915 Bearing plate Installation?

[jamesjedi]

I have searched and not found an answer.

I am looking at the Guard Transmission bearing plate for my mag 915, but cant see what is involved in installing it.

Anyone done it? My box is in the garage floor.

Thanks!

[jamesjedi]

Hopefully someone has done this? Thanks.

[Josh D]

Originally Posted by jamesjedi

Hopefully someone has done this? Thanks.

Are you talking about the side differential carrier bearing plate, or the 4 point bearing retainer plate? What bearing plate are you talking about? be more specific.

[The cap'n]

If you're looking at the 4 point bearing clamping plate, you'll have to pretty much disassemble the whole transaxle to do the job. Special tools are involved, and it would be wise to check the pinion depth while you're doing the job. If you're speaking of the side cover, you'll have to recalculate and possibly adjust the differential bearing pre-load.

The Cap'n

[jamesjedi]

Thanks for the replies, sounds like more than pulling the cover off. Here is a picture of it;

[gregwils]

Comments Grady Clay shared regarding an intermediate plate, which is what you showed in the picture. Not a step by step, but confirmation that you need to measure backlash and preload in advance.

Billet gearbox intermediate plate

[jamesjedi]

Thanks for the replies. This is a little more involved than I thought. I am glad I asked.

I know someone that may be able to help me. Thanks again.

[Josh D]

Originally Posted by gregwils

Comments Grady Clay shared regarding an intermediate plate, which is what you showed in the picture. Not a step by step, but confirmation that you need to measure backlash and preload in advance.

Billet gearbox intermediate plate

What he is showing is the 4 point bearing retainer plate, not an intermediate plate for a 901.

The original pinion depth shims is all that is needed. However, dissassembly of the input and output shafts is required.

[jamesjedi]

Thanks for the clarification. My box is a magnesium 915 from a 3.0 RS.

[Peter Zimmermann]

This might help to clarify a few things...

Welcome to Red Line Porsche Wiki - Porsche Wiki

Scroll the left side of page, click on "915" under "Page tags," and the site will take you to my 9-part 915 repair Tutorial.

[john walker's workshop]

you basically remove the gears from the shafts, slide the plate over both 4 point ball bearings and torque up the nuts, then reinstall the gears and other parts alternately, size-wise. check the shift fork adjustment with the proper jig. of course, any worn parts should be addressed at the time. keep the original stack of pinion depth shims under the plate and measure the thickness and replace any shims that have been beat up under the bearing lip. hopefully, the roller bearing races are not loose in the diff housing. mag cases tend to be ok more than the aluminum ones.

[Josh D]

Originally Posted by john walker's workshop

you basically remove the gears from the shafts, slide the plate over both 4 point ball bearings and torque up the nuts, then reinstall the gears and other parts alternately, size-wise.

I'm not seeing how to do it this way, as the first gear is part of the input shaft? How would you install 4th, 3rd, and 2nd over 1st?

The way I did it was assembled the output shaft with the retainer in place on the output 4 point bearing, then assembled the input shaft up to the 4 point bearing. When I got to that point, I put the input shaft through the retainer, tied the input shaft to the output shaft with zip ties, slid on the input shaft 4 point bearing, then torqued the input shaft nut. Then installed on the case with the shims as an assembly.

I'm having a hard time invisioning it done any other way.

[john walker's workshop]

ya got me there. been a while since i did one. so you would assemble the mainshaft, gearwise, set the plate on, and press on the bearings. then slide in the pinion shaft and finish stacking the assembly. then install the works into the diff housing.

[Jon B]

Originally Posted by john walker's workshop

so you would assemble the mainshaft, gearwise, set the plate on, and press on the bearings...

...then install, torque and peen the M30 collar nut, while holding the mainshaft.
Porsche increased this torque spec in later 915's to 230 Nm, which is 170 lbs-ft.

[Walt Fricke]

What you will find using this one piece bearing retainer plate is an intimation of why Porsche started out with two. You have to put on more stuff ahead of time than with the split retainers, and juggle a much heavier assembly into place before finally putting the nuts on the studs and tightening everything down. At least that is what I remember from first having reassembled with the two piece plate, and some years later doing it with the one.

If Peter's tutorial addresses using this one piece plate, just follow his instructions.