915 Trans Swap in 1971 T

[Rexs-911T]

I am planning on pulling my 2.4 and 901 trans out of my 1971 911T and replacing it with a 2.7 and 915 trans.

Other than having to re-work the trans tunnel to accommodate the slightly larger diameter of the 915 trans in place of the 901 is there any other issue that I might encounter with the clutch cable and clutch operation using the original pedal to clutch linkage setup to this 915 trans?

[Eagledriver]

I don't know for sure, but I think the original 71 clutch was a push direction and the 915 clutch is a pull direction. Might need to re-work the cable routing or use a later cable.

-Andy

[safe]

You need a 915 shifter and shift linkage.
You also need to sort out the drive shafts, I think.
If its a 76 or newer transmission you need an electronic speedo and wiring.

[Rexs-911T]

Thanks for the info, this 915 is a 1972 with mechanical speed "O". Didn't realize the cable and the push pull setup. Something I need to find more detail on I guess. Anyone out there know where I can acquire such detail on the cable swap for this conversion??

Thanks

[MdR]

Originally Posted by Rexs-911T

Anyone out there know where I can acquire such detail on the cable swap for this conversion??

I've not long since fitted an '83 915 & 3.0SC into my '69T
Clutch pedal is as original, clutch cable is now as spec'd for an '83 car.
My 915 clutch release arm is the later type with the helper spring.
You need a cable that corresponds to the age of your gearbox (assuming it has the original release arm)
PET lists 911 423 401 00 for the 73MY onward which to my mind would be your gearbox.
I had to change my output shafts to match the CVs on the axles.
I'll reiterate you need both the 915 shifter and the 915 shift rod.

[safe]

Originally Posted by MdR

I've not long since fitted an '83 915 & 3.0SC into my '69T

I had to change my output shafts to match the CVs on the axles.

I'm putting a 79 in my 69T.
Did you find pre-76 output shafts for your 915 or did you make a new flange on the existing shafts?

[MdR]

Originally Posted by safe

I'm putting a 79 in my 69T.
Did you find pre-76 output shafts for your 915 or did you make a new flange on the existing shafts?

I used locally sourced fine spline 930 Turbo output shafts that match the spline on my '83 SC 915 diff and the 108mm PCD of the '69 CV bolts
The 930 output shafts have 6 x M10 bolts fixing for the CVs
The '69 901 CVs have 4 x M10 bolts & 2 x dowels
I drilled through the '69 CV dowel holes to accept M10 bolts, sourced two half moon plates and new Schnorr (sp?) washers.
I also drilled out the CV tin boot cover.

Kevin Roush @ GAS Motorsport & Grady Clay were both really helpful in passing on this information to me back in May

[safe]

Originally Posted by MdR

I used locally sourced fine spline 930 Turbo output shafts that match the spline on my '83 SC 915 diff and the 108mm PCD of the '69 CV bolts
The 930 output shafts have 6 x M10 bolts fixing for the CVs
The '69 901 CVs have 4 x M10 bolts & 2 x dowels
I drilled through the '69 CV dowel holes to accept M10 bolts, sourced two half moon plates and new Schnorr (sp?) washers.
I also drilled out the CV tin boot cover.

Kevin Roush @ GAS Motorsport & Grady Clay were both really helpful in passing on this information to me back in May

Ok, thanks. I have been looking replacement shafts but they are rare.

When I meassured the transmisions width flange-to-flange I found that the original 901 was 1 cm wider than the 915. But you used the original axles, the 5mm probably doesn't matter?

[MdR]

Originally Posted by safe

Ok, thanks. I have been looking replacement shafts but they are rare.
When I meassured the transmisions width flange-to-flange I found that the original 901 was 1 cm wider than the 915. But you used the original axles, the 5mm probably doesn't matter?

Originally Posted by Grady Clay, via PM

There are some important but little known considerations.
The centerline of the differential on a 915, 930 and G50 is 10 mm closer to the engine than that of a 901, 911 and 914 transmissions.
The flange-to-flange dimension is also different.
In general, the CV joints can absorb these differences but you must be careful.

Empirically speaking I've had no problems so far.
The 915 conversion into an Early car seems common enough that I'm happy mine works OK.

[safe]

Interesting, haven't thought about the centerline!

Thanks!