flipping the R & P, How To Options

[statesblue]

Is there anyone out there who knows how to flip the R & P ? Looking for some detail as to how its done. Is there a tech article on the subject ? Any help would be appreciated.

[pcar916]

Have you considered flipping the 914 transmission and converting to a cable shifter? Simpler in my book! The 901, 914, and early mag-case 915 transmissions use the same carrier bearings, shims and LSD/TBD carriers. But as the Captain has said, the R&P's in the 901 (and 915) are already like you want them!

Now, to answer your question...

Which transmission are you talking about and what application (i.e. hp / torque requirements)?

Note: Just flipping the diff won't change the pinion depth. You only need the pinion depth tool (the previously mentioned expensive tool) if you are changing gears with slightly different thicknesses, or installing a new R&P. FYI you can do this without that tool but it takes longer, and you need more trial-and-error shims.

All of this assumes you are familiar and competent with all of the tools to do this. Not just dial calipers, but dial indicators, torque wrenches (both ft-lbs and in-lbs) and the like. It's also good to have at hand lots of pry bars/pullers to get bearings off if you need to. The carrier bearings don't give you much room to work with on the ring side. If you have to replace your bearings, care must be taken not to goober-up the shims and spacers. They can be hard to find.

The side cover on the 914 transmission or the case on the 915 may need relief for the ring bolt heads and the vent tube has to be relocated. I've heard some that grind the bolt heads, but that's not a process I like. It screws up their heat-treatment.

Theoretically, assuming the preload is good already, and if the bearings are good and can be reused (i.e. not removed) then the shims will maintain the offset in the other direction if the carrier is simply flipped. I haven't checked that because I've always started from scratch with new bearings.

I'd not do it without completing the entire procedure. That means checking the preload, backlash, and tooth contact pattern.

The pinion depth would stay the same and the preload would be close, but the carrier shims and intermediate-plate gaskets might need some tweakin' to get the proper contact pattern.

If you install new bearings on the 914 carrier...
The 914 factory manual has the instructions for differential setup but you would have to transpose the ring offset. That said...

The 911 factory manual has the instructions for the 901 and the ring configuration you want, but the preload values are different and you'll want to use those from the 914 manual.

Note: If you flip the transmission... whichever model, then external cooling is advised. They don't have the big oil galleries on the "top" of the cases that exist on the "bottom".

Good luck.