type 911 to 915 conversion - questions
 

Hi guys,

Swapping out my 4-speed type 911 transmission for a 5-speed 915.

do I need to swap axles, or will they bolt right up?
I'll need a new shifter, currently have the old 901 style
Any problems bolting an aluminum 915 to a mag case?
Anything else I need to look out for?

edit: motor is a 2.2T by the way. Plan is to swap in a 3.2 later, transmission being an intermediate step.

You will need to swap the axles. Tranny bolts to engine fine, but you need to replace your clutch/flywheel.

What year 915?

Your 74 should have the 108mm 4bolt/2pin axles along with the matching stub axles and output flanges on the Type 911 transmission.

If the 915 is one of the early ones through 75-ish then you can just use the same CV axles.

If you have the later 915 with the 100mm 6 bolt output flanges then you will need the 6 bolt CV axles. You will also have to get the 6 bolt stub axles and swap them into your trailing arms.

The 2.2T should have a 225mm flywheel, clutch and pressure plate on a 6 bolt crank. At a minimum you will need a 915 clutch plate and throw-out bearing. The pressure plate and flywheel will still be usable though it is wise to replace the pressure plate and potentially have your flywheel surfaced.

The shifter needs to be changed as the reverse lockout is on the wrong side. When you change the shifter you also need to change the shift rod that connects the shifter to the transmission selector shaft. The 901/911 variant is longer than the 915 version. The same shift coupler can be used for either.

You will also need a new clutch cable. The type 911 actuation does not work with the 915 clutch cable and vice versa.

The 915 has a different transmission crossmember mount. Make sure you get it with the transmission.

the 74 should have a cable actuated speedometer. If you get a later transmission it may have an electric speedometer. You will need to make sure it has the wiring harness attached to the transmission and you will have to run wires to the dashboard for the speedometer. A new speedometer is required (electric versus mechanical).

This should get you started.

A '74 should already have a 915 in it. I think we need some clarification on what is going on here.

The 915s started in 1972 model year, so something is unclear unless we're going from a four speed to a five speed box.

Sorry guys, type 911 transmission is a '71, as is the 2.2T in the car. should have been more clear, motor and transmission are not original to the car.

Then proceed as jpnovak and I advised. I didn't mention the electronic speedo part. Also let us know what year Alu 915 so we can advise on axles and stub axles.

will do, presently dealing on an '83 from a weisach 911, hoping it pans out. really appreciate the help, as I may see if I can get a few more parts of the car being parted out.

figured I'd bump this, the later ('83) 915 I was looking at never panned out, buyer decided to keep the car. Currently dealing on a '74 915 5-speed. From my reading I should be able to keep the mechanical speedo that way.

I have (or on the way) new :
Shift tower (915 style)
shift rod
axles
aluminum rear trailing arms
915 transmission
clutch

need to acquire:
915 style clutch* cable (apparently my type 911 cable is incorrect?)

haha. and of course, as soon as I think something is on the way the seller pulls the rug out from under me and it gets sold locally.

Shift Cable? - Do you mean the rod in the tunnel?

I think clutch cable. Yes, you will need a clutch cable to match whichever transmission you choose.

A '74 should have had aluminum trialing arms, so I have no idea why you're buying those...


The shift cable is probably actually a clutch cable...


JR

yes, clutch cable.

My car has early ('71 i think) steel trailing arms. almost nothing is correct for the year on that car. the drivetrain and suspension is all from an early donor car, slowly replacing it.

I have a set of axles for a 915. Needs a pair of boots due to my screw up. You can fix or I can, PM me.