915 transaxle question / info, a silly question... Options

[CCSmith58]

Hello 914world… Just renewed my Membership !! Now looking to get my moneys worth...

I’m having a ’75 914 built into a 914-6.
Maybe 10 or 20 years ago I might have tried to do (some of) it myself.
Now I’m more a “pay the money, turn the key” guy.
Here’s a “silly” question. Likely the first of many….
How does a 915 Transaxle work when converted to a mid engine application ??
Not looking for a “how to” just an overview for personal info.
I’ve searched for articles, webpages and / or videos and don't find much.
I find acknowledgements of the conversion but no detailed or even general description.
I see the term “flipped ring and pinion”.
Does the whole gear system run backwards ??
Does just the differential run backwards ??
How would a LSD work in a converted 915 ??
Are the available 916 Kits good ??
Etc...
Any info or links to info would be appreciated !!

[Dave_Darling]

Some basics, here--

The "ring and pinion" are the parts that change the rotation axis of the transmission's output to be the same axis as the wheels spin. (It does more than that, but that's the part that matters here.)

This isn't from a 915 or any Porsche transmission, but it does show a ring and pinion assembly:

(IMG:http://www.914world.com/bbs2/uploads_offsite/www.crawlpedia.com-121-1670320783.1.jpg)

If you move the ring gear (the big one whose axis is side-to-side) onto the other side of the pinion gear (the small one whose axis is fore-and-aft) you change which direction the ring gear spins when the pinion gear spins a given direction.

Since a 911 has the transmission in front of the engine, it spins the ring gear (and therefore the wheels) so the bottom of the wheel goes toward the bellhousing when the transmission is in a forward gear. The 914 has the transmission behind the engine, so spinning the bottom of the wheels toward the bellhousing would be spinning it in reverse. So you have to move the ring gear to the other side of the pinion gear in order for the wheels to turn the correct direction when a forward gear is selected.

Other issues with the 915 transmission include the mounting setup, the shift linkage, and the clutch linkage. All of those need to be different when the transmission is installed in a 914. The transmission linkage usually is rather more complicated than a standard 914 linkage, unless you can find the now-rare parts to convert the 915 box to use a 916-style linkage.

--DD