901/914 transmission end cover interchangeability ?

[andyjboy]

Are the end covers (nosecones) from a 914 transmission & a magnesium-cased 901/911 transmission directly interchangeable ?

In other words, can I replace the 914 end cover with one from a 901/911 transmission ?

I want to install an uprated/close-ratio 914 transmission that I've bought in another mid-engined car where there's no room to facilitate the 914 mounting 'ears'.

[stownsen914]

If your 914 trans is a side shifter (edit - not tail shifter), you should be able to interchange them. The main difference between the 901/911 and 914 transmissions at the nose cone end, is the shift linkage. You'd just have to plug the hole where the 911 shift linkage pokes through.

I would think the interchange wouldn't work on a 914 tail shifter though.

Scott

[andyjboy]

Scott - you seem to have contradicted yourself - first line of your reply :

If your 914 trans is a tail shifter, you should be able to interchange them

& the last line:

I would think the interchange wouldn't work on a 914 tail shifter though

- my 914 transmission is a side-shifter.

[Grady Clay]

The 914 nosecones will interchange with the type 911 but not with the 901. With the tail shifters (both 914 and 914-6), all the linkage must change. The same is true when using a side-shifter on a type 911. You can use a tail-shifter nosecone in place of the side-shifter nosecone if you plug the shifter opening.

The other way around (using a 914 in a 911 application), all of the transmission can be used in a type 911 (’70-’71) except the internal shift linkage and nosecone. Using a 914 for a 901 application, needs (most – not all) the internal gears to exchange. The castings are not interchangeable without a LOT of work.

Some important differences are:
The longer type 911 TO bearing guide tube must be used with the pull-type clutch and cannot be used with the push-type..
The 901 main castings (alu & mag) do not have the provision for re-positioning the clutch arm pivot fot the pull-type clutch. The 914 castings do.
The ring gear must be reversed between 914 and 911 application.
The speedometer angle drive is different 911-to-914.
The transmission breather is positioned differently 914 to 901/911.
The 901 differential is smaller than the 911/914 differential.
Axle flanges are all mixed up – but solvable.
The 901 mag casting is different from the 911 and 914 castings.
The 914 and 914-6 mag castings are different material.
There are two different type 911 main castings.

There are more.

Best,
Grady

[andyjboy]

Thanks for the comprehensive reply (as always) Grady.

Just to clarify, I will be using the close ratio uprated 914 tarnsmission c/w its original sideshifter mechanism in a mid-engined position mated to a 911 (2.5 litre twin-plug) engine but there's no room for the 'mounting ears' of the 914 end cover.

I could simply cut these off but thought that if a magnesium 901 or 911 end cover (nosecone) was a direct swap then this would provide a neater solution.

[stownsen914]

Originally Posted by andyjboy

Scott - you seem to have contradicted yourself - first line of your reply :

If your 914 trans is a tail shifter, you should be able to interchange them

& the last line:

I would think the interchange wouldn't work on a 914 tail shifter though

- my 914 transmission is a side-shifter.

Yes, sorry. First line should say side shifter. I've edited the post.

Scott

[Matt Monson]

If it were me, I would cut the ears versus putting the 911 mag tailcone on the gearbox.

[andyjboy]

Why do you say that Matt ?

[Matt Monson]

It's the path of least resistance. If it's cut properly, it can be done pretty cleanly and doesn't have to come out like a hack job. Just be careful since mag is flammable under the right (or wrong) conditions.

You don't have to mess with the speedo angle drive issues. You don't have to mess with the shift rod sealing issues (which could be a bit messy). You just take it off, cut it and put it back on with a fresh gasket and sealant.