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 !!

[Cairo94507]

Welcome. Contact Patrick Motorsports in Phoenix, AZ. They wrote the book on this modification. (IMG:style_emoticons/default/beerchug.gif)

[mepstein]

Welcome. Contact Patrick Motorsports in Phoenix, AZ. They wrote the book on this modification. (IMG:style_emoticons/default/beerchug.gif)

You also have to be ready to drop $10-15K (or 15-20K for PMS). I'm not saying it's not worth it but it's a bit of a commitment.

[Steve]

(IMG:style_emoticons/default/agree.gif)
I’m running the setup in my 914. Works great and love it. You’re also buying a piece of 916 history. The car that never was and personally mine is better without the 916 price tag.
Check out this link for more information.
http://www.914world.com/bbs2/index.php?showtopic=102988

[stownsen914]

If you'd like to do a 915 in a 914, you might keep your eyes open for an already converted box to save a few $$. I saw one recently on the Pelican forum.

To answer your q, yes you need to flip the R&P or you'll have 5 reverse gears in a 914. The shift mechanism is the other challenge area - there are a few solutions out there, some NLA.

[Steve]

PMS sells all the conversion parts and shift linkage.

[Cairo94507]

I just re-read the entire linked thread....really want a 915 with this complete conversion process. Very jealous Steve @Steve . (IMG:style_emoticons/default/beerchug.gif)

[sixnotfour]

Ring and Pinion Ratios are Motor specific.. early versus late.. 911 engine and or choice..

[troth]

PMB was just advertising a conversion package on Facebook earlier this week. Not sure if it’s the same as Patrick’s kit.

[brant]

Short answer about the 915

In the 911 that it was designed for….

The tranny is “flipped”. In orientation
With the motor in back of the engine compared to a 914

So flipping the ring and pinion for a mid engine application
Gives you 5 forward gears

Instead of 5 reverse gears

[echocanyons]

Eric and the PMB team just finished the 916 conversion on my car.
I am looking forward to picking this up soon.

[Cairo94507]

I am so very jealous. PM sent. (IMG:style_emoticons/default/beerchug.gif)

[rgalla9146]

Did the conversion myself except for R&P set up.
Used the Martin Bott kit from Germany.
Early mag 915 with ZF LSD and mechanical speedo drive.
Not a picnic.
Driven it about a hundred miles before putting the car aside for a while, so not enough
to have a strong opinion.
Nice to have a conventional H shift pattern
Felt I needed it behind a 3.0 or a 3.2 short stroke.

[stownsen914]

The thing I don't love about 915 conversions for the 914 is that the 915 shifter adds complexity to an already complex 914 shift linkage. The 915 shift reverses rotation of the shift rod not unlike the early tail shifter linkage.

[Steve]

(IMG:style_emoticons/default/confused24.gif)
No different than a 911….

[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

[mepstein]

Martin Bott has the 916 conversion parts for sale.

https://www.bugat5speed.de/en/beetle-co/tra...mission-901-914

[T.Rick6]

CCSmith58 Question for ya, what size engine / HP are you running ? Depending on HP you may be better off with a beefed up 901 and save you tons of $$$.

If you still want a 915 another contact would be Joe Cogbill @ CogsCogs.com; he's just finished another flipped 915 with the Martin Bott kit.

In preparation for my factory 6 build I purchased a rebuilt '71 914-6 901 ($3,800), had it converted to side shift ($250), replaced the intermediate plate, bearing retainer and bearing ($1200), 108mm output flanges & hubs ($700) for a mild twin plug 3.0 ..

The deal with the 3.0 engine fell thru; I ended up buying a package deal out of a failed 914-6 race program; 330 hp 3.4 with a flipped 915 for less than a bare bones 3.0. Not trying to sell you anything but my 901 is available if interested.

There are downsides to a flipped 915, weight and shift linkage are 2 most common issues.

Good luck, add pics when you can..

Todd (IMG:style_emoticons/default/beerchug.gif)

[Cairo94507]

I would spend time researching Joe Cogbill before making a decision. I have no personal experience with this shop, but in looking and considering a 915 his name came up so I looked around. (IMG:style_emoticons/default/beerchug.gif)

[mepstein]

I would spend time researching Joe Cogbill before making a decision. I have no personal experience with this shop, but in looking and considering a 915 his name came up so I looked around. (IMG:style_emoticons/default/beerchug.gif)

I agree. Do your homework.