put it in the transmission.

Any opinions / experience regarding these two bearings?

Dave

[Jon Bunin]

The bearing on the left is made in Asia.
Did your supplier imply it was genuine Porsche or OEM, and charge you accordingly?

[David Vellutini]

The supplier does not mention the origins of the bearing nor imply that it is OEM. The bearing on the suppliers website is described as 'Original Pinion Shaft Bearing'.

The picture on the supplier's website shows 13 rollers. The bearing supplied to me has only 12 rollers.

Please note that the intention of my post is not to disparage anyone. My note is more of an inquiry into which bearing is the best choice for my transmission and why there is a difference in construction in the bearings.

[Jacques Lefriant]

actually there is a reason the VP bearing is riveted together the peened one will eventually get loose. that is why it is preferable to place the ring near the first gear washer. Timken may be the supplier to Porsche at this time but both FAG and SKF supplied them in the past. The designation N2206ENMC3 no matter who supplies them meet the same load/ rpm specifications. Both bearings will give excellent service. If you have an old original bearing it is probably riveted together yes theoretically the greater amount of rollers increase the load capacity but if you have a cage failure it is catastrophic. Fag no longer makes many roller bearings in Germany they have a plant in India.
j

[Al Zim]

The 915 bearing was used in the 915 transmission from the start of 1972 production through 1986 production. al zim

[David Vellutini]

Thanks for all your responses.

Both bearings were/are sold as 915-302-399-06. As previously mentioned, there are notable differences in the number and size of rollers, the thickness of the races, and the construction of the cages.

My question is twofold: are the construction/design differences of concern; and, if so, which bearing style is the best choice.

I believe that Jacques is suggesting that both bearings will perform equally well, regardless of the design/construction differences.

Dave