So What's the Deal?

[gsjohnson]

While attending the 356 Concours in Dana Point last Sunday I took notice of the early 911 engine mounts, more specifically the orientation of the large cupped washers. I found examples with the cupped washers facing down as well as them being oriented in the up position. I know my SWB cupped washers were in the up position (Cup facing away from the mount) when I pulled the motor and trans. This was also the case with the same trans mount cupped washers as well.

After doing some research, the general consensus was that they should be facing in the up position, but others stated that there was a TSB (which I couldn't locate) from Porsche stating that the washer orientation should be flipped around so the cup side is facing towards the bushing. I also found where others stated that the later cars came with the washers oriented in the alleged TSB fashion. This I did confirm at the 356 Concours, although the late washers appeared to be different in nature with less of a cup. I pondered whether there was confusion between the supposed TSB and the late cars...

I'm getting ready to install my engine and trans tomorrow and would like to know...
Does anyone know the real deal is with this issue? Or does it even matter?

[Mr9146]

While attending the 356 Concours in Dana Point last Sunday I took notice of the early 911 engine mounts, more specifically the orientation of the large cupped washers. I found examples with the cupped washers facing down as well as them being oriented in the up position. I know my SWB cupped washers were in the up position (Cup facing away from the mount) when I pulled the motor and trans. This was also the case with the same trans mount cupped washers as well.

After doing some research, the general consensus was that they should be facing in the up position, but others stated that there was a TSB (which I couldn't locate) from Porsche stating that the washer orientation should be flipped around so the cup side is facing towards the bushing. I also found where others stated that the later cars came with the washers oriented in the alleged TSB fashion. This I did confirm at the 356 Concours, although the late washers appeared to be different in nature with less of a cup. I pondered whether there was confusion between the supposed TSB and the late cars...

I'm getting ready to install my engine and trans tomorrow and would like to know...
Does anyone know the real deal is with this issue? Or does it even matter?

They are correct either way, and I've spent a while discussing the cup up or cup down scenario with Scott and Dan from Scott's Independent.

One way puts more pressure on the rubber than the other. I think cup down is more pressure and cup up is less pressure, but I don't really know for sure. I usually do them cup up in my shop.

On a related note, I wasn't going to say anything, but since you're splitting hairs on cupped washers I'll say something - I noticed in the photo of your engine in the other thread that you have the crossbar bolts facing the wrong direction. The nuts go on the outside and the bolts go on the pulley side.

[gsjohnson]

Yes I already fixed that, but thanks. I'm always open to constructive criticism. Afterall, this was my first 911 motor and I have had to correct several items as I have gone along

I agree with your view on the cupped washers facing up and I think that I will assemble them as they were when I took it apart.

[66S]

Convex side towards rubber is the way I've always done it. The other way would defeat the purpose of the rubber center Id think.

[Silverbullit]

Oddly enough, I was at EASY a while back getting, amongst many things, those large washers. I noticed about 90% had a lockwasher 'witness mark' suggesting they were mounted with the cup away from the mount, and I'll mount mine as such (someday). Brian

[kentf14]

So, I don't know anything about the official TSB, but my mechanic told me to orient the cups facing down to firm up the mounts. FWIW he's an old IMSA racer and said that this is the "sport" configuration.

I'd love to hear what Scott has to say on the subject Marco.

[Mr9146]

So, I don't know anything about the official TSB, but my mechanic told me to orient the cups facing down to firm up the mounts. FWIW he's an old IMSA racer and said that this is the "sport" configuration.

I'd love to hear what Scott has to say on the subject Marco.

It's was about a year or two ago when we had our chat, but I think the decision was either way is technically correct.

I was always taught to put cup side to the rubber when I wanted to firm up the mounts (in my own car, for example, which is what prompted my discussion with Scott), but for 90% of applications I run them cup out. I'm not really sure it made a huge difference.

The razors we use are splitting finer hairs, boys.