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915 (‘85) swap into 1972 911T


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Hi PFAers

I am looking to do a transmission swap on my 1972 911T. I would be grateful for any advice you can share for a problem I have. 

I have a viper green 1972 911T, fitted with a 2.7L and magnesium case 915 from a ‘74 911.  The control arms are original steel control arms for the ‘72 and the trans is fitted with course spline 4 hole flanges. 

I recently bought a rebuilt 3.2L and alloy case 915 from an ‘85 911. The trans has fine spline 6 hole flanges. 

The problem: the fine spline 6 hole flanges (from the ‘85) are thinner and  have a smaller bolt pattern than the course spline 4 hole flanges (from the ‘74).  This means the axles, CVs, and control arms can’t bolt straight up.

The question: what is the easiest way to get the alloy case ‘85 915 in the car? Do I need SC/Carerra control arms and axles? Or does someone make CV flanges that would bolt into the newer 915 to be able to use the original CV shafts (eg a fine spline, 4 hole flange that has the larger bolt pattern)?

I am hoping this is no reinventing the wheel as I’ve seen plenty of long hoods cruising around with SC/Carerra drive lines. 

Thanks in advance for any advice you can share. 




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I am no expert, but can offer the following:

I recently had my late year 915 rebuilt with a new lsd etc. and part of the build was to convert to a fine spline turbo flange. This required new axles to be mated with the flange shafts.

My guesstimate is that you may be able to purchase the appropriate axles to work, (which I may incidentally have as spare parts)

Bob Wynn did the work for me, might be worth giving them a call to ask what the way forward is.

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