How to Re-Build a Porsche 915 Transmission Pinion Shaft.

Pinion Shaft from a Porsche 915 Transmission

Last lesson, We took apart the input shaft, replaced the parts, and reassembled the shaft. Now, we do the same thing to the Pinion shaft.

Disassembling the Pinion Shaft

We use the press to press off the bearings holding the gears to the pinion shaft. Support the bearing and push the shaft through from the top. With the attached gear at the bottom. Do not let the shaft fall thru.

Lay out the pieces on the bench as you take them off in order. Clean the parts, keeping them in order. Just take a few at a time. We are going to replave the bearings and synchros but will inspect the dog-teeth for wear when they are all cleaned up.

Taking apart a gear assembly

Just like in the input shaft, we will take apart the gear assembly to replace the synchro band. Starting with a set of circlip pliers, we work off the big clip holding everything in place.

Take out the energizer bands and inspect them for wear. Take out the synchro band and take a good look at the wear on the dog teeth. We pre-ordered parts and were held up a little bit when we found more wear than we expected on the gears.

Notice that first gear dog teeth only go in one direction, as you do not up-shift to this gear. See the differences between first and second gear. The slider should be assessed as well and if you change the dog teeth you should change the slider.

the gear showing the splines for dog teeth on the pinion shaft.
We found adhesive under the dog teeth on this gear. It is a press fit and no loctite is necessary. This adds time to the build from extra cleaning.

The tool for removing and replacing the dog teeth is the same process as third gear but a different size. Take care when resetting that you line up the splines perfectly, they are very shallow splines! Finish putting the gear back together, finishing with the big snap ring. Check your work, the synchro should move, even if they are stiff. But you should still have the rattle from the energizer parts.

Reassembling the Pinion Shaft

After rebuilding the gear sets and double cleaning all parts, it is time to reassemble the pinion shaft. With the fixed gear on this shaft, you can just stand the pinion shaft up for reassembly. To put on the bearings you can choose two ways to get them back on. You can heat your bearings or use a press to press them on. We choose the press for the first bearing. On the second bearing, we press the first part and heat the second part. Put on the intermediate plate.

The pinion shaft from a Porsche 915 manual transmission

Take a look at your gears as you install them. The wear on the parts will show you which way they install. The first and second slider will also tell you which way it goes on. Asymmetrical on the asymmetrical side and the same for the symmetrical teeth.

We press on the last bearing, and the pinion shaft is looking good. Remember, as we changed out all the bearing, you will need to rplace the bearing races into the transmission cases.

porsche 915 transmission open differential

Up next in Your Porsche 915 Transmission Rebuild

With the gear sets all finished, we can turn our attention to the Differential. There are a lot of measurements to make on the differential. You will need lots of specialized tools and break out the calculator. Join us for the differential build.


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