Marking the ring-differential assembly

[Jim Hunter]

Hello,

Today I was spoke with a retired "Senior" Porsche mechanic.
He told me that when we have to remove the ring-differential assembly from a transmission we have to mark it's position regarding the pinion
If we don't do that we have excessive wear and noise

Forget my ignorance but I wonder if this make any sense as the r&p are always moved so they not retain in one position.

What do you guys think about it ?

[Peter Zimmermann]

Originally Posted by Jim Hunter

He told me that when we have to remove the ring-differential assembly from a transmission we have to mark it's position regarding the pinion
If we don't do that we have excessive wear and noise

No marking required. A note should be made regarding the thickness of the shims required that set pinion head depth, and those shims, or new replacements of the same thickness, must be re-installed at assembly. Of course, there are a number of measurements, when the ring & pinion and/or diff carrier bearings are replaced, that require set-up, such as bearing pre-load, backlash, pinion depth, etc., but for R&I purposes that is usually not necessary. There are times when pre-load is not satisfactory, but that can be reset without affecting other operations. That said, if the transmission's history is an unknown it is better to check/verify than assume.

[Flieger]

Any "hunting tooth" gear ratios will ensure that the teeth mesh up to different partners each revolution for many revolutions until a complete circumferance of the ring has been made. The engineers use prime number ratios and such to even out wear. This is seen in the intermediate shaft-camshaft-crankshaft sprokets in the 917 and also the 911, I think.

[Matt Monson]

Jim,
What transmission are we talking about here? Or was it a generalized statement he was making?

[Jim Hunter]

Thanks for the info Pete.
Flieger :I didn't know that too !
Matt :1973 915 !

[Peter Zimmermann]

Jim: In addition, unusual and premature wear are controlled by following factory setup literature for operations such as backlash, which is always measured in more than one ring gear position, and those measurements must fall into a +/- range to be acceptable.