Long time periodic lurker, first time poster.

Read a number of threads here and other forums. I *think* I understand this topic just enough to be dangerous to my checkbook.

That said, I think In understand that the 915 can be used in the 914 as a direct bolt-on to the chassis and will accommodate all of the 3.0, 3.2 and 3.6 air cooled engine variations.

The ideal final drive ratio appears to be the 8.3:1

However, one still needs to do some work to complete this swap. A shift adapter kit, and a speedo adapter kit are needed to fully complete the mod. Kits are available from bugat 5 speed and Auto Atlanta (maybe other sources as well...).

Also needs a special flywheel (patrick motorsports can hook you up with the right on) to provide the correct input needed for your engine management if using Motronic or other aftermarket standalone engine management system.

How does this sound to the seasoned veterans here, missing something?

What about axle shafts/CV joints to line the drive train tot he wheels?

Thanks in advance for your constructive comments.

The 915 doesn’t bolt onto the chassis unless you change the tail cone to a Wevo -$2,200 or Martin Bott (916 style) $3,200. You also need to flip the differential, fabricate a shift rod, use a 915 style shifter and the proper clutch. Also modify the trans for the electronic speedo if it’s a later trans. The trans will need to be notched for a 3.2 or 3.6 sensor.

Patrick sells the KEP (kennedy engineering products) conversion clutch and ring gear. You can also buy it direct from Kennedy for less. You also need clutch and throttle cables.

You will need a conversion axle to connect the 915 trans stubs to the 911 hubs and stub axles. Sway away sells it. The best thread ever on 5 lug for big engines is the one Eric Shea wrote. http://www.914world.com/bbs2/index.php?showtopic=91963

Thanks for adding the detail.

Especially the info on the axles.

I am currently running a 1986 915 trans with Martin botts kit with my 3.2 motor. The 1984-1986 915 trans is already notched for the 3.2 sensors. My clutch and flywheel are stock 3.2 parts. You only need an adapter flywheel for the 3.6 engines since they were not designed for the 915 trans. PMS sells the adapter flywheel. You have to flip the differential to run a 915 in a 914. This also flips the electric speedo pickup to the other side. Wevo sells a side billet plate with a pocket for the electronic speedo sensor. I am also running 3.2 gauges including the electronic speedo and Tach. For the shifter I am running a 915 rennshift and home made shift rod. I am running swayaway axles with stock 1986 915 108mm cv’s on the trans side and 1973 911 108mm cv’’s. Stubs disks,etc. on the outside.
I am also running Boxster brakes front and rear with a rear 911 parking brakes.

I am very happy with the setup. It’s nice having a trans and gears that were designed for my motor.

Did you just go with the 19mm Master Cylinder to use the Boxster calipers?

Yes!! The 19mm master cylinder works fine
I’m using Rich Johnson adapters.