Intermediate shaft advice needed

[Shorty911]

Hi all,

I need some advice please.

I am new to building up a 911 engine, but have decided to take it on while Zag builds the rest of my car. I will try and document it when it comes time to assemble, I am just pulling it all together first.

My question is, should I be asking the machine shop to bore out the case to allow for a later model intermediate shaft bearing? or rely on no bearing and the intermediate shaft mounted directly in the magnesium case?

If you think I should bore out to accept a bearing, what should I be asking the machine shop? I am using Duncan Foster engineering in Sydney to do the machine work.

Thanks in advance!

 

[Peter M]

Shorty,

It would have replaceable bearing shells like this:

http://www.pelicanparts.com/catalog/SuperCat/5880/POR_5880_ENGCAM_pg5.htm#item15

Assuming the journals on the shaft are OK - diameter in spec and not heavily scored - you just have to replace the bearing shells and check the clearances are correct by doing a "dry" assembly.

I understand there is no need to modify the stock set up as it's bulletproof.  Unlike the later 996/997.1 IMS bearings!

 

[ber911]

The early cases pre 1970 have no intermediate shaft bearings as per the first post. I assume you are having the case line bored, in which case machining it for intermediate shaft bearings would be pretty easy for them. Supply them with the bearing shells and intermediate shaft and they can machine to fit with the correct clearances.

Rob

[Peter M]

Sorry, didn't notice the SWB reference......

[Mike D'Silva]

The early cases pre 1970 have no intermediate shaft bearings as per the first post. I assume you are having the case line bored, in which case machining it for intermediate shaft bearings would be pretty easy for them. Supply them with the bearing shells and intermediate shaft and they can machine to fit with the correct clearances.

Rob

I just learned something new; I never realised the early cases didn't have the bearing!

[Shorty911]

 

The early cases pre 1970 have no intermediate shaft bearings as per the first post. I assume you are having the case line bored, in which case machining it for intermediate shaft bearings would be pretty easy for them. Supply them with the bearing shells and intermediate shaft and they can machine to fit with the correct clearances.

Rob

Thanks Rob and all,

I should have elaborated. It is a 1970 2.2 engine, going in a 68 swb car.

Rob, do you know what year model I would be asking for for the bearings?

 

[ber911]

I am not sure about the 964 and later, but the 2.2, 3.0 and 3.2 all used the same intermediate shaft bearings.

Rob

 

[Peter M]

The 996.XXX.XXX.XX.XXX part numbers I linked above would suggest they're the same all the way through to the Mezger engined 996's.

Shorty, being a 1970 engine are you sure it doesn't have replaceable shells already?? 

(Downloading the PET for that year from the Porsche Classic website might save you pondering along with double checking the engine number to confirm year)

Nevermind.....

[Shorty911]

The 996.XXX.XXX.XX.XXX part numbers I linked above would suggest they're the same all the way through to the Mezger engined 996's.

Shorty, being a 1970 engine are you sure it doesn't have replaceable shells already?? 

(Downloading the PET for that year from the Porsche Classic website might save you pondering along with double checking the engine number to confirm year)

Nevermind.....

ok, so the 1970 engine has an intermediate shaft thrust bearing, but no general bearing.

See the picture below of my intermediate shaft positioned in the case. (Don't worry I will clean everything before assembling as I had to have the case machined .25mm oversized)

so, from reading and advice on here I will ask the machine shop to bore out the case to accept the bearing shell that came in engines 71 onwards.

thanks for all your advice, I will start a thread soon as I go through the assembly process.